A. E. Morgan1, L. Ge4, W. G. Morrel5, J. L. Pantoja5, E. A. Grossi3, M. B. Ratcliffe1,2 1University Of California – San Francisco,Surgery,San Francisco, CA, USA 2San Francisco VA Medical Center,Surgery,San Francisco, CA, USA 3New York University School Of Medicine,Cardiothoracic Surgery,New York, NY, USA 4University Of California – San Francisco,Bioengineering,San Francisco, CA, USA 5University Of California – San Francisco,School Of Medicine,San Francisco, CA, USA
Introduction: Mitral valve repair is superior to replacement in terms of long-term survival, but recurrent mitral regurgitation after repair for degenerative disease occurs at a rate of ~2.6% per year, with a 20% reoperation rate at 20 years. We hypothesize that durability of repair is related to geometry of initial repair, as well as stress distribution over the mitral valve and left ventricle. Previous studies demonstrate that repair by posterior leaflet resection increases stress across the posterior leaflet; we tested the hypothesis that repair by placement of prosthetic chordae tendinae resulted in reduced overall stress as compared to leaflet resection.
Methods: Magnetic resonance imaging and intra-operative 3D trans-esophageal echocardiography were performed before surgical repair of isolated P2 prolapse in a single patient. A finite element model of the left ventricle and mitral valve was created. Stress was examined in the preoperative state for the mitral valve and left ventricle, and for the following repairs: Triangular resection; Placement of one PTFE chord; Placement of two PTFE chords.
Results: The principal findings of this study are the following: 1) Placement of prosthetic chordae resulted in stable or decreased overall posterior leaflet stress for all phases of the cardiac cycle; 2) In contrast, triangular resection resulted in increased posterior leaflet stress, most prominently in diastole; 3) All repair techniques reduced stress on the anterior leaflet; 4) All repair techniques restored normal leaflet coaptation. An example of pre- and post-repair leaflet geometry is shown in the attached figure, for placement of two prosthetic chordae.
Conclusion: All repair techniques eliminated mitral regurgitation and restored normal leaflet coaptation. Finite element analysis revealed that mitral valve repair with prosthetic chordae restored normal leaflet geometry without creation of excessive stress on the valvular tissues, in contrast to leaflet resection, which significantly increased stress across the posterior leaflet. Future studies will examine this effect across a broad range of patients with the aim of developing a patient-specific tool for mitral valve repair preoperative planning and surgical education.
