[Left atrial systolic time intervals: their relations to left atrial preload, afterload and acute left ventricular pressure loading].

Using pulsed Doppler echocardiography, the left atrial pre-ejection period (LAPEP) and left atrial ejection time (LAET) were studied in relation to left atrial loading and acute left ventricular pressure loading conditions in 17 patients with various heart diseases. LAPEP was defined as the time interval from the onset of a right atrial pacing pulse to the upstroke in the atrial contraction phase on the mitral flow velocity pattern; LAET was defined as the duration of left ventricular filling due to atrial contraction. 1. LAPEP did not correlate significantly with mean pulmonary capillary wedge pressure (mPCWP) indicating preload for the left atrium, nor with left ventricular end-diastolic pressure (LVEDP) indicating afterload for the left atrium. There were significant inverse correlations of LAET with mPCWP (r = -0.72) and with LVEDP (r = -0.75). 2. LAPEP, LAET and LAPEP/LAET correlated significantly with the ratio of the peak velocity in the atrial contraction phase and to that in the rapid filling phase (r = -0.62, -0.50 and -0.59, respectively). There was a significant inverse correlation of LAPEP/LAET with the left ventricular ejection fraction (r = -0.62). 3. When left ventricular systolic pressure became elevated by 25% of its basal value at a constant right atrial pacing rate, LAPEP decreased from 110 +/- 21 msec to 103 +/- 22 msec (p less than 0.05), LAET increased from 123 +/- 33 msec to 129 +/- 24 msec and LAPEP/LAET decreased from 0.95 +/- 0.37 to 0.84 +/- 0.32 (p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)