An Attempt at the Assessment of Myocardial Contractility from Phonocardiographically Measured Time Components of Ventricular Contraction in Patients with Prosthetic Aortic Valves
Asynchronous Activation as a Cause of Diminished Velocity of Contraction
The phonocardiographically recorded time interval between the first heart sound and the mid-ejection point is a rough guide to the time interval between the onset and the peak ventricular pressure in patients with the University of Cape Town aortic valve prosthesis. This time interval is insensitive to changes in stroke volume and aortic pressure produced by variations in ventricular filling and may be used to show changes in contractility in any one patient.
In a group of 42 patients with 64 postoperative phonocardiograms, mid-ejection time varied between 140 and 250 msec. A strong negative correlation with heart rate, and a strong positive correlation with the width of the QRS complex were present without any significant correlation with heart size or with other estimates of left ventricular function.
It is suggested that in the abnormal myocardium, ventricular asynchrony may seriously interfere with the velocity of the ventricular contraction invalidating the assessment of contractile element velocity from the velocity components of the ventricular pressure pulse.
- First heart sound
- Mid-ejection time
- Force-velocity relationship of heart muscle
- Ventricular pressure pulse
- Heart rate
- Aortic pressure
- © 1968 American Heart Association, Inc.