Determination of systolic time intervals using the apex cardiogram and its first derivative

Abstract

Certain characteristic points of the first derivative in time of the apex cardiogram are suitable to determine left ventricular mechanical events despite certain modifications in the shape of the curve due to technical error. Notch dN 1 in the first derivative of the cardiac apex curve signals the beginning of the rise of left ventricular pressure; notch dN 2 signals the conclusion of left ventricular ejection. With the aid of the apex cardiogram and its first derivative, the periods of left ventricular systole can be accurately and conveniently defined.