Shape and volume changes during "isovolumetric relaxation" in normal and asynergic ventricles.

SUMMARY Clinically suspected coronary artery disease was assessed in 52 patients by 16-mm biplane left ven-triculography. Outward movement of the left ventricular wall was observed prior to mitral valve opening in normal patients and those with coronary artery disease. In the normal ventriculogram, outward movement was usually visible in the anterior wall and the apex. In the asynergic ventricle, the outward movement almost invariably occurred at the region of optimal contraction. Outward movement of the ventricular wall during protodiastole and isovolumetric relaxation was accompanied by a significant volume increase over the end-systolic volume. The volume increase was greater in the abnormal than in the normally contracting ventricle. The altered ventricular volume was probably associated with the return to the ventricle of blood contained between the patent aortic leaflets at the end of ventricular ejection. This event occurs during aortic valve closure when ventricular pressure is falling more rapidly than aortic pressure. It accounts for the alteration in volume between end ejection and pre-mitral valve opening. The stroke volume, which is generally calculated from end-systolic and end-diastolic volumes, may therefore be inaccurate by at least 10% because ventricular volume immediately before mitral valve opening is not utilized in the calculation. Some of the discrepancies between angiocardiographic stroke volume and ejection fraction measurements and those obtained by other methods may be explained by failure to use pre-inflow volume (PIV) in the calculations. Isov Coronary artery disease IT IS COMMONLY ASSUMED that there is no change in left ventricular volume during the period between termination of left ventricular ejection and mitral valve opening. This phase of the cardiac cycle has traditionally been divided into protodiastole (end-ejection to aortic valve closure) and isovolumetric diastole (aortic valve closure to mitral valve opening). In recent years this division has been abandoned by some physiologists, and the entire period has been designated by the term isovolumetric diastole.' Observations made in our laboratory have suggested that outward movements of the left ven-tricular wall (ventricular shape changes) occurring during aortic valve closure and before mitral valve olumetric diastole Protodiastole opening have been accompanied by left ventricular volume increments in man.2 We have termed the phenomenon of outward left ventricular wall motion occurring prior to mitral valve opening pre-inflow relaxation (PIR). In order to examine its characteristics in greater detail, a series of ven-triculographic and coronary arteriographic studies have been critically analyzed. Materials and Methods Fifty-two patients with clinically suspected …