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1

What are the first branches of the ascending aorta, proximal to the arch?

Coronary Arteries

2

What are the three major branches off the aortic arch (in order)?

Innominate /Brachiocephalic - Divides into the right common carotid and subclavian arteries.

Left Common Carotid (LCCA)

Left Subclavian Artery

3

Where does the vertebral artery branch from?

The subclavian artery

4

What is the arterial anatomy of the upper extremity (in order) starting from the top?

Subclavian artery ----> Axillary artery ----> Brachial artery ----> Radial and Ulnar arteries ----> Superficial and Deep palmar arches ----> Digital arteries

5

Subclavian Artery

Runs laterally to outer border of 1st rib becoming axillary artery.

Some branches include: Vertebral, thyrocervical, costocervical.

6

Axillary Artery

After giving off several branches, becomes the Brachial artery.

7

Brachial Artery

Branches into the radial and ulnar arteries at the inner aspect of the elbow.

8

What is the antecubital fossa?

A triangular cavity at the inner aspect of the elbow that contains a tendon of biceps, the median nerve, and the brachial artery which starts branching into the radial and ulnar arteries.

9

Radial Artery

Travels down lateral side of forearm into hand, branching to form:

Superficial Palmar (Volar) arch

Terminates in the deep palmar arch by joining deep branch of ulnar artery.

10

Ulnar Artery

Travels down medial side of forearm into hand, branching to form:

Deep palmar (volar) branch

Terminates in superficial palmar arch

Predominate source of blood flow to the hand

11

The superficial palmar arch includes:

Distal portion of the ulnar artery

Branch of the radial artery

12

The Deep palmar arch includes:

Deep palmar branch of the ulnar artery

Distal portion of the radial artery

13

Where do the digital arteries arise from?

Digital arteries arise from the palmar arches and extend into the fingers dividing into lateral and medial branches.

14

What are the visceral branches of the abdominal aorta (in order from proximal to distal)?

Celiac Artery
Superior Mesenteric Artery
Renal Arteries
Inferior Mesenteric Artery

15

Celiac Artery

Also termed "CA"

Supplies stomach, liver, pancreas, duodenum, spleen.

Branches into left gastric, splenic, and common hepatic arteries.

16

Superior Mesenteric Artery

Also termed "SMA"

Supplies the small intestine, cecum, parts of colon.

Located about 1 cm behind celiac artery.

Can be a common trunk of the celiac artery and SMA.

17

Renal Arteries

Supply blood to the kidneys, suprarenal glands, ureters.

Multiple renal arteries not uncommon bilaterally.

In transverse, a landmark for locating the left renal artery is the left renal vein which crosses the aorta interiorly. The artery is just posterior.

18

Inferior Mesenteric Artery

Also termed (IMA)

Supplies transverse, descending colon, and part of the rectum.

Arises from abdominal aorta about 3-4 cm above the bifurcation.

Can act as a collateral connection.

19

What are the terminal branches of the abdominal aorta?

Both common iliac arteries (CIA) are the most distal branches that carry blood to the pelvis, abdominal wall and lower limbs. The CIA divides into:

Internal iliac artery (hypogastric)

External iliac artery: travels along medial side of Psoas major muscle. Passing underneath inguinal ligament, becomes the CFA.

20

What is the arterial anatomy of the lower extremity (in order from top to bottom )?

Common Femoral ----> Superficial femoral artery and Deep femoral artery ----> Popliteal artery ----> Anterior Tibial arteries, Posterior Tibial arteries, and the Peroneal artery.

21

Superficial Femoral Artery

SFA

Runs the length of the thigh, passing through an opening in the tendon of the adductor hiatus (adductor canal, Hunter's canal).

Enters the popliteal fossa behind the knee.

22

Deep Femoral Artery

Also called the Profunda Femoris artery

A large branch; arises about 5 cm from the inguinal ligament on the lateral side.

Can act as a collateral connection.

23

Popliteal Artery

Adductor hiatus: termination of the SFA and beginning of popliteal artery.

Gives off a number of genicular branches.

At interval between tibia and fibula, divides into anterior and posterior arteries.

24

What branches make up the popliteal trifurcation?

Anterior tibial, posterior tibial, and peroneal arteries.

25

Anterior Tibial Artery

ATA

First branch off distal popliteal artery.

At its lower end, becomes dorsalis pedis artery (DPA) and is directed across dorsum of the foot towards base of great toe.

26

What is a major branch of the DPA?

Deep plantar artery; penetrating the sole of the foot, it unites with lateral plantar artery to complete plantar arch.

27

Posterior Tibial Artery

PTA

Extends obliquely down posterior/medial side of leg.

Major Branches: Lateral and medial plantar arteries, branching below medial malleolus to supply sole of foot.

28

What is the tibioperoneal trunk?

Short segment between ATA branch and branches of PTA and peroneal arteries.

29

Peroneal Artery

Passes toward fibula, travelling down medial side of that bone to supply structures of the lateral side of leg/foot.

30

The ___________ and ___________ distribute blood to the digits in the foot.

Plantar and Dorsal metatarsals.

31

The ___________ consists of the __________ (branch of DPA and the ____________ (branch of PTA)

Plantar arch; Deep Plantar Artery; Lateral Plantar artery.

32

Arteries transport ________, __________, and other essential substances to the ____________.

gases, nutrients, capillaries

33

What is the largest artery? The smallest?

Aorta; Arterioles

34

Arterioles

Considered resistive vessels

Assist with regulating blood flow through contraction and relaxation.

35

Capillaries

Nutrients and waste products are exchanged between the tissue and blood.

Capillaries are semi-permeable

36

Tunica Intima

Inner layer of artery

Thin

Consists of a surface layer of smooth endothelium, base membrane, and connective tissue.

37

Tunica Media

Intermediate layer of artery

Thicker

Composed of smooth muscle and connective tissue, largely of the elastic type.

38

Tunica Externa

Outer layer of artery

Also called adventitia

Somewhat thinner than media, contains fibrous connective tissue; some muscle fibers

Contains the vasa vasorum, tiny vessels that carry blood to the walls of the larger arteries.

39

What is being described by "Multi branched elastic conduit set into oscillation by each beat of the heart"?

The arterial system

40

Each beat pumps about _________ of blood into the aorta causing a blood pressure pulse.

70 milliliters

41

What happens to the arterial system when cardiac contraction begins?

Pressure in the left ventricle rises rapidly

Left ventricle pressure exceeds that in the aorta

Aortic valve opens, blood is ejected, BP rises

42

Increased heart rate delivers an _______________ blood volume

Increased

43

When the heart generates pressure to move blood, the pressure (energy) wave travels rapidly through the system in what order?

1. Left ventricle
2. Aorta
3. Large arteries
4. Arterioles
5. Right atrium
6. Vena Cava
7. Large veins
8. Venules
9. Capillaries

44

Pumping action of the heart results in a __________ blood volume in the arteries to maintain a high _____________ between the arteries and veins.

High
Pressure gradient

45

What determines the amount of blood that enters the arterial system? The amount that leaves?

Cardiac output

Arterial pressure and total peripheral resistance

46

What happens to the arteries upon cardiac contraction?

Each cardiac contraction distends the arteries, which serve as reservoirs to store some blood volume and potential energy supplied to the system.

47

Pressure is greater _______________ gradually ___________ as the blood moves _____________.

at the heart
decreasing
further away

48

Movement of any fluid medium between two points requires what two things?

A pathway along which the fluid can flow

Pressure differential

49

The amount of flow depends upon:

Energy difference: includes losses resulting from fluid movement

Any resistance which tends to oppose such movement

50

Lower resistance =
Higher resistance =

Lower resistance = Higher Flow rate
Higher resistance = Lower Flow rate

51

The total energy contained in moving fluid is the sum of what?

Pressure, kinetic, and gravitational energies

52

Pressure Energy

Potential/stored energy

Major form of energy for circulation of blood

Expressed in mmHg

53

Kinetic Energy

Velocity

Small for circulating blood

Expressed in terms of fluid density and its velocity measurements.

54

Gravitational Energy

Hydrostatic pressure (HP)

Equivalent to the weight of the column of blood extending from the heart to the level where pressure is measured.

55

Blood flows from ________ energy to ________ energy.

High to Low

56

An ___________ is needed to move blood from one point to another, the greater the ___________, _________ the flow.

Energy Gradient

Gradient

Greater

57

Inertia

Relates to the tendency of a fluid to resist changes in its velocity (a body at rest tends to stay at rest)

58

Energy is continually restored by?

The pumping action of the heart

59

As the blood moves farther out to the periphery, energy ___________, largely in the form of __________.

Dissipated

Heat

60

Movement of flow is dependent upon what?

Physical properties of the fluid and what its moving through.

61

Resistance is directly proportional to what?

Viscosity and length

62

Resistance is inversely proportional to ___________.

Radius

63

Of viscosity, vessel length, and vessel diameter, which has the most dramatic effect on resistance?

Vessel Diameter

64

Internal friction within a fluid is measured by its ____________

Viscosity

65

How does hematocrit effect viscosity?

Elevated hematocrit increases blood viscosity while severe anemia decreases blood viscosity.

66

What happens to energy when there is internal friction?

Energy is lost in the form of heat when the layers of rbc's rub against each other

67

Increased Viscosity = _____________ Velocity
Decreased Viscosity = _____________ Velocity

Decreased
Increased

68

How does vessel size effect energy loss?

Diminishing vessel size increases frictional forces and heat energy losses.

69

Laminar Flow

-Consists of evenly distributed frequencies during
systole
-Well organized
-Higher frequency flow in the center
-Stationary layer remains at the wall
-Laminar flow is considered stable flow
-Plug flow is likely seen at the vessel origin
-Parabolic profile of laminar flow usually seen downstream

70

What causes viscous energy loss?

Viscous energy loss is due to increased friction between molecules and layers which ultimately causes energy loss.

71

What causes inertial energy loss?

Inertial energy losses occur with deviations from laminar flow, due to direction and/or velocity changes.

This is the type of energy loss that occurs at the exit of a stenosis

72

What is the biggest source of energy loss?

Inertia

73

Poiseuille's Equation

-Defines the relationship between pressure, volume flow, and resistance.
-Helps define how much fluid volume moves through vessel.

Q= volume flow P= Pressure R= Resistance

Q= P/R

74

How are radius of the vessel and volume of flow related?

They are directly proportional

Small changes in radius may result in large changes in volume of flow

75

Law of Conservation on Mass

Explains the relationship between velocity and area

Area and velocity are inversely related

Q=A x V

76

What physicist is involved with pressure/velocity relationships?

Bernoulli

77

What happens to velocity when pressure is decreased in a supine patient? Why

When pressure increases, velocity decreases.

When velocity increases, pressure decreases.

The total energy contained in moving fluid is the sum of pressure, kinetic, and gravitational energy. In a supine patient there is no gravitational energy (hydrostatic pressure), velocity and pressure are the only two variables. Since they are inversely related, when one goes up the other goes down.

78

Why do pressure gradients (flow separations) occur?

Because of a geometric change with or without intra-luminal disease; and because of curves or tortuosity.

79

What are some results of flow separations?

Regions with reverse flow

Regions of stagnant flow or little movement.

80

What is a Reynolds number?

"Re"

Predicts when fluid becomes unstable or disturbed.

>2000 means laminar flow tends to become disturbed.

81

Steady Flow

-Originates from a steady driving pressure
-More predictable behavior
-In a rigid tube, energy losses mainly viscous; can be described by Poiseuille's equation.

82

Pulsatile Flow

-Changes both the driving pressure conditions as well as the response of the system.

83

The ____________ is related to the closure of the aortic valve and the influence of peripheral resistance.

Dicrotic notch

84

Describe the typical waveform related to pulsatile flow.

Systole: Forward flow throughout periphery

Late systole/early diastole: Temporary flow reversal, due to a phase shifted negative pressure gradient and peripheral resistance, causing reflection of the wave proximally.

Late Diastole: Flow is forward again, as reflective wave hits the proximal resistance of the next oncoming wave, and reverses.

85

Low Resistance Flow

Flow is steady in nature feeding a dilated vascular bed.

Examples: ICA, Vertebral, Renal, Celiac, Splenic, Hepatic.

86

High Resistance Flow

Flow pulsatile in nature. Reflections travel back up the vessel from the periphery producing flow reversals in vessel flow.

Examples: ECA, Subclavian, Aorta, Iliac, extremity arteries, fasting SMA.

87

What happens to flow distal to a stenosis?

-Reversal component of a high resistant signal may disappear due to decreased peripheral resistance, secondary to ischemia.

-Doppler flow distal to significant stenosis is lower resistant. In addition it's more rounded in appearance and is weaker in strength.

88

What happens to flow proximal to a stenosis?

- A normally high resistant (biphasic or triphasic) signal may become monophasic as it approaches the significant stenosis or obstruction.

- Doppler flow proximal to a significant stenosis is higher resistant in quality (could have no diastole or minimal diastole),

89

Peripheral resistance during Vasoconstriction

Pulsatile changes in medium/small sized arteries of the limbs are increased. When this occurs, pulsatile changes are usually decreased in the minute arteries.

