Valvular Heart Disease

Question 1

1. Explain the timing of the four major heart sounds (S1-4) in relation to aortic, LV, and LA pressure curve.

Answer 1

S1 occurs with mitral valve closing, at the cross point of rising ventricular pressure and declining atrial pressure

S2 occurs at aortic/pulmonic closing with declining ventricle pressure and increasing atrial pressure

S3 occurs during early diastolic filling of the ventricle when the greatest gradient between LA and LV exists due to stiff ventricle

S4 occurs in late diastole, associated with increased filling of atrial systole caused by cardiac diseases that reduce LV compliance (associated with a wave of arterial waveform)

Question 2

1. Explain the timing of the four major heart sounds (S1-4) in relation to Doppler derived forward flow velocities

Answer 2

S1 corresponds to c wave on the left atrial pressure tracing
S2 associated with the V wave, just before the surge
S3 associated with excess velocity of E wave on doppler waveform
S4 can occur towards the end of the A wave in doppler waveform with increased filling velocity due to atrial kick

Question 3

Relate the pitch of a murmur to the associated velocity

Answer 3

high pressure gradient means high flow velocity and high pitched murmur, analogous for low pitch

Question 4

2. Contrast mid systolic ejection murmur and holostystolic regurgitant mumurs re: their cause and morphology. These are examples of the two types of systolic murmurs (ejection and regurgitant murmurs)

Answer 4

mid systolic ejection murmurs rise and fall in intensity due to turbulent flow exiting the pulmonic or aortic valves

holosystolic regurgitant murmurs are caused by blood leaking form the LV to the LA because of insufficiency and high pressure differential (longer, occurring during the time when mitral valve is closed)

Question 5

2. Contrast diastolic regurgitant and diastolic filling murmurs. These are representative of the two types of diastolic murmurs

Answer 5

aortic valve insufficiency decrescendos due to decreasing pressure across the aortic valve

diastolic filling creating large to begin and the crescendos up during atrial kick due to mitral valve dysfunction

Question 6

Why is it important that a diaphragm is rigid when trying to hear high frequency sounds?

Answer 6

diaphragm will help to filter out low frequency sounds and resonate at higher frequencies

note the electrical stethoscope has additional amplification mechanisms

Question 7

Name the 3 primary diseases of the aortic valve stenosis?

Answer 7

calcific degeneration/senile calcific: degeneration and calcium deposits associated with aging causing greater force generation necessary to open valve
rheumatic disease: causes inflammation that can seal leaflets together over time (valve doesn’t open fully)
congenital heart disease/bicuspid valve: deformation resulting in only 2 leaflets present at birth, overtime can lead to asymmetry of opening and closing and further degeneration over time

Question 8

What part of the leaflet first suffers damage in disease? What are the signs of clinical progression of valvular disease?

Answer 8

mechanical stress is highest near the base of the leaflet and higher in a bicuspid valve.

valvular disease progression is apparent with progressively smaller leaflets, symptoms may not be apparent in sedentary patients until area is 40mmHg

several factors including: genetics, atherosclerosis (lipids), inflammation, extracellular matrix (metaloproteases) bone/ca metabolism and angiogenesis may play a role in pathogenesis progression as well

Question 9

Describe the primary symptoms of aortic stenosis.

Answer 9

exertional angina (most common): sub endocardial inschemia due to high wall stress hypertrophy
exertional syncope: inadequate CO; Benzold Jarisch reflex- pressure triggers C fibers causing a reduction in contraction and vasodilation
dyspnea on exertion: due to diastolic and systolic failure

** primary pathology is a pressure overload

Question 10

What are common approaches to tx. of aortic stenosis, especially given the prognosis of new clinical signs.

