From the Guidelines
Mitral regurgitation is not a diastolic murmur, but rather a systolic murmur. Mitral regurgitation occurs when the mitral valve does not close properly during systole (ventricular contraction), allowing blood to flow backward from the left ventricle into the left atrium when the heart contracts. This abnormal backflow of blood creates a characteristic "holosystolic" or "pansystolic" murmur that begins with the first heart sound (S1) and continues throughout systole until the second heart sound (S2) [ 1 ]. The murmur is typically heard best at the apex of the heart and may radiate to the axilla.
The timing of mitral regurgitation during systole is explained by the pressure gradient between the left ventricle and left atrium during ventricular contraction, which forces blood through the incompetent mitral valve. In contrast, diastolic murmurs occur during ventricular relaxation and filling, and include conditions like mitral stenosis or aortic regurgitation [ 1 ]. Key characteristics of mitral regurgitation include:
- A holosystolic or pansystolic murmur
- Best heard at the apex of the heart
- May radiate to the axilla
- Associated with a third heart sound and a diastolic flow rumble in severe cases [ 1 ]
It is essential to distinguish mitral regurgitation from other valvular heart diseases, as the management and prognosis differ significantly [ 1 ]. Accurate diagnosis and assessment of the severity of mitral regurgitation are crucial to determine the best course of treatment and to improve patient outcomes.
From the Research
Mitral Regurgitation Murmur Timing
- Mitral regurgitation (MR) is typically associated with a systolic murmur, as seen in studies 2, 3, 4
- However, diastolic mitral regurgitation (DMR) is a type of functional MR that occurs during the diastolic phase of the cardiac cycle, as described in studies 5, 6
- DMR is often associated with specific conditions, such as high-degree atrioventricular block, restrictive cardiomyopathies, and acute severe aortic regurgitation, as noted in studies 5, 6
Characteristics of Diastolic Mitral Regurgitation
- DMR is characterized by a reversal of the left atrioventricular pressure gradient during diastole, leading to incomplete closure of the mitral valve, as explained in study 5
- The appearance of DMR may prompt further clinical considerations and has incremental value for diagnosing and evaluating underlying cardiovascular disease, as stated in study 5
- DMR can be detected using echocardiography and continuous wave Doppler, as demonstrated in study 6
Differentiation from Systolic Mitral Regurgitation
- Systolic MR is typically associated with a pan-systolic or late-systolic murmur, as seen in study 2
- In contrast, DMR occurs during diastole and may be associated with a distinct murmur timing, as described in studies 5, 6
- The differentiation between systolic and diastolic MR is important for accurate diagnosis and treatment, as emphasized in studies 2, 5, 3, 4, 6