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Flashcards in Aortic Surgery- Exam 2 Deck (115):
1

What is the goal of aortic surgery?

Enable aortic repair while limiting ischemic injury to the CNS

2

We utilize different perfusion strategies depending on what?

What portion of the aorta is affected

3

What are the 4 portions of the aorta?

Ascending
Arch
Thoracic
Descending

4

What are the two different types of aortic conditions?

Aneurysms
Dissections

5

Ascending Aorta

Begins at the AV annulus and extends to the proximal innominate artery

6

Transverse Arch

Where 3 brachiocephalic branches arise

7

How does the treatment for ascending and transverse arch compare?

Very similar

8

Descending Thoracic and Thoracoabdominal Aorta

Lies just beyond the subclavian to the aortoiliac bifurcation

9

Dissection

Occurs when blood penetrates the intima of the aorta; creates an expanding hematoma between medial layers; true lumen is not usually dilated/compressed by dissection

10

Are the branching vessels affected in a dissection?

May not be

11

Aneurysm

Dilation of all 3 layers

12

Incidence of Aortic Dissections

According to European Autopsy Study
Occurs in 3.2 dissections per 100,000 autopsies

13

What occurs in more deaths: Aortic Dissection or Aneurysm rupture?

Aortic dissection

14

Aortic Dissection risk factors

Hypertension (90% pts), advanced age (>60), male sex, Marfan's Syndrome, Coarctation, bicuspid AV, pregnancy, toxins and diet

15

Marfan's Disease

Connective Tissue disorder

16

Aortic Dissection Causes (Inciting Events)

Increased Physical Activity
Emotional Stress
Blunt Trauma
Can occur w/o any physical activity (i.e. cannulation for bypass)

17

Aortic Dissection Mechanism

Intimal Tear; presence of a weakened aortic wall; areas experiencing greatest mechanism shear forces, points where the aorta is fixed, there is increased shear stress applied to the aortic wall

18

What percent has intimal tear in ascending aorta?

61%

19

What percent has intimal tear in descending aorta?

24%

20

What percent has intimal tear in descending aorta; isthmus (distal to left subclavian)

16%

21

What percent has intimal tear in arch?

9%

22

What percent has intimal tear in abdominal?

3%

23

What percent has intimal tear in other areas?

1%

24

How fast does propagation occur?

Within seconds

25

What is propagation driven by?

Pulse pressure and ejection velocity

26

What may be involved in aortic dissections?

Origins of arteries; vessel occlusions can also occur due to compression by the false lumen

27

DeBakey Classification

3 types based upon location of intimal tear and which section of the aorta is involved; Type 1, 2, 3A, 3B

28

Debakey Classification: Type 1

Intimal Tear: Ascending Aorta
Dissection: All parts of the thoracic Aorta (ascending, arch, and descending)

29

DeBakey Classification: Type 2

Intimal Tear : Ascending Aorta
Dissection: Ascending Aorta only
stops before innominate artery

30

DeBakey classificaiton: Type 3A

Intimal Tear: Descending Aorta
Dissection: Descending Thoracic only distal to left subclavian, ends above diaphragm

31

DeBakey Classficiation: Type 3 B

Intimal Tear: Descending Aorta
Dissection: below diaphragm

32

Whats the "easier" classification system?

Stanford (Daily) Classficiation; Type A and Type B

33

Stanford (Daily) Classification: Type A

Ascending Aorta
Any involvement regardless of where tear is
regardless of how far it propagates; usually emergent/urgent cases more virulent course

34

Stanford (Daily) Classification: Type B

Distal Aorta
Any part of aorta distal to left subclavian

35

Prognosis for untreated ascending dissection

Dismal
2 day mortality- 50%
3 month mortality- 90%

36

What is the usual cause of death in aortic dissection?

Rupture of the false lumen into the pleural space or percardium

37

Lower incidence of death in what types of patients...

Debakey Type III
Stanford B

38

Other causes of death

Progressive heart failure (AV involvement)
MI (Coronary involvement)
Stroke (Occlusion of cerebral vessels)
Bowel Gangrene (Mesenteric artery occlusion)

39

Surgical Mortality of Aortic Dissections

3-24%
Depends on affected section of aorta
Aortic arch- highest mortality
Descending Thoracic- lowest mortality

40

What is the incidence of Thoracic Aneurysms? What percent of hwat types?

