Acute Aortic Syndromes

Question 1

how do the features of the aortic artery change as it descends?

Answer 1

diameter decreases, there is less elastin and collagen

Question 2

what are normal consequences of aging on the aortic artery?

Answer 2

elastic fibers degenerate, leaving more collagen than elastin —> aorta stiffens, systolic blood pressure rises

Question 3

what congenital heart defect is associated with coarctation of the aorta in most cases?

Answer 3

bicuspid aortic valve

*also associated with Turner syndrome

Question 4

in adults, coarctation of the aorta is almost always located where?

Answer 4

at the junction of the distal aortic arch and descending aorta, roughly corresponding to the area of the ductus arteriosus (right after the branching of the L subclavian)

Question 5

describe how HTN develops in adults with aortic coarctation

Answer 5

if aortic coarctation is being discovered in an adult, then the coarctation is distal to where the ductus arteriosus was, and therefore collateral circulation developed in utero

overtime, increased afterload will cause concentric LV hypertrophy

mechanical obstruction will cause huge pressure drop at the coarctation, leading to low renal perfusion - this will activate RAAS

RAAS activation will cause development of HTN

Question 6

Pt is a 35yo M presenting with HTN and complaints of leg pain, despite a generally healthy lifestyle. PE reveals systolic HTN in the upper extremities, but reduced systolic BP in the lower extremities. There is a delay between the radial artery and femoral pulse.

What is likely going on?

Answer 6

coarctation of the aorta

mechanical obstruction increases afterload and there is a huge drop of pressure at the coarctation —> low renal perfusion chronically activates RAAS —> HTN develops

constriction/pressure drop is also cause of pulse delay and claudication (leg pain with exertion)

differential systolic BP between upper/lower extremities + radial-femoral pulse delay = aortic coarctation

Question 7

what would you hear upon cardiac auscultation in an adult with aortic coarctation? (3)

Answer 7

obstruction is causing increased afterload and major drop in pressure at the obstruction

—> palpable thrill
—> continuous machine-like murmur
—> in 50% of patients who also have bicuspid aortic valve - systolic murmur following ejection click (for opening of valve)

Question 8

in adults with aortic coarctation, where are the 2 places in which you would hear the continuous machine-like murmur?

Answer 8

1. posterior chest thoracic spine - over where the coarctation is (usually where ductus arteriosus was)
2. over scapula bilaterally due to intercostal artery collaterals

Question 9

what kind of murmur does a bicuspid aortic valve make?

Answer 9

systolic murmur following ejection click (sound of valve opening)

*note bicuspid aortic valve is found in ~50% of adults with aortic coarctation

Question 10

what might chest x-ray reveal in an adult with aortic coarctation?

Answer 10

rib notching, due to enlarged/tortuous intercostal arteries forming as collaterals

Question 11

what causes aortic dissection?

Answer 11

damage to aortic wall —> intimal tear —> blood enters underlying media, creating “false lumen” —> false lumen can spread proximally/distally

may be caused by HTN —> fibrosis of media —> cystic medial degeneration (elastin fragments and is replaced with proteoglycans)

Question 12

where is aortic dissection most likely to develop?

Answer 12

75% begin in ascending aorta

Question 13

how could each of the following cause aortic dissection?
a. chronic arterial HTN
b. syphilis
c. cocaine use

Answer 13

aortic dissection = false lumen

a. chronic arterial HTN —> media fibrosis
b. syphilis —> inflammation decreases blood supply of vaso vasorum
c. cocaine use —> very high blood pressure damages media

—> cystic medial degeneration

Question 14

Which of these is NOT associated with development of aortic dissection?
a. Down Syndrome
b. syphilis
c. cocaine use
d. Marfan Syndrome
e. Turner Syndrome
f. bicuspid aortic valve
g. HTN

Answer 14

these ARE factors associated with medial damage, which may result in aortic dissection:

b. syphilis
c. cocaine use
d. Marfan Syndrome
e. Turner Syndrome
f. bicuspid aortic valve
g. HTN

ALSO Loeys-Dietz (TGF beta mut.), Ehler-Danlos (Type IV collagen mut.)

Question 15

What mutations are associated with each of the following genetic disorders, all of which put patients at risk for aortic dissection or aneurism?
a. Marfan syndrome
b. Loeys-Dietz syndrome
c. Ehler-Danlos syndrome

Answer 15

*note these are all AUTOSOMAL DOMINANT genetic mutations affecting the integrity of the ECM

a. Marfan syndrome: fibrillin (glycoprotein, tethers smooth muscle to matrix of elastin/collagen)
b. Loeys-Dietz syndrome: TGF beta
c. Ehler-Danlos syndrome: collagen (several mutations)

Question 16

explain how a mutation in Fibrillin-1 can put a patient at risk for aortic dissection or aneurysm?

