Valvular Regurgitation

Question 0

Generally compared to stenosis, how well are hearts with a regurgitant valve able to increase CO?

Answer 0

Hearts with a regurgitant valve are better able to increase CO.

Question 1

What is regurgitant volume?

Answer 1

The extra volume that the upstream chamber receives through the regurgitant valve.

Question 2

What’s the best way to express the severity of regurgitation?

Answer 2

Regurgitant volume and regurgitant fraction.

Question 3

What’s the regurgitant fraction?

correction: this is just for mitral regurgitation

Answer 3

The fraction of total stroke volume (TSV = EDV - ESV) that enters the upstream chamber.

Question 4

What’s the regurgitant fraction?

Answer 4

The fraction of total stroke volume (TSV = EDV - ESV) that enters the upstream chamber.

Question 5

What is the “mission statement” of eccentric hypertrophy?

Answer 5

To minimize the increases in wall stress associated with increases in wall pressure.

Question 6

Do the mitral valve leaflets normally overlap?

Answer 6

Yes. If the valve annulus gets stretched, they might overlap less, and have more risk of regurgitation.

Question 7

What are the 3 Carpenter types of valve motion perturbation in mitral regurgitation (MR)? (conditions that cause these)

Answer 7

Type I: normal leaflet motion (e.g. perforation, annular dilation)
Type II: increased motion (e.g. snapped chordae, myxomatous degen.)
Type III: decreased motion (IIIa is due to rheumatic disease, IIIb is due to things like dilated cardiac myopathy)

Question 8

3 causes of reduced leaflet motion in type III MR?

Answer 8

Dilated cardiac myopathy.
Remodeling in response to ischemia (MI).
Rheumatic disease.

Question 9

Two types of myxomatous degneration MR?

Answer 9

Fibroelastic deficiency (isolated flail segment)
Barlow's disease (prolapse)

Question 10

How can ischemia cause transient MR?

Answer 10

The posteromedial papillary muscle has a single blood supply, and can have reduced function that resolves when the ischemia does.

Question 12

How can ischemia cause chronic MR?

Answer 12

Post-MI remodeling of the ventricle can change the angles by which papillary muscles pull on the leaflets, causing MR.

Question 13

How does mitral valve prolapse (MVP) sound different from other MR regurgitation?

Answer 13

MVP often occurs in late systole, preceded by a click.

Other MR murmurs are holosystolic (present all the way from S1 to S2).

Question 14

What’s the forward stroke volume (FSV)?

Answer 14

The portion of the stroke volume that moves into the downstream chamber.

Question 15

3-4 variables effecting the regurgitant volume?

Answer 15

Pressure gradient from LV to LA.
Size of mitral regurgitant orifice.
LV systolic ejection time, and time that orifice is regurgitant.

Question 16

How does SVR affect the regurgitant fraction?

Answer 16

The lower the SVR, the greater the proportion of blood flow that enters systemic circulation.

Question 17

What happens in acute MR? (to the LA, LV, CO, LVEF)

Answer 17

LA pressure increases (pulmonary edema if severe)
CO is reduced, though preload does increase.
Ejection fraction increases, but much of it isn’t useful.

Question 18

Compensatory mechanisms that occur during acute MR?

Answer 18

LV dilation (sarcomere stretching) due to increased volume.
Adrenergic circulatory reflexes: increased HR, contractility, and vasoconstriction to maintain BP/perfusion (but overall SVR does drop)

Question 19

Bad consequences of severe acute MR?

Treatment?

Answer 19

Rise in LA pressure transmitted to pulmonary veins -> acute pulmonary edema. (acute congestive HF).
Treatment = O2, diuresis, vasodilators, and immediate valve repair/replacement.

Question 20

What does the LA pressure waveform look like in acute MR?

Answer 20

The V waves are high due to augmented diastolic filling.

Question 21

How does the LV change in chronic MR?

How doe the LA change?

Answer 21

Eccentric hypertophy - allowing increased LVEDV at lower LVEDP.
The LA becomes more compliant.

Question 22

How is CO in chronic compensated MR?

Answer 22

It’s actually pretty close to normal.

Question 23

Why does decompensation of chronic MR occur?

Answer 23

Loss of contractile function -> reduced EF, FSF, and increased RF.

Question 24

3 reasons that make you think it’s time to replace/repair the valve in MR?

Answer 24

Symptoms of HF (acute or decompensated chronic).
Reduced LV contractility.
Significant LV remodeling.

Question 25

Should you worry if someone in MR has a normal EF?

Answer 25

Yes. Their EF should be hypernormal. Normal EF will probably be producing inadequate FSV and CO.

Question 26

Does a good repair beat valve replacement?

Answer 26

Yup.

Question 27

Major problem with mechanical valves?
With bioprosthetic valves?
With both?

Answer 27

Mechanical valves require lifelong warfarin.
Bioprosthetic valves wear out relatively quickly.
Both are quite susceptible to endocarditis.

Question 28

In aortic regurgitation (AR), how does the FSV compare to TSV?

Answer 28

FSV = TSV, because regurgitation occurs in diastole.

Question 29

How is the regurgitant fraction defined in AR?

Answer 29

Regurgitant stroke volume / TSV.

Question 30

5 causes of AR?

Answer 30

Aortoannular ectasia (dilation).
Dissection (esp. in Marfan's).
Congenitally abnormal aortic valve.
Fixed leaflets w/ mixed stenosis/regurg (rheumatic or calcific).
Endocarditis.

Question 31

What’s the association between a bicuspid aortic valve and aortic enlargement?

Answer 31

Both are products of abnormal development.

Question 32

What do aortic valves affected by rheumatic disease look like?

Answer 32

Fixed orifices due to fused commissures. Will have both stenosis and regurg.

Question 33

How does LV wall stress in AR compare to that in MR? What effect does that have?

Answer 33

LV wall stress is greater in AR, leading to a higher degree of eccentric hypertrophy.

Question 34

Why does exercise actually help some aspects of AR?

Answer 34

SVR drops, so more blood flows forward.

Diastole is shortened, so there’s less time for regurgitation.

Question 35

What do systolic / diastolic BP do in severe AR?

Answer 35

Systolic increases with increased FSV.

Diastolic drops due to rapid regurgitation back into LV (you can see a pressure like 170/50).

Question 36

Consequences of acute severe AR?

Answer 36

LVEDP and LA pressure rise dramatically -> CHF.
Sympathetic responses kick in, but the tachycardia and increased contractility aren’t enough to get CO up.
Low CO -> cardiogenic shock.

Question 37

Review: Which pressure gradient drives coronary perfusion?

Answer 37

Aortic diastolic pressure - LVEDP

Question 38

How can AR cause angina despite absence of CAD?

Answer 38

Impaired coronary perfusion: Aortic diastolic pressure is low, and the LVEDP is high. Also increased HR -> shorter diastole. (and high endocardial pressures impair subendocardial perfusion)
Increased metabolic demands of heart due to increased HR and wall stress.

Question 39

4 indications for surgical in AR?

Answer 39

Symptoms
LV end systolic dimension too big.
Fall in EF to normal range.
LV end diastolic dimension too big.