Austin Flint Murmur
A55-year-old man complained of dyspnea on exertion. On examination, he had a loud parasternal diastolic murmur indicative of aortic valve regurgitation and an apical middiastolic and presystolic rumble (Austin Flint murmur). The patient was referred for a cardiac MRI examination to quantify aortic regurgitation and determine ventricular volumes.
A horizontal long-axis imaging plane through the aortic valve and the apex of the heart was used. Sixteen ECG-gated gradient-echo (bright-blood) images were obtained at equally spaced time points over the cardiac cycle. An early-systolic image shows the mitral valve leaflets closed and aortic valve open in a normal fashion (Figure 1⇓). An early-diastolic image shows a dark regurgitant jet of aortic insufficiency extending posteriorly, impinging on the anterior leaflet of the mitral valve before the mitral valve opens during isovolumic relaxation (Figure 2⇓). A middiastolic image shows the regurgitant jet continuing to impinge on the anterior leaflet of the mitral valve (Figure 3⇓). The jet limits the opening swing of the anterior leaflet and restricts the mitral orifice to opening only 6 mm, producing a functional mitral stenosis. A late-diastolic image taken at the R wave shows the pandiastolic nature of the regurgitation; the regurgitant jet is present even as the mitral valve is closed (Figure 4⇓). This type of severe aortic regurgitant jet has been linked to the Austin Flint murmur, although the exact cause of the murmur is still not known. Several theories have been suggested for the origin of the murmur: (1) vibration of the anterior mitral valve leaflet due to the regurgitant jet, (2) collision of the jet with mitral inflow, (3) increased mitral inflow velocity due to narrowing of the valve orifice by the jet, and (4) vibration from the jet impinging on the myocardial wall. On the basis of the images in this single case, any of the mechanisms, and in particular the first 3, could be etiological factors.
The patient had an end-diastolic volume of 350 mL, an end-systolic basal diameter of 65 mm, and a regurgitant fraction of 0.6 (60% of forward systolic aortic flow returned into the left ventricle in diastole). The patient is now doing well after replacement of the aortic valve.
The editor of Images in Cardiovascular Medicine is Hugh A. McAllister, Jr, MD, Chief, Department of Pathology, St Luke’s Episcopal Hospital and Texas Heart Institute, and Clinical Professor of Pathology, University of Texas Medical School and Baylor College of Medicine.
Circulation encourages readers to submit cardiovascular images to Dr Hugh A. McAllister, Jr, St Luke’s Episcopal Hospital and Texas Heart Institute, 6720 Bertner Ave, MC1-267, Houston, TX 77030.
- Copyright © 1998 by American Heart Association