Dynamic RING + STRING for ischemic mitral regurgitation: Papillary muscle repositioning and modification of the septal–lateral diameter in the loaded beating heart under echocardiographic guidance

Abstract

Ischemic mitral regurgitation (MR) involves annular dilatation in all cases. Some patients, however, also exhibit severe leaflet tethering due to papillary muscle displacement. Leaflet tethering is the strongest predictor of repair failure in up to 30% of patients treated by undersized ring annuloplasty (RING). These failures emphasize the need for subvalvular strategies. Several adjunctive techniques have been proposed, but only 3 techniques have received clinical acceptance. Borger and associates reported initial results of cutting second-order chordae. The impact of this technique on left ventricular systolic function, however, has been discussed controversially. Leaflet extension has been performed successfully in a case series by de Varennes and associates. We have reported a technique (RING þ STRING) that allows repositioning of the posterior papillary muscle under transesophageal echocardiographic (TEE) guidance. Even though midterm results with this technique have been encouraging, we have been looking for further improvement. Reduction of the septal–lateral diameter has been the key to reduction of ischemic MR in the experimental setting. This observation has been the basis for the use of aggressively undersized complete rings used clinically. Recently, however, Magne and colleagues documented functional mitral stenosis with associated pulmonary hypertension and reduced functional capacity as result of aggressive undersizing, the equivalent of patient–prosthesis mismatch in mitral valve repair.