Murmur of Mitral Stenosis

The next important bedside finding we should know is the murmur of mitral stenosis. Now, the mitral valve, of course, is open in diastole, but if it is narrowed, stenosed, then a rumbling, low frequency murmur is generated. Let’s all listen together at the apex with the bell for low frequency sounds, using the cotton swab to measure systole and, therefore, diastole. Everyone listen together. [sounds]

We heard the classic murmur of mitral stenosis. Light pressure on the bell at the apex to appreciate the low frequency sound, and you hear [sounds]. You mimic that, [sounds]. There are many features that tell us this is severe. Most important of which is the length of the murmur. Remember that when you are dealing with a valve that is stenosed, the longer the murmur, the more severe the stenosis, because even during periods of relatively modest flow, there is enough narrowing of the valve to generate turbulence that you appreciate as the murmur.

Now, in addition to that, when you do the rest of the exam, you feel an impulse at the parasternal edge, it is a right ventricular impulse and when you listen at the upper left sternal edge, you hear [sounds], a loud pulmonary second sound. This tells us this patient has pulmonary hypertension, with a loud P2 and with a right ventricular impulse. All of this, length of the murmur and these findings tell us this is severe mitral stenosis. This is a young woman who is in her third trimester of pregnancy, had a remote, but definite history of rheumatic fever, and she has rheumatic mitral stenosis and it is severe. Let’s mimic that murmur one more time. At the apex, low-frequency [sounds]. You do it [sounds]. Mitral stenosis and severe.

Murmur Location and Radiation

The murmur is best heard at the apex, or mitral area, and the location is related to the underlying lesion. The left atrium is posterior to the left ventricle and flow through the stenosed mitral valve results in turbulent anterior flow toward a localized area at the apex. [sounds]

MS Heart Animation

This is a graphic example of the heart in a patient with mitral stenosis. In the animation that follows, we can appreciate that the murmur is generated across the stenosed mitral valve during left ventricular diastole. [sounds]

MS Pressure Curves

These simultaneous left atrial and left ventricular pressure curves illustrate the relationship of the hemodynamic events to the timing, contour and frequency of the murmur. The murmur begins with the opening of the mitral valve, as atrial diastolic flow enters the left ventricle. It is long, as a gradient between the left atrium and left ventricle persists throughout all of diastole. There is an early diastolic accentuation of the murmur, as most diastolic flow occurs at this time and a presystolic accentuation, as left atrial contraction again augments flow. The murmur is low frequency primarily because blood is flowing from the relatively low pressure left atrium to the low pressure left ventricle. [sounds]