Page 18, Cardiac Performance, Dr. D. Penney

The pre-ejection period (PEP), is the period when the ventricle is electrically activated (Q wave to S1) plus that period when it is contracting isovolumically (ICT). The PEP ends with aortic valve opening, which is determined superficially from the carotid pulse. PEP is prolonged (Figure 2.08) in cases of heart failure, coronary ischemia, and conduction disturbances.

The use of the ratio of PEP to left ventricular ejection time (LVET) as a measure of performance was developed at Wayne State University Medical School some years ago. The normal value of 0.35 is elevated in cases of pathology. As shown graphically in Figure 2.09, the end of LVET is indicated by the second heart sound. The fact that PEP/LVET can be obtained non-invasively from the ECG, heart sounds, and carotid pulse is a major advantage.