Timing of Electrical and Mechanical Events of the Left Side of the Human Heart

Abstract
Temporal relationships between electrical and mechanical events and the duration of individual phases of the cardiac cycle of the left side of the human heart were measured in 14 patients by direct needle puncture of the chambers at operation. The interval between onset of the P wave to onset of left atrial contraction averaged 0.068 seconds. The interval from the onset of the Q wave in lead n to the onset of left ventricular contraction averaged 0.041 seconds. The isometric contraction period of the left ventricle averaged 0.50 seconds in the 14 patients studied.