Systolic time intervals in valvular aortic stenosis and idiopathic hypertrophic subaortic stenosis.

Corrected systolic time intervals of the left ventricle: the interval between the onset of the Q wave and the first heart sound (Q-MI), isovolumic contraction time (IVCT), and left ventricular ejection time (LVET) have been measured by noninvasive techniques in 26 patients with valvular aortic stenosis and in 25 patients with idiopathic hypertrophic subaortic stenosis. The results were compared with the peak systolic pressure gradient across the aortic valve or the subaortic stenosis. It was shown that the Q-Mi interval was pathologically long in patients with idiopathic hypertrophic subaortic stenosis. Isovolumic contraction time was derived by two different measurements (IVCT I and IVCT 2) and in both groups ofpatients it was shortened. A significant inverse relation was established between the gradient and the isovolumic contraction time only in patients with valvular aortic stenosis. When the LVET/IVCT ratio was compared with the gradient, a linear correlation was demonstrated (r=o84, P< o.ooi) in patients with valvular aortic stenosis. In patients with idiopathic hypertrophic subaortic stenosis no single parameter was found to be of value in assessing the degree of intraventricular pressure gradient.