Answer 16

Marfan syndrome: AD mutation in Fibrillin-1, glycoprotein that tethers smooth muscle to matrix of elastin and collagen, found in aortic wall

deficiency in fibrillin-1 causes smooth muscle to detach from elastin/collagen, inducing apoptosis and loss of ECM integrity

aortic dissection (creation of “false lumen”) can occur

Question 17

how do patients with aortic dissection present? contrast this to how patients with MI present

Answer 17

severe chest pain with SUDDEN onset at MAX intensity, described as sharp and tearing, radiation to back or scapula

MI: progressively worsening pain, dull/heavy pressure

Question 18

Pt is a 32yo F presenting to the ER with sudden on onset of severe chest pain she describes as sharp and tearing and 10/10 intensity. Which of these is LEAST likely to be found associated with the patient’s condition?
a. aortic regurgitation
b. pulse deficit
c. limb ischemia
d. myocardial infarction
e. descending diastolic murmur
f. PMH of Turner syndrome
g. bicuspid aortic valve

Answer 18

patient has aortic dissection, which is associated with:
a. aortic regurgitation
b. pulse deficit
c. limb ischemia
e. descending diastolic murmur
f. PMH of Turner syndrome
g. bicuspid aortic valve

differentiate from (d.) myocardial infarction because pain in MI is gradually worsening and dull/heavy - note that severe aortic dissection can cause MI!

[note a = e]

Question 19

why does aortic regurgitation occur with aortic dissection? what does this murmur sound like?

Answer 19

aortic regurgitation: diastolic decrescendo murmur right at S2 (may obscure S2)

dissection usually begins in ascending aorta, but can move back towards the heart —> can tear aortic valve, causing regurgitation

Question 20

explain why a pulse deficit occurs with aortic dissection

Answer 20

aortic dissection = “false lumen”

blood in false lumen can obstruct or completely occlude a branch of the aorta - can cause limb ischemia, mesenteric ischemia, neurological deficits, renal failure, etc

patient may present with stroke symptoms

Question 21

sudden onset of 10/10 tearing chest pain + pulse deficit + aortic regurgitation murmur (diastolic decrescendo) = ?

Answer 21

most likely aortic dissection (“false lumen”)

[pulse deficit due to occlusion by false lumen, aortic regurgitation due to tear of valve leaflet]

risk factors include HTN, syphilis (inflammation), cocaine (high BP), Marfan syndrome (fibrillin), Loeys-Dietz (TGF beta), Ehler-Danlos (Type IV collagen), Turner Syndrome, bicuspid aortic valve

Question 22

what are 3 catastrophic outcomes of aortic dissection?

Answer 22

1. free rupture: dissection progresses to adventitia and aorta freely ruptures
2. occlusion of coronary ostia: causes MI
3. proximal rupture into the pericardium: blood fills pericardium, causing pericardial tamponade

Question 23

if a patient has a history of Marfan’s syndrome, bicuspid aortic valve, or thoracic artery aneurism AND is presenting with a perfusion deficit between L/R or upper/lower, focal neurological deficit, or aortic regurgitation murmur… what should you be most concerned about?

Answer 23

aortic dissection (“false lumen”)

—> perfusion deficit will show as pulse deficit

—> focal neurological deficit can be caused by occlusion/obstruction of branch of aorta by false lumen

—> aortic regurgitation can be caused by dissection progressing towards valve and causing leaflet tear

Question 24

where do traumatic aortic injuries usually occur? (such as from a vehicle accident)

Answer 24

usually at point of ligamentum arteriosum because it fixes the aorta at that point, while momentum pulls the rest of it forward - causing tear

Question 25

where are aortic aneurisms most likely to occur?

Answer 25

can occur anywhere, but most occur in infrarenal abdominal aorta

aneurysm = localized of diffuse dilation of an artery with diameter at least 50% greater than normal size

in abdominal aorta, aneurism = 3+ cm

Question 26

how does the pathophysiology of thoracic vs abdominal aortic aneurism compare?

Answer 26

thoracic (TAA): cystic medial degeneration (fragmented elastin) mediated by damage to structural proteins, occurs at younger age, M=F, strong family history

abdominal (AAA): inflammation mediated and metalloprotease activity, associated with increased age, mostly males

recall as aorta descends, becomes more narrow and collagen>elastin

Question 27

young females are more likely to present with:
a. thoracic aortic aneurism (TAA)
b. abdominal aortic aneurism (AAA)

Answer 27

most likely TAA

thoracic (TAA): cystic medial degeneration (fragmented elastin) mediated by damage to structural proteins, occurs at younger age, M=F, strong family history

abdominal (AAA): inflammation mediated and metalloprotease activity, associated with increased age, mostly males

Question 28

Pt is 26yo F presenting with chest and back pain, coughing and wheezing, hoarseness, and difficulty swallowing. PMH is significant for Turner Syndrome. Pt smokes 3 packs/week cigarettes.

Given the most likely diagnosis, what management strategies will you employ?

Answer 28

thoracic (TAA): cystic medial degeneration (fragmented elastin) mediated by damage to structural proteins, occurs at younger age, M=F, strong family history

genetic risk factors: Marfan Syndrome, Ehlers-Danlos, Turner syndrome, bicuspid aortic valve

symptoms due to compression by distended aorta

management: lower BP, stop smoking, statins (lower lipids), surgery (possibly stent if descending aorta)

Question 29

Pt is a 72yo M presenting with sudden onset of abdominal pain, cold and clammy extremities, and low BP. Which of these is most likely?

a. ruptured thoracic aortic aneurism (TAA)
b. ruptured abdominal aortic aneurism (AAA)

Answer 29

most like ruptured AAA because pt is older male and AAA are usually asymptomatic until they expand or rupture - HIGH mortality

cold/clammy extremities due to peripheral vasoconstriction to increase BP following loss of volume in circulation

*ultrasound screening is standard for M > 65yo with smoking history OR family history of aortic aneurism

[thoracic (TAA): occurs at younger age, M=F, strong family history]