Answer 10

tx. hypertension
avoid heavy exertion if severity of AS is moderate or great
maintain sinus rhythm esp for atrial kick
follow up based on severity and advise patients on signs to watch for

**patients with symptoms should be referred for surgery, asymptomatic surgery can be considered under situations (during CV sugary, symptoms on stress test, LV dysf, LVH or critical valve area reduction)

surgery greatly improves survival

Question 11

2. Relate the changes in intensity of heart sounds and the generation of extra heart sounds found in patients with aortic stenosis and mitral stenosis.

Answer 11

aortic stenos causes a diamond shaped ejection murmur, prorgressive increases in Ca on the valve stiffens the leaflets and reduce valve motion reducing S2

when the problem is mild the murmur is short and peaks in mid systole; as the stenosis becomes more sever, the murmur becomes more prolonged, peaking later systole, pitch also increases normally with severity

Question 12

How do myocytes deal with after load and increased wall stress?

Answer 12

eccentric hypertrophy, changes that help to maintain output; and once cells are unable adapt, more ischemia and expression of embryonic genes occurs (females tend toward concentric hypertrophy and males toward eccentric hypertrophy)

increase in pressure leads to increased atrial filling and atrial hypertrophy resulting in S4 sound

Question 13

List the resultant compensatory changes in hypertrophy.

Answer 13

diameter and volume density of myocytes leads to normalized wall stress
coronary flow, active relaxation and extent of relaxation is impaired
increased filling pressures resulting in mild pulmonary HTN
cardiac response to exercise reduced
outflow obstruction

in AS the pressure volume loop is slightly shifted leftward, and the diastolic filling curve is shifted upward and to the left

Question 14

How is damage to valves in insufficiency/regurgitation different than stenosis?

Answer 14

generally the same causes of damage, although the resulting injury is more degenerative but additionally: primary aortic root abnormality (AAA or aortic dissection)W

i.e.. direct leaflet destruction such as that caused by endocartitis; congenitally unequal cusp size, fibrosis of rheumatic disease, destructive toxins ad inflammatory deterioration

Question 15

What is the major pathophysiology of aortic insufficiency?

Answer 15

primary problem of volume and pressure overload in ventricle leading to increase preload and possibly increased after load
within this process, mechanical stretch signals initiate genetic reprograming causing myocyte elongation and activation of matrix metalloproteinases

Question 16

What is the major architectural change initiated by aortic regurgitation?

Answer 16

predicted by Frank-Starling relationship, increased pressure leads to increasing volume of ventricle chamber, compensating for increases in ventricular wall stress

in AR, the pressure volume loop shifts rightward as does the diastolic filling curve

Question 17

What effect does exercise have on AR?

Answer 17

shorter diastole is the less time there is for insufficiency to occur and aortic insufficiency volume decreases with faster heart rates; in this regard, aerobic exercise has no harmful effects on aortic insufficiency

Question 18

3. Describe the hemodynamic effects of acute aortic insufficiency.

Answer 18

the ability of left ventricle to acutely dilate to accommodate volume overload is limited and HR increases in attempts to compensate for inadequate stroke volume

the greatest change caused by acute AR is increase in LV diastolic pressure which in turn causes a marked increase in LA pressure (accompanied by SOB)

both a systolic and diastolic murmur and inverted T wave may be present

Question 19

3. Describe the changes in ventricular and aortic pressure during acute aortic insufficiency.

Answer 19

central aortic pressure declines rapidly due to aortic regurgitation
LV pressure rises quickly due to volume form mitral valve and aortic regurge.
aortic and left ventricular cavity pressures reach equilibrium before end-diastole which has profound effects on left atrial pressure and flow across the mitral valve

at end-systole, left atrial pressure is considerably higher than normal and only partially declines in early diastole as the mitral valve opens

Question 20

Describe the murmur of aortic insufficiency.

Answer 20

high pitched decrescendo murmur, beginning at end-systole but rapidly declines to nothing before the end of diastole

amplitude is proportional to the pressure gradient between central aorta dn left ventricle

usually accompanied by a systolic ejection murmur