90

Peripheral resistance during Vasodilation

Pulsatile changes in medium/small sized arteries of the limbs are decreased. When this occurs, pulsatility changes are increased at the minute arteries.

91

As inflow pressure falls due to stenosis; the usual response in periphery is to maintain flow by
____________.

vasodilation

92

Can total blood flow be fairly normal even in the presence of stenosis/complete occlusion? Why/why not?

Yes, due to the development of a collateral network and a compensatory decrease in peripheral resistance.

93

Why are location of collaterals important?

The location may help to determine tentative location of the stenosis/obstruction.

94

How does exercise effect the arterial system?

- Exercises causes peripheral vasodilation which lowers distal peripheral resistance, enhancing blood flow
- Vasoconstriction and vasodilation of blood vessels within skeletal muscles also influenced by sympathetic nervous system for regulation of body temperature.
- Exercise is a key vasodilator of resistance vessels within skeletal muscle.
- Autoregulation
-Decreases resistance in working muscles = decrease in the flow reversal component of the Doppler waveform.
-Higher resistant signals may result from normal vasoconstriction at arteriolar level OR from distal arterial obstruction.

95

Autoregulation

-Ability of most vascular beds to maintain constant level of blood flow over a wide range of perfusion pressures.
-Not present: perfusion pressure drops below a critical level

96

How does blood pressure effect resistance vessels?

BP rise = constriction of resistance vessels
BP fall = dilation of resistance vessels

97

What Doppler flow signal will appear after exercise?

-A low resistant, monophasic flow signal is normally present in extremity arteries after vigorous exercise due to vasodilation.
-This same type of pattern is also seen with disease. Peripheral dilation occurs in response to proximal arterial obstruction.
-Same monophasic pattern also seen pathologically. Peripheral dilation occurs in response to proximal arterial obstruction.

98

Do pulsatility changes differentiate well between occlusion and severe stenosis?

No, waveforms may not be altered with good collateralization.

99

Distal effects of obstructive disease may only be detectable following ________.

Stress (exercise)

100

Flow to a cool extremity (vasoconstriction) =

Flow to a warm extremity (vasodilation) =

Pulsatile signals

continuous signals

101

A hemodynamically significant stenosis causes a notable reduction in ____________ and _________.

Volume flow and pressure

102

Cross sectional area reduction of 75% = diameter reduction of _______

50%

103

Effects of flow abnormality produced by stenosis depends on factors such as what?

1. Length, diameter, shape of narrowing
2. Multiple obstructions in the same vessel: resistance to flow is additive; it results in a higher resistance than in each individual narrowing.
3. Obstructions in different vessels that are parallel: resistance to flow is less than the resistance in each individual narrowing because less volume of blood is going through each narrowing.
4. Pressure gradient; peripheral resistance beyond stenosis.

104

What happens to flow proximal to a stenosis?

Flow frequencies are usually dampened, with or without disturbance.

105

What happens to flow at the stenosis?

- Entrance into the stenosis produces increased Doppler shift frequencies (DSF), resulting in spectral broadening and elevated velocities.

- Flow disturbance occurs with high velocities and eddy currents

- Abnormal "jet" (elevated velocities) may be isolated to area of stenosis, but also approaching and/or leaving it.

106

Frequency and ___________ may be used interchangeably in regards to stenosis.

velocity

107

What happens to flow after a stenosis?

- At stenosis exit, flow reversals, flow separations, vortices/ eddy currents occur near edge of flow pattern.
- Flow quality has multiple changes in direction and spectral broadening.
- Energy expanded as heat
- Post-stenotic turbulence

108

What are some types of chronic occlusive disease?

-Claudication
-Ischemic rest pain
-Tissue loss

109

Claudication signs/symptoms

-Pain in muscles usually occurring during exercise; subsides with rest
- Results from inadequate blood supply to muscle
-Discomfort is predictable and subsides within minutes after exercise
-Level of disease usually proximal to location of symptoms.
- Pseudo-claudication mimics vascular symptoms but is neurogenic or orthopedic in origin.

110

Ischemic Rest Pain signs/symptoms

-Severe symptom of reduced blood flow
-Occurs when limb not dependent; BP decreased (sleeping)
- Affects forefoot, heel, toes.

111

Tissue loss signs/symptoms

-Necrosis or death of tissue

-Due to deficient or no blood supply

112

Acute Arterial Occlusion

-Symptoms include the 6 P's:
Pain, Pallor, Pulselessness, Paresthesia,
Paralysis, Polar.

- Possible causes: Thrombus, emboli, trauma

- Emergency situation since no time for development of collateral channels.

113

Vasospastic Disorders

-Raynaud's phenomenon: symptoms of intermittent digital ischemia occur due to cold exposure or emotional stress.
-Changes in skin color may include pallor, cyanosis, or rubor

114

Primary Raynaud's

-Ischemia due to digital arterial spasm
-Common in young women; may be hereditary, bilateral
-Benign condition

115

Secondary Raynaud's

-Also known as Obstructive Raynaud's syndrome
-Normal vasoconstriction of arterioles present with a fixed artery obstruction.
-Ischemia constantly present
-May be the first manifestation of Buerger's disease.

116

What things should be evaluated in regards to skin changes upon physical exam prior to arterial testing?

-Color
-Temperature
-Lesions
-Capillary filling
-Elevation/dependency changes

117

How are skin color changes evaluated?

Pallor: Result of deficient blood supply; skin pale.

Rubor: Suggest dilated vessels or vessels dilated secondary to reactive hyperemia; skin is reddened.

Cyanosis: A Concentration of deoxygenated hemoglobin, causes a bluish discoloration

118

What are some examples of skin lesions that may be found upon physical exam prior to arterial testing?

Ulcerations located: Tibial area, foot, toes.
Deep and more regular in shape
Quite painful

Gangrene: Tissue death due to lack of blood supply

Should question the duration of ulceration

119

An increase in capillary refill time denotes ___________ arterial perfusion.

Decreased

120

What should one look for upon elevation during physical exam?

Cadaveric pallor during elevation with ruborous red discoloration with dependency (dependent rubor).

121

What should be evaluated when examining with palpation during physical exam?

-Rhythmic pulsation of artery signifies adequate circulatory status
- Grading pulses on scale of 0 (none) - 4+(bounding) is fairly standard.
-Aneurysms can be palpated and described as bounding.
-Palpable "thrill" over pulse site may indicate a fistula, a patent dialysis access site or post-stenotic turbulence.

122

Which arteries have palpable pulses?

Aorta, femoral, popliteal, dorsalis pedis (DPA), posterior tibial artery (PTA)

123

How do you palpate the peroneal artery?

The peroneal artery is NOT palpable.

124

Where might one use a stethoscope to auscultate a bruit?

-Bruit auscultation most often done with carotid examination.

- Also done for heart, aorta, femoral, and popliteal.

125

What are some risk factors for Arterial disease?

-Diabetes
-Hypertension - may cause or enhance the development of the atherosclerotic process
-Hyperlipidemia - Elevated plasma lipids assoc. with atherosclerosis development.
-Smoking - studies suggest chemicals in cigarettes irritate the artery's intimal lining causing vasoconstriction.
-Other (non-controllable) like age or family history

126

Why is Diabetes such a strong risk factor for arterial disease?

-Atherosclerosis: more common; occurs at a younger age.
-Higher incidence of disease: Distal Pop and tibial arteries
-Medial calcification develops in LE arteries
-Poor sensation (neuropathy) may lead to increases injury
-Higher incidence of gangrenous change, amputations.

127

Atherosclerosis (Obliterans)

-Most common arterial pathology: thickening, hardening, loss of elasticity of the artery walls.
-Changes occur in intima and media layer of the vessel
-Major risk factors: Smoking, hyperlipidemia, family history
-Less important risk factors: Hypertension, Diabetes, sedentary lifestyle and arterial wall shear/stress

128

What are the most common sites for atherosclerosis?

Carotid Bifurcation
Aorto-Iliac system
CFA bifurcation
SFA- distal (Hunter's Canal)

129

Leriche Syndrome

- An example of atherosclerotic disease
- Caused by obstruction of the aorta
-Occurs in males
-Characterized by: Fatigue in hips, thighs, or calves with exercise
- Absence of femoral pulses
-Impotence
-Often times, pallor and coldness of LE

130

Embolism

-Obstruction of vessel by foreign substance or blood clot.
-Emboli may be solid, liquid, or gaseous
- Most frequent cause: small plaque breaks loose
-Sudden onset of blue
-Example: blue toe syndrome. Toe ischemia results; often improves, mainly from other smaller branches.

131

True Aneurysm

Dilation of all three arterial wall layers.

Fusiform- Diffuse, circumferential dilation

Saccular: Localized "sac like".

132

A ____________ happens when a small tear of the inner wall allows blood to form a cavity between two wall layers. Often occurs in thoracic aorta.

Dissecting aneurysm

133

Pseudoaneurysm

Results from a defect in main artery wall. Must be a channel communication from main artery to pulsatile structure outside vessel walls.

134

What are some common locations for a true aneurysm? What is the most common?

Thoracic aorta, femoral, popliteal, renal.

Infrarenal aorta is the most common.

135

Patients who have an aneurysm have a higher incidence of _________________.

getting a second one.

This is mostly true of the CFA or popliteal as opposed to elsewhere.

136

The cause of an aneurysm is ___________.

Unknown

137

What is the most frequent complication with an aortic aneurysm? Peripheral?

Rupture of the aortic aneurysm.

Embolization of the peripheral.

Both types can accumulate thrombus inside.

138

What are some examples of non-atherosclerotic lesions?

Arteritis
Coarctation of the aorta
Dissection
Vasospastic disorders
Entrapment syndrome

139

Arteritis

-Can affect tibial, peroneal arteries, or smaller more distal arterioles.
-Inflammation of arterial wall can lead to thrombosis
-Buerger's disease (Thromboangiitis obliterans)
-Occurs primarily in men <40 yr. old who smoke heavily
-Patients present with occlusions of the distal arteries.
-Rest pain and ischemic ulceration present

140

Coarctation of the aorta

-One of several congenital anomalies of arterial system.
-Congenital stricture of thoracic aorta; but could affect abdominal aorta
Clinical findings:
HTN due to decreased kidney perfusion
Symptoms of LE ischemia e.g. reduced
pulses

141

Dissection

-Can affect aorta/peripheral arteries
-Thin membrane divides the arterial lumen into 2 compartments
-Intima develops tear through which blood leaks into the media (false lumen)
-Flow velocities differ in each lumen
-Aortic Dissections can extend to iliacs.
-Cause could be due to HTN or severe chest trauma.
Complications include stenosis, occlusion, or thrombus.
-Death from rupture of an aortic dissection can occur.

142

General Considerations for Interpretation

1. Include clinical indication(s) for the exam
2. Adequate description of the exam performed
3. Description of positive as well as negative findings.
4. Characterization of disease.
5. Reasons for technically limited or incomplete exam.
6. Comparison with previous studies if applicable.
7. Identification of the technologists/sonographer who performed the exam.

* Preliminary findings provided according to protocol.

143

What are some limitations to achieving an adequate Doppler waveform?

a. Patients with casts or extensive bandages.
b. Ambient temperature can affect waveform quality
c. Congestive Heart failure may result in dampened waveform.
d. Cannot discriminate stenosis from occlusion
e. Technically dependent test

144

What is the proper patient positioning to achieve an accurate Doppler waveform?

1. Patient supine with the extremities at the same level as the heart to decrease influence of hydrostatic pressure.
2. The patient's hip is externally rotated, knee slightly bent.
3. Other positions: Rt/Lt lateral decubitus position, or prone.

145

The Doppler effect

- When a wave is reflected from a moving target, the frequency of the wave received is different (Doppler shift) from the transmitted wave.

-This effect occurs with relative motion between the sound source and the receiver of sound.

-Blood is the moving target; Transducer is the stationary source.

146

Continuous wave Doppler

- Two piezo-electric crystals: one constantly sending ultrasound, one constantly receiving reflected waves.
-The reflected frequency is higher/lower than the transmitted frequency, depending on direction of flow.

147

Analog Doppler velocimetry

-Employs a zero crossing frequency meter to display signals graphically on a strip chart recorder. paper speed = 25 mm/sec.
-Has acceptable accuracy
-Drawbacks include: noise, less sensitivity
-When system activated, self calibration is done.

148

Zero Crossing frequency meter

-Circuitry counts each time the input signal crosses through zero (the baseline) within a time span.
- High frequency wave have many oscillations; low frequency waves have few.
-Direction of blood flow varies during the cardiac cycle.
-Machine estimates frequencies present in reflected signals and displays them.

*This approach provides an estimate.

149

Spectral Analysis Doppler velocimetry

-Individual frequencies displayed by Fast Fourier Transmission (FFT) method.
-More commonly used during duplex evaluation.
-Time displayed on the horizontal axis (X); Frequency shifts displayed on the vertical axis (Y).
-Free of many of the analog recording drawbacks.

150

In the UE, Doppler velocity waveforms should be recorded from what arteries bilaterally?

