Mild mitral regurgitation. Its characterization by intracardiac phonocardiography and pharmacologic responses.

Abstract Fifteen patients with apical or peri-apical systolic murmurs without accompanying conventional roentgenologic or electrocardiographic evidence of cardiac enlargement were studied. All were shown to have mild mitral regurgitation. Investigative technics included intracardiac, esophageal and external phonocardiography coupled with pharmacologic responses and left ventricular angiography. The murmurs were of high frequency and low intensity. Their configuration varied from pansystolic to entirely late systolic. Typical responses to phenylephrine and amyl nitrite are reported. The value of transseptal intracardiac phonocardiography in making this diagnosis is emphasized. Intracardiac recordings suggest that the position of the regurgitant jet in relation to the chest wall is a factor in the configuration of the murmur as appreciated externally. Evidence is presented that associated mid- to late systolic clicks and whoops are mitral valvular in origin. Despite the evident longevity of patients with mild mitral regurgitation, arrhythmia, embolization and endocarditis may occur.