Insights into the physiologic significance of the mitral inflow velocity pattern.

The ability to measure mitral inflow velocities by Doppler echocardiography has allowed us to examine left ventricular filling noninvasively (1,2). Initially, the availability of this information generated great enthusiasm for extracting intrinsic diastolic properties of the left ventricle from a simple analysis of these velocities, in particular, the early and late diastolic filling velocities (the E and A waves) and their ratio. This initial enthusiasm has been tempered by the growing realization that inflow patterns result from a complex amalgam of ventricular, atria1 and mitral valve properties and are profoundly influenced by superimposed loading conditions (3-5). Because of these multiple determinants, similar mitral inflow patterns could appear in different clinical settings if the time course of the transmitral pressure gradient is similar in those conditions. The hypertrophic pattern versus decreased preload. One of the earliest characteristic abnormal patterns described (6-8) was the diminished early filling (E) wave and decreased E/A wave ratio in patients with hypertrophic cardiomyopathy. These findings were explained by delayed ventricular relaxation causing relatively high early diastolic left ventricular pressures and, therefore, a relatively low early diastolic gradient across the mitral valve. More recently, however, a similar pattern has been reproduced simply by decreasing left-sided filling pressures without intrinsic myocardial changes, for example, by nitroglycerin infusion: the de-