-Subclavian
-Axillary (axilla)
-Brachial (at elbow-antecubital fossa
-Radial (thumb side, at wrist)
Ulnar (5th finger side, at wrist)

151

In the LE, Doppler velocity waveforms should be recorded from what arteries bilaterally?

-Common femoral (CFA)
-Superficial Femoral (SFA)
-Popliteal
-Posterior tibial (PTA) (medial malleolus)
- Dorsalis Pedis (DPA) (top of foot)
-Peroneal (if necessary) (location: lateral malleolus)

152

What are some potential sources of technical error when recording Doppler waveforms?

-Incorrect probe position
-Incorrect angle of incidence
-Inadequate amount of gel
-Excessive pressure on the probe tip
-Insufficient period of rest before testing

153

What are the three basic types of Doppler waveforms?

Triphasic- Rapid upslope, sharp peak, rapid downstroke; Flow reversal; Resumption of forward flow

Biphasic- Rapid upslope, sharp peak, fairly rapid downstroke, Flow reversal, no resumption of forward flow, considered as normal in some patients.

Monophasic- Slow upslope, rounded peak, slow downstroke, no reversal.

154

Vasodilation of _____________ vessels often occur with proximal obstruction, reducing __________; causing the signals to have ______________ resistant (steady) flow quality.

Distal
Pulsatility
lower

155

Qualitative interpretation

1. Normal/abnormal signals
2. Look for deterioration in signal quality from one level to the next; as well as deterioration from a previous study.
3. A monophasic/ pulsatile signal often obtained proximal to an obstruction.
4. Well collateralized occlusions can appear similar to flow distal to a stenosis.

156

Upper extremity Doppler signals

-Subclavian artery: High resistant, multiphasic flow. Proximal occlusion or critical stenosis will make the signal more monophasic.
-Flow patterns in hand quite variable; e.g. lower resistant signals can be found in the brachial, radial, and ulnar arteries in the relaxed and warm patient.

157

Describe Doppler waveforms post exercise

Normal: Pre-exercise wave form qualities are maintained and /or augmented. No reverse component.

Abnormal: More rounded peak, no reverse component.

158

Analog Doppler is NOT capable of portraying velocities of less than _______.

6 cm/sec

159

What are some troubleshooting issues associated with Doppler recording?

-Recorder stylus not recording? Check that proper test selection and/or probe type has been made.
-"60 cycle" noise on tracing- (located on both sides of the baseline)? Decrease gain; turn system off/on; increase filter; try another plug receptacle.
-Recording stylus "stuck" at the lower or upper portion of tracing? Activate "re-set" control to re-center.

160

Pulsatility Index

(PI)
Calculated by dividing the peak to peak frequency difference (P1-P2) by the mean (average) frequency.

161

Acceleration Time

-Proximal arterial obstruction results in a slowing of the time interval between the onset of systole to the point of maximum peak.
-Example Criteria: An acceleration time of >133 msec suggest presence of proximal iliac disease.

162

Diastole tells you about where the blood is _________ and systole tells you about where the blood is _____________.

Going
Coming from

163

What is an example of "inflow disease"? "Outflow"?

-Inflow represents the blood flowing into the lower extremities (Aorto-iliac disease)

-Outflow represents the blood flow going out into the extremities (femoral-popliteal disease).

164

What are the capabilities of Doppler segmental pressures of the Lower Extremities?

1. Assess presence/severity of arterial disease
2. Combined with Doppler velocity or volume pulse waveforms.

165

What are some limitations to obtaining Doppler segmental pressures in the Lower extremities?

1. Cannot discriminate between stenosis and occlusion, precisely localize area of obstruction, nor discriminate between CFA and external iliac disease.
2. Calcified vessels (medial calcinosis) render falsely elevated Doppler pressures; e.g. Diabetes, end-stage renal disease.
3. Uncompensated CHF may result in decreased ankle/brachial indices.
4. Artificially elevated high thigh pressures when narrow cuff used on thigh. (When cuff is too large on limb, BP is falsely lower.)
5. Difficult to interpret with multi-level disease.
6. The following conditions preclude taking a segmental limb pressure: DVT, dialysis access, lymphedemia, (stent, bypass graft, pt. who had mastectomy needs to be checked with DR who performed the procedure.

166

What is the proper patient positioning for obtaining segmental pressures of the lower extremities?

-Patient should rest 20 minutes prior to exam, especially when vascular disease is present.
-Supine with legs about the same level as the heart.

167

What is the technique for obtaining segmental pressures of the lower extremities?

-Appropriately sized blood pressure cuffs applied to both extremities.
-Place cuff "straight" on the extremity site, not encircling any bony prominence.
-Should fit snugly.
-Ideally the cuff bladder should be placed over the artery .
-The bladder inflation should transmit pressure quickly into the tissue to compress the artery.
-Width of cuff should be about 20% greater than diameter of limb.

168

What size cuffs should be used for segmental pressures?

12 x 40 cm with longer cuff bladders for thighs.

169

What are the major differences between the 3 and 4 cuff methods?

-Two thigh cuffs (provide proximal and distal pressure measurements) but artificially elevated BP's are obtained.
-The 3 cuff method utilizes one large thigh cuff (high on the thigh) providing a more accurate pressure reading.

170

How does one optimize the Doppler signal for segmental pressures?

-Use an 8-10 MHz Doppler frequency probe
-Angle the CW Doppler probe 45-60 degrees to the skin.
-Due to vessel angulation, probe angle behind the knee may be closer to 90 degrees to the skin.
-Angle the probe so blood flow moves antegrade (towards the probe.)

171

Using a handheld sphygmomanometer, or an automatic cuff inflator, segmental Doppler pressures are obtained in the following order bilaterally:

1. Brachial (upper arm) using brachial artery
2. Ankle (Use PTA and DPA; Peroneal A only if necessary.
3. Calf (BK)(use the site- PTA or DPA - that had the highest pressure, for obtaining the pressure for this level.
4. Above the knee (AK) (same as calf; may need to use popliteal . If difficult to obtain)
5. High Thigh (HT) (Same as above knee)
6. If one large thigh cuff used, protocol same as for the calf.
*Start at the ankle and move proximally to eliminate the possible underestimation of the systolic pressure measurement.

172

What are some hints regarding segmental blood pressures?

- Complete cessation of blood flow is required; cuffs inflated 20-30 mmHg beyond last audible Doppler arterial signal; OR
-Inflate the cuff 20-30mmHg higher than the highest brachial pressure.
-If pressure measurements must be repeated, the cuff should be fully deflated for about a minute prior to repeat inflation.
- The systolic pressure is recoded as the pressure at which the first audible Doppler arterial signal returns.

173

What is another term for Ankle/Brachial Index (ABI)?

Ankle/Arm Pressure Index (API)

174

What are the criteria for normal/abnormal ABI?

>1.0 = Normal
>0.9 - 1.0 = May be within normal limits
0.8 - 0.9 = Mild arterial disease
0.5 - 0.8 = Claudication (moderate disease)
1.3-1.5 is considered incompressible/unreliable.

175

Some authors feel an absolute ankle pressure of ___________ rather than and ABI of _________ has stronger weight for predicting symptoms at rest.

<50 mmHg
0.5

176

ABI of greater than or equal to 0.5 represents ____________. Less than 0.5 suggests ____________.

Single segment disease
multiple lesions

177

Segmental pressure drops of _________________ between two consecutive levels suggest significant obstruction.

A horizontal difference of ____________ suggests obstructive disease at or above the level in the leg with the lower pressure.

> 30 mmHg ( some say greater than or equal to 20-30mmHg)

Greater than or equal to 20 or 30 mmHg

178

In the four cuff method, the high thigh pressure is normally ______________ than the highest brachial pressure.

The AK and BK pressures should be at least the same as the __________.

In the three cuff method, thigh pressure is ____________ to the highest brachial pressure.

Greater than or equal to 30 mmHg

highest brachial pressure

Similar

179

Toe pressures of less than or equal to ________ are present in foot/toe ulcers that didn't heal.

30 mmHg

180

Exercise and segmental pressures

- Compare resting values to those obtained after exercise.
-Helps differentiate true vs. false claudication
-Contraindications include: SOB, severe HTN, significant cardiac problems, stroke, walking problems.

181

What is the technique for exercise and segmental pressures?

After resting exam
-Pt. walks on a constant load treadmill at a less than or equal to 12% elevation.
-Speed: 1.5 MPH for a maximum of 5 minutes or until symptoms increase to such severity that pt. must stop.
-Document: Duration of walking, MPH, onset, location and progression of symptoms.
-Post exercise Doppler pressures obtained: both ankles (abnormal first), then higher brachial
-Post-exercise ABI's are obtained: immediately (Normal ABI increases) Abnormally, ABI decreases minimally or to a severe amount. With drop after exercise, pressures obtained every two minutes until pre-exercise pressures are attained.

182

Interpretation of segmental pressures with exercise incorporates:

-Duration of exercise
-Length of time to recover
-Pressure changes from pre to post exercise.

183

What are the criteria for single level disease regarding segmental pressures with exercise? Multi-level disease?

-Takes 2 to 6 minutes for the ABI's to increase back to resting levels after they dropped to low or unrecordable levels after exercise.

-Takes from 6 to 12 minutes for the ABI's to increase back to resting levels after they remained low or at unrecordable levels after exercise.

184

Reactive Hyperemia

-An alternate method for stressing the peripheral circulation. Used when patients have: PVOD in contralateral leg, use a cane or a walker, have pulmonary problems, poor cardiac status.
-Bilateral thigh cuffs (19 x 40) inflated to suprasystolic pressure levels (20-30mmHg above highest brachial) maintaining pressure 3-5 minutes.
-Produces ischemia and vasodilation distal to the occluding cuffs.
-Upon release of cuff occlusion, ABI's are obtained.
-Normal limbs may show a transient drop of 17-34%
-Single level disease: < or equal to 50 % drop in ankle with reactive hyperemia.
-Multi-level disease- > 50% ankle pressure drop
-Treadmill testing is the preferable test because it produces a physiologic stress that reproduces a patient's ischemic symptoms.

185

What is the proper patient positioning for obtaining segmental pressures of the upper extremities?

-Supine with arms relaxed at the patient's sides.
- Cuffs should be on snug, but not tight.

186

What is the proper technique for obtaining segmental pressures of the upper extremities?

- 12 x 40 cm cuff placed snugly on the upper arm; 10 x 40 cm cuff on the forearm bilaterally.
- Brachial artery used to obtain upper arm BP; radial and ulnar arteries used to obtain forearm pressure.
-Pressures are combined with Doppler velocity wave forms

187

What is the Allen test used for?

To evaluate the patency of the palmar arch.

188

What is the technique involved with the Allen test?

-With manual compression of radial artery by the technologist, patient clenches ipsilateral fist (<1 min) inducing pallor, while at the same time increases resistance.
-With manual compression of the radial artery continuing, patient is asked to relax the hand.
-Although more difficult to compress, the ulnar artery can be evaluated similarly to assess radial artery flow.
-Use a PPG on the index finger to document arterial pulsations before and after the clenched fist.

189

Describe a normal Allen test result? Abnormal?

Normal- Reappearance of the normal color to indicate the ulnar artery is providing flow to the palmar arch.

Abnormal- Color does not reappear to indicate: an ulnar artery occlusion or palmar arch obstruction.

190

What are some limitations associated with the Allen test?

-Excessive dorsiflexion of wrist may compress radial and ulnar arteries leading to a false positive test.

-If hand is opened, fingers forcible extended; the skin over palm can be stretched, (could lead to pallor due to compression of small vessels).

191

Interpretation of segmental pressures for the UE includes criteria such as:

-A 15-20 mmHg difference from one brachial pressure to the other, suggests a > 50% stenosis of the subclavian artery and/or the vessel under the cuff.
-A > 15-20 mmHg drop from upper arm to forearm suggests: 1) a brachial artery obstruction distal to the upper cuff. 2) Obstruction in single forearm artery which has decreased pressure. 3) Obstruction in both radial and ulnar arteries.
-A difference of greater > or = to 20 mmHg between radial and ulnar pressures suggests obstruction in vessel with lower pressure.

192

What is the purpose of a penile study?

Helps determine whether impotence is related to peripheral vascular insufficiency.

193

What are some limitations to performing a penile study?

Sensitivity to injectable medication; and/or anticoagulation therapy may prevent use of the injection component.

194

What is the proper patient positioning for a penile study?

Supine, with appropriate draping done to maintain privacy.

195

What is the technique for a non-imaging penile study?

-Doppler velocity signals obtained bilaterally (CFA, PTA, DPA)
-Appropriate BP cuffs placed upper arms, and ankles: Calculate ABI ( poor arterial inflow to LE due to proximal obstruction may affect penile arterial flow.
-Penile pressures obtained with Doppler or PPG as the "end-point detector." Probe placement: Lateral or Ventral. Cuff size: 2.5 cm x 12.5 cm
-Penile plethysmographic wave forms obtained as needed.
-Reduced pressure highly suggestive of more proximal arterial disease.
-Abnormal plethysmographic tracings show marked reduction in amplitude.

