27. Aortic Valve Disease

Question 1

what is one (relatively common) congenital abnormality of the aortic valve that leads to aortic stenosis?

Answer 1

bicuspid aortic valve.

Question 2

what is the manifestation of a congenitally bicuspid aortic valve over the lifespan?

Answer 2

younger: prob only a murmur. however, the normal degenerative process is accelerated and may lead to sig stenosis later in life.

Question 3

what is a less common congenital abnormality of the aortic valve?

Answer 3

unicuspid valve. more likely to cause problems in infancy

Question 4

what is supravalvular stenosis?

Answer 4

a version of aortic stenosis: a fibrotic membrane located above the valve causes LV outflow obstruction.

Question 5

what is subvalvular stenosis?

Answer 5

similar to supravalvular, but here the fibrotic membrane is below the valve. fixed area of fibrosis as opposed to the variable subvalvular stenosis in IHSS.

Question 6

what does degenerative aortic stenosis look like?

Answer 6

gradual thickening and calcification of the valve leaflets, calcification of the mitral annulus. results from years of wear and tear.

Question 7

describe rheumatic aortic stenosis

Answer 7

gradual fusion of the commissures, years after an episode of acute rheumatic fever. sometimes coexists with aortic regurg, also with mitral valve involvement.

Question 8

what is hypertrophic obstructive cardiomyopathy?

Answer 8

HOCM: also idiopathic hypertrophic subaortic stenosis (IHSS) or asymmetric septal hypertrophy (ASH). so much hypertrophy that the septum impinges on the anterior leaflet of the mitral valve, producing a functional obstruction to left ventricular outflow below the aortic valve. DYNAMIC subaortic stenosis

Question 9

what is the dominant pathophys abnormality in HOMC? is the obstruction fixed or dynamic?

Answer 9

dominant pathophys = poor diastolic compliance.
the obstruction is dynamic. obstruction and murmur vary preditably with changes in heart size and contractility so it can be distinguished from valvular aortic stenosis.

Question 10

how can you distinguish HOMC from valvular aortic stenosis?

Answer 10

perform maneuvers: things that will decr heart size and increase contractility will increase the obstruction and inc the murmur. ex: valsalva, standing up, digitalis: these will decr venous return. most impt: make the heart smaller, so septum is closer to valve and there is more obstruction.

Question 11

how can you decr the obstruction/murmur in HOMC?

Answer 11

pt does maneuvers that increase heart size and decr contractility (lying down with legs up, beta blockers, Ca channel blockers).

Question 12

how does the LV overcome the resistance to outflow introduced by an aortic stenosis?

Answer 12

increases its contractile force, incr systolic pressure in ventricle.

Question 13

how does the LV respond to an increased pressure load?

Answer 13

LVH, concentric.

Question 14

what is the problem with LV hypertrophy?

Answer 14

decr LV compliance, ischemia, ultimately myocardial failure.

Question 15

hypertrophied myocardium resists ventricular filling. what is the compensation mechanism to make up for this?

Answer 15

LAE and atrial kick/S4 gallop!

Question 16

what is the result of LAE and atrial kick on the rest of the circ system?

Answer 16

higher LA pressure can cause pulm venous congestion, which may cause dyspnea even before LV systolic dysfunction develops.

Question 17

myocardial ischemia affects myocardial 02 supply how?

Answer 17

supply: decreases 02 supply via decr BP, compression of subendocardial arteries by contracting myocardium, greater diccusion distance from capillaries to hypertrophied fibers

Question 18

myocardial ischemia affects myocardial 02 demand how?

Answer 18

increased demand: increases myocardial mass, increases wall tension reqirements

Question 19

what is the ultimate cause of LH failure in aortic stenosis?

Answer 19

LV systolic function failure.

Question 20

what is the average survival after the development of sx of aortic stenosis?

Answer 20

after angina - 5 y
after syncope - 3 y
after CHF - 2 y

Question 21

what are 3 sx of valvular aortic stenosis?

Answer 21

1. antina
2. syncope. usually associated with exercise concurrent with fixed stroke volume
3. congestive heart failure (dyspnea, orthopnea, PND due to decreased LV compliance - diastolic failure - or systolic dysfunction)

Question 22

what are 6 physical findings suggesting significant aortic stenosis?

