Can we repair the mitral valve from outside the heart? A novel extra-cardiac approach to functional mitral regurgitation.

摘要

BACKGROUND: Functional mitral regurgitation (FMR) is primarily due to abnormalities of the ventricular muscle in the presence of normal mitral leaflets. Present surgical treatment options address the mitral valve annulus and leaflets but not the ventricular muscle. We discuss the evolution of a concept that describes a ventricular solution to this problem, and report preliminary clinical results from the first five subjects implanted with the latest version of this device. METHODS: Evaluation of safety and efficacy of the latest version of the BACE (Basal Annuloplasty of the Cardia Externally) Device was done first in sheep with rapid ventricular pacing to induce severe MR. The BACE Device was implanted around the base of the heart and chambers on the device filled with normal saline through the subcutaneous ports under echocardiogram until there was no evidence of MR. Once MR was effectively reduced, the chest was closed and the animals recovered, with clinical and echocardiographic analysis through six months of follow-up. Human studies were done with in a similar manner, with subjects that were already undergoing concomitant open-chest coronary artery bypass graft (CABG) surgery. Five subjects with ischaemic MR and triple vessel coronary artery disease were first implanted with the BACE Device, applied epicardially on a beating heart without use of cardiopulmonary bypass, before coronary artery bypass grafting was done. RESULTS: In five sheep, epicardial application of the BACE Device effectively reduced mitral regurgitation from Grade 4 to Grade 0, and the effect was sustained through six months despite ongoing pacing. Terminal studies at six months showed no adhesion to the silicone band. All five human subjects were male, NYHA Class III, with LVEF of 20-40%. Epicardial application and adjustment of the BACE Device was performed safely on a beating heart with effective reduction in FMR to grade <1. All five subjects had three bypass grafts. Reduction in MR was sustained for at least six months and there were no unanticipated or device-related adverse events. CONCLUSION: Epicardial application and adjustment of the BACE Device can be performed safely without CPB with effective reduction in MR.