Invasive and noninvasive phonocardiography and orifice-view aortography in the diagnosis of left ventricular outflow obstruction.

Phonocardiography and orifice-view aortography for the detection of valvular and subvalvular stenosis is reviewed. Intracardiac phonocardiography may be useful in detecting a left ventricular outflow tract obstruction, and in distinguishing it from other conditions that can produce an apparent pressure gradient during cardiac catheterization. The frequency analysis of heart sounds on noninvasive phonocardiograms may be useful in identifying subclinical aortic stenosis. Orifice-view aortography can show the anatomy of deformed aortic valves and is useful in measuring the orifice area. In patients with heavily calcified valves, plain orifice-view roentgenograms may enable one to assess the valve area. Therefore the use of these techniques in selected patients may help establish a definitive diagnosis.