Effects of postural changes on cardiac function in healthy subjects.

Aims: To analyse the response of Doppler measurements to increased venous return in middle-aged healthy subjects.

Methods And Results: Left ventricular pulsed Doppler parameters, colour M-mode of early left ventricular filling and septal mitral annulus velocities were measured at baseline and after leg lifting (n=24). Leg lifting resulted in increased stroke volume (69 +/- 14 to 74 +/- 14 ml, P<0.01) and peak systolic annulus velocity (6.8 +/- 1.3 to 7.3 +/- 1.1 cm/s, P<0.01). Leg lifting enhanced peak early (E) mitral flow (74 +/- 13 to 80 +/- 14 cm/s, P<0.01), flow propagation (53 +/- 10 to 59 +/- 13 cm/s, P<0.01) and E' diastolic mitral annulus velocity (10.8 +/- 2.2 to 11.7 +/- 2.0 cm/s, P<0.01). There was a shortening of E wave deceleration time (178 +/- 27 to 163 +/- 27 ms, P<0.01) and isovolumic relaxation time (76 +/- 11 to 68 +/- 10 ms, P<0.01). However, individual changes in Doppler parameters differed among subjects.

Conclusions: Leg lifting improved myocardial function as manifested by increase in stroke volume, systolic annulus motion and acceleration of relaxation. Flow propagation velocity and diastolic mitral annulus velocities were influenced by the induced change in cardiac preload as well.