Left ventricular ejection time by densitometry in patients at rest and during exercise, atrial pacing and atrial fibrillation. Comparison with central aortic pressure measurements.

A comparison of left ventricular ejection time (LVET) measured directly from the central aortic pressure tracing (CAPT) and a densitogram recording was carried out in 39 patients during diagnostic cardiac catheterization. The correlation coefficient between the LVET derived from the CAPT and densitogram of 32 patients while at rest was 0.974 with a standard deviation from regression (SDR) of 6.2 msec. Sequential LVETs were analyzed in two patients during atrial pacing, three patients during exercise and three patients with atrial fibrillation. Correlation coefficients were 0.981, 0.951 and 0.974 with SDRS of 5.3, 6.2 and 6.7 msec respectively. Assuming LVET from the CAPT to be error free, the over-all error of estimating LVET by densitogram was less than 5% for over 95% of the measurements. The largest mean difference between CAPT and densitogram derived LVETs was present during atrial pacing and corresponds to an error of less than 2% of the average LVET for the group. We conclude that densitometry is a practical and reliable noninvasive method for LVET measurements in a variety of physiological and pathological conditions.