III A - Mitral regurgitation
With mitral regurgitation the valve leaflets fail to close properly
to prevent blood flow from the LV to the LA during ventricular
systole. The large systolic pressure gradient between the LV
and LA is the driving force for backward flow across the mitral valve;
this pressure gradient, coupled with the severity of the mitral pathology
(i.e. the resistance to flow across the malfunctioning valve) leads to a
portion of ventricular ejection that is retrograde; this portion is termed
the regurgitant volume. The ratio of this regurgitant volume and the
total volume ejected from the ventricle is termed the regurgitant
fraction.
Vary the severity of mitral reguritation and make the following observations:
1. How does mitral regurgiation affect the shape of the P-V diagram?
2. How does mitral regurgitation affect cardiac output
and left ventricular end-diastolic pressure?
3. Why are right and left ventricular stroke volume no longer equal?
4. In the presence of mitral regurgitation, what is the impact of increasing
afterload on regurgitant fraction?