Answer 22

1. carotid pulse parvus et tardus (small and late)
2. concentric LVH, s4 gallop
3. murmur, S4
4. LVH in EKG
5. CXR. not abnl in early stages since concentric LVH does not cause cardiomegaly. but later on there may be pulm congestion
6. ECHO: concentric LVH, abnl leaflets, doppler flow abnormalities
7. pressures in LV that are far higher than those that make it into the aorta.

Question 23

what are the treatments for aortic stenosis?

Answer 23

aortic valve replacement. can be done open heart or via TAVR (catheter delivery of the new valve)

Question 24

what are the most common causes of chronic aortic regurg?

Answer 24

aortic valvular disease, aortic root damage.

Question 25

types of aortic valvular disease that can lead to aortic regurg?

Answer 25

• congenital/bicuspid valve

- rheumatic, resulting from having had rheumatic fever in past

Question 26

types of aortic root disease that can lead to aortic regurg?

Answer 26

• tertiary syphilis

- Marfan’s - loss of elastic tissue

Question 27

pathophysiology of chronic aortic regurg?

Answer 27

• LV volume overload.
• eccentric LV hypertrophy
• myocardial failure
• ischemia

Question 28

describe the LV overload that occurs with chronic aortic regurg

Answer 28

up to 80% of ejected stroke volume can be regurg back to LV during diastole. to compensate, the heart incr SV by ventricular dilatation (acute) and hypertrophy (chronic)

Question 29

which is preferable: mitral regurg or aortic regurg?

Answer 29

mitral, because the ventricle pumping against the LA is much easier than pumping against the aorta.

Question 30

what kind of hypertrophy do we get in chronic aortic regurg?

Answer 30

eccentric, since the problem requires additional flow. sarcomeres added in series. allows greater SV

Question 31

is ischemia in aortic regurg better or worse than for aortic stenosis?

Answer 31

better - because a tension load requires less additional 02 than a pressure load.

Question 32

what are the most common sx in chronic aortic regurg?

Answer 32

dyspnea, orthopnea, PND. because of diminished ejection of blood, as well as ultimate LV failure

Question 33

what are the indications for surgical management of aortic stsnosis?

Answer 33

• symptoms of syncope, angina or heart failure
• signs of severe stenosis: abnl carotid pulse, LVH, doppler problems, transvalvular pressure gradient >60mmHg, small enough calculated valve area.

Question 34

syncope: more common in aortic regurg or aortic stenosis?

Answer 34

stenosis.

Question 35

findings suggestive of significant aortic regurg?

Answer 35

1. widened pulse pressure.
2. LV enlargement
3. murmurs. early diastolic near sternum.
4. CXR: LV enlargement (since eccentric not concentric).
5. ECHO: aortic root dilatation, valve deformity, dilated LV.
6. can see the degree of regurg with contrast dye/imaging.

Question 36

indication for surgery from aortic regurg?

Answer 36

dilation and dysfunction of LV, incr LV diastolic pressure. once symptoms occur, aortic valve replacement is indicated because post-op benefit is limited once LV dysfunction has begun.

Question 37

Treatment for aortic regurg?

Answer 37

surgical replacement of the valve.

Question 38

what are some causes of acute aortic regurg?

Answer 38

bacterial endocarditis leading to valve perforation.
aortic dissection - may cause separation of the aortic leaflet.
rupture of the aortic sinus (aortic root area)

Question 39

therapy for acute aortic regurg?

Answer 39

emergent valve replacement. may be able to manage temporarily with vasodilators (to reduce afterload).

Question 40

when aortic regurg is acute, how does the ventricle respond?

Answer 40

does not have time to hypertrophy as with chronic. size remains normal, compliance becomes very low, pressure gets very high. increases wall tension requirements dramatically, causing acute systolic dysfunction and myocardial failure

Question 41

how is the murmur for acute regurg different from the murmur in chronic regurg?

Answer 41

with acute, you might not hear it - so much regurg/open flow that there is less turbulence.

Question 42

general clinical differences between chronic and acute aortic regurg?

Answer 42

with acute: acute onset, murmur may be softer, no LVH on EKG, no LV enlargement on CXR, smaller chambers on ECHO.