European studies show 460/100,000 thoracic aneurysms
45% involved ascending aorta
10% involved arch
35% involved descending aorta
10% thoracoabdominal

41

Aneurysms Classification by shape

Fusiform
Saccular

42

Fusiform

entire circumference of the aortic wall

43

Saccular

Involves only part of the circumference of the aortic wall

44

Arch aneurysms are typically what shape?

saccular

45

What type of classification is used to classify thoracoabdominal aortic anuerysms?

Crawford Classification

46

Crawford Classificiation

used to describe the extent of aorta requiring replacement
Crawford Extents I-IV

47

Crawford Classificiation: Extent 1

involves most or all of the descending thoracic aorta and upper abdominal aorta

48

Crawford Classification: Extent 2

Involves most or all of descending thoracic aorta and extends into infrarenal abdominal aorta

49

Crawford Classification: Extent 3

Involves the distal 1/2 or less of descending thoracic aorta and varying portion of abdominal aorta

50

Crawford Classification: Extend 4

involves most of all abdominal aorta

51

Aneurysms: Natural Hx

Progessive dilation

52

What fraction of aortic aneurysms rupture?

more than 1/2

53

What is the untreated 5 year survival of the thoracoabdominal aortic aneurysm?

13-39%

54

What are other complications of aneurysms?

Mycotic infection
Atheroembolisation
Dissection (Rare)

55

What are some predictors of poor prognosis in aneurysm patients?

Larger size (less than 10 cm max transverse diameter)
Presence of other symptoms
Associated CV disease (CAD, MI, CVA)

56

When do the majoriy of thoracic artery tears occur?

After a trauma; involve a deceleration injury (MVA)

57

MVA

desceleration injury; large shear stress on points of aortic wall that are relatively immobile

58

What does thoracic artery tear lead to?

Immediate exsanguination and death
10-15 % are lucky and make it to the hospital (maintain integrity of the adventitial covering of the aortic lumen)

59

Where do most thoracic artery ruptures occur?

Most occur distal to the origin of the left subclavian artery; due to fixation at the point of the ligamentum arteriosum

60

What is the 2nd most common site of a thoracic artery rupture

ascending aorta just distal to the aortic valve

61

Aortic Dissection diagnosis

dramatic onset

62

Aneurysm Diagnosis

asymptomatic until late in course
medical evaluation for unrelated problem or complication of aneurysm

63

Trauma Rupture Diagnosis

if they surivve trauma
s/s similar to descending aortic aneurysm

64

Indications for Surgery: Ascending Aorta Dissection

Acute Type A
Virulent course
high mortality

65

Indications for Surgery: Ascending Aorta Aneurysm

Persistent pain despite small aneurysm
AV involvement creating MI
angina
rapidly expanding
greater than 5- 5.5 cm diameter

66

Indications for Surgery: Aortic Arch Dissection

acute, limited to arch (rare)

67

Indications for Surgery: Aortic Arch Anuerysm

repiar of arch aneurysm is more complicated
carries increased morbidity and mortality
persistent symptoms
greater than 5.5-6 cm
progressive expansion

68

Indications for Surgery: Descending Aorta Dissection

Medical management in acute phase
failure to control hypertension medically
continued pain
enlargement on CSR, CT, Angio
Neurologic Deficit
Renal/ GI ischemia

69

Indications for Surgery: Descending Aorta Aneurysm

Greater than 5-6 cm
Expanding
Leaking
Chronic, causing persistent pain

70

Perfusion: Aortic Surgery Considerations

Where is the aneurysm located?
Where do we need to cannulate?
Do we need to circ arrest?
Median sternotomy vs. Thoracotomy
Full CPB or Left heart bypass?

71

Very proximal aneurysms limited to what regions?

Aortic root or ascending aorta

72

CPB w/o Circ Arrest Cannulation

Ascending aorta or transverse aorta, and dual stage in RA or Bicaval

73

Where is the XC in CPB w/o circ arrest

proximal to the innominate artery

74

If patient is unstable prior to sternotomy, where do you cannulate?

Femoral to go on CPB prior to sternotomy

75

CPB w/o Circ arrest LV/PA Vent adn CPG

Normal LV/PA vent
Normal cpg

76

DHCA

bloodless field
uncluttered by clamps and cannulas

77

Does DHCA abate cerebral metabolic demands?

doesn't necessarily abate cerebral metabolic demands; significant cerebral metabolic activity occurs at temperatures at which DHCA is initiated; promotes brain ischemia; accumulation of metabolic wastes

78

When did RCP gain popularity?

90s

79

When was RCP first done? By who?

