The factor dominating the determination of left ventricular filling varies during the first five days after acute myocardial infarction

Abstract

Left ventricular diastolic dysfunction may occur after the onset of acute myocardial infarction. Left ventricular diastolic filling dynamics are related to many factors. To evaluate the influence of left ventricular filling pressure on Doppler-derived left ventricular diastolic flow profiles in patients with acute myocardial infarction, we studied serial changes in filling during the first 5 days after the onset of uncomplicated acute myocardial infarction. The study population consisted of 14 patients with acute myocardial infarction and 15 normal subjects: Doppler echocardiographic studies (left ventricular transmitral inflow and outflow velocity patterns) were performed on admission, and on the third and fifth days after infarction. Hemodynamic parameters were measured simultaneously using Doppler echocardiography. The E wave was lower, the A wave and A:E ratio were higher, deceleration half time and isometric relaxation time were prolonged, and peak left ventricular ejection flow velocity was lower in myocardial infarction patients than in normal subjects. The E wave and pulmonary capillary wedge pressure were positively correlated on the first and the third day (r = 0.77, P < 0.001, and r = 0.67, P < 0.01, respectively), but not on the fifth day. The E wave and isometric relaxation time were negatively correlated on the fifth day (r = -0.72, P < 0.01), but not on the first and third day. Left ventricular filling pressure (preload) was an important mechanism for maintaining left ventricular filling during the first 3 days, but the relaxation of the ventricle began to play a dominant role on the fifth day.