Duration of ejection in aortic stenosis: effect of stroke volume and pressure gradient.
The theoretical effect of variable ventricular function on left ventricular ejection time in aortic stenosis was predicted by applying data measured in 52 patients with pure aortic stenosis to equations derived from the relations of Gorlin and Gorlin and Weissler et al. Ejection time and aortic valve area are not, of necessity, linearly related because (Formula: see text) where LVET is left ventricular ejection time, k is a constant, SV is stroke volume, PG is mean aortic pressure gradient and AVA is aortic valve area. When the patients were separated into performance groups on the basis of cardiac index (at 2.8 liters/min per m2), the linear regression relating the measured SV/square root PG with valve area in 18 patients with normal function (SV/square root PG = 11.1 AVA + 2.0, r = 0.969, p less than 0.001) predicted ejection time prolongation with decreasing valve area. In 34 patients with poor function, however, the decrease in SV/square root PG with decreasing valve area was more marked (SV/square root PG = 12.6 AVA + 0.4, r = 0.894, p less than 0.001), predicting a shorter ejection time at any given valve area in this group. As predicted by the effect of valve area on the equation, ejection time becomes most variable at a small aortic valve area. Independent ejection time measurement in these patients validated the predicted effect.