Cardio Formulas and Cardiology Flashcards
(155 cards)
1
Q
Velocity of blood flow
A
v = volume of blood flow/cross sectional area
2
Q
Blood flow is also the
A
Ohm’s law
3
Q
Blood flow formula
A
Flow rate = P1 - P2/Resistance
4
Q
Tendnecy for turbulent flow =
A
Reynolds number = (velocity of blood flow x diameter x density) / viscosity
Re = vdp/n
cm/sec, cm
Greatest in proximal aorta and pulmonary artery
5
Q
Resistance of the entire peripheral circulation =
A
TPR = 100mmHg (Pa - Pv)/ 100ml/sec (CO or blood flow)
6
Q
Total pulmonary vascular resistance =
A
TPVR = (16 - 2)/100
(Pulmo artery pressure - left atrial pressure)/ 100 (CO, blood flow)
Total pulmo vascular resistance = 0.14 PRU
7
Q
Conductace =
A
Conductance = 1/ resistance
8
Q
Conduntance of vessel
A
inc in proportion to fourth power of diameter
C inc in proportion to fourth power of diameter
9
Q
The great inc in conductance when diameter inc is exemplified by
A
Poiseuille’s law
10
Q
Velocities of all concentric rings of flowing blood x areas of the ring
A
Poiseuille’s law
11
Q
Poiseuille’s law =
A
Rate of Flow = pie(pressure difference between ends of vessels)radius raised to the 4th power / 8(viscosity)(length=1)
12
Q
The greatest role of all factors in determining rate of blood flow
A
Diameter
13
Q
2/3 of total systemic resistance to blood flow comes fr
A
arterioles
14
Q
Arterioles regulate blood flow by
A
Turning off blood flow (arterioloconstriction) and inc flow by 256fold by arteriolodilation
15
Q
The flow through artery, arteriole, cap, venule and vein are arranged in
A
Series
Rtotal = R1 + R2 + R3
16
Q
Blood flow to organs are arranged in
A
Parallel
1/Rtotal = 1/R1 + 1/R2
Total conductance = C1 + C2
Amputation of limb or removal of kidney reduces total vascular conductance and total blood flow (CO) inc total peripheral vasc resistance
17
Q
Viscosity of blood is
A
3x as great as water
18
Q
Vascular distensibility =
A
Vascular distensibility = inc in volume / inc in pressure x original volume
fractional inc in volume for each millimeter of mercury rise in pressure
19
Q
Vascular compliance =
A
VC = inc in volume/inc in pressure
Compliance = distensibility x volume
So a highly distensible vessel may have far less complaince than a vessel with large volume
20
Q
Pulse pressure =
A
pulse pressure = stroke volume/arterial compliance
21
Q
Damping =
A
Damping = resistance x compliance
22
Q
MAP is not just average of systolic and diastolic pressure bec
A
Bec greater fraction of cardiac cycle is spent in diastole
60 Diastolic
40 Systolic
23
Q
MAP =
Averahe arterial pressure with respect to time
A
MAP = (SBP + 2DBP)/3
Diastolic pressure + 1/3 of pulse pressure
24
Q
Four primary forces determining fluid movement in capillary membrane:
A
Starling forces
1 Capillary pressure
2 Interstitial fluid pressure
3 Capillary plasma colloid osmotic pressure
4 Interstitial fluid colloid osmotic pressure
25
Net Filtration Pressure =
NFP = (Pc-Pif)-(Plasmacoll+Ifcolloid)
26
Filtration=
Filtration= capillary filtration coeff x NFP
27
Plasma colloid osmotic pressure is 28 mmHg; 19 by proteins and 9 by Na, potassium and cations. Extra osmotic pressure is called
Donnan effect
28
Physiologic properties of the heart:
All or none principle
No fatigue, no tetany
Duration of cardiac muscle contraction is a function of the duration of the action potential
29
Is the principle that the strength by which a nerve or muscle fiber responds to a stimulus is not dependent on the strength of the stimulus
All-or-none Law
30
If the stimulus is any strength above threshold, the nerve or muscle fiber will give a complete response or otherwise no response at all
All-or-none law
31
Increase in contractility
Positive inotropic effect
32
Decrease in contractility
Negative inotropic effect
33
Ability to initiate its own beat
| Ability to generate spontaneous action potential
Automaticity
34
Regularity of such pacemaking activity
Rhythmicity
35
Fibers of SA node connect with surrounding atrial muscles
Conductivity
36
Conduction velocity in atrial muscle
0.3-0.5 m/sec
37
Ability of the heart to initiate an action potential in response to an inward depolarizing current
Excitability
38
Smallest branches of the arteries
Arterioles
39
The site of highest resistance in the cardiovascular system
