TOPIC40: aortic dissection

Question 1

what is aortic dissection?

Answer 1

1. due to high pressure–>intima rupture–>pressurized blood enters the wall of the artery through the surface defect–> separation of the aortic walls–> more damage to intima–>blood to media extends the diameter of the blood vessel (false lumen formation)
2. it is a catastrophic event where blood spreads apart the laminar planes of the media to form a blood filled channel within the aortic wall.

Question 2

etiology of AD

Answer 2

1. chronic HTN (usually men 40-60 years)
2. CT disorders (Marfan sy, Ehler Danlos, Turner)
3. pregnancy( due to increased blood plasma volume)
4. Bicuspid aortic valve
5. Chest trauma: either blunt or iatrogenic in open heart surgery, diagnostic catheterization or cardiopulmonary bypass.
6. aortic coarctation
7. aneurysms ( can cause dissection but also dissection can cause an aneurysm)

Question 3

morphology of AD

Answer 3

1. Intimal tear usually in the first 10cm of the ascending aorta (transverse or oblique tears)–> dissection can extend retrograde towards the heart and cause tamponade
2. the tear can extend distally and a branching artey can be compressed by bleeding–> ischemia, infarct, atrophy
   (compression of renal artery)

3.sometimes the dissecting hematoma spreads along the laminar planes of the aorta and it often ruptures out through the adventitia producing a second distant intimal tear creating a new vascular channel.

Question 4

classification of AD

Answer 4

DeBakey Ai: ascending
DeBakey Aii: ascending and descending
DeBakey Biii: starts distal to the left subclavian artery

A- needs surgery
B- doesn’t need immediate surgery

Question 5

symptoms of AD

Answer 5

1. Sudden tearing chest pain (may or may not radiate to the back)
2. Different BP and unequal arm pulses (bec the subclavian arteries may be blocked)
3. Nausea, syncope, dyspnea, weakness
4. when occluding distal arteries: acute limp ischemia, anuria
5. when occluding proximal arteries: MI
6. when tamponade forms or if aortic regurgitation forms: CHF

Question 6

complications in AD

Answer 6

• Channel may rupture THROUGH the adventitia and blood may escape to various spaces–> MASSIVE HEMORRHAGE or cardiac tamponade
• may reach the aortic valve causing aortic regurgitation
• may block distal(renal) or proximal arteries(subclavian)
• may cause pericardial tamponade
• can also rupture the media and enter in the aorta again

Question 7

diagnosis of AD

Answer 7

A. history & physical

• AR murmur
• pulse
• BP differences

B. LAB: biomarkers, amylase (if rupture), Hb, crossmatch blood

C.ecg

D. imaging: CXR, TEE, MRI, Angio

E. PAINKILLER RESPONSE( no resp because no pain fibers in arteries)

Question 8

Treatment of AD

Answer 8

1. ABC-resuscitation
2. Keep systolic blood pressure at 100-110mmhg using Esmolol, Labetalol or Ca channel blockers ( if beta blockers are CI)
3. Surgery: all pts with type A AD should be considered–> replaced by artificial graft