Flashcards in Valvular Heart Disease 2 Deck (19):
Describe the volume and pressure characteristics of a heart with aortic stenosis that is chronically compensated
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
Describe the change between chronic compensated to chronic decompensated
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
Explain the cause of reduced response to exercise in patients with aortic stenosis.
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
Describe the changes in pressure and volume in acute v. chronic aortic insufficiency (regurgitation).
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
Note the difference between aortic stenosis and insufficiency changes of pressure volume curves.
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
How does symptom progression vary based on LV in aortic insufficiency?
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
When is the best time for interventional surgery for aortic insufficiency?
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)
Contrast the advantages and disadvantages of porcine and stentless porcine valves.
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
Describes options of homographs and autographs.
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
What are different types of mechanical valves? What are their advantages and disadvantages?
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)
List events of valvelet destruction with bioprosthesis.
fibrous thickening of leaflets
tissue overgrowth with leaflet retraction
similar damage to native valve
4. Describe the sequence of events that take place in the alveoli as left atrial pressure rises.
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
The majority of cases of mitral stenosis is cause by __- ___ leading to what condition of the valves?
rheumatic fever causing fusion of various portions of the mitral apparatuses: commissures, cusps, and chord tendinae
What symptoms are typical of mitral stenosis presentation?
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
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.
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
What hemodynamic and heart sound changes occur with mitral stenosis.
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
Describe how murmur changes with gradient or exercise during mitral stenosis.
murmur amplitude is somewhat proportional to the size of the gradient across the valve; murmur amplitude is directly proportional to the cardiac output
A less common consequence of mitral stenosis is the development of severe pulmonary hypertension, describe two mechanism that may contribute to pulmonary hypertension
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