The Effect of Premature Ventricular Contraction on Left Ventricular Relaxation, Chamber Stiffness, and Filling in Humans

To investigate the influence of single spontaneous premature ventricular ectopic beats on left ventricular contraction, relaxation, chamber stiffness, and filling, we examined 21 patients with simultaneous micromanometer left ventricular pressure tracings and echocardiograms. Instantaneous left ventricular diameter and mitral valve inflow velocity were obtained by using of M-mode and pulsed Doppler echocardiography, respectively. The isovolumic relaxation time constants (TL and TD) were calculated by mean of a zero (TL) and variable (TD) asymptote pressure. The chamber stiffness constants were derived from the diastolic pressure-diameter (kd) and pressure-volume (kv) relationships. The extrasystolic beat was associated with marked impairments of relaxation, systolic function, and diastolic filling as seen by an increased TL (53 to 71 msec; p less than 0.001), TD (59 to 89 msec; p less than 0.005), time from maximum negative dp/dt to the lowest diastolic pressure (147 to 170 msec; p less than 0.05), and decreased number of elasped TDs (3.1 to 2.4; p less than 0.05), end-systolic pressure-diameter ratio (2.4 to 1.7; p less than 0.001), maximum positive dp/dt (1904 to 1326 mm Hg/sec; p less than 0.001), shortening fraction (31% to 21%; p less than 0.001), and peak early filling velocity (59 to 49 cm/sec; p less than 0.001). Chamber stiffness constants were unchanged. Relaxation and chamber stiffness were unchanged during the postextrasystolic beat as reflected by TL, TD, maximum negative dp/dt, and kd and kv.(ABSTRACT TRUNCATED AT 250 WORDS)