ZSFG AM report: Acute mitral regurgitation

Huge thanks to Jin and the SF Cards team who, after a crazy night, presented a young woman with mitral valve endocarditis leading to acute mitral valve failure and shock requiring an intraortic balloon pump.
Acute mitral valve failure is a rare, terrible diagnosis. These pearls summarize a 2009 review in Circulation on the topic.
They point out that acute mitral and aortic regurgitation can present similarly, but management and prognosis differs. So priorities include
Causes
Divided into organic (valve is permanent destroyed) versus functional (LV dilation). This distinction is important because organic causes are treated surgically, while functional causes are treated focusing on the underlying cause.
  • organic
    • Chordal rupture
    • endocarditis
    • papillary muscle rupture (due to ischemia or other causes)
    • acute rheumatic fever
    • prosthetic valve dysfunction/failrue
  • functional
    • acute cardiomyopathy with LV dilation from any cause
    • acute rheumatic fever with carditis
    • ischemia with paresis of the papillary muscle or LV wall (differnet from rupture)
Pathophysiology
The primary problem in acute MR the increase LV volume. In chronic mitral regurgitation, the LV dilates to accommodate this so that cardiac output can be maintained. In the acute setting, tachycardia can increase CO to some extent, there is not adequate time for the LV to accommodate. So in the acute setting the LVEDP and LA Pressure skyrocket, leading to pulmonary edema, decreased cardiac output, and shock.
  • physical exam pearl: in acute MR, the holosystolic murmur is faint due to rapid equilibration between LV and LA pressures during systole. Don’t expect the loud, blowing, holosystolic murmur that you hear in chronic, severe MR
Hemodynamics and physical exam findings in table form
hemodynamics of acute MR.JPG
Management
Depends on identifying the underlying cause.  See below. We ended our report with a discussion of relative and absolute contraindications to emergency valve surgery in endocarditis. We will save those for future pearls.
acute MR flowsheet.JPG
Stout KK1, Verrier ED. Acute valvular regurgitation. Circulation. 2009 Jun 30;119(25):3232-41.
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