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Heart Sounds Podcast Series
Austin Flint


In 1862, Austin Flint, Sr., MD (1812 – 1886), Professor of the Principles and Practice of Medicine at Bellevue Hospital and Medical College in New York, published a paper classifying cardiac murmurs and offering methods for determining a murmur’s importance and severity. He describes the murmur now named for him and offers what is now known to be a correct hypothesis for the origin of the murmur—a remarkable achievement. His classification scheme and interpretation of cardiovascular physical findings remain the underpinnings of the methods still used today. Such a visionary should be remembered by recognizing his murmur by its proper name, the Austin Flint murmur.

The lesion and murmur, which now bear his name, are indicative of chronic severe aortic valve insufficiency. In addition to the early diastolic decrescendo murmur of aortic valve insufficiency already so well recognized, a second murmur mimicking mitral stenosis could be recognized in the absence of mitral valve pathology. He described the murmur as, “Oftener rough than soft. The roughness is often peculiar. It is a blubbering sound, resembling that produced by throwing the lips or the tongue into vibration with the breath of respiration.” * 

In common parlance, the Austin Flint rumble is a mid-diastolic, low frequency murmur that is best heard at the apex with little radiation. It mimics rheumatic mitral stenosis in its characteristics and physiology. The murmur is the result of competition between the regurgitant jet of the aortic valve and the attempt to fill the left ventricle from the left atrium—in essence, functional mitral stenosis. It differs in that it occurs in the presence of a murmur of aortic valve insufficiency and in the absence of the rheumatic, mitral opening snap.

For this recording, samples were taken from the lower left sternal border (LLSB) where the murmur of aortic valve insufficiency is most prominent. This recording alternates with a recording from the apex. You will note a difference in the murmurs.

  • From the LLSB, the murmur is initiated and reaches peak intensity with the second heart sound decaying thereafter.
  • At the second site (apex), you hear S1 and S2 followed by a brief period of silence before initiating the murmur (‘lup-tu- uuuuh’). It is thus, by definition, a mid-diastolic murmur.
  • In addition, there is a slight difference in pitch with the mid-diastolic murmur at lower pitch, so that the ‘uuuuh’ part sounds more like a groan or a grunt. Blubbering? I’ll let you decide.

The reliable physical findings of severe aortic valve insufficiency include the Austin Flint rumble, a diastolic blood pressure less than 40 mmHg, and a difference in thigh and brachial pressure greater than 20 mmHg. (40mmHg is more specific than 20, and 60 is a slam dunk.)

*Acierno, Louis J. The History of Cardiology. 1993. London: Parthenon, p. 486. 

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Updated April 2009
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