Alpha 1 and beta 2 adrenergic
Arterioles
40
Arteriole SNS receptors
Alpha 1 and beta 2 adrenergic
41
Contains the highest proportion of blood in the cardiovascular system
Largest total unstressed blood volume
Thin walled
Low pressure
Alpha 1 adrenergic
Veins
42
Gas and nutrients exchange in the cardiovascular system
Largest total cross sectional and surface area
Capillaries
43
A collapsed larger lumen
Thin wall
No Internal elastic lamina
Tunica media has large quantity of collagen (few smooth muscles and less elastic fibers) that is the reason they are easily compressed
Tunica adventitia is thicker than tunica media in large veins
Presence of valves to prevent back flow
Medium sized vein
44
Thick wall
Arteries retain their patency
Internal elastic lamina is present only in arteries
Tunica media is thicker than adventitia
Medium sized artery
45
Inotropic drugs
Dopamine
| Dobutamine
46
Pacemaker of heart
Located near:
SA Node
Sulcus terminalis and SVC as it enters the right atrium
47
Formed bt the left and right brachiocephalic/innominate vein
SVC
48
Level at which the SVC is formed
1st right costal cartilage
49
Send blood from the heart
High pressure
Narrow lumen diameter
Thick walled
Wall layers:
T. Adventiria
T. Media
T. Intima
Large amounts of muscle and elastic fibers
No valves
Arteries
50
Change in HR
Chronotropic
51
Change in conduction velocity
Dromotropic
52
Send blood to the heart
Low pressure
Wide lumen diameter
Thin walled
Wall layers:
T. Adventitia
T. Media
T. Intima
Small amounts of muscle and elastic fibers
With valves
Veins
53
Thick walled
| Extensive elastic tissue and muscles
Artery
54
Material exchange with tissues
Low pressure
Extremely narrow lumen diameter
Extremely thin walled
Wall layers:
T. Intima
No muscle and elastic fibers
No valves
Capillaries
55
Receives blood from left ventricle
Aorta
56
Transport under high pressure, strong vascular walls
Arteries
57
Control conduits, last branch of arterial system, strong muscular walls that can strongly constrict or dilate
Arteriole
58
Exchange substances through pores
Capillaries
59
Collect blood from capillaries
Venules
60
Low pressure, transport blood back to the heart, controllable reservoir of extra blood
Veins
61
Means blood flows crosswise in the vessel and along the vessel
Forms whorls in the blood called
Turbulence
Eddy currents
62
Normal blood flow is
Laminar
63
Turbulence occurs when
```
Radius is large (aorta)
Velocity is large (cardiac output)
Vessel diameter (arterial stenosis)
Low viscosity (anemia)
Density of blood
```
64
Reynolds number of 2000 or less is
Laminar
65
Reynolds number is inversely proportional to the
viscosity
66
Pressure gradient and blood flow
directly proportional
67
Pressure gradient and viscosity
Directly proportional
68
A high Reynolds number meant
A high possibility of turbulence
69
Pressure gradient and length
Directly proportional
70
Pressure gradient and fourth power of radius
Inversely proportional
71
Pressure gradient and flow rate
Directly proportional
72
Flow rate and vascular resistance
Inversely proportional
73
Volume of blood passing through per unit of time
Flow rate
74
Difference between the systolic and diastolic pressures
SBP-DBP
Pulse pressure
75
Most inportant determinant of pulse pressure
Stroke volume
76
Pulse pressure is increased in aging population because of
Decreased capacitance
77
MAP is maintained at
110-130
78
MAP also =
CO x SVR + CVP
79
The highest arterjal pressure during a cardiac cycle
Occurs when the heart contracts and blood is ejected into the arterial system
Systolic pressure
80
Lowest arterial pressure in the cardiac cycle
Occurs when the heart is relaxed and blood is being returned to the heart via the veins
Diastole
81
Fall in the pressure by 20mmHg and or >10 mmHg diastolic in resposne to moving from supine to standing
Orthostatic hypotension
82
At least 2 separate clinic-based measurements
>140/90 mmHg
and at least 2 non clinic measurements <140/90 mmHg in the absence of end organ damage
White coat hypertension
83
PD
Rigidity, tremors
Dysautonomia
Hypotension
Shy-Drager syndrome
| Multiple Systems Atrophy
84
Cardiac Output =
CO = HR x SV
85
Cardiac reserve
If resting, CO is
After exercise,
6L/min
Inc to 21 L/min
Cardiac reserve?