196

What is the technique for an imaging penile study?

-Use a 7 to 10 MHz transducer
-Obtain informed consent
- Prior to injection of medication, the cavernous (cavernosal) arteries are measured in transverse approach; PSV and EDV obtained.
-Specific medication is injected into lateral aspect, proximal shaft of penis to induce erection.
- After 1-2 minutes post-injection, the same measurements are obtained as before injection.
-Dorsal veins flow velocity measured.
- Dorsal veins flow should not change with injection.
- If rigid erection is maintained for up to 3 hours, patient must be instructed to contact his urologist immediately to reverse priapism (sustained erection).

197

How is a penile imaging study interpreted?

Normal- Diameter of the cavernous arteries should increase post injection. Doppler flow is higher resistant pre-injection. Lower resistant post.

PSV measurements should increase. Normal range: PSV approx. 30 cm/sec or higher. Anything less often considered abnormal.

Dorsal vein velocities should not increase; an increase could suggest venous leak. Normal: <3cm/sec.

198

Why is plethysmography performed?

-In combination with Doppler segmental pressures helps differentiate true claudication from non-vascular sources.
-Detect presence/absence of arterial disease while defining its functional aspects.
-Help localize the level of obstruction
-Assessment of follow-up treatment
-PPG mainly used for evaluation of digits and penile vessels.

199

What are some limitations for plethysmography?

-Cannot be specific to one vessel. Tracing reflects all arterial flow below the cuff.
-Cannot discriminate between major arteries and collateral branches (venous influence not completely eliminated).
-Difficult to perform volume plethysmography on obese patients.

200

What is the proper patient positioning for plethysmography?

-Most exams can be done with the limbs in resting position (patient supine).
-The patient can be sitting for evaluation of upper limb digits.

201

Volume (air) plethysmography

-Measurement of volume change
-Pneumatic cuffs are placed around specific levels of the extremities or digits.
-A measured amount of air is sequentially inflated into a cuff to pressure ranging from 10 to 65 mmHg, depending on cuff size.
-As arterial flow moves under the cuff, momentary volume changes in the limb segment occur.
-These changes beneath cuff are converted to pulsatile pressure changes with the air-filled cuff bladder.
-A pressure transducer converts the pressure changes into analog waveforms for display on strip-chart recorder. Chart paper speed = 25mm/sec.

202

Photo-plethysmography (PPG)

-Consists of transducer, amplifier, strip-chart recorder (25 mm/sec)
-Detects cutaneous blood flow, rather than truly measuring volume change.
-Photocell consists of light emitting diode and photo-sensor.
-Diode transmits infrared light into subcutaneous tissue with backscattered light reflected back to the adjacent photo-sensor.
-The cutaneous blood flow determines the amount of reflection.
-Blood attenuates light in proportion to its content in tissue.
-Increased blood flow results in increased attenuation which decreases this reflection. However, that's displayed as a positive upstroke of the waveform.

203

What is the appropriate technique associated with volume plethysmography?

-Patient supine with heels slightly elevated on a cushion.
-Using 3 or 4 cuff method, appropriately sized pneumatic cuffs applied snugly to: thigh, calf, and ankle bilaterally.
-Appropriate amount of air used to bring cuff pressure to predetermined levels. begin with upper part of extremity, moving distally. Record at least 3 pulse cycles.
-Artifacts not uncommon due to improper cuff application.
-Similar "gain" setting is maintained throughout the study. If a different setting is used, note on the recording paper.

204

What is the criteria for interpretation of plethysmography?

Normal- Fairly rapid upslope, sharp systolic peak with reflected wave.
Mildly abnormal- Sharp peak, absent reflected wave, downslope is bowed away from the baseline.
Moderately abnormal- Flattened systolic peak, upslope and downslope more delayed; reflected wave (notch) absent.
Severely abnormal- Low amplitude, or may be absent.

205

What are some trouble shooting procedures associated with plethysmography?

-Can't center stylus? Check the "mode." AC mode for arterial; DC mode for venous.
-Stylus wandering on paper? Activate the "re-set" control; be sure correct exam function is selected.
-Unable to obtain clean waveform? Reapply the PPG. Patient tremors make an exam nearly impossible.
-No tracing? Check the exam mode, paper, and connection points.

206

Displacement plethysmography

-Any change in volume of the enclosed part will displace an equal amount of water. Displacement is measured by the height of the water in the chimney; Volume change measured by spirometer.
-Pulse plethysmography refers to transient changes in (limb) volume related to the "pule by pulse" activity of the left ventricle; the (body) part expands when arterial inflow exceeds venous outflow.

207

Digit Plethysmography

-Help detect presence of arterial disease
-Differentiate fixed arterial obstruction from vasospasm
-For toes: Patient positioned supine with some elevation of the head
-For fingers: Patient sitting with arms resting on a pillow placed on patient's lap

208

What are some limitations associated with digit plethysmography?

-Quality of tracings greatly affected by the vasoconstricted state of arteries before testing begins (Patient has come in from cold weather, been smoking)
-With volume plethysmography, cuffs applied too tightly, can diminish the wave forms.
-With PPG improper contact with skin surface will cause poor results.
-Bandages that can't be removed; ulcerations and/or gangrene may prevent placement of cuff or photocell.
-Patient with extremity tremor.

209

What is the proper technique for plethysmography of the toes?

-Patient should be kept as warm as possible.
-The study is done in combination with a complete
-LE arterial exam, or a limited version like an ABI.
-An appropriately sized cuff, the width at least 1.2 times that of the toe (2.5-3 cm) is applied to base of great toe.
-Equipment does a self calibration when activated.
-Plethysmographic waveforms are recorded for all toes as previously described (if poor waveforms, warm the toes).
-Usual method for obtaining great toe pressures is PPG: (photocell as end-point detector).

210

What is the method for PPG of the great toe?

-Digit cuff placed at the base of great toe.
-Photocell securely attached to plantar side of toe using double stick tape or Velcro strap.
-Pulses recorded; paper speed 5mm/sec.
While pulsations are recorded, cuff is inflated to 20-30mmHg above highest brachial pressure.
-No pulsations should be seen.
-Cuff is slowly deflated, watching for return of first pulse to define pressure level.
-Can also be done with volume plethysmography.

211

What is the proper technique for performing plethysmography on the fingers without cold stress?

-Upper extremity arterial study is completed initially.
-Evaluate Doppler signals and obtain pressures.
-Doppler exam of palmar arch to evaluate patency.
-Apply finger cuffs (sizes 2-2.5).
-Pressures and waveforms obtained (using similar method as toes).

212

What is the proper technique for performing plethysmography on the fingers with cold stress?

-Performed in cases of symptoms occurring due to cold sensitivity. (Toes can also be evaluated)
-After resting study is performed, hands are immersed in ice cold water for 3 minutes if possible.
-Following cold stress, waveforms and pressures are obtained: Immediately after and 5 minutes after
-Document patient symptoms, skin color observations, and other pertinent findings on report.

213

What is the interpretation criteria for plethysmography of the digits?

Normal waveform qualities- Sharp upstroke during systole, Reflected wave seen in down slope.
Abnormal Obstructive waveform qualities- Slow upslope to rounded peak, downslope that bows away from baseline.
Abnormal peaked waveform qualities- Upslope is slowed, reflected wave located high on the downslope, has qualities of both normal and obstructive waveforms.
-Organic (fixed) obstructive disease has abnormal Doppler arterial signals, systolic pressure and PPG tracings.
-Functional (intermittent) disease has normal Doppler signals and pressures, and/or PPG tracings; but abnormal after cold stress.
-Peaked pulse is unique to waveform contours of patients with Raynaud's phenomena.

214

Digit Pressure Measurements

UE digits: Finger/brachial indices = 0.8-0.9

LE digits Toe/brachial index (TBI)
-Normal toe pressures vary from 60-80% of brachial pressure.
-A toe/ankle pressure index cannot be relied upon with artifactually high ankle pressures.
-Digital Artery Occlusion: severely reduced pressure.

215

Transcutaneous Oximetry (TcPO2)

-Wound healing and amputation level determination
-Limited by the inability to keep electrode fairly flat on the skin surface.
-Electrode placement must be on intact skin.
-Patient supine, head slightly elevated; room is warm.
-Electrode heats skin to 45 degrees C; Blood flow increases; lipid layer in fatty tissue melts; more "O2" escapes through skin, measured sensor in electrode.
- As "O2" escapes, a chemical reaction occurs in electrolyte solution, located between skin and electrode surface.
-Electrode converts chemical reaction to a "current" reading which is converted to a PO2 reading in mmHg.

216

What is the proper technique involved with TCPO2?How is it interpreted?

-Skin cleansed with alcohol wipe; air dried.
-Airtight self-adhesive fixation ring placed in the skin.
-Few drops of electrolyte solution put inside the ring.
-Electrode/sensor is affixed to fixation ring.
-Reference reading (upper lat. chest) obtained first; followed by specific sites (e.g. near toes, BK, AK)
-After manual calibration, it takes approximately 15-20 min per site to obtain "po2" reading.

-Normal values vary in literature and with manufacturer. Healing should occur with a PO2 reading of 70-80 mmHg.
-Borderline healing: 30-40 mmHg
-Non-healing: 10-15 mmHg. This number also varies.

217

What is the purpose of Duplex/Color Flow imaging in UE?

-Localize stenosis/occlusion
-Determine the presence of aneurysm
-Post-op study: hemodialysis access or arterial bypass graft.
-Detect AVF's

218

What are the limitations associated with Duplex/Color Flow in the UE?

-Limited access to extremity (e.g. dressings, skin staples or sutures, open wounds, IV site)
-Pertaining to hemodialysis access grafts: Graft angulation, difficult to adequately evaluate the outflow vein in an obese patient.

219

What is the proper positioning for Duplex/color of the UE?

-Patient is supine
-Arm is at a 45 degree angle from the body, and externally rotated ("pledge position").

220

What are the physical principles of duplex/ color flow in the UE?

-Duplex scanning: combination of real-time B-mode imaging and Doppler spectral analysis.
-Doppler Color Flow imaging: Doppler information is displayed on image after evaluated for phase (direction toward or away from transducer) and its frequency content (hue or shade of color).
-Sample size for acquiring pulsed Doppler information is usually 1-1.5 mm. Size is increased incrementally if needed.

221

What is the technique for duplex/color imaging in native UE arteries?

-Use a 7 or 5 MHz linear array transducer.
-Neck vessels identifies, with attention given to innominate artery on the R. The LCCA branches off the arch.
-Color/duplex scanning is used to evaluate: subclavian, axillary, brachial, radial, ulnar, palmar arch (if needed)
-It is uncommon for arteries in the UE to become stenotic, the main use is evaluation of dialysis access grafts.

222

What is the technique for duplex/color imaging for hemodialysis access in the UE?

-Auscultate the access for bruit and/or palpate for a "thrill". A patent dialysis access, as well as a stenotic one can produce a "thrill."
-Use a 7 or 5 MHz linear array transducer.
-Evaluate dialysis access grafts.

223

How should a dialysis access graft in the UE be evaluated?

-Inflow artery
-Arterial anastomosis
-Continue through the body of the graft
-Observe for aneurysm, puncture sites, peri-graft fluid.
-If color available, observe the image for flow changes, turbulence.
-Venous anastomosis.
-Outflow vein

*Dialysis access graft examples include: Brescia-Cimino fistula; straight, looped synthetic grafts.

224

Interpretation of native arteries in the UE

-Currently no criteria for classifying disease.
-Normal peak systolic velocities vary widely with skin temperature changes.
-Doppler signal quality is usually triphasic.
-If a >50% stenosis is suspected, observe for characteristics of the "stenosis profile".
-If occlusion is suspected; observe for lack of Doppler signals and the proverbial "thump" which is obtained proximal to occlusion.
-Check for aneurysm.
-Ulnar artery aneurysms can form in response to using the palm as a hammer.
-Subclavian artery aneurysms are often associated with embolization to the digits.

225

Interpretation for hemodialysis access in the UE

-Identify any aneurysmal changes, puncture sites, peri-graft fluid, thrombus if present.
-PSV and EDV vary as to the type of access; normally both are elevated.
-Low PSV obtained in access graft could indicate arterial inflow problems.
-No standardized velocity criteria; Follow up studies provide specific comparison to previous studies on the same patient.
-Venous anastomosis and outflow vein most common sites for stenosis possibly due to intimal hyperplasia or elevated arterial pressure.

226

Other hemodynamic complications associated with hemodialysis access in the UE

-The large blood volumes in the venous circulation, can increase venous return resulting in congestive heart failure.
-A "steal syndrome:" the distal arterial blood flow is reversed into the venous circulation and can cause hand pain on exertion, pallor and coolness of the skin distal to the shunt.

227

How is "steal" syndrome accessed?

-With dialysis access open/functioning, use PPG to evaluate flow in at least 2 digits, one at a time.
- Apply manual pressure to dialysis access and retake digit PPG tracings and/or pressures.
-If flow improves, there is a steal
-If flow stays the same, there is probably not a steal.

