The movements of the dog's aortic valve studied by high speed cineangiography

A method for obtaining high-speed cineangiograms (312 FPS) of the dog's aortic root is described. Movement of the aortic root and leaflets are analysed. Valve opening is divided into three stages. The first stage occurs during ventricular isometric contraction and takes 35 milliseconds during which time the aortic leaflets rise cephalad and their curvature diminishes. The second stage lasting 14·3 milliseconds commences at the onset of ejection and comprises the main leaflet movement. More gradual opening continues for a further 13·2 milliseconds. Valve closure is also a series of movements, of which the principal movement occupies 17·1 milliseconds It takes place by means of a multihinge mechanism, and is probably initiated during the later part of systole by returning laminae of blood lying close to the aortic wall. The advancement wave can be explained by geometric changes occurring in the aortic root during isometric ventricular contraction. Reasons are given for suggesting that valve closure is three quarters accomplished at the time of aortic/ventricular pressure cross over. The relationship of these findings to previous observations is discussed.