Shape Pitch and Duration of Mitral Regurgitation Murmurs

1. What are all the possible shapes of an MR murmur?

Note that when the MR murmurs begin late, they always go to the second sound, and when they begin early, they always start with the first sound.

2. What shape are the loudest MR murmurs?

ANS: Pansystolic and slightly crescendo-decrescendo. The crescendo-decrescendo shape in these patients is better described as a spindle shape on a phonocardiogram.

3. How does the pitch of a murmur correlate with gradient and flow?

ANS: High gradients and little flow produce high-pitched murmurs. High flow and low gradients produce low-pitched murmurs.

4. Which MR murmurs are always associated with almost pure high frequencies, i.e., only a blowing sound?

ANS: All soft murmurs with small volume flows and high gradients, e.g., those due to trivial MR.

Note: The gradient between the left atrium and LV usually reaches more than 100 mmHg during the peak of systole.

5. Why does the MR murmur extend slightly beyond the S2?

ANS: Because LV pressure is higher than left atrial pressure even after the aortic valve closes. (See figure on p. 218.)

6. Is an MR murmur louder on inspiration or expiration?

ANS: It is usually louder on expiration because that is when blood is pushed into the LV from the lungs.

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