CR = 21-6 L/Min
86
Atrial contraction forces blood into ventricles
P wave
Atrial depolarization
Atrial systole
87
Ventricular contraction pushes AV valves closed
AV Closure
QRS Complex
Ventricle depolarization
```
Ventricular systole (first phase)
Atrial Diastole
```
88
Semilunar valves open and blood is ejected
T wave ventricular repolarization
Ventricular systole second phase
| Atrial diastole
89
Absence of p wave is seen in
atrial fibrillation
90
```
Preceded by the p wave
Activation of stria
Contributes to ventricular filling
Increase in atrial pressure (A wave)
Ventricular hypertrophy
Fourth heart sound
```
Atrial systole
91
Begins at QRS complex
Activation of ventricles
AV valves close when V pressure is greater than A pressure
Closure of AV valves -> S1, ventricular pressure increases, no blood leaves yet because aortic valve is CLOSED
constant ventricular volume
Isovolumetric ventricular contraction
92
Max V pressure
C wave on venous pulse curve due to bulging of tricuspid valve intro right atrium, aortic valve opens
Ventricular volume decreases dramatically
Atrial filling begins
Onset of T wave (repolarization)
Rapid ventricular ejection
93
Slower ejection of blood
Ventricular pressure decrease
Aortic pressure decreases
Runoff of blood from large arteries to smaller arteries
Atrial filling
V wave (blood flow into right atrium, rising phase)
Flow to right atrium into right ventricle (falling phase)
Reduced ventricular ejection
94
Chambers relax and blood fills ventricles passively
```
Ventricular diastole (late)
Atrial diastole
```
95
SV =
```
SV = EDV - ESV
Normal = 120-50 = 70ml
```
96
Ejection fraction =
EF = SV/EDV
Normal is 70/120 = 58%
97
Extrinsic control of Stroke Volume: SNS
```
Arterial muscle (increases contractility)
Ventricular muscle (increases contractility)
Adrenal medulla (increase epinephrine augments the sympathetic actions on the heart)
Veins (increase venous return)
```
98
Contraction of atria
| Absent in atrial fibrillation
A wave
99
```
Ventricular contraction (tricuspid bulges)
Won’t see
```
C wave
100
There are two positive waves
One occuring just before the first heart sound or the carotid impulse
One just after
When HR is 80 or less, they are fairly easy to time. But if the heart rate is fast, you may need to asucultate while you observe.
