Direct Detection and Timing of Aortic Valve Closure

Abstract

A special electrical contacting device was developed and used to time the relationship between aortic valve closure and the aortic incisura in closed chest anesthetized dogs. High speed tracings showed that the aortic valve is closed at least 5 to 13 msec before the incisura. It is concluded that the aortic pressure incisura results from rebound of the aortic blood column and walls after valve closure and that the second heart sound is not caused by collision of the valve leaflets but by the same mechanical factors which are responsible for the incisura.