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Flashcards in Cameron.AcuteAorticDissection Deck (51):
1

What is the definition of Intramural Hematoma

an aortic dissection without an intimal flap.

2

what is the radiographic definition of an intramural hematoma?

regional thickening of the aortic wall, >7mm in circular or crescent shape without intimal flap and without enhancement s/p contrast injection

3

what is the underlying pathophysiology of intramural hematoma (2)

1) spontaneous rupture of vasa vasorum --> aortic wall disintegration --> dissection +/- tear **OR** 2) intimal fracture of atherosclerotic plaque --> allows blood to propogate in the aortic media

4

what is the initial management of intramural hematoma

aggressive BP control in the ICU

5

what anatomic involvement is associated with highest involvement with intramural hematoma

ascending aortic arch and/or coexisting aneurysm --> warrant aggressive approach

6

how can intramural hematoma exist on a spectrum of disease with aortic dissections?

intramural hematoma and intact intima (like an acute aortic dissection with thrombosed lumen) --> full blown aortic dissection

7

what is the early mortality of acute aortic dissection per hour?

1-2% per hour; therefore misdiagnosis causing a delay in treatment --> catastrophe

8

define a DeBakey Type I dissection

involving ascending, arch, and descending aorta

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9

define a DeBakey Type II dissection

involves only ascending aorta

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10

Define a DeBakey Type III dissection

originates and propagates distal to the left SCA

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11

Distinguish a DeBakey Type IIIa and IIIb dissections

Type IIIa: descending thoracic aorta; Type IIIb: extends beyond diaphragm

12

Define a Stanford Type A dissection

positive ascending aortic involvement

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13

Define a Stanford Type B disection

no ascending aortic involvement (therefore arch and/or descending involvement)

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14

What is the relative duration of acute, subacute, and chronic dissections?

<2 weeks: acute; 2-6 weeks subacute; > 6 weeks, chronic

15

What percent of all dissections are acute Stanford A and how are they managed?

60%, surgical emergency, needs immediate OR

16

what is the difference between "complicated" and "uncomplicated" Stanford Type B dissections in presentation and management? What are their relative frequencies?

Complicated (20%) rupture/impending rupture; malperfusion; refractory pain/HTN --> needs open or endovascular repair. Uncomplicated (80%) manage with aggressive medical therapy

17

What percent of patients with clinical picture of acute aortic dissection actually have intramural hematoma?

10-20% have IMH --> incorrectly referred to as dissection with thrombosed false lumen. Have clinical picture but no blood flow to false lumen or identifiable lesions

18

name three underlying causes of possible intramural hematoma

microscopic intimal tear; penetrating aortic ulcer; vaso vasorum hemorrhage

19

what disease process is intramural hematoma managed like?

managed like acute aortic dissection

20

what is the classic presentation of acute aortic dissection? (5 S/Sx)

10/10 ripping chest or back pain; asymmetric pulses; differing BP in extremities +/- S/Sx of malperfusion (pulseless extremities, new neuro deficit); new diastolic murmur 2/2 retrograde dissection into coronary arteries / aortic valve

21

What underlying process should you suspect in an aortic dissection patient with hypotension and shock?

tamponade; cardiac dysfunction; ongoing hemorrhage

22

what is the gold standard study for acute aortic dissection and its associated sens/spec? what are its limitations?

CTA: sens/specificity is 90-100%. Scans limited to the thoracic aorta can confirm diagnosis, scanning the entire aorta helps with surgical planning and assessnig for subclinical disease

23

What are the three diagnostic benefits of TEE?

rapid assessment for tamponade; valve dysfunction; and cardiac wall motion alone

24

what are the BP meds of choice and BP goals for acute aortic dissection patients

- hemodynamic monitoring with arterial line; - start beta blockade with goal SBP 100-110 and goal HR 60-70; add vasodilators prn (nitroprusside / hydralazine)

25

why shouldn't you initiate BP control for aortic dissection patients with vasodilators?

increases left ventricular contractility (dp/dT) = increased aortic shear = increased rupture risk

26

What subtype of aortic dissections should not be managed with beta blockers and why?

Acute Stanford Type A with either a diastolic murmur or TEE evidence of significant aortic regurgitation should not be managed with beta blockers because they increase the risk of worsening CHF (reduced HR leads to increased diastole leads to increased congestion?)

27

why should patients with acute Type A dissections undergo central repair in the setting of cerebral / renal / visceral malperfusion?

central aortic reconstruction will correct malperfusion

28

What is the goal of surgery for acute Type A dissection?

prevents imminent death from : aortic rupture --> exsanguination / tamponade; acute aortic insufficiency; malperfusion of coronary / cerebral / systemic ciruclation. Accomplished with tube interposition graft and reestablishing true lumen blood flow

29

What should be monitored during anesthesia for ascending aortic dissection repair?

arterial line for invasive BP; CVP monitoring; TEE; temperature of bladder/venous/arterial (ensures uniform cooling); EEG; cerebral oximetry

30

is CPB required for ascending aortic replacement?