A (atrial contraction, absent in atrial fibrillation)
V waves
101
Descent
| Atrial relaxation
X wave
102
Atrial venous filling
| Occurs at the same time of ventricular contraction
V wave
103
Descent
Ventricular filling
Tricuspid opens
Y descent
104
Intrinsic control of SV
Inc strength of cardiac contraction
Inc EDV
Inc venous return
105
Conditions with elevated a wave
Resistance to atrial emptying may occur at or beyond the tricuspid valve
Pulmonary hypertension
Rheumatic tricuspid stenosis
Right atrial mass or thrombus
106
Large positive venous pulse during a wave
| It occurs when an atrium contracts against a closed tricuspid valve during AV dissociation
Premature atrial/junctional/ventricular beats
Complete atrio-ventricular (AV) block
Ventricular tachycardia
107
Most common cause of elevated v wave
Tricuspid regurgitation
| Lancisi sign
108
The ventricle contracts and if the tricuspid valve does not close well, a jet of blood shoots into the right atrium
Tricuspid regurgitation if significant will be accompanied by a pulsatile liver (feel over the lower costal margin)
You will also hear the murmur of tricuspid regurgitation - a pansystolic murmur that increases on inspiration
Elevated v wave
109
Neck veins rise in inspiration rather than fall
Seen in pericardial tamponade
Right heart failure
Acute right ventricular MI
Kussmaul’s sign
110
Exaggerated x wave or diastolic collapse of the neck veins
From constrictive pericarditis
Friedrich’s sign
111
Initial depolarization of ventricle
| Conduction velocity through AV node
PR interval
112
Ventricular depolarization
QRS Complex
113
Entire ventricular depolarization and repolarization
QT interval
114
Muscle length prior to contractility
| It is dependent of ventricular filling or EDV
Preload
115
Period when ventricles are depolarized
ST segment
116
Ventricular repolarization
T wave
117
Preload =
EDV
118
RMP of ventricle, atria and Purkine
-90mV
119
Upstroke
| Increase in Na conductance
Phase 0
120
Initial repolarization
Brief
K ions move out
Na decrease conductance
Phase 1
121
Plateau
| Transient increase in calcium conductance, inward Ca
Phase 2
122
Calcium conductance decrease
K increase
Membrane hyperpolarizes
Phase 3
123
Resting membrane potential
Phase 4
124
This value is related to right atrial pressure
Preload
125
Most important determining factor for preload is
venous return
126
Conduction system
SAN -> AVN -> AV bundle -> Bundle branches -> Purkinje fibers
127
The tension or arterial pressure against which the ventricle must contract
If arterial pressure increases,
this also increases
Afterload
128
Provides direct flow of current from the atrium to ventricle
Cardiac skeleton
129
Slowest velocity of conduction is in the
AV Node
130
Fastest conduction of velocity in the
Purkinje fiber
131
Afterload =
End systolic wall stress
| Resistance
132
AV Node is in
Triangle of Koch
133
Boundaries of Triangle of Koch
Septal leaflet of tricuspid valve
Opening of coronary sinus
Tendon of Todaro
134
SA NODE aka
Node of Keith and Flack
135
Lies in the sulcus between superior vena cava and right atrium
Exhibits self excitation
SA Node
136
RMP of SA Node
-55 mv to -60 mv
137
Volume of blood pumped per minute
CO = HR (75) x SV (70)
About 5.25 L/min
Cardiac output
138
Difference between resting and maximal cardiac output
Cardiac reserve
139
Volume of blood that filles the ventricle during diastole or relaxation
EDV
| 120 ml
140
Anterior internodal pathway
Bachmann
141
Middle internodal pathway
Wenkebach
142
Posterior internodal tract
Thorel
143
Volume of blood remaining in ventricle after systole
ESV
| 50 ml
144
Difference between EDV and ESV
Stroke volume
145
Found in the posterior wall of the right atrium
Behind the tricuspid valve near the opening of the coronary sinus
Delay of impulse transmission
Small bundle fibers
Less number of gap junctions
Atrio-Ventricular Node
146
Divides into one single right bundle branch and 2 branches of left bundle (anterior and posterior fascicles)
His Bundle
147
Merges with myocardial fibers
Conduction velocity is rapid
Higjly permeable gap junctions
Large fibers
Purkinje system
148
CV Response to exercise
| Central command
Inc Sympathetic outflow
Dec Parasympathetic outflow
```
Inc heart rate
Inc contractility
Inc cardiac output
Constriction of arterioles (splanchnic and renal)
Constriction of veins
Inc venous return
```
Inc blood flow to skeletal muscle
149
Exercise
| Local responses
Inc vasodilator metabolites
Dilation of skeletal muscle arterioles
Dec TPR
Inc blood flow to skeletal muscles
150
Long QT syndrome pathogenecity genes
HERG gene (K channel gene chromosome 7)
SCN5A gene (Na gene chromosome 3) Brugada
syncope
151
Polymorphic ventricular tachycardia
Hypokalemia
with long QT interval
Torsade de pointes
152
Lead II, III, aVF
Inferior
153
Lead I and aVL
| V5, V6
Lateral
154
Lead VI, V2
Septal
155
V3, V4
Anterior
