[Cardiac function noninvasively evaluated by phasic pattern analysis of ventricular power during ejection].

To evaluate cardiac function, ventricular power during ejection (power) and the rate of change of power (dPower/dt) were assessed noninvasively. Power was determined from the product of aortic flow (Fa(t] and brachial arterial pressure (Pa(t]. Fa(t) was measured at the suprasternal notch using an ultrasonic pulsed Doppler flowmeter with a 2 MHz carrier frequency and 10 KHz repetition frequency. The maximum detectable blood velocity was 380 cm/sec. Pa(t) was measured using a newly-developed method based on indirect unloading techniques and an air pressure system. There were 21 normal subjects and seven patients with coronary artery disease in this study. The following results were obtained. There was no significant difference between power patterns calculated by Pa(t) and Pao(t) (aortic pressure measured by catheter). The average peak dPower/dt was 160.2 J/sec2 in normal subjects, 145.2 L/sec2 in patients with ejection fractions greater than 50%, and 93.5 J/sec2 in patients with ejection fraction less than 50%. Peak dPower/dt was significantly decreased in patients with the lower ejection fraction (p less than 0.005). The results indicated that this index is clinically useful in evaluating cardiac contractility.