Valvular Regurgitation

Question 1

Regurgitant fraction/volume

Answer 1

severity of valvular regurg expressed as volume overload due to addition of regurg volume

Question 2

What kind of hypertrophy occurs in adaptation to regurg?

Answer 2

eccentric hypertrophy minimizes increase in wall stress associated w/increase in diastolic volume and pressure via laplace –> increase wall thickness, increase mass, no change in relative wall thickness

Question 3

How do the papillary muscles close valve leaflets?

Answer 3

they don’t –> they simply prevent the leaflets from going into the atria by holding them at tension against ventricular pressure (which actually closes them)

Question 4

3 functional etiologies of regurg a la carpentier

Answer 4

1. normal leaflet motion (annular dilation, perforation)
2. increased leaflet motion (myxomatous, flail)
3. decreased leaflet motion (rheumatic disease)

Question 5

Etiology of myxomatous mitral valve disease

Answer 5

increased leaflet motion due to mitral prolapse or flail leaflet (chords ruptured)

*associated w/Marfan’s, eccentric mitral regurg (away from leaflet that prolapses)

Question 6

Etiology of ischemic mitral regurg

Answer 6

1. posteromedial papillary muscle more vulnerable to ischemia (single blood supply)
2. MI causes thinning and dilatation of the wall –> asymmetric distortion of valve

Question 7

What factors determine absolute volume of mitral regurg

Answer 7

1. pressure gradient between LV/LA
2. size of orifice area
3. LV systolic ejection time and time orifice is regurgitant

*if parallel emptying into Ao and A, then possibility of lowering SVR might increase flow into systemic circulation (mostly when acute) –> but doesn’t really work b/c systemic pressure is so much higher than atrial pressure

Question 8

What happens to LA pressure during acute MR?

Answer 8

increase

Question 9

What happens to afterload during acute MR?

Answer 9

lower –> increases TSV

Question 10

What happens to preload during acute MR?

Answer 10

increase due to return of RV (regurgitant volume), increased SV, increased LVEDP

Question 11

What happens to ejection fraction during acute MR?

Answer 11

higher

Question 12

What happens to forward stroke volume during acute MR?

Answer 12

lower

Question 13

What happens to RF during acute MR?

Answer 13

increase –> regurgitant fraction should normally be zero

Question 14

Compensatory changes in chronic MR

Answer 14

initial LV dilation increases EDV and total stroke volume –> eccentric hypertrophy serves to normalize wall stress

*the story is that in MR you get better contractility and contraction of the ventricle but you still have a reduced CO because a bunch of the blood is ending up in the LA instead of the Ao

Question 15

Why are sarcomeres more stretched out in acute vs chronic MR?

Answer 15

chronic can remodel and add more in series to cause eccentric hypertrophy

Question 16

Is EF higher in AMR or CCMR?

Answer 16

higher in acute mitral regurgitation

Question 17

Is FSV higher in AMR or CCMR?

Answer 17

CCMR

Question 18

Is CO higher in AMR or CCMR?

Answer 18

CCR is normal, AMR is decreased

Question 19

Is LV Size bigger in AMR or CCMR

Answer 19

mildly vs severely increased

Question 20

What causes decompensation in CMR?

Answer 20

loss of contractile function (due to loss of contractile elements, abnormal calcium handling, catecholamine excess) –> reduced EF, FSV, increase in RF, increase in afterload (b/c wall stress from size of ventricle counteracts the reduction of afterload from the regurg)

Question 21

What happens to forward stroke volume and total stroke volume in aortic regurgitation?

Answer 21

nothing changes b/c regurg occurs during diastole vs. systole

Question 22

Is there higher wall stress in LV during mitral regurg or aortic regurg?

Answer 22

AR –> need to push out higher volume at a high pressure –> higher overall wall stress –> more eccentric hypertrophy

Question 23

What is the consequence of exercise on aortic regurg?

Answer 23

makes it feel better–> less diastolic time b/c of higher heart rate = reduced time for regurg

Question 24

How does coronary ischemia occur in AR?

Answer 24

increased LV diastolic pressure and decreased Ao diastolic pressure –> reduced pressure gradient to drive coronary blood flow AKA diastolic pressure time integral is low

Question 25

What is the indication for surgery for AR?

Answer 25

a fall in EF (even if it goes from hypernormal to normal)