Sympathetic control of diastolic function in congestive heart failure.

Sympathetic cardiac stimulation is a major extrinsic compensatory mechanism that maintains or augments systolic and diastolic ventricular function during physiological stress or pathological conditions. In particular, catecholamines may selectively improve diastolic function by reducing myofilament calcium sensitivity, accelerating sequestration of calcium into the sarcoplasmic reticulum, and increasing the rate of actin-myosin cross-bridge turnover. These subcellular mechanisms, unique to inotropic agents that increase myocyte cyclic adenosine monophosphate, result in an increased rate and extent of ventricular relaxation and diastolic filling and a decrease in cardiac filling pressures. Despite these potentially favorable biochemical and mechanical actions, a number of limitations and theoretical concerns remain to be addressed before catecholamine therapy is widely administered to patients with congestive heart failure and diastolic dysfunction.