Type A Dissection

Question 1

What occurs in an aortic dissection?

Answer 1

There is an intimal tear allowing blood to go between the medial and intimal layers

Question 2

What is the Stafford Classification of aortic dissections?

Answer 2

Type A = ascending aorta involved; Type B = only descending thoracic aorta and below are involved (may involve the arch though)

Question 3

What is the mortality rate without surgery with a Type A dissection?

Answer 3

1-2% per hour for the first 48 hours; 74% by 2 weeks

Question 4

How are dissections characterized via timing?

Answer 4

Hyperacute = <24 hours, Acute = 1 day to 2 weeks, Subacute = 2 weeks to 3 months, Chronic = > 3 months

Question 5

What is the incidence rate for acute aortic dissections?

Answer 5

3 cases per 100,000 per year

Question 6

What are risk factors for aortic dissection?

Answer 6

Male + connective tissue disorders (Marfan, Ehlers-Danlos, Loeys-Dietz) + bicuspid AV + Aortic coarctation + HTN

Question 7

Do men or women have worse outcomes?

Answer 7

Women typically have worse outcomes because of delayed diagnosis due to atypical symptoms

Question 8

What is the DeBakey classification of aortic dissections?

Answer 8

Type I = originates in ascending aorta and propagates distally into the descending aorta; Type II = originates in ascending and confined to the ascending only; Type IIIa = originates in the descending thoracic and confined to descending thoracic; Type IIIb = originates in descending and propagates below the diaphragm

Question 9

What is the SVS/STS classification system for aortic dissections?

Answer 9

Based on the location of the intimal tear and the proximal and distal extent of the dissection; Zones 0-12 where Zone 0 is the ascending aorta up to innominate artery, Zone 1 is from innominate to left carotid, Zone 2 is from left carotid to left subclavian, etc.

Question 10

What is a Type A(d) dissection based on the SVS/STS classification system?

Answer 10

The aortic dissection originates in the ascending aorta and goes distally to d (tells us where the distal zone is)

Question 11

What is a Type B(pd) dissection based on the SVS/STS classification system?

Answer 11

The aortic dissection originates from Zone 1 or below (p will tell you where the proximal zone is and d tells you where the distal zone is)

Question 12

What is a Type I(d) dissection based on the SVS/STS classification system?

Answer 12

Indeterminate location for the entry tear and the dissection extends distally to zone d (whatever zone that is)

Question 13

What should be measured in patients with suspected aortic disease based on 2022 ACC/AHA guidelines?

Answer 13

Aortic diameters (longest diameter and its perpendicular diameter at a reproducible anatomic landmark) + root and ascending aortic diameters from edge to edge using ECG synchronized technology

Question 14

Where should you put your arterial line in type A dissections?

Answer 14

Right radial monitors flow to the innominate artery; if axillary cannulation is performed, then left radial artery pressures are needed; sometimes femoral pressures are needed for distal aortic perfusion sensing

Question 15

What neuromonitoring can you do in Type A dissections?

Answer 15

EEG (for deep hypothermic circulatory arrest) + SSEP/MEP + cerebral oximetry

Question 16

How does hypothermia provide neuroprotection?

Answer 16

Decreases global cerebral metabolism of glucose and oxygen + reduces temp-dependent release of glutamate and other excitatory neurotransmitters + inhibits proapoptotic activity + lowers levels of free radicals and inflamatory cytokines

Question 17

How long can you have deep hypothermia (18-19C) for?

Answer 17

Up to 40 minutes

Question 18

What are the major complications of deep hypothermic circulatory arrest?

Answer 18

1. Coagulopathy
2. Post-ischemic hypothermia
3. Impaired autoregulatory mechanisms
4. Damage to the blood brain barrier

Question 19

How do you use antegrade cerebral perfusion?

Answer 19

Commonly done via axillary or brachiocephalic artery; can also be done selectively (cannula into each head vessel)

Question 20

How do you use retrograde cerebral perfusion?

Answer 20

With SVC cannula, blood flows retrograde to the brain