Preload dependence of the time interval between onsets of mitral inflow and early diastolic mitral annular velocity: a study in healthy subjects

The time interval (TEa-E) between onsets of early diastolic mitral annular velocity (Ea) and early mitral inflow velocity (E) has been proposed as a new index of left ventricular (LV) relaxation. We aimed to assess the influence of preload changes on this parameter by examining 25 healthy volunteers at rest, after passive leg lifting, and after administration of nitroglycerin combined with Valsalva maneuver. To obtain septal and lateral TEa-E, the time intervals between peak R-wave on electrocardiogram and the onsets of Ea and E were measured in different cardiac cycles. E and Ea were significantly changed by preload manipulations. We did not observe significant changes of TEa-E intervals after leg lifting or after nitroglycerin administration combined with Valsalva maneuver (P = NS). TEa-E was < 0 ms in several subjects using either septal or lateral Ea recordings. We conclude that TEa-E may be load independent in subjects with normal LV systolic and diastolic function as compared to other Doppler parameters. Therefore, this index could be potentially used as a reliable noninvasive parameter of LV relaxation. Nevertheless, even slight differences in cardiac cycle lengths might influence the measurements of TEa-E interval. For that reason, the clinical use of TEa-E seems to be significantly limited because of a wide margin of error in its measurement due to the inability to obtain Doppler recordings during the same cardiac cycle.