228

Duplex/Color Flow imaging LE

-Determines presence of >50% diameter reduction or occlusions.
-Determine presence of aneurysms
-Follow up of bypass grafts
-Localize stenosis prior to balloon angioplasty.
-Study can be limited by presence of dressings, skin staples, incisional tenderness, obesity, calcific shadowing.
-Patient should be supine with head on pillow
-Patient's hip slightly rotated externally, with knee flexed.
-Prone or lateral decubitus position may be required for assessment of popliteal artery.

229

The Doppler equation

Df = 2 FO V Cos 0/ c
Df = Doppler shift frequency
Fo = Carrier frequency (transducer)
c = speed of ultrasound in soft tissue (1540 m/s)
V = Velocity of the moving reflectors
Cos 0 = Angle
-The number "2" represents two Doppler shifts
-Red blood cell is first an observer of a stationary ultrasound field then acts as a wave source.
DF = Known value; measured by duplex. Proportional to the velocity of the source.
V = calculated value which represents velocity of flow (moving reflectors). To calculate, the frequency (Df) must be known.
-Source of error (solving for velocity) is the Doppler angle theta which increases its nonlinear influence as the angle becomes closer to 90 degrees.

230

What is the ideal Doppler angle for vascular exams?

-60 degrees, obtained center stream, parallel to walls. Vessel tortuosity and other conditions will cause Doppler angle to be 60 not reliable

231

What is the technique for duplex/color evaluation of the LE native arteries?

-Use a 7 or 5MHz linear array transducer.
-Distal external iliac artery
-CFA
-CFA bifurcation; SFA; Profunda femoris
-Popliteal artery
-Trifucation; Anterior tibial artery (ATA); Posterior tibial artery (PTA); Peroneal artery.
-Observe gray scale for plaque/other abnormalities.
-Observe color flow patterns
-Obtain PSV from each major vessel (prox, mid, dist if vessel is long).
-Characterize Doppler signals
-If >50% diameter reduction is suspected obtain pre-stenotic, highest PSV in stenosis.
-Identify post-stenotic turbulence.

232

Reversed Saphenous Vein graft (RSVG)

-Small end is now proximal
-Large end is distal
-Vein valves stay open due to arterial flow pressure
-Branches are ligated.

233

In-situ Vein graft

-GSV stays in place
-Small end is distal
-Large end is proximal
-Prior to surgery, valves broken up with special instrument; branches ligated.

234

Technique for duplex/color evaluation of LE bypass grafts

-Know type, location, and age; such as synthetic (Gortex)
-Protocol usually combined with ABI's
-Vein bypass graft evaluation includes: Inflow artery, proximal anastomosis, entire length of the vein bypass graft, distal anastomosis, outflow artery, also check for branches that could form AV fistulas, valves, and/or other abnormalities.
-Synthetic bypass graft evaluation includes: Inflow artery, proximal anastomosis, mid graft, distal anastomosis, outflow artery.

235

Interpretation of duplex/color exams in the LE native arteries

Normal - Doppler signals are triphasic; a change to biphasic can be significant; however some patients normally have biphasic flow without evidence of disease.
Abnormal:
Compare stenotic PSV to pre-stenotic PSV
-2:1 ratio = > or = to 50% diameter reduction
-4:1 ratio = > or = to 75% diameter reduction
>400 cm/sec PSV = > or = to 75% diameter reduction.
-Never accept the value of numbers alone, post-stenotic turbulence should be present.
-Don't go with a choice that says ">80% or >90%" only one that says ">75%"
-Observe for occlusions; aneurysms

236

Interpretation of duplex/color exams in the LE Bypass grafts

Normal- Lower resistance flow patterns may normally be expected.
-Some retrograde flow in the native artery may be evident at the distal anastomosis of a RSVG, which provides an additional source of collateral flow. (Retrograde flow results from pressure gradient)
Abnormal findings (compare with previous studies): - Decrease of 30 cm/sec in any graft segment .
-Reduced PSV's in smallest graft diameter that were greater previously.
-Change from triphasic to biphasic
-Decrease in ABI of >0.15
-Observe for post-complications such as: AV fistula (can siphon off graft flow); valve cusp.
Synthetic grafts: Can loosely apply the previous exam data; Anastomosis sites should be evaluated well for aneurysm and/or stenosis.

237

In general, normal stented arteries may have __________ PSV. Greatly __________ PSV are ___________ and suggest a _________________.

elevated
elevated
abnormal
hemodynamically significant diameter reduction

238

What are the purposes of duplex/color flow imaging of abdomen?

-Aorto-iliac vessels: Evaluate vessels for stenosis, status of bypass grafts, aneurysmal disease.
-Renal artery: to document >60% diameter reduction
-Kidney: presence of disease, and transplants.
-Mesenteric arteries: to document significant stenosis.
-Liver: suspected portal hypertension; pre/post liver transplants; other.

239

What are some limitations that may occur with duplex/color examination of the abdomen? What is the proper positioning to help with this?

-Size of patient
-Bowel gas
-Previous abdominal surgery (scar tissue)
-Shortness of breath and/or rapid respirations
-Patient in non-fasting state
-Patient should be supine, with minimal head elevation.
-Left lateral decubitus (LLD) for access to the right flank and the right lateral decubitus(RLD) for access to the left flank.

240

What is the appropriate transducer selection for an abdominal duplex/color exam?

Transducer selection related to size of patient; Most adult patients require 5, 3, or 2.25 MHz linear array transducer. A phased array transducer may also be used for imaging the deeper structures of the abdomen (small footprint with fan or sector shaped image)

241

What is evaluated in a abdominal duplex/color flow exam?

-Observe celiac and SMA
-Observe renal arteries
-Aorta: Proximal, mid, and distal
-Common iliac arteries bilaterally
-Bilateral external iliac arteries prox-dist
-Internal iliac arteries bilaterally

242

Interpretation for Aorto-iliac arteries

Aorto-iliac stenosis- Follow the same rules as LE arteries 2:1 and 4:1
Aorto-iliac arteries aneurysm-
-A dilation of >3cm OR an increase in diameter of 50% greater than original artery.
-Majority of AAA are atherosclerotic and infrarenal
-Type of aneurysm; True (saccular or fusiform), false (thrombus present?)
-The most frequent complication: Rupture of the AAA; embolization of the peripheral aneurysms.
-AAA should be measured from outer wall to outer wall.

243

Duplex/color evaluation of Renal arteries

-Many patients with present with HTN.
-Many pt's who have HTN have renovascular HTN, usually caused from renal artery stenosis (which can be secondary to atherosclerosis, fibromuscular dysplasia, or occlusion.
-Mechanism for HTN: Renin: an enzyme that converts angiotensinogen to angiotensin.

244

What is the proper technique for duplex/color evaluation of the renal arteries?

-Celiac artery and SMA velocity data
-Obtain Aorta PSV near SMA level
-In transverse, locate renal arteries (LRV is a landmark for identifying LRA. RRA is anterolateral off aorta).
-Obtain kidney size (length), observe morphology bilaterally.
-Obtain PSV and EDV bilaterally of:
-Renal artery Prox, mid, and dist
-Upper/lower pole of the kidney in segmental arteries.
-Observe for secondary or accessory renal arteries.

245

Interpretation for renal arteries

-Renal arteries and kidney arteries are normally low resistant in quality as are: celiac, hepatic, and splenic arteries.
-The aorta is usually higher resistant in quality, as are a fasting SMA and IMA.
-Obtain a Renal to Aortic Ratio (RAR)
-Observe the kidney for morphologic abnormalities (cyst, cortex thickening, other defects)
-Normal pole to pole length varies from 10-12cm depending on patient's size.
-Use End diastolic ratio (EDR) and Resistivity index (RI)
-An acceleration time (AT) of >100msec is considered abnormal. Proximal high grade stenosis/occlusion of renal artery may result in dampened, weak Doppler signals distally, but still low resistant quality. This is also called a Tardus-Parvus waveform.

246

What are the normal values for the renal artery ratios?

Normal RAR = < 3.5
> or = 3.5 suggests > or = to 60% diameter reduction
*RAR cannot be used if: AAA is present, or aortic PSV > 90 cm/s or < 40 cm/s

Normal EDR = >0.2

Normal RI = < 0.8 ( > or = to 0.8 is abnormal)

247

Mesenteric Arteries

-Patients presenting with hx of dull, achy or crampy abdominal pain 15-30 minutes after meals are suspect for mesenteric ischemia. The pain (mesenteric angina) may be due to a stenosis or occlusion of the SMA, celiac, or IMA.
-Chronic and acute mesenteric ischemia: difficult to diagnose; requires arteriogram.
-Perform exam on fasting pt.
-Obtain PSV and EDV of Celiac artery (may use tx approach), prox mid dist SMA, IMA, Aorta.
-Although not routinely done, the food challenge test consists of ingesting high caloric liquid (Ensure). Repeat exam 20-30 min (sooner if symptomatic); Hyperemic response begins after about 10 minutes, with maximum response in approximately 30 minutes.
-Post prandially, the PSV and EDV of the SMA are obtained.

248

Interpretation of Mesenteric artery exams

SMA-
-High resistance flow pre-prandial (some flow reversal present)
-Converts to lower resistance flow post prandial
-Normal velocities: range from 110-177 cm/sec
-Abnormal velocities: PSV > or = 275 cm/sec predicts > or = 70% diameter reduction.
-If pre-prandial waveform remains high resistant post prandial, distal mesenteric disease is suggested.
Celiac Artery
-Low resistance flow pre-prandial
-Remains low resistance post-prandial
-Normal velocities: range from 50-160 cm/sec
-Abnormal velocities: PSV > or = 200 cm/sec predicts > or = 70% diameter reduction.
*In most cases, 2 of 3 mesenteric vessels have to be abnormal to be consistent with chronic mesenteric ischemia.

249

What is Celiac band syndrome?

-Extrinsic compression of celiac artery origin by the median arcuate ligament of the diaphragm (frequently seen).
- A reversible celiac artery stenosis occurs during expiration (ligament presses down over artery); rarely the cause of clinical symptoms.
-The high velocity signals, indicative of stenosis, are substantially improved with deep inspiration.

250

Why isn't the celiac artery influenced by eating?

Celiac artery branches into the hepatic and splenic arteries. The liver and spleen have fixed metabolic requirements.

251

What does it most likely mean if the IMA is easily observed?

Due to small caliber, difficult to locate IMA off distal aorta, if easily observed often suggests SMA occlusion.

252

What is an Allograft?

Organ transplant
-Combine B mode, Doppler, and the use of a 5 or 3 MHz transducer to obtain useful information.

253

Liver transplant

-Treats patients with end-stage liver disease.
- Pre and post operative evaluation includes documenting patency of: portal vein, hepatic vein, IVC, and/or hepatic artery leading to hepatic infarction.
-Acute rejection will cause liver dysfunction.
-Many suggest rejection is a cellular process.

254

Renal Transplant

-5 MHz transducer for evaluation
-Both living-related or cadaveric donor kidneys used
-Transplanted RA anastomosed to EIA or IIA
-Transplanted RV anastomosed to EIV
-Post op eval: Doppler, careful B mode observation for conditions such as hematoma and parenchymal echogenicity.
-Increased renal transplant size is a sign of rejection
-Acute rejection often increases arterial resistance; although other conditions can as well.
-Many consider biopsy to be most reliable method for rejection diagnosis; others use indicator of increased arterial resistance.

255

Arteriovenous Fistulae (AVF)

-Abnormal connection between high-pressure arterial system and low pressure venous system; Marked anatomic and hemodynamic changes.
-Congenital or traumatic
-Fistula close to heart, potential for cardiac failure increases.
-Fistula located peripherally, more likely to cause ischemia.
-AVF may involve proximal and distal arteries/veins as well as collateral arteries/veins. Diameter and length predicts resistance it offers.

256

Flow surrounding AVF

- Proximal arterial flow (prox to AVF) has greatly increased diastolic flow because the fistula reduces resistance.
-Depending on size of the fistula, distal arterial flow may resume its normal triphasic pattern or may be somewhat reduced.
-Flow through the AVF has higher velocities; Lower resistant flow.
-Venous outflow takes on the flow quality of the fistula's low resistant, more pulsatile flow.

257

Compartment Syndrome

1. Can occur in sites such as the arm, leg, or abdomen.
Example: Following repair of a tibial artery (from trauma, occlusion) swelling may be evident. The compartment is bound by bone, fascia, and interosseous membrane, which does not allow for expansion.
2. Any swelling may cause extrinsic compression on the tibial arteries resulting in necrosis of the muscles causing severe pain, tenderness, foot drop, and other neurological changes.
3. Treatment for anterior compartment syndrome is fasciotomy.

258

Treatment of Pseudoaneurysm (PSA)

1. Determine the size and location of the PSA and the size and location of the neck.
2. Ultrasound guided compression
-The key to success is whether the neck/communicating channel between the native artery and PSA can be uniformly and completely compressed.
-Alternating compressions of 10-15 minutes with short rest period performed with MD present; Monitoring of distal perfusion necessary; length of time to thrombose PSA varies widely.
3. Ultrasound guided Thrombin injection
-PSA, neck, adjacent vessels identified; MD mixes thrombin solution, inserts needle clearly into the PSA. slowly injects thrombin until thrombosis occurs (usually within a few seconds); monitoring of distal perfusion necessary.

