We are now going to examine a patient with classic mitral regurgitation. This patient moved here from South America not long ago, and she has had a murmur known for years after she had had rheumatic fever. We examine her and find no other abnormality, but we listen at the apex and, let’s listen together, and we hear the classic murmur. Everyone listen at the apex, firm pressure on the diaphragm. [sounds]
That is the typical murmur of mitral regurgitation: apex, high frequency, radiates back towards the axilla. You mimic it by going [sounds], it is like telling someone “be quiet.” [sounds] You do that [sounds]. It is throughout all of systole, because the pressure is higher in the left ventricle than the left atrium during all of that time. It is high frequency, because of the big pressure difference between the left ventricle and the left atrium. Do it again, mimic it [sounds]. Mitral regurgitation, common important murmur.
Murmur Location and Radiation
The murmur is best heard at the apex, or mitral area, and this location is related to the underlying lesion.
The left ventricle is anterior to the left atrium and regurgitation through the mitral valve usually results in turbulent posterior flow, with radiation of the murmur toward the axilla
MR Heart Animation
This is a graphic example of the heart in a patient with mitral regurgitation. In the animation that follows, we can appreciate that the murmur is generated across the regurgitant mitral valve during left ventricular systole.
MR Pressure Curves
These simultaneous left atrial, left ventricular and aortic pressure curves illustrate the relationship of the hemodynamic events to the timing, contour and frequency of the systolic murmur. The murmur begins with mitral closure obscuring the first heart sound. It continues up to and through aortic closure, as left ventricular pressure exceeds left atrial pressure throughout this period. The murmur is plateau-shaped because there is a significant pressure gradient between the left ventricle and left atrium throughout all of systole. The murmur is high in frequency primarily because blood is flowing from the high pressure left ventricle to the low pressure left atrium.
Mitral Valve Prolapse
There are many causes of mitral regurgitation and amongst the most common is mitral valve prolapse. The character of that murmur on auscultation is distinctively different from the classic holosystolic murmur of mitral regurgitation. Let’s all listen at the apex, time the murmur in systole with the carotid, firm pressure on the diaphragm [sounds].
This is not the holosystolic [sounds], rather, it is [sounds]. It starts in mid systole, crescendo, introduced by a click [sounds]. So it is [sounds]. You mimic it [sounds]. Common murmur you will hear on patients you examine. Mitral valve prolapse.
Mid-Late Systolic Murmur
In a patient with a mid-to-late systolic murmur early systole is silent. Our patient has several mid systolic clicks that introduce the murmur. The murmur crescendoes into the second sound and is high frequency.