From the Guidelines
The murmur of mitral regurgitation typically becomes louder when the patient is in the left lateral decubitus (LLD) position. This is because the left lateral decubitus position enhances the audibility of the murmur during auscultation by moving the heart closer to the chest wall, which improves sound transmission of the murmur to the stethoscope 1. The key factors to consider when assessing the effect of position on heart murmurs include:
- Respiration: Left-sided murmurs usually are louder during expiration
- Valsalva maneuver: Most murmurs decrease in length and intensity, but the systolic murmur of HCM becomes much louder
- Exercise: Murmurs of MR, VSD, and AR increase with handgrip exercise
- Positional changes: With standing, most murmurs diminish, but the murmur of HCM becomes louder Some of the interventions used to alter the intensity of cardiac murmurs are:
- Pharmacological interventions: During the initial relative hypotension after amyl nitrite inhalation, murmurs of MR, VSD, and AR decrease
- Transient arterial occlusion: Transient external compression of both arms by bilateral cuff inflation to 20 mm Hg greater than peak systolic pressure augments the murmurs of MR, VSD, and AR The mitral regurgitation murmur is characteristically a high-pitched, blowing, holosystolic murmur best heard at the apex of the heart (fifth intercostal space, midclavicular line) 1. When examining a patient with suspected mitral regurgitation, having them roll onto their left side while auscultating can help confirm the diagnosis by accentuating this characteristic murmur. This maneuver is particularly helpful in patients with subtle murmurs or in those with body habitus that makes standard auscultation challenging.
From the Research
Mitral Regurgitation Murmur Characteristics
- The intensity of the mitral regurgitation murmur can be affected by various factors, including posture and the degree of regurgitation 2.
- In patients with mitral valve prolapse, the murmur may become louder when assuming an upright posture due to greater prolapse of the mitral leaflets and a smaller left ventricular volume 3.
- However, the relationship between murmur intensity and regurgitation severity is not always straightforward, as the murmur can become louder despite a decrease in regurgitation 2.
Posture-Related Changes in Mitral Regurgitation Murmur
- When a patient is in the left lateral decubitus (LLD) position, the mitral regurgitation murmur may become louder due to the increased proximity of the mitral valve to the chest wall and the resulting improved transmission of the murmur sound.
- However, there is no direct evidence from the provided studies to support this specific claim, as the studies primarily focus on the effects of upright posture or dobutamine infusion on mitral regurgitation murmur intensity.
Diagnostic Considerations for Mitral Regurgitation
- Echocardiography and Doppler ultrasound are useful tools for evaluating the severity of mitral regurgitation and its associated hemodynamic consequences 2, 4, 5.
- The intensity of the mitral regurgitation murmur, as assessed by phonocardiography or auscultation, may not always accurately reflect the severity of regurgitation 2, 6.