Diseases of the Aorta

Question 1

most common aortic pathologies

Answer 1

1. aortic aneurysm (AAA)
2. aortic dissection

Question 2

aneurysm - defined

Answer 2

*focal dilation of an artery involving an increase in diameter to 1.5x its normal size
*aorta > 3 cm
*associated with transmural inflammation (all 3 layers) and extracellular matrix degradation

Question 3

“true” vs. “false” aneurysms

Answer 3

*true aneurysms have ALL of the vessel wall layers (intima, media, adventitia)
*false aneurysms do NOT have all of the vessel wall layers

Question 4

aortic aneurysms (AAA) - pathophysiology

Answer 4

*excessive elastin degradation via MMPs → decreased elastin content relative to collagen (collagen is the “safety net” that resists aneurysm rupture)
*fragmented elastin fibers seen on elastin stains of laminae of media

Question 5

risk factors for abdominal aortic aneurysms (AAA)

Answer 5

*TOBACCO SMOKING
*increased age ( > 65yo)
*male gender
*family history
*hypercholesterolemia
*HTN
*white race

Question 6

abdominal aortic aneurysm (AAA) - natural history

Answer 6

*growth rate: 0.2-0.5 cm/year
*variable growth patterns:
-aneurysms of 3-4 cm tend to grow 0.2 cm/year
-aneurysms of 5-6 cm tend to grow 0.5 cm/year

Question 7

abdominal aortic aneurysm (AAA) - clinical presentation (unruptured)

Answer 7

*usually ASYMPTOMATIC
*physical exam is notoriously unreliable; sometimes can identify a pulsatile mass
*most commonly as incidental finding
*best test for screening or suspected AAA = ULTRASOUND
*screening is approved for: Welcome to Medicare physical; male over age 65; and any time smokers

Question 8

abdominal aortic aneurysm (AAA) - clinical presentation (RUPTURED)

Answer 8

*natural history is to expand and RUPTURE
*ruptured AAAs present with:
-pulsatile abdominal mass
-abdominal/back pain
-hypotension
-syncope
-shock
-sudden death

*elective surgery is therefore PROPHYLACTIC

Question 9

abdominal aortic aneurysm (AAA) - risks of rupture

Answer 9

*yearly risk of AAA rupture is related to diameter:
< 4cm: 1% risk of rupture
4-4.9cm: 1-3%
5-5.9cm: 3-10%
6-6.9%: 10-20%
> 7cm: 20-40% risk of rupture

Question 10

abdominal aortic aneurysm (AAA) - diagnosis

Answer 10

*ULTRASOUND is best
*CTA or MRA if we are going to operate

Question 11

abdominal aortic aneurysm (AAA) - indications for repair

Answer 11

*rupture
*symptomatic
*rapid growth ( > 0.5 cm in 6 months)
*mycotic aneurysms
*5.5 cm+ aneurysms (this is the cutoff at which the risk of rupture outweighs the risks associated with surgical repair)

Question 12

surgical treatment options for abdominal aortic aneurysm (AAA)

Answer 12

*endovascular repair (EVAR)
*open repair
*iliac branch device
*fenestrated grafts

Question 13

repair of abdominal aortic aneurysm (AAA) is indicated for what size?

Answer 13

*repair indicated for patients with an aneurysm > 5 to 5.5 cm

Question 14

aortic dissection - defined

Answer 14

*longitudinal intimal tear forming a fake lumen

Question 15

aortic dissection - pathophysiology

Answer 15

*characterized by separation of the aortic wall layers by extra-luminal blood that usually enters the aortic wall through an INTIMAL TEAR
*blood may circulate between the normal aortic lumen (true lumen) and the abnormal channel (false lumen)
*septum separates lumen
*multiple re-entry sites

Question 16

aortic dissection - pathology

Answer 16

*CYSTIC MEDIAL NECROSIS

Question 17

Stanford Type A aortic dissection

Answer 17

*proximal
*involves ASCENDING AORTA
*may extend to aortic arch or descending aorta
*may result in acute aortic regurgitation or cardiac tamponade
*treatment = SURGERY

Question 18

Stanford Type B aortic dissection

Answer 18

*distal
*involves only DESCENDING AORTA (below left subclavian artery)
*treatment = BETA BLOCKERS, then VASODILATION

Question 19

aortic dissection - risk factors

Answer 19

*HYPERTENSION
*bicuspid aortic valve
*inherited connective tissue disorders (ex. Marfan Syndrome - defect in fibrillin 1 gene)
*cocaine use

Question 20

aortic dissection - clinical presentation

Answer 20

*PAIN - sharp, ripping, tearing, sudden-onset chest pain
-usually does not radiate to neck, shoulder, or arm (contrast to acute coronary syndrome)
-may radiate or penetrate into back (between scapulae)
*hypertension
*CXR can show mediastinal widening

Question 21

aortic dissection - differential diagnosis

Answer 21

*acute MI
*thoracoabdominal aneurysm
*pericarditis
*pulmonary embolus
*mediastinal tumors
*pleuritis

Question 22

aortic dissection - potential manifestations

Answer 22

1. acute aortic regurgitation (diastolic murmur)
2. shock (pericardial tamponade, coronary artery compression with MI, rupture)
3. obstruction of branch arteries (stroke, spinal cord ischemia, renal failure, pulse deficit)

Question 23

aortic dissection - diagnosis

Answer 23

*CXR shows widening of mediastinal shadow
*EKG - nonspecific changes; helpful to rule out acute coronary syndrome
*imaging techniques: CT, MRI, TEE, angiography