chapter  91
Diastolic Heart Function
Pages 14

Normal left ventricular (LV) diastolic function can be defined as the ability of the ventricle to fill to a normal end-diastolic volume, during both rest and exercise, with a mean left atrial (LA) pressure that does not exceed 12 mm Hg. Because the process of LV relaxation is more energy dependent than contraction, abnormalities of LV diastolic function occur earlier than systolic dysfunction in virtually all cardiac diseases. They increase in frequency with aging, so that about 50% of patients over 70 years old with symptoms of heart failure (HF) have a normal LV ejection fraction, or “diastolic heart failure” (DHF) as their primary cardiac problem. Studies show the symptoms of diastolic and systolic heart failure (SHF) are clinically indistinguishable. Patients with DHF are either unable to adequately distend their slowly relaxing and stiffened left ventricles, or can do so only with elevated filling pressures.This results in symptoms due to pulmonary congestion, atrial arrhythmias or reduced exercise capacity due to a inability to increase LV stroke volume at faster heart rates. Recognition of patients with DHF is important because they have a prognosis nearly as poor as SHF, and even asymptomatic patients with diastolic dysfunction are at increased risk for adverse cardiovascular events. In addition, in patients with

SHF, the degree of diastolic dysfunction is a powerful predictor of mortality. Reliable, noninvasive ways to diagnose diastolic function at its earliest stages continue to be pursued and potential therapies for LV diastolic function are being studied.