259

What are some contraindications for ultrasound guided compression of a PSA? For Thrombin injection?

Compression-
-Inability to uniformly compress neck
-Patient on anticoagulation therapy
-Multiple communicating channels
-Infection is usually NOT considered a contraindication.
Injection-
-Allergy to thrombin or bovine materials
-Infection in the groin
-Ischemia of the overlying skin
-Distal limb ischemia
-Very short and/or wide neck which may preclude this technique.

260

Popliteal Artery Entrapment Syndrome

1. Popliteal artery possibly compressed by medial head of gastrocnemius muscle (anomalous origin), or fibrous bands.
2. Often found in young men; Repeated trauma to artery may result in development of aneurysm, thrombosis, emboli.
3. Patients present with symptomatic arterial occlusion or intermittent claudication.
4. Flow to great toe is monitored with an "end-point detector" such as PPG. Diminished pulsations considered abnormal.
5. Abnormal example: With knee extended and active plantar flexion or with passive dorsiflexion of the foot against resistance, PPG pulsations may diminish or obliterate.

261

Preoperative Arterial Mapping of the Epigastric artery (EA)

1. Deep superior EA is terminal branch of internal mammary artery
2. Both arteries and perforators, take blood to the rectus abdominis muscle, (long strap muscle) vertically oriented, each side of midline.
3. Rectus abdominis muscle, sub q fat, arteries, perforators, overlying skin: called the transverse rectus abdominis myocutaneous (TRAM) flap.
4. Reason for mapping: Surgeon wants to use the best arterially supplied muscle section for TRAM flap for autogenous breast reconstruction.

262

Preoperative Arterial Mapping of the Internal Mammary Artery (Internal Thoracic Artery)

1. Arises off arch of subclavian artery, descending on posterior side of cartilage of upper 6 ribs, about 1 cm from sternum.
2. Reasons for mapping:
-Utilized as a recipient site for free flaps in breast reconstruction.
-Second important use for this artery is as graft to the left anterior descending (LAD) coronary artery.

263

Preoperative Radial Artery Mapping

1. Determine suitability for use as graft for coronary artery bypass.
2. Technique
-Asses patency of palmar arch utilizing modified Allen test. The patient doesn't make fist in this instance; rather, use PPG to monitor various digit pulses both without/with radial compression.
-Normally the plethysmography pulsations should continue during radial compression. If pulsations disappear, no need to proceed. Removal of radial artery will compromise the hand.
-Using duplex (7.5 or 5 MHz) assess brachial and radial arteries.
-Observe for abnormalities: focal elevated PSV, abnormal Doppler quality, intimal thickening, aneurysm , calcification.
-Measure diameter of radial artery (proximal, mid, and distal)
3. Limitations may include wall calcification.

264

Preoperative Vein mapping

Indications-
-Determine suitability for use as extremity or coronary bypass.
-Determine suitability of veins for use in dialysis access/graft.
Normal findings-
-Compressibility of veins without evidence of thrombosis.
-Acceptable diameter measurement criteria varies; However, vein dimensions should be at least 2-3mm; basilic vein is often larger than cephalic vein.
-Comment made regarding presence of: high bifurcation of brachial A, duplicate venous system, presence of vein wall thickening or mural calcifications: findings which could prevent use of vein bypass graft or dialysis access.

265

What is the technique for preoperative vein mapping?

LE
-7.5 MHz or higher transducer
-GSV (sometimes SSV) mapped proximal to distal.
-Measurements obtained incrementally along extremity: proximal, mid, distal of each segment; thigh and BK.
UE
-Cephalic and basilic veins are mapped
-Measurements obtained incrementally along extremity; proximal, mid, and distal upper arm and forearm.
In General
-Proximal tourniquet to increase vein size
-Vein wall compressibility is evaluated
-"Outer edge to outer edge" diameter measurements (mm), incrementally along extremity. Vein length (cm) obtained.

266

Thoracic Outlet Syndrome (Arterial Component)

1. Occurs with neurovascular bundle compression by shoulder structures (cervical rib, clavicle, scalene muscle); occurs in certain arm positions.
2. Etiology not well understood; most symptoms due to neurogenic compression of brachial plexus (97%); small percentage due to subclavian vein or artery compression.
3. Symptoms: Numbness/tingling of the arm, pain/aching of shoulder/forearm, exercise/upward positions increase discomfort/symptoms, 25-30% of population have asymptomatic compression.
4. PPG and or Doppler waveforms used to monitor and changes.
-PPG on index finger or CW Doppler on radial artery .
-Resting waveforms obtained.
-Patients arm placed in various positions while arterial pulsations monitored.
-Abnormal waveform: Attenuation or flattening of the waveforms in one or more of the positions.

267

What arm positions are used to evaluate Thoracic Outlet Syndrome?

Patient sits erect off side of the exam table
1. Resting position - hand in lap
2. Arm at 90 degrees
3. Arm at 180 degrees
4. Exaggerated military stance
5. Adson maneuver positioning
-Same as exaggerated military position but head turned sharply to right.
-Same as exaggerated military position but head turned sharply left.
6. Causative position as described by patient.

268

What is the treatment for Thoracic outlet syndrome?

Conservative: Shoulder exercises, however, surgical treatment done by first rib resection with/without scalene muscle splitting.

269

What is the method for Arteriography?

1. Percutaneous puncture of artery; insertion of thin catheter.
2. Most common arteries used are the CFA (safest approach), or the brachial.
3. After proper pt. positioning, contrast agent injected into catheter, flows with moving blood; gives picture of lumen.
4. Rapid film changer technique used to expose the films sequentially.
5. Using fluoroscopy, digital information obtained.
6. Catheter removed; Pressure held on puncture site; Patient supine for 6-8 hours. Sandbag placed on top of dressing.

270

What is the criteria for interpretation of Arteriography?

1. Primarily an anatomic study not a functional study.
2. Hemodynamically significant stenosis usually defined as a 50% diameter reduction.
3. Normal anatomy seen on films as contrast media fills vessel.
4. Extent and location of filling defect is determined
5. Atherosclerotic plaque appears as irregular or smooth.
6. Vessel occlusion: no filling seen; collaterals may be present.
7. Miscellaneous findings:
-Aneurysm appears as dilated artery
-Vasospasm - severe narrowing
-Fibromuscular dysplasia: multiple arterial stenoses caused by medial hyperplasia. Also known as "string of pearls."

271

What are some limitations and complications associated with arteriography?

Limitations-
-May be contraindicated in patients allergic to contrast agent or in kidney failure.
- Inaccurate in its hemodynamic assessment because of inability to provide many images in multiple planes in "real time". 2D view is standard.
Complications-
-Puncture site hematoma
-Pseudoaneurysm
-Local arterial obstruction
-Neurologic complications

272

MR Angiography (MRA)

-Employs radio frequency energy and a strong magnetic field to produce images in multi planes.
-MRI instruments quantitate blood flow- MRA looks like an angiogram.
-Flowing blood well distinguished from soft tissue without using contrast agents.
-Can be limited by: Presence of metallic clips, pacemakers, monitoring equipment; Can overestimate stenosis due to slow flow or turbulence; expensive; claustrophobia may limit some patients.
-Useful for AAA, dissections, peripheral artery evaluation.

273

Computerized Tomography (CT)

-Employs ionizing radiation to obtain cross sectional images of the aorta and other body structures.
-IV contrast allows more discrete evaluation.
-study can be limited by pt. motion and presence of metal surgical clips, limited application in PAD due to smaller vessels; One plane used.
-Identifies size of aorta; extent and size of aneurysm.
-Helps define relationship of aorta to renal artery origins.

274

Angioplasty
Percutaneous Transluminal Angioplasty (PTLA)

-Used to dilate focal plaque formation in vessel (plaque is not removed).
-Same technique used for arteriography except a balloon tipped catheter is used.
Under Fluoroscopy:
-Catheter tip is brought to the region of stenosis.
-Balloon is slowly inflated, pushing plaque against the walls of vessel, dilating artery lumen.
-Balloon deflated, catheter removed.
-Can not be done on all vessels nor on all types of lesions.
-Usually performed in vessels with focal stenosis such as: renal, iliac, femoral, or popliteal.
-Serious complications occur in less than 5% of cases. 2-3% of PTLA patients have complications requiring surgery or alter hospital stay.
-Minor discomfort with the procedure
-Morbidity, mortality, cost of angioplasty are low.

275

Intravascular ultrasound (IVUS)

-Tiny ultrasound probe at tip of catheter provides image of vessels from inside out.
-Evaluate plaque formation on arterial wall, post-procedure to assess need for further treatment, determine correct placement of stent, identify aortic dissection, as well as applications for venous evaluations e.g. chronic iliocaval obstruction.

276

Stent/Stent graft

1. To maintain intraluminal structure/patency; Acts as a type of scaffold.
2. Insertion and deployment technique varies with stent type.
3. Similar techniques as arteriography are utilized with insertion of stent introducer sheath.
4. Limitations:
-Abdominal gas
-Inability of patient to lie flat
-Complications similar to those of arteriography
5. Used in vessels: Aortal, renal, iliac, femoral, repair of AAA with stent grafts.
6. May expect some flow acceleration post-stenting
7. Problems: restenosis due to intimal hyperplasia, stent migration, graft limb compression, twisting, dislodgement, endoleaks.

277

What are the main types of Endoleaks?

Type I - Attachment sites
Type II - Branch vessels (IMA, lumbar)
Type III - Modular connections/graft tear
Type IV - Transgraft (increased poracity)

278

Describe the anterior circulation for the cerebrovascular anatomy.

1. CCA
-Right CCA branches off the right innominate
-Left CCA is a branch off the aortic arch
-More than 50% of blood flows into the ICA
2. ICA
-Originates from the CCA
-Travels into base of skull without branching
-Intracranial branches include: Ophthalmic artery (originates near carotid siphon, a significant curve of ICA
-Posterior communicating
-Terminates in the middle cerebral artery (MCA) and anterior cerebral artery (ACA)
-Distributes blood to low resistant vascular beds.
3. ECA
-Originates from CCA
-Has eight major branches
-Distributes blood to high resistance vascular beds.

279

Describe the posterior circulation for the cerebrovascular anatomy.

1. Vertebral arteries
-First branch off the subclavian artery
-Right is usually smaller than the left
-Unite after entering skull to form basilar artery
2. Basilar artery
-Formed by confluence of vertebral arteries
-Divides into posterior cerebral arteries.

280

Periorbital circulation

1. Supraorbital artery: arises from ophthalmic artery; travels anteriorly and superiorly to the globe; joins ECA via some of its branches (STA superficial temporal artery)
2. Frontal Artery: arises from ophthalmic artery; exits orbit medially to supply mid-forehead; joins ECA via some of its branches.

281

Cerebrovascular collateral pathways

1. Largest intra-arterial connection is the circle of Willis
2. Important anastomoses include:
-ECA/ICA connections via orbital and ophthalmic arteries.
-Occipital branch of ECA with Atlantic branch of vertebral
-Deep cervical and ascending cervical branches of subclavian to branches of lower vertebral artery.

282

Poiseuille's Law

-Quantity of flow (Q) is related to the pressure gradient across an arterial segment (p), radius of vessel (r), viscosity of fluid (n), and length of vessel (L)

Q = P pie r to the 4th /8nl

-Flow is directly related to (P) and r to the 4th
-Flow is inversely related to n and L

283

Effects of stenosis on flow characteristics

1. Velocity acceleration results because velocity and area are inversely proportional.
2. Blood flow must change direction as the flowstream narrows entering the stenosis and enlarges as it exits; eddy currents, turbulence, and vortices cause energy loss through inertia.

284

Transient Ischemic Attack (TIA)

-A fleeting neurological dysfunction
-Symptoms last less than 24 hours
-Usually embolic from heart or carotid artery

285

RIND (Resolving Ischemic Neurologic Deficit)

-Symptoms last more than 24 hours
-Complete recovery usually occurs

286

VBI

Vertebral basilar insufficiency

287

Cerebrovascular accident (CVA)

-Symptoms last more than 24 hours
-Complete recovery does not occur

288

Atherosclerosis (Cerebrovascular)

-Atheromatous plaque: a form of arteriosclerosis; localized accumulations of lipid-containing material (atheroma), smooth muscle cells, collagen, fibrin and platelets.
-Formed within or beneath the intima
-Causes thickening, hardening, & loss of elasticity of the walls.
-Can result in decreased perfusion to the brain.

289

Types of atheromatous plaque (Cerebrovascular)

1. Fatty streak- Thin layer of lipid material on intimal layer.
2. Fibrous plaque- Accumulation of lipids.
3. Complicated lesion - A fibrous plaque that includes fibrous tissue, more collagen.
4. Ulcerative Lesion- Fibrous cap deteriorates - emboli.
5. Intra-plaque hemorrhage.