Yes

31

Name three possible sites for arterial cannulation for CPB for ascending aortic dissection repair and associated pros/cons

1) CFA - easily accessible and familiar. 2) right axillary/SCA with 8-10mm Dacron graft anastomosed end-to-side to axillary artery --> allows for antegrade systemic perfusion --> selective antegrade cerebral perfusion. 3) direct central ascending aortic cannulation with TEE (TEE to guide to true lumen), difficult but lifesaving in unstable patients

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32

What is the incision for ascending aortic dissection repair?

median sternotomy to expose heart and ascending aorta

33

what is cannulated for CPB venous drainage for ascending aortic repair?

right atrium can be easily cannulated

34

what is the next step if the patient on CPB develops aortic insufficiency or coronary malperfusion?

vent the left ventricle on bypass; protect myocardium with direct antegrade coronary ostial / retrogradecoronary sinus cardioplegia strategies

35

What is the optimal temperature for profound hypothermia prior to cardioplegia?

18 degrees celsius in the nasopharynx before turning off circulation, be sure hypothermia occurs uniformly (perfusion and cooling)

36

What are the steps to reconstruct the ascending aorta with acute aortic dissection

patient in Trendelenberg; resect entire ascending aorta - sinotubular junction --> innominate artery; evaluate dissection flap --> make sure that brachiocephalic branches arise from true lumen; reconstruct all layers of the proximal aortic arch --> obliterate false lumen

37

Describe two techniques to reconstruct the proximal aortic arch with ascending aortic dissection

1) reconstructive aortic wall between two Teflon felt strips; anastomose Dacron graft to aorto-felt "sandwich"; 2) insert Teflon into false lumen --> obliterates false lumen --> sew Dacron graft to reconstituted aorta buttressed with strip of Dacron around adventitia (creates "neo-media")

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38

Why is it advised to avoid glue during ascending aortic dissection repair?

although they allow for easier tissue handling, can increase risk of pseudoaneurysm

39

what step should be completed after the distal anastomosis of ascending aortic dissection repair?

-"deair" the aortic arch; -clamp proximal graft; -CPB resumed through Dacron graft --> promote true lumen flow

40

When should aortic arch replacement be considered for acute aortic dissections? (3 scenarios)

- complex intimal disruptions in the arch; - arch aneurysm > 5cm; - connective tissue syndromes (Marfan's, Loeys-Dietz, Ehler-Danlos)

41

What step should be performed with arch replacements that is a/w improved neuro outcomes?

antegrade cerebral perfusion

42

Describe two methods for constructing the proximal aortic anastomosis in ascending aortic dissection repair

b/c aortic root is usually uninvolved in the dissection, can do "sandwich" technique (reconstitute aortic wall between two teflon felt strips and anastomose dacron graft to aorto-felt sandwich) or "neomedia" technique if dissection extends to the root (insert Teflon into false lumen --> obliterates false lumen, sew Dacron graft to reconstituted aorta buttressed with strip of Dacron aroudn adventitia ("neomedia")

43

What is the most common cardiac complication a/w acute Type A aortic dissection?

aortic regurgitation

44

Describe three mechanisms of Type A dissection --> aortic regurgitation

1) acute dilatation of sinotubular junction 2/2 expanding false lumen = incomplete coaptation of valve cusps; 2) dissect through aortic root --> disrupts commisurial posts --> prolapse of valve cusps; 3) aortic flap prolapses through valve during diastole, thereby preventing appropriate valve function

45

Name four scenarios where you should consider composite aortic root replacement with coronary button reimplantation

aortic root aneurysms > 5 cm; complex aortic valve pathology; dissection approaching coronary ostia; connective tissue syndromes

46

What is the overall mortality of acute type A dissections? How is this affected by preop instability? Name 8 causes of preop instability.

Approx 25% mortality, if unstable preop = 31% mortality. Tamponade, shock, CHF, stroke, coma, MI, ARF, and mesenteric ischemia are all causes of preop instability.

47

Name 7 early postop complications after treatment of acute type A aortic dissection requiring ICU care

transient neuro dysfunction; CVA/TIA; acute lung injury; refractory hypotension; new malperfusion syndromes; renal insufficiency; multisystem organ failure

48

What is the preferred management of Acute Type B dissection?

Medical management with BP control

49

What is the mortality of uncomplicated Type B dissection?

< 10%

50

What percent of acute type B aortic dissections are "complicated"? Name 5 S/Sx of "complicated" Type B.

~25% complicated. S/Sx: refractory HTN (to three different drug classes); malperfusion syndromes; increasing periaortic hematoma; bloody pleural effusions; shock

51

What is the preferred surgical management of complicated Type B dissection? What is its associated 5-year survival and how does this compare to medical management?

TEVAR has a 5-year survival of 60-80%, preferred for complicated patients. Has not yet been compared to medical management in uncomplicated patients.