218
CARDIOVASCULAR PHYSIOLOGY CONCEPTS
Systolic Failure
Diastolic Failure
Systolic & Diastolic Failure
■ FIGURE 9.9 Effects of systolic, diastolic, and combined failure on left ventricular pressure-volume loops.
Panel A shows that systolic failure (loss of inotropy) decreases the slope of the end-systolic pressure-
volume relationship and increases end-systolic volume. This causes a secondary increase in end-diastolic
volume, which is augmented under chronic conditions by ventricular dilation that shifts the passive filling
curve down and to the right. The net effect is that stroke volume and ejection fraction decrease. Panel B
shows that diastolic failure increases the slope of the end-diastolic pressure-volume relationship (pas-
sive filling curve) because of reduced ventricular compliance caused by either hypertrophy or decreased
lusitropy. This reduces the end-diastolic volume and increases end-diastolic pressure. End-systolic volume
may decrease slightly as a result of reduced afterload. The net effect is reduced stroke volume; ejection
fraction may or may not change. Panel C shows that combined systolic and diastolic failure reduces end-
diastolic volume and increases end-systolic volume so that stroke volume is greatly reduced; end-diastolic
pressure may become very high.
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