290

Thromboembolic (Cerebrovascular)

-Obstruction of a blood vessel by a piece of thrombus
-Thrombus: Large amounts of red blood cells trapped within a fibrin network, clumps of platelets may also be evident.
-Embolism: Piece of thrombus breaks loose and travels distally until it lodges in a small vessel.

291

Aneurysm (Cerebrovascular)

-Localized dilatation of a blood vessel due to congenital defects or weakness of the wall.
-Rarely seen in cervical carotid artery.
-Pulsatile mass in neck is usually a very tortuous CCA.

292

Non-atherosclerotic conditions (Cerebrovascular)

1. Dissection; Trauma results in sudden tear in intima; Creates false lumen which may gradually extend proximally or distally; Blood in the false lumen may thrombose; High resistant Doppler flow in "blind pouch." (Must have change in flow in lumen.)
2. Fibromuscular Dysplasia (FMD);Most commonly caused by dysplasia of media in mid/distal ICA; Characteristic bead-like appearance on angiography; Often seen in young women.
3.Carotid Body Tumor (CBT); Carotid body; a small structure located just above the carotid bifurcation; CBT is a highly vascular structure that develops between the ECA and the ICA and is usually fed by the ECA; Treatment is ligation of feeding vessel which is usually the ECA.
4. Neointimal hyperplasia; Intimal thickening from rapid production of smooth muscle cells; A response to vascular injury/reconstruction e.g. post carotid endarterectomy. Significant stenosis may occur within 6-24 months (after that period it is just considered re-stenosis.)

293

Bruit

-A noise heard as a result of turbulent flow
-Frequently associated with a hemodynamically significant lesion.
-Bruit may not be evident with a very tight stenosis >90% (bad sign for a pt. who has hx of bruit.)
-Common sites for Bruit evaluation: Carotid and subclavian.

294

Anterior Circulation (carotid)

-Hemispheric (lateralizing) symptoms: Since the left hemisphere of the brain controls the right side of the body, and vice versa, a left hemispheric CVA results in neurological deficits on the right side of the body.
-Specific eye symptoms (amaurosis fugax) are suggestive of ipsilateral ICA disease.

295

Symptoms frequently seen with ICA lesion

-Unilateral paresis: weakness or slight paralysis on one side of body.
-Unilateral paresthesia: Prickling or tingling of the skin.
-Aphasia- Inability to speak
-Amaurosis Fugax: Temporary, partial or total blindness, usually of one eye.
-Myopia, commonly referred to as nearsightedness, and homonymous hemianopia, defective vision or blindness in the right or left halves of the visual fields, are NOT consistent with ICA lesions.

296

Symptoms frequently seen with MCA lesions

-Aphasia or dysphasia
-More severe facial and arm hemiparesis or hemiplegia (rather than in the leg)
-Behavioral changes

297

Symptoms frequently seen with ACA lesions

-More severe leg hemiparesis or hemiplegia
-Incontinence
-Loss of coordination

298

Symptoms frequently seen with vertebrobasilar lesions

-Vertigo; difficulty maintaining equilibrium
-Ataxia: Muscular uncoordination, i.e. inability to control gait
-Bilateral visual blurring or double vision (diplopia)
-Bilateralparesthesia or anesthesia
-Drop attack: falling to the ground without loss of consciousness.

299

Symptoms frequently seen with PCA lesions

-Dyslexia
-Coma
-Paralysis usually does not occur

300

Non-localizing symptoms

-Dizziness- sensation of whirling with a tendency to fall
-Syncope- transient loss of consciousness
-Severe headache

301

What could overestimate disease in the carotids? Underestimate?

Overestimate:
-Increased cardiac output
-Tortuous vessel
-Compensatory flow
-Inappropriate Doppler angle

Underestimate:
-Poor cardiac output
-Jet of accelerated flow missed
-Long, smooth plaque formation
-Stenosis at area of dilatation, i.e. carotid bulb
-Inappropriate Doppler angle

302

Carotid Doppler signals

1. Stenosis; High pitch sound and waveform with higher velocity; Spectral broadening is evident; Loss of spectral window also represents loss of laminar flow.
2. Distal to stenosis: Disturbed flow patterns e.g. turbulent, bi-directional, then can become dampened and monophasic/continuous.
3. Consider disease at carotid siphon when high resistant flow patterns are evident in the ICA; Disease is distal.
4. Diminished CCA velocities bilaterally may indicate poor cardiac output or stroke volume.
5. Diminished velocities unilaterally suggests proximal disease e.g. innominate or common carotid artery.
6. Essential to compare flow characteristics bilaterally; and proximal to distal segments of ipsilateral vessel.

303

Categorizing Carotid Disease

Based on 60 degree angle of insonation

Normal = 125 cm/sec PSV and 125 cm/sec PSV and >140 cm/sec EDV
Occluded = Absent PSV and EDV

NASCET Criteria: > or = to 70%
ICA/CCA Ratio - > or = to 4.0

*CCA velocity should be obtained somewhere in the mid to distal CCA approx. one transducer length from the bifurcation.

304

Criteria critical in determining carotid occlusion

-CCA may have a very low or absent diastolic component. (high resistant)
-Evidence of collateralization e.g. ECA may exhibit high flow in end diastole.
-Absent ICA Doppler signal or pre-occlusive thump
-Although an absent signal may indicate occlusion, a tight stenosis (also termed string sign) cannot be ruled out.

305

Aliasing

-PRF is too low
-Maximum frequency is 1/2 the PRF (Nyquist limit)
-Increase PRF by:
-Decrease baseline; Increase Doppler scale
-Change transducer frequency
-Alter angle of insonation
-Decrease depth
-Use CW Doppler

306

Mirror Imaging

-Doppler Shifts above and below the baseline
-Display duplicate spectrum or color-flow Doppler
-Artifact from strong reflectors (pleural lining) or too much gain

307

Helical flow

-Occurs when flow moves intro wider portion of the vessel (e.g. carotid bulb, AAA)
-Spectral waveforms are different above and below the baseline
-Doppler angle constantly changing
-Flow is not laminar; spectral broadening present

308

Carotid intraoperative monitoring

-Identification of defects secondary to surgery and/or areas of platelet aggregation.
-Evaluates hemodynamically significance of wall irregularity
-Use highest frequency transducer (>= 12MHz)
-Sterile sleeve or plastic bag containing acoustic gel
-Wound filled with sterile saline
-Areas of flow disturbance identified with color flow Doppler
-Gray scale imaging critical in detecting subtle wall defects.

309

What are the capabilities of Transcranial Doppler?

-Detect intracranial stenosis, occlusions, and assess collateral circulation.
-Evaluate onset, severity, and time course of vasoconstriction from subarachnoid hemorrhage
-Evaluate intracranial arteriovenous malformations
-Assess patients with suspected brain death

310

What are some limitations associated with transcranial Doppler?

-Recent eye surgery may eliminate transorbital approach.
-Inadequate penetration of temporal bone from hyperostosis
-Inaccurate vessel identification with non-imaging technique

311

Patient positioning for transcranial Doppler

Patient should be supine and avoid speaking during exam

312

Important points related to transcranial Doppler

-2 MHz pulsed Doppler used with spectrum analysis
-Zero angle of insonation is assumed
-Three acoustic windows used: Transtemporal, transorbital, and transforaminal/suboccipital

-Accurate vessel identification requires:
-Depth of sample volume
-Velocity of blood flow
-Direction of blood flow
-Relationship of flow patterns to one another

-Time averaged maximum velocity (TAMV) or mean velocity used

313

What is the technique associated with transcranial Doppler?

-Unilateral transtemporal approach for MCA, ACA, PCA, and terminal ICA
-Ipsilateral transorbital approach to evaluate ophthalmic artery and carotid siphon
-Preceding two steps completed contralaterally
-Transforaminal/suboccipital approach used to evaluate the intracranial vertebral and basilar arteries
-Inappropriate Doppler angle usually negates ability to insonate posterior communicating (PCom) arteries. However, flow direction is normally from anterior to posterior.

314

Interpretation of transcranial Doppler

1. Flow: Direction, velocity, turbulence, pulsatility, systolic upstroke.
2. Collateral pathways: Antegrade flow in anterior cerebral artery (ACA) from cross-over collateralization, e.g. flow from contralateral ACA via anterior communicating artery; External to internal is retrograde flow in ophthalmic artery (OA); Posterior to anterior is increased flow in posterior cerebral artery (PCA), reversing direction of flow in the PCom artery.
3. Factors that may alter intracranial blood flow (age, sex, hematocrit, blood gasses, metabolism)
4. Occlusion: Most accurate in ICA or MCA; Criteria similar to those used in other vessels.
5. Vasospasm: Most accurate in MCA; serial recordings necessary; Mean velocities >120 cm/sec, severe vasospasm = >200 cm/sec
6. Arteriovenous malformation: Increased systolic and diastolic flow velocities; Very low pulsatility indices; reduced flow in adjacent arteries.

315

Intraoperative transcranial monitoring

-Identification of flow abnormalities may warrant change in surgical technique
-Headset used for continuous monitoring
-Not working in sterile field
-Significant decrease in MCA flow velocities during cross-clamping of vessel may indicate need for shunting
-Audible signals related to micro-emboli may alter surgical technique.

316

Subclavian Steal

-Subclavian occlusion results in retrograde flow in ipsilateral vertebral artery; Also its high resistive
-Alternating flow usually correlates with angiographic evidence of high-grade subclavian stenosis. Tu-Fro flow in the vertebral
-Pts. are usually asymptomatic; arm claudication is rare.
-May have BP difference of >= 15-20 mmHg; may have decreased pulses in affected arm.
-Ipsilateral vertebral artery feeding high-resistance vascular bed
-Surgical treatment may include a bypass graft or endarterectomy.

317

Temporal arteritis

-Inflammation of the arterial wall of the superficial temporal artery or its branches.
-Inflamed arterial segments often larger in diameter with homogeneous thickening evident on B mode
-An anechoic "halo" from edema of the intima may be seen
-Intimal thickening may result in significant stenosis where PSV's are doubled

318

Misc. Diagnostic tests

1. Arteriography- Abnormalities include filling defects, absent vessels, aberrant anatomy; Percent stenosis calculated.
2. MR Angiography- Extremely sensitive to the presence of stenosis but tends to overestimate the disease process; May be used when carotid duplex study is equivocal or technically limited.
3. CT-
most frequent application in cerebrovascular disease; Evaluate the nature of cerebral infarctions, intracranial aneurysms, hemorrhage, and AVM's

319

What are Venae comitantes?

-The paired deep veins of the calf follow corresponding arteries.
-Corresponding veins

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Paired Peroneal Veins (PerV)

-Formed by confluence of venules
-Empties lateral leg
-Paired veins may form common trunk and carry blood cephalad into tibial-peroneal trunk.

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Paired Posterior Tibial Veins (PTV)

-Formed by confluence of venules
-Empties back of leg
-Paired veins may form common trunk and carry blood cephalad into tibial-peroneal trunk.

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Paired Anterior Tibial Veins (ATV)

-Formed by confluence of venules
-Empties front of leg

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Popliteal Vein (PopV)

-Formed by union of the ATV and Tib-peroneal trunk.
-Usually just below the knee
-Becomes femoral vein when passes through adductor hiatus in lower thigh

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Femoral Vein (FV)

-Popliteal vein becomes femoral vein when vein passes through the adductor hiatus

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Common Femoral Vein (CFV)

-Formed by joining of FV and deep femoral vein

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External Iliac Vein (EIV)

-CFV becomes EIV when vein passes through inguinal ligament

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Common Iliac Vein (CIV)

-Formed by confluence of external and internal iliac veins.
-Because the left common iliac vein passes under the right common iliac artery, extrinsic compression may be evident. This pressure point may account for left sided DVT; Also known as May-Thurner Syndrome

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Inferior Vena Cava (IVC)

-Formed by confluence of common iliac veins
-Commonly at level of 5th lumbar vertebra
-Carries blood into the right atrium of the heart

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Superficial Veins LE

1. Small saphenous (formerly Lesser) vein (SSV); Ascends back of calf joining popliteal vein.
2. Great (formerly greater) saphenous vein (GSV)
-Longest vein in body originating on dorsum of foot; travelling medially to saphenofemoral junction in the groin (about level of CFA bifurcation)

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Perforators

-Carry blood from superficial veins into deep veins
-Posterior Arch Vein: Has three ankle perforators; Plays a major role in development of venous stasis ulcers.
-SSV has an important lateral perforating branch

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Venous Sinuses

-Intracranial: Spaces between Dura mater and periosteum that drain blood into the IJV.
-LE: Dilated channels in soleal and gastrocnemius muscles; Drains blood into the PTV and PerV; Major part of calf muscle pump.

