Postextrasystolic potentiation worsens fast filling of the hypertrophied left ventricle in aortic stenosis and hypertrophic cardiomyopathy.

Abstract

Impaired left ventricular (LV) filling in aortic stenosis (AS) and in hypertrophic cardiomyopathy (HCM) is caused by slow LV pressure decay, which could be explained by depressed inactivation of hypertrophied myocardium. Postextrasystolic potentiation (PESP), which increases activator calcium, could lead to further deterioration of LV relaxation. The influence of PESP on LV filling dynamics was, therefore, investigated in normal controls and in patients with LV hypertrophy caused by AS or by HCM. LV hemodynamics and LV hemodynamic relaxation indexes were determined during normal sinus rhythm (NSR) and after PESP. LV pressures were recorded by micromanometer tip catheters (controls, n = 10; AS, n = 17; HCM, n = 11). Simultaneous mitral flow Doppler echocardiograms were obtained in patients with LV hypertrophy (AS, n = 8, HCM, n = 5). Despite significant increases of LV dP/dtmax after PESP in all three study groups, PESP affected LV hemodynamic relaxation indexes differently. The time constant of LV pressure decay (TPB) derived from exponential curve fits with nonzero asymptote pressure remained unaltered after PESP in normal controls, rose from 62 +/- 17 to 74 +/- 21 msec (p less than 0.02) in patients with AS, and rose from 74 +/- 18 to 84 +/- 19 msec (p less than 0.02) in patients with HCM. Early diastolic LV pressure decay was measured by phi (phase of the first harmonic of a Fourier transform applied to the diastolic LV pressure waves) and by t (time interval from LV dP/dtmin to LV minimum diastolic pressure). After PESP, phi remained unaltered in normal controls but decreased in AS from 42.8 +/- 19.1 degrees to 24.0 +/- 28.8 degrees (p less than 0.001) and in HCM from 39.7 +/- 15.4 degrees to 26.9 +/- 15.7 degrees (p less than 0.001). Similarly, t was unchanged after PESP in normal controls but prolonged in AS from 146 +/- 48 to 205 +/- 86 msec (p less than 0.001) and in HCM from 168 +/- 40 to 208 +/- 53 msec (p less than 0.02).(ABSTRACT TRUNCATED AT 400 WORDS)