The Austin Flint Murmur Phonocardiographic and Patho-anatomical Study

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Based on 15 autopsy cases including 13 of isolated aortic insufficiency and 2 of dissecting aortic aneurysm, the phonocardiogram of the Austin Flint murmur was analysed and the patho-anatomical determinant was investigated.
The Austin Flint murmur was not infrequent in cases of severe aortic insufficiency, and the phonocardiogram as well as the auscultation revealed this murmur in all 15 cases. This murmur was composed of both mid-diastolic and presystolic (atrio-systolic) components of low-pitched vibration. The former was the essential component, which was following the third heart sound and had a decrescendo configuration. The latter showed little tendency of presystolic crescendo, and was not the essential component in some cases. The earlier appearance of the peak amplitude of the atrio-systolic component was illustrated and the importance of this graphic characteristic to differential diagnosis from organic mitral stenosis was suggested.
Based on the patho-anatomy, the possibility of several assumptions advocated as to the cause of the Austin Flint murmur was discussed. In this respect, the importance of aortic regurgitant jet on the ventricular surface of the anterior leaflet of the mitral valve was stressed as a cause of this particular functional mitral stenosis.