Left ventricular diastolic function in the normal and diseased heart. Perspectives for the anesthesiologist (1)

Attempts to quantitatively describe ventricular function during diastole have been stimulated by the recognition that diastolic mechanics significantly influence overall cardiac performance, and that diastolic dysfunction may precede, or substantially contribute to, abnormalities of systolic function in various pathologic conditions (table 1). Indices of diastolic function can be derived invasively or noninvasively, and focus on the measurement of a diverse and complex set of separate, but intimately interrelated, processes that, while complementary, may not be directly comparable. Measurement of these indices is complicated, because diastolic function depends on several determinants: active, energy-dependent forces (isovolumic ventricular relaxation); passive and dynamic filling characteristics (chamber and myocardial stiffness); and extrinsic factors (left atrial function, ventricular interaction, valvular integrity, pericardial restraint, and myocardial blood flow), as well as other conditions that affect myocardial function during systole (preload, afterload, heart rate, and inotropic state). The diversity of events occurring during diastole indicates that a single index of diastolic function cannot adequately describe this period of the cardiac cycle, and the physiologic implications of diastolic dysfunction may be different, depending on the period of diastole affected (table 1). Thus, assessment of diastolic function is complicated, because of the heterogeneity of the event and the multiple factors that influence it. Despite the inherent potential limitations of indices describing diastolic function, these parameters provide useful references for evaluating the natural history of patients with diastolic heart failure, for assessing the benefits of therapeutic interventions of anesthetic actions, and for enhancing our knowledge of cardiac pathophysiology.