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Paired Radial Veins (RadV)

-Formed by confluence of venules
-Empties lateral hand and forearm

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Paired Ulnar veins (UlnV)

-Formed by confluence of venules
-Empties medial hand and forearm

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Paired Brachial Veins (BraV)

-Formed by confluence of radial and ulnar veins

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Axillary Vein (AxV)

-Formed by confluence of brachial vein and basilica vein (basilic vein in superficial system)

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Subclavian Vein (SubV)

-Formed by confluence of axillary vein and cephalic vein (cephalic vein in superficial system)

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Innominate Vein (InnV)

-Formed by confluence of subclavian vein and internal jugular (also called brachiocephalic)

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Superior Vena Cava (SVC)

-Formed by confluence of right and left innominate veins
-Carries blood to right atrium

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Superficial Veins (UE)

1. Basilic vein- Formed by the digital veins; Empties medial aspect of the arm; Joins brachial vein to form axillary vein; Can be harvested for arterial bypass conduit
2. Cephalic vein- Formed by digital veins; Empties lateral aspect of the arm; Joins axillary vein to form subclavian vein; Can be harvested for arterial bypass conduit.

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Central Veins

1. Superior Vena Cava (SVC)- Formed by confluence of innominate veins; Drains head and upper extremity veins; Terminates in right atrium.
2. Inferior Vena Cava (IVC)- Formed by confluence of common iliac veins; Drains lower half of body; Terminates in right atrium.
3. Portal system-
Portal vein- Formed by superior mesenteric and splenic veins; Drains abdominal part of digestive tract, pancreas, spleen, and gall bladder; carries blood into sinusoids of the liver (hepato-petal flow); Carries approx. 80% of blood flow to the liver.
Hepatic vein- Carries blood from the liver into the IVC (Flow away from liver is hepato-fugal)
4. Renal veins- Empty into the IVC

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Structural anatomy of veins

-Thin walled, collapsible tubes that transport blood from capillaries toward heart.
-Carry away waste products of cellular activity
-Not passive structures; have reactivity, also called veno-motor tone; contraction of smooth muscle cells can occur in response to sympathetic nervous system stimulation (temp, exercise, stress).
-Same three layers as arteries; med. layer very thin
-Venous system starts at capillary level with progressive increase in size.
Venous valves
-Extensions of intimal layer
-Bicuspid structures providing unidirectional flow
-Valves of lower extremities more susceptible to disease e.g. secondary to the effects of venous thrombosis; increased ambulatory venous pressure due to gravity.

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What is the largest vein? Smallest?

Vena Cava
Venules

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Veins without valves

-Soleal sinuses
-External iliac vein; contains valves approx. 25% of the time
-Common iliac and internal iliac
-Innominate
-Superior and inferior vena cava

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Veins with valves

-GSV has approx. 12 valves most BK
-SSV 6-12 valves
-Perforators: Each contains a valve
-Infrapopliteal (deep veins): 7-12 valves each
-Popliteal and femoral: 1-3 valves each
-EIV: contains valves approx. 25% of the time.
-Common femoral- 1 valve
-Jugular vein - 1 valve
-Basilic and Cephalic
-Variable number in UE deep veins

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Venous resistance

1. Peripheral venous and arterial resistances are similar
-Both arteries and veins carry the same amount of blood flow
-This is explained by the colllapsable nature of the venous wall
2. Flattened shape offers more flow resistance than circular shape.

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Venous pressure/volume relationships

1. When distended, cross-sectional area of the vein is about 3-4 times that of the corresponding artery. The extra-pulmonary veins carry about 2/3's of the blood in the body.
2. Shape of veins determined by transmural pressure (pressure within the vein vs. pressure outside the vein.)
-Low transmural pressure: low volume of blood results in dumbbell shape.
-High transmural pressure: high volume results in circular shape.
3. Small pressure changes can expand or distend vein from normal dumbbell shape to a circular one.

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Hydrostatic pressure

-Equivalent to the weight of a column of blood pressing against the vessels of the body; uses the heart as a reference point (HP is zero at heart)
HP=PGH
P=specific gravity of blood
G= acceleration due to gravity
H= distance from the heart
-HP is added to the existing circulatory pressure and is related to position

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Factors affecting Venous flow

1. Venous/skeletal muscle pump/ "venous heart"
-Veins are reservoirs for blood collection
-Muscle contraction squeezes vein propelling blood toward heart; Effective pump blood moves from superficial to deep system, valves prevent reflux, volume and pressure decrease, venous return increase; Ineffective pump incompetent valves cause reflux, volume and pressure increase, results in venous pooling/ambulatory venous HTN
2. Respiration
-Inspiration: Decrease in intra-thoracic P; Increases blood flow from UE; Increase in intra-abdominal P; Decreases blood flow from LE
Exhalation: Increase intra-thoracic P; Decrease blood flow from UE; Decrease in intra-abdominal P; Increased blood flow from LE
3. Valsalva Maneuver; Pt. takes a deep breath and holds it, then bears down; intra-thoracic and intra-abdominal P increase significantly; all venous return is halted; This maneuver equates with proximal compression while performing Doppler of the LE.

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Most common findings of DVT

-Swelling
-Pain
-Redness
-Warmth

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Differential diagnosis of DVT

-Muscle strain
-Direct injury to leg
-Baker's cyst
-Cellulitis
-Heart failure
-Extrinsic Compression

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Most common findings: Chronic Venous Disease

-Swelling
-Heaviness
-Discoloration
-Ulcers
-Varicosities

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Skin changes associated with venous disease

-Induration of tissue (edema): Fluid accumulation
-Redness (erythema): Inflammatory process e.g. cellulitis
-Brownish discoloration (brawny): Venous stasis usually lower leg-to-ankle area (gaiter zone)
-Whiteness (pallor): arterial spasms secondary to extensive, acute, iliofemoral thrombosis; limb threatening; called phlegmasia alba dolens.
-Bluish discoloration (cyanosis): Severely reduced venous outflow from iliofemoral thrombosis markedly reduces arterial inflow; limb threatening; called phlegmasia cerulean dolens.

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Venous ulcers vs. Arterial ulceration

Venous:
-Often near medial malleolus
-Shallow, irregular shape
-Stasis changes: e.g. inflammation, brawny discoloration, presence of varicosities.

Arterial:
-Tibial area, bony prominences
-Deep, regular shape
-Trophic changes: e.g. dry, scaly skin, loss of hair, thickened toenails.

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Edema

-Edema: Body tissue contains an excessive amount of fluid.
-"Pitting" edema: Fluid in subcutaneous tissue; Depression of skin surface with manual pressure; Can be related to many conditions (fluid retention, CHF, elevated venous pressure.

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Lymphedema

-Not related to DVT; Usually related to cancer treatment.
-Normally, lymphatic system drains excess fluid from tissue. Fluid accumulates when lymph nodes and/or lymph vessels are removed or damaged.
-Frequently seen after many types of cancer surgery.
-Non-pitting edema

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Paget-Schroetter Syndrome

-Stress/effort thrombosis
-Involves axillary or subclavian vein
-Venous component of TOS

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Superior Vena Cava (SVC) syndrome

-Obstruction, e.g. neoplasm, dialysis catheter, central lines.
-Edema and engorgement of vessels evident.
-Pt. may have cough and/or difficulty breathing.
-Flow in the UE remains the same during inspiration i.e. continuous flow.

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Virchow's Triad

1. Trauma to vessel/endothelial damage
2. Venous stasis- immobility, COPD, obesity, pregnancy, previous DVT, extrinsic compression.
3. Hypercoagulability- e.g. certain protein deficiencies, pregnancy, cancer, hormones, i.e. estrogen intake.

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Acute Thrombosis

1.Intraluminal thrombi frequently begin at valve cusps or in soleal sinuses secondary to stagnation.
2.Thrombi resulting from trauma occur at any site.
3. Sequelae:
-Chronic venous insufficiency; stretching of walls results in damage to valves; Increased venous pressure causes flow changes.
-Post-phlebitic syndrome; chronic flow changes result in persistent edema, stasis changes and pain; may also lead to ulceration.
-Pulmonary embolism; Thrombus breaks loose; travels into pulmonary circulation; CTA chest and pulmonary angiography are currently the definitive diagnostic tools; can be life threatening.

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Valvular Incompetence

-Valve no longer maintain unidirectional flow
-Calf muscle pump no longer forces blood back towards heart or from superficial system into deep.

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Results of Venous Incompetence

-Increased pressure/venous hypertension
-Ambulatory venous hypertension: increasing pressure when patient stands or walks.
-Precipitates varicosities
-Fluid, red blood cells, and fibrinogen may leak into surrounding tissue; hemosiderin, from breakdown of stagnant red blood cells, cause brawny discoloration.
-Breakdown of other substances prevents proper tissue nutrition and oxygenation, leading to ulceration.

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Varicose Veins

Primary- Dilated veins secondary to valvular incompetence of superficial system; deep system intact.

Secondary- Dilated veins caused by incompetence of the superficial system resulting from a deep venous obstruction; Deep system not intact.

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Portal Hypertension

-Elevated venous pressure results from obstruction of blood flow; May result in reverse (hepato-fugal) flow in the portal vein and increased portal venous pressure that impedes blood flow into the liver.

-Usually related to some form of advanced chronic liver disease, e.g. hepatitis C; cirrhosis

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Miscellaneous Venous Disease

1. Congenital Venous Disease
-Avalvular (valveless) vein (s)
-Arteriovenous malformations (AVM)
-Syndromes: Klippel-Trenaunay- can include multiple varicosities of the superficial system and hypoplastic or absent deep veins.
2. IVC tumor
-Renal cell carcinoma is the most common solid renal mass in the adult.
-The most common cause of an IVC tumor is renal cell carcinoma.

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Electric coupling (Photo-Plethysmography)

-Method to increase gain and display signal
-Only two types available: DC and AC
-Allows one type of current to pass and blocks the other type.

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DC coupling

-Direct current
-Electric voltage that is either positive or negative
-Current flows in only one direction
-Batteries are DC
-Detects slower changes in blood content
-Used for Venous studies

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AC coupling

-Alternating current
-Electric voltage that reverses polarity (positive or negative) 60 times a second.
-Current flows in both directions
-Wall plugs deliver 120 volts of AC
-Detects fast changes in blood content
-Used for arterial studies

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What are some limitations of continuous wave Doppler for venous evaluation?

-Unable to differentiate abnormal flow patterns from DVT versus extrinsic compression i.e. tumor, ascites, pregnancy.
-Normal flow patterns may be evident with partial or well collateralized thrombosis
-Paired deep veins in calf limit diagnosis of an isolated calf clot.
-Requires a very experienced tech
-Sources of false positives: Extrinsic compression; improper pt. position; PAD (reduced venous filling); COPD; Doppler angle
-Sources of false negatives- Collateral development; Presence of bifed system (multiple deep veins)

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What is considered the "gold standard" in venous testing?

Contrast venography

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Sensitivity

The ability of a test to detect disease

Sensitivity = # of true positive tests /
# of all positive diagnoses
detected by the gold standard

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Specificity

The ability of a test to identify normalcy

Specificity = # of true negative tests/
# of all negative diagnoses
detected by the gold standard

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Positive Predictive value (PPV)

How often a positive study is correct

PPV = # of true positive tests/
# of all positive noninvasive studies (true
positives and false positives)

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Negative Predictive value (NPV)

How often a negative study is correct

NPV = # of true negative tests/
# of all negative noninvasive studies (true
negatives and false negatives)

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Accuracy

How good a test is

Accuracy = Total # of correct tests/
Total # of all studies

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What are the capabilities of a Duplex/color flow venous exam for peripheral veins?

-Identify venous thrombosis (differentiate acute from chronic)
-Evaluate non-occluding/partial thrombus
-Detect calf lesions
-Distinguish between extrinsic compression and intrinsic obstruction
-Evaluate soft tissue masses
-Detect venous incompetence
-Document collateralization

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What are the capabilities of a Duplex/color flow venous exam on the abdominal and pelvic veins?

-Assist with documenting elevated systemic venous pressure.
-Identify venous thrombosis
-Evaluate patency of IVC interruption devices
-Assess portocaval shunts

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What are some limitations to a duplex/color flow venous exam?

-Visualization may be sub-optimal secondary to edema, scarring, recent surgery, obesity (use low frequency transducer)
1. False positive studies could be caused by: Extrinsic compression; PAD; COPD; Improper Doppler angle
2. Sources of false negative studies: Proximal obstruction; technically limited studies
3. Peripheral veins LE- May be difficult to thoroughly evaluate infra-popliteal veins secondary to vessel size, depth, and course.
4. Peripheral veins UE- Difficult to thoroughly evaluate subclavian and brachiocephalic/innominate veins secondary to bony structures.
5. Abdominal and pelvic veins- May be difficult to evaluate veins due to vessel depth and/or presence of bowel gas.

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What is the proper patient positioning for a venous duplex/color flow exam?

1.Peripheral veins LE: Facilitate venous filling (reverse Trendelenburg); Diminish extrinsic compression (lateral decubitus); For reflux testing when pt. is standing he/she bears weight on the contralateral leg.
2. Peripheral veins UE: Supine or low fowlers position; Arm in pledge position.
3. Abdominal and pelvic veins: Supine with head slightly elevated; Left lateral decubitus with head of bed elevated slightly; Reverse Trendelenburg; Whatever works!