Role of the Phonocardiogram in Evaluation of the Severity of Mitral Stenosis and Detection of Associated Valvular Lesions

Abstract

The phonocardiogram was correlated with hemodynamic measurements and with the results of surgical exploration in 141 patients with pure or dominant mitral stenosis. The study revealed the following results: 1. A diastolic murmur at the apex was absent in only two of 141 patients. [see figure in the PDf file] 2. The opening snap (OS) was absent in 29% of all patients and in 10% of patients with pure mitral stenosis and noncalcified mitral valve. The most important single factor contributing to the absence of an OS was calcification of the mitral valve. Other factors included young age and associated aortic stenosis or mitral insufficiency. 3. There was no significant correlation between the (Q-1)-(2-OS) interval (PCG index) and the diastolic pressure gradient across mitral valve at rest. The correlation between the PCG index and the calculated mitral valve area (MVA), and the diastolic pressure gradient across the mitral valve during exercise was significant ( P <0.05). 4. The PCG index correctly predicted whether the MVA was smaller or greater than 1.2 cm 2 in 85% of patients with pure mitral stenosis but in only 57% of patients with associated lesions. The MVA was less than 1.2 cm 2 in 36 of 39 patients with pure mitral stenosis in whom the PCG index ranged from +2 to +6. Of 42 operated patients with pure mitral stenosis, the PCG estimate was correct in 36. The PCG index did not underestimate MVA in any of the operated patients. 5. In a group of patients with the same left atrial (LA) pressure, the 2-OS interval was longer in patients with low cardiac output. The relation between the 2-OS interval and the cardiac output could explain in part the lack of correlation between LA pressure and 2-OS interval and the smaller number of correct estimates of MVA made by the 2-OS interval as compared to the Q-1 interval and the PCG index. 6. There was no significant correlation between the amplitude of the first sound at the apex and the severity of mitral stenosis. Several patients with associated mitral insufficiency had a first sound of high amplitude. 7. There was no significant correlation between the amplitude of the sound of pulmonary valve closure (P 2 ) and the pulmonary artery pressure. P 2 amplitude was significantly greater in slender patients. 8. An apical systolic murmur was recorded in 48% of patients with pure mitral stenosis. The longer the murmur, the greater was the likelihood of associated mitral insufficiency. A pansystolic murmur at the apex usually indicated an associated mitral or tricuspid insufficiency.