Essentially, all degen-erative mitral valves are repairable. By matching echocardiographic findings to the appropriate surgical skill level required to consistently deliver a repair, valve replacement for degenerative mitral valve disease should be infrequent.
Most patients with mitral regurgitation remain asymptomatic for long periods of time. The most common presenting signs and symptoms include fatigue, decreased exercise capacity, shortness of breath, and palpitations or supra-ventricular arrhythmias such as atrial fibrillation. Auscultatory examination usually reveals a high-pitched systolic murmur radiating from the apex to the axilla. A holosytolic murmur suggests prolapse simultaneous with ejection typical of chordal rupture, whereas a murmur beginning in mid- or late systole favors billowing or chordal elongation. Radiographic findings may include left atrial and ventricular dilatation and prominent pulmonary vasculature in patients with long standing severe mitral regurgitation. The electrocardiogram may be normal, or show evidence of left atrial enlargement or atrial fibrillation.
Table 1: Selected ranges for grading severity of mitral regurgitation. Rvol, regurgitation volume, ERO, effective regurgitant orifice1, 2.
Two dimensional echocardiography with doppler is essential to determine the mechanism (dysfunction) and severity of mitral regurgitation. Semi-quantitative assessment of regurgitant flow using maximal jet length, area, and ratio of jet to left atrial area is recommended to assess the severity of mitral regurgitation1. Regurgitant jet geometry and area are assessed in multiple views and mitral regurgitation severity is graded typically as a rank order variable (e.g. 1+ trace, 2+ mild, 3+ moderate and 4+ severe mitral regurgitation). The direction of the jet provides evidence of segmental involvement as it is typically opposite to the prolapsing segment. Quantitative doppler grading of mitral regurgitation is gaining in popularity and is based on the calculation of regurgitant volume (the difference between the mitral and aortic stroke volumes) and effective regurgitant orifice (ratio of regurgitant volume to regurgitant time velocity integral). Table 1 shows the correlation between the semi-quantitative and quantitative grading of mitral regurgitation in degenerative mitral disease. Transesophageal echocardiography (TEE) is a useful adjunct to confirm the diagnosis and understand the mechanism of degenerative valve disease in the case of a non-definitive transthoracic examination. Experience is also gaining with three dimensional echocardiography in the assessment of annular geometry and leaflet dysfunction in the setting of mitral regurgitation, and can be predicted to have a more significant role in planning reparative procedures in the future.
(1) Zoghbi WA, Enriquez-Sarano M, Foster E et al. Recommendations for evaluation of the severity of native valvular regurgitation with two-dimensional and Doppler echocardiography. J Am Soc Echocardiogr
(2) Dujardin KS, Enriquez-Sarano M, Bailey KR, et al: Grading of mitral regurgitation by quantitative Doppler echocardiography: calibration by left ventricular angiography in routine clinical practice. Circulation 96(10):3409-15 1997.