Left Ventricular Function Following Replacement of the Aortic Valve

Evaluations of left ventricular myocardial function were carried out in 14 patients 4 to 16 months after stenotic or regurgitant malformations of the aortic valve had been corrected by valve replacement. The circulatory responses to exercise, judged by the increases in cardiac output in relation to the increases in oxygen consumption, were normal or only mildly reduced in 12 patients. In five patients, the relationships between the change in the left ventricular end-diastolic pressure and the alteration in the stroke volume were also normal, a fall or an increase in left ventricular end-diastolic pressure of less than 3 mm. Hg being accompanied by an increase in stroke volume. In eight patients, however, abnormal increases in the left ventricular end-diastolic pressure occurred during exercise, and in four the left ventricular end-diastolic pressure was increased to levels above 12 mm. Hg. Variable alterations in the stroke volume accompanied these increases in end-diastolic pressure. It is suggested that in the three patients who exhibited simultaneous increases in left ventricular end-diastolic pressure and stroke volume, the changes were either a manifestation of the Frank-Starling mechanism, or primarily the result of a positive inotropic influence. In the five patients who exhibited increases in left ventricular end-diastolic pressure, but no change or a fall in stroke volume, it is proposed that a distinct depression of left ventricular performance was present. Thus, while the cardiac output response was adequate to meet the stress of exercise in the majority of the patients studied following aortic valve replacement, determination of the relationship between the left ventricular end-diastolic pressure and the stroke volume permitted the detection of abnormalities in the function of the left ventricle.