Mitral Valve Repair

Pre–Cardiopulmonary Bypass Transesophageal Echocardiographicexamination

Clinical studies have suggested that the pre–cardiopulmonary bypass (CPB) transesophageal echocardiographic (TEE) examination prompts changes in surgery in 9% to 13% of patients undergoing MV surgery. During the pre-CPB TEE examination, the severity, mechanism, and location of MV disease, including subvalvular involvement, annular calcification, and dilatation, and leaflet motion abnormalities, as well as the status of left ventricular (LV) function, should be identified to help determine whether an MV replacement, repair, or neither is indicated. It is particularly important to identify risk factors for difficult MV repair ( Box 112.1 ). In patients with functional mitral regurgitation (MR), approximately 30% of repairs may fail within the first 6 postoperative months. Risk factors for limited durability include significant LV geometrical distortion, excessive apical tethering of the MV leaflets or annular dilatation, and severe MR. Evidence in patients with ischemic functional MR undergoing coronary artery bypass grafting and randomized to either MV repair or MV replacement have demonstrated that although baseline echocardiographic measures of MV geometric leaflet tethering by themselves may not be associated with postoperative moderate or severe recurrent MR, the presence of LV basal aneurysm or dyskinesis is strongly associated with this outcome. Others have shown that concurrent posteromedial MV leaflet tethering along with LV basal aneurysm or dyskinesis is most important for predicting MV repair failure associated with ischemic functional MR. Difficult MV repair in patients with degenerative disease may be predicted by the presence of extensive anterior leaflet (AL) or multiple scallop involvement. These patients may also be at risk for developing systolic anterior motion (SAM) with LV outflow tract obstruction, especially if they present preoperatively with an excessively long or asymmetric AL; a redundant posterior leaflet (PL), especially when longer than the AL; a short coaptation–septal distance; a narrow mitral-aortic angle; or a nondilated LV ( Fig. 112.1 and Box 112.2 ). Finally, in patients with rheumatic heart disease, extensive mitral annular or subannular calcification, as well as a limited AL length, have been associated with an especially difficult MV repair.