Idiopathic hypertrophic subaortic stenosis with and without mitral regurgitation. Phonocardiographic differentiation from rheumatic mitral regurgitation.

The murmur of idiopathic hypertrophic subaortic stenosis has been confused with that of mitral regurgitation due to rheumatic heart disease. To determine if these two entities can be consistently differentiated, phonocardiograms were studied in 41 patients with idiopathic hypertrophic sub- aortic stenosis with and without mitral regurgitation and compared to I7 patients with rheumatic mitral regurgitation. All patients with rheumatic mitral regurgitation had holosystolic murmurs beginning with S, and ending at or after A2. In idiopathic hypertrophic subaortic stenosis the murmur either began after S1, ended before A2, or both, in all but one patient in whom the mitral regurgitation persisted after operative relief of outflow obstruction. We conclude that the duration of the recorded murmur is valuable in distinguishing patients with idiopathic hypertrophic sub- aortic stenosis with or without mitral regurgitation from those with rheumatic mitral regurgitation. A true holosystolic murmur in a patient with idiopathic hypertrophic subaortic stenosis suggests that organic disease of the mitral valve may coexist, in which case mitral regurgitation may persist despite successful operative relief of obstruction.