Diagnostic value of configuration of left ventricular outflow pressure gradient in differentiating hypertrophic obstructive cardiomyopathy from discrete types of aortic stenosis.

Since obstruction to left ventricular (LV) outflow in hypertrophic obstructive cardiomyo- pathy (HOCM) is dynamic, whereas that in discrete aortic stenosis is fixed, the shape of the transaortic pressure gradient should be characteristically altered in HOCM and thereby provide a means of differentiating these two disparate types of aortic stenosis. In all 22 HOCM patients, peak arterial pulse always occurred in the initial half of the systolic ejection period, while in 37 of 40 patients with discrete types ofaortic stenosis it appeared in the final half. Peak left ventricular pressure was delayed significantly (P < 0.01) in HOCM compared with fixed aortic stenosis. Furthermore, the interval from onset of ejection to peak left ventricular pressure divided by ejection period was increased in HOCM, 0 59 compared with 0 49 (P < 0.01) in fixed aortic stenosis. The early arterial and late left ventricular pressure pulse peaks in HOCM are related to absence of obstruction to ejection early in systole. Moreover, the ratio of mean pressure gradient during the first half of ejection to that of the last half averaged 0 59 in HOCM. In contrast, this ratio averaged 1 *24 in 23 patients with valvular aortic stenosis, 1 13 in 12 patients with discrete subvalvular stenosis, and 1-85 in 5 patients with supravalvular stenosis. This ratio allowed complete separation of HOCM from fixed aortic stenosis; < 0-80 identified HOCM while greater indicated fixed aortic stenosis. Whether brachial arterial pulse, appropriately adjusted for time, or central aortic pressure pulse was used did not alter these results.