Mitral Regurgitation, Acute

KEY FEATURES

ESSENTIALS OF DIAGNOSIS

• Sudden, severe orthopnea

• Evidence of pulmonary edema

• S₄

• Early systolic murmur due to rapid equilibration of left ventricular and left atrial pressures

• Doppler echocardiography establishes diagnosis, severity, and cause of mitral regurgitation

GENERAL CONSIDERATIONS

• Disruption of the mitral valve apparatus leading to severe regurgitation is uncommon but often results in profound pulmonary edema

• Because there is insufficient time for the left ventricle and atrium to dilate, filling pressures rise dramatically back to the lung capillaries

• Forward stroke volume is markedly reduced because of the large regurgitant volume with a normal left ventricular diastolic volume, resulting in forward heart failure as well

• If not corrected quickly, acute, severe mitral regurgitation can be rapidly fatal

• The most common causes of acute, severe mitral regurgitation:

  • – Acute myocardial infarction with papillary muscle rupture or dysfunction

  • – Chordal rupture in mitral valve prolapse

  • – Leaflet disruption due to trauma or endocarditis

CLINICAL PRESENTATION

SYMPTOMS AND SIGNS

• Severe orthopnea, frank pulmonary edema (pink foam in mouth)

• Symptoms and signs of the causal event may be present, such as acute myocardial infarction, endocarditis, or trauma

PHYSICAL EXAM FINDINGS

• Low-volume, low-amplitude, and rapid pulse

• Reduced pulse pressure

• Low blood pressure may be present later in course

• Jugular venous distention may be present later in course

• Increased respiratory rate and diffuse pulmonary rales

• Pleural effusion may occur later in course

• Auscultation:

  • – Owing to rapid equilibration of systolic pressure between the left ventricle and atrium, the mitral regurgitant murmur may be short and early systolic, if audible at all

  • – S₄ is frequently heard owing to vigorous atrial contraction because of augmented left atrial expansion during systole

  • – P₂ may be loud if pulmonary pressures are significantly increased

  • – The murmurs of pulmonic and tricuspid regurgitation may be present with increased pulmonary pressures

DIFFERENTIAL DIAGNOSIS

• Other causes of acute pulmonary edema not associated with mitral regurgitation

• Aortic stenosis with heart failure

• Mitral stenosis with heart failure

DIAGNOSTIC EVALUATION

LABORATORY TESTS

• Tests specific to the cause of acute mitral valve disruption, such as blood cultures, may be useful

ELECTROCARDIOGRAPHY

• Signs of acute myocardial infarction may be present in cases of papillary muscle rupture

IMAGING STUDIES

• Chest x-ray:

  • – Pulmonary edema without cardiomegaly is classic

  • – Later, other signs of heart failure such as pleural effusions may be seen

  • – Rib fractures may be present if trauma disrupted the mitral valve

• Echocardiography:

  • – The detection of mitral regurgitation is the most important goal of echocardiography

  • – The color flow jet may not persist ...