S3 and Mitral Regurgitation

[chromuffin]

I've been going through FA 2016 and I came across the statement on page 270 that S3 is associated with increased filling pressures like mitral regurgitation and HF. My question is this... How can S3 be associated with mitral regurgitation? Mitral regurgitation is an AV valve defect resulting in backflow of blood from the left ventricle to the left atrium during systole whereas S3 occurs in early diastole (i.e. right after the mitral valve opens). This would make me think S3 would be associated with mitral stenosis (diastolic) or . I think I understand that S3 is related to HF as a result of the systolic dysfunction acting to increase preload, increasing LVEDP and thus "increasing filling pressures" in the atria.

Overall, I just don't understand how a systolic problem (mitral regurgitation) can cause a diastolic heart sound. Maybe I just don't have the physiology down? Thinking about a mitral regurgitation would increase filling pressure in the atria, but I would think this heart sound would be consistent with a SYSTOLIC murmur.

Help?

EDIT: Is the S3 due to the effect of mitral regurgitation rather than the act of the regurgitation? In other words, is the S3 due to the mitral regurgitation increasing blood volume in the atria during systole, which then results in an increased pressure gradient from LA --> LV (i.e. rapid filling)?

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[immolard]

I've been going through FA 2016 and I came across the statement on page 270 that S3 is associated with increased filling pressures like mitral regurgitation and HF. My question is this... How can S3 be associated with mitral regurgitation? Mitral regurgitation is an AV valve defect resulting in backflow of blood from the left ventricle to the left atrium during systole whereas S3 occurs in early diastole (i.e. right after the mitral valve opens). This would make me think S3 would be associated with mitral stenosis (diastolic) or . I think I understand that S3 is related to HF as a result of the systolic dysfunction acting to increase preload, increasing LVEDP and thus "increasing filling pressures" in the atria.

Overall, I just don't understand how a systolic problem (mitral regurgitation) can cause a diastolic heart sound. Maybe I just don't have the physiology down? Thinking about a mitral regurgitation would increase filling pressure in the atria, but I would think this heart sound would be consistent with a SYSTOLIC murmur.

Help?

EDIT: Is the S3 due to the effect of mitral regurgitation rather than the act of the regurgitation? In other words, is the S3 due to the mitral regurgitation increasing blood volume in the atria during systole, which then results in an increased pressure gradient from LA --> LV (i.e. rapid filling)?

You got it in your edit.