1980 by Milles and Oschner; treating massive air embolism

80

When was RCP used as neuroprotection?

1990

81

What are the benefits of RCP?

Homogeneous cerebral cooling
air bubble wash out
wash out of embolic debris
wash out of metabolic wastes
prevent cerebral blood cell micro aggregation
Delivery of oxygen and nutrients to the brain

82

ACP

older tehcnique
maintained pre-DHCA jugular venous sats and cerebral oxygen extraction

83

Circ Arrest: Monitor Temps

Nasopharyngeal/Bladder
Arterial
Venous
Water

84

Circ Arrest: Monitor Brain

EEG- brain activity
Electrocerebral silence dictates adequate cerebral cooling

85

Circ Arrest: Drugs

Mannitol (25g) and steroids
enhances cerebral protection
put in the pump prior to turning off the pump

86

Circ Arrest: Cannulation

Axillary Cannulation is preferred
artery is usually exposed prior to sternotomy
after heparin is given- 8mm graft is sewn to the artery
cannula is placed in the 8mm graft

87

Circ Arrest: Cannulation in an emergency

femoral artery is used; if its a dissection, make usre that the cannula is in the true lumen; venous cannula- RA, bicaval, femoral depends on need and access

88

Circ Arrest case: Cooling

10 degree C drop in temperature- reduces rate of oxygen consumption by 50%; as temperature decreases metabolic demand decreases; pump flows can be reduced to a CI of 1.6-1.8 L/min/m2

89

A 10 degree C decrease in temperature causes what percent increase in blood viscosity?

20-25%

90

Circ Arrest: Hemodilution to a hematocrit less than what percent?

25%

91

When doing a circ arrest case, how long do you keep cooling?

Keep cooling until EEG shows no cerebral electrical activity
Usually takes about 20-25 minutes
brain temp 18-20C
cool no lower than 15 C

92

When not using an EEG, cool for how long?

At least 25 minutes to a target core temp of 18-20 C

93

At EEG silence, give what drug?

Pentobarbital
Circulate for 3 minutes

94

What position is a patient put in during a circ arrest case?

Trendelenburg position

95

Why would the head be packed in ice in a circ arrest case?

Facilitate Surface cooling

96

ACP is at how many ml/kg/min?

10 ml/kg/min

97

When the aorta is opened, you could get bleed back from what?

L Common Carotid and L Subclavian obscure field view; cardiotomy suction in distal arch; possible use of balloon occluder in both vessels

98

Circ Arrest Case: End of gRaft is sewn where?

Sewn to proximal descending thoracic aorta, transverse arch or distal ascending aorta; attach head vessels (island, branched graft)

99

Off pump: Want systolic BP of what?

100-120 mmHg

100

Off pump: MAP

70-90 mmHg

101

Off pump: HR

60-80 BPM

102

Off pump: CI

2.0-2.5 L/min/m2

103

Complications of Aortic Surgery and DHCA

Air Emboli
clots
LV dysfunction
MI (reimplanting coronaries)
renal failure
respiratory failure
coagulopathy
hemorrhage

104

Other procedures of Aortic Conditions

Endovascular REpair
Left Heart Bypass

105

When was an endovascular repair 1st done?

1991 on abdominal aortic aneurysm

106

TEVAR

Thoracic Endovascular aortic repiar

107

Endovascular Repair required proximal "landing zone" of what lenght?

15mm

108

TEVAR Con

Side branches- possibility of occluding a vessel that branches off the aorta

109

TEVAR Considerations

Aortic Tortuosity, calcification, atherosclerosis

110

TEVAR Advantages

reduces mortality
reduces morbidity
less blood loss
quicker recovery
hemodynamic stability
pulmonary and cardiac comorbidities that may have not made them a candidate for open surgeries, allow them to have this option

111

TEVAR Complications

Conversion to open procedure (aortic rupture/dissection, malposition causing visceral ischemia)
bleeding
endoleak (blood flows back into the aneurysmal sac after the endovascular graft is placed; usually observe and hope it spontaneously resolves)
stroke
paraplegia
contrast nephropathy

112

Left Heart Bypass

shunt around the aneurysm/dissection; used on descending legions

113

Left Heart Bypass: ECC

tubling
centrifugal pump
noreservoir
n H/E
no bubble trap
exclusing those help minimize the heparinization required

114

Who gives volume in left heart bypass?

Anesthesia

115

What does connective tissue do?

Provides strength and support to tendons, ligaments, cartilage, blood vessel walls and heart valves