Myocardial contraction velocity and acceleration in man measured by ultrasound echocardiography differentiation1

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Abstract
Four healthy subjects were studied with ultrasound echocardiography during rest and during graded exercise. The myocardial contraction displacement s[t] of the posterior wall of the left ventricle was recorded (maximal displacement: ΔS). 'On line' differentiators were developed to differentiate the s[t]-curves. In this way the velocity (=ds/dt) and acceleration (Å= d2s/dt2) of contraction were recorded. The velocity and acceleration curves showed two major positive peaks and one negative peak. The first positive peak of each curve (1 and Ä1) refers to the first part of the myocardial contraction period. Average (n = 31) values at rest (± SE of mean) for a 50 kg female were: Δs = (4±0·1) mm, 1 = (2·3 ± 0·2) x 10−2 mm/msec, and Å1 = (3·3±0·2)x 10"4mm/msec2. These values were approximately doubled at a work rate of 300 kg/min. Resting averages for a 91 kg male were: Δs = (6·5±0·l)mm,V1 = (3·9±0·l)x10-2mm/sec,and Å1 = (4·4±0·2)x10-4mm/msec2; these values increased by 40-50% at a steady state work rate of 600 kgm/min. The size of Δs, maximum velocity, and acceleration were correlated with the relative steady state work rate of each subject. At identical heart rates the parameters were reproducible from day to day in each individual. The sizes of the majority of the parameters were correlated with the size of the subject, and to individual variations in heart rate.

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