Acute Mitral Regurgitation

Abstract

The mitral apparatus is a complex structure with many components. Diseases affecting any part of this apparatus may result in acute mitral regurgitation. The most common causes are ruptured chordae tendineae and ischemic dysfunction of the papillary muscles. Sudden disruption of the mitral apparatus markedly elevates pulmonary capillary pressure and results in acute pulmonary edema. Consequently, patients with acute mitral regurgitation usually are admitted to acute care facilities. The physical examination sometimes is misleading because the characteristic holosystolic murmur may be absent. In some patients with acute mitral regurgitation, such high left atrial pressures develop during the latter part of systole that the pressure gradient between the left ventricle and atrium is obliterated, resulting in cessation of the murmur in late systole. This regurgitant v wave in the left atrial or pulmonary capillary pressure tracing is the characteristic hemodynamic finding in acute mitral regurgitation, but it may not always be present. Currently, the best diagnostic technique is two-dimensional and Doppler echocardiography. The former provides anatomic detail of the mitral apparatus, and the latter confirms and quantifies the mitral regurgitation. Although left ventricular angiography can be used to make the diagnosis, Doppler echocardiographs provide more information, are equally sensitive, and are noninvasive. Cardiac catheterization is now largely used to define the coronary anatomy prior to valvar operation. Management of patients with acute mitral regurgitation includes the use of vasodilators, mechanical circulatory support, and finally valvoplasty or replacement.