Nikolay V. Vasilyev1, Franz P. Freudenthal2, Douglas P. Perrin1, Peter E. Hammer1, Ivan S. Salgo3, Pedro J. del Nido1.
1Children's Hospital Boston, Harvard Medical School, Boston, MA, USA, 2Kardiozentrum, La Paz, Bolivia, 3Philips Medical Systems, Andover, MA, USA.
OBJECTIVE: Current approaches to beating heart intracardiac repair of mitral valve prolapse rely mostly on edge-to-edge techniques. We are developing an alternative repair technique for isolated leaflet prolapse designed to plicate the prolapsed segment with a novel clip, using real-time three-dimensional echocardiography (RT3DE) to provide detailed visualization and assessment of mitral valve morphology.
METHODS: Isolated porcine hearts (n=8) were placed into a custom water filled tank and mounted on an ex vivo experimental setup. Physiologic pressure in the left ventricle was generated by retrograde pulsatile flow through the aortic valve. Prolapse of the posterior leaflet (PL) at P2 segment was created by cutting the primary chordae. The detachable Mitral Clip made of Nitinol consists of a loop with two sharpened side arms. The clip was designed to plicate the prolapsed segment including the annulus. The clip was deployed under RT3DE guidance from the left atrium. The effectiveness of the repair was assessed by the degree of mitral regurgitation.
RESULTS: The leaflet prolapse and regurgitation was successfully eliminated in 7 of 8 cases. In 1 case, residual regurgitation was present, and two additional smaller clips were deployed; this reduced the regurgitation but did not eliminate the prolapse completely. Only 1 clip per procedure was needed in all other cases. The total time per procedure, from introduction of the device to disconnecting the clip, was 7.1±3.8 min. No surrounding anatomical structures were compromised in any of the cases.
CONCLUSIONS: This ex vivo study was performed as a first step in the development of a beating-heart intracardiac mitral valve prolapse repair technique without cardiopulmonary bypass. Unlike the edge-to-edge technique, the plication concept mimics quadrangular resection and annulus plication. These initial experiments demonstrate feasibility of RT3DE-guided mitral valve PL prolapse repair using the Mitral Clip device. 
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