Valvular Heart Disease 2

Question 1

Describe the volume and pressure characteristics of a heart with aortic stenosis that is chronically compensated

Answer 1

state of near normal end-systolic wall stress

increased pressure within the ventricle causes volume enlarged and maintains a constant ejection fraction,

men often tend toward chamber enlargement, not maintaining normal walls stress and showing decrease in ejection fraction

Question 2

Describe the change between chronic compensated to chronic decompensated

Answer 2

with valve issues that are not addressed ventricle continues to enlarge, walls thin and patient starts to loose systolic pressure

pressures may also back up into the left atrium causing dilation, and additional S4 sound as contraction becomes more powerful and higher velocity

this level of remodeling is dangerous and may not be reversible, leading to serious dysfunction; changes are only apparent on echocardiogram

progression of stenosis is also associated with subendocardial ischemia

Question 3

Explain the cause of reduced response to exercise in patients with aortic stenosis.

Answer 3

heart is not able to respond to increased output needs, there is no preload augmentation leading to decreased end systolic and diastolic volumes to decrease

Question 4

Describe the changes in pressure and volume in acute v. chronic aortic insufficiency (regurgitation).

Answer 4

overall both are a pressure and volume overload state

increased pressure in aorta per beat and a slow decrease in aortic pressure due to the leaking back through aortic valve, diastolic murmur may lengthen

note tremendous pulse pressure will lead to observed bounding pulse and apical pulse may be large and laterally displaced

after load overload is hight due to back flow through valve, and LV responds with enlargement (mediated by metalloproteinases)

in chronic insufficiency the compensatory mechanisms begin to fail and systolic performance can decline with increased fibrosis

Question 5

Note the difference between aortic stenosis and insufficiency changes of pressure volume curves.

Answer 5

AS: pressure volume loop shifted leftward and diastolic filling curve is shifted upward, stroke volume is about the same

AR: pressure volume loop shifted rightward, as does the diastolic filling curve and stroke volume is increased

Question 6

How does symptom progression vary based on LV in aortic insufficiency?

Answer 6

if LV function is normal, the conversion to symptomatic limitation is low, once there is LV disfunction (LVEF <50%) symptoms increase

note in AS exercise is preserved surprising long because there is a reduction in diastolic time caused by an increase in HR, also vasodilation lowers after load

Question 7

When is the best time for interventional surgery for aortic insufficiency?

Answer 7

usually not wait until symptoms appear, decision is based on serial evaluation by echocardiography to monitor LV size and function along with function along the aorta (treatment can cause regression of reverse remodeling)

Question 8

Contrast the advantages and disadvantages of porcine and stentless porcine valves.

Answer 8

both are non-thrombogeneic and require no long term anticoagulation, there is relatively poor hemodynamics leading (better with scentless) and progressive calcification/ heart failure

bovine pericardial valves are upcoming

Question 9

Describes options of homographs and autographs.

Answer 9

cryoperserved explanted human aortic root are implanted in a technically more challenging procedure, viability is difficult to judge at present

autographs includes removal of pulmonic valve to replace the aortic valve and pulmonic valve is replaced with bioprosthesis (long and difficult) degeneration at pulmonic valve slower than in the aortic position

Question 10

What are different types of mechanical valves? What are their advantages and disadvantages?

Answer 10

single leaflet or doulbe leaflet (better flow profile)

both provide fairly good hemodynamics and excellent durability but require thrombosis prophylaxis blood thinners

note future directions for non-sugerical candidates for percutaneous AV replacement via catheter (edwards valve)

Question 11

List events of valvelet destruction with bioprosthesis.

Answer 11

fibrous thickening of leaflets
tissue overgrowth with leaflet retraction
collagen disruption
leaflet tears
leaflet calcification

similar damage to native valve

Question 12

4. Describe the sequence of events that take place in the alveoli as left atrial pressure rises.

Answer 12

1. fluid starts leaking out of capillaries at higher pressures, lymph compensation
2. at higher pressures, lymph return is overcome and fluid accumulates in the interstitial space, causing more force for inspiration
3. at higher pressures, tight junctions near alveolar are broken apart and inhibits exchange
4. in very serious cases fluid begins to fill the alveolar cavities and completely use ability to exchange gas (can be lethal) pressures greater than 25mmHg

Question 13

The majority of cases of mitral stenosis is cause by __- ___ leading to what condition of the valves?

Answer 13

rheumatic fever causing fusion of various portions of the mitral apparatuses: commissures, cusps, and chord tendinae

Question 14

What symptoms are typical of mitral stenosis presentation?

Answer 14

predominantly dyspnea, from high filling pressures and fatigue from reduced CO

left atrium is enlarged, RV and RA may become enlarged and dysfunctional later in the disease

symptoms vary directly with increased fusion of leaflets (particularly below a valve area of >1.4), note mean gradient is till relatively low (5-10mmHg) even with significant dysfunction

symptoms are worse with exercise

Question 15

The left atrium is thin-walled and unable to hypertrophy to any substantial degree resulting in enlargement, discuss several sequelae that might accompany this complication.

Answer 15

increased propensity to change form sinus rhythm to atrial fibrillation

thrombus formation with embolism upstream of mitral valve

substantial change in exercise capacity due to shortening of diastolic filling time and loss of synchronous atrial contraction

hemoptypsis- hemorrhages in the pulmonary vasculature due to increased filling pressure; increased chronic bronchitis and pulmonary edema

Question 16

What hemodynamic and heart sound changes occur with mitral stenosis.

Answer 16

reduction in valve office causes pressure gradient during diastole (produces low-pitched two component murmur) increased amplitude of S1 (may decrease with calcification), opening snap and diastolic rumble

primary hemodynamic abnormalities are found in the left atrial pressure tracing

Question 17

Describe how murmur changes with gradient or exercise during mitral stenosis.

Answer 17

murmur amplitude is somewhat proportional to the size of the gradient across the valve; murmur amplitude is directly proportional to the cardiac output

Question 18

A less common consequence of mitral stenosis is the development of severe pulmonary hypertension, describe two mechanism that may contribute to pulmonary hypertension

Answer 18

reactive pulmonary hypertension due to arteriolar constriction presumably triggered by left atrial and pulmonary venous hypertension (can severely increase afterload of right ventricle)

end stage result of organic obliterative changes in pulmonary vascular that occur with long standing untreated disease

results in paradoxical reducing in dyspnea but fluid retention

Question 19

What is the standard treatment for mitral stenosis?

Answer 19

medical treatments only address the consequences of hemodynamic abnormalities, definitive therapy is surgical although in some cases the valve can be opened via percutaneous commissurotomy without valve replacement for several more years