Right Ventricular Papillary Muscle Approximation Is An Effective Surgical Repair For Functional Tricuspid Regurgitation
Dongyang Xu, Daisuke Onohara, Kirthana Sreerangathama Suresh, Qi He, Muralidhar Padala.
Emory University, Atlanta, GA, USA.
Objective: Traditionally, undersizing ring annuloplasty (URA) is used to correct FTR, but its long-term durability is unsatisfactory due to excessive leaflet tethering. Right ventricular papillary muscle approximation (RV-PMA) draws the muscles inwards, relieve valve tethering and can improve coaptation. In this study, we seek to study the hemodynamic efficacy of RV-PMA and compared to URA in an ex-vivo FTR model. Methods: Tricuspid valve (TV) apparatus (n=11) were excised from fresh porcine hearts and mounted into a right heart simulator (Fig. 1A), in which a peak transvalvular pressure of 40mmHg, cardiac output of 5L/min at 70bpm were mimicked. At baseline, all valves coapted well (Fig. 1B1). FTR was then created by annular dilation and PM displacement so that a central coaptation gap is formed (Fig. 1B2). URA was performed in the form of true-size ring (TSR, 30mm) and downsized ring (DSR, 28mm) using a custom-built adjustable ring. RV-PMA was performed by moving the anterior PM closer to the septal-posterior PM plane. Finally, TSR and DSR were performed again together with PMA. Tricuspid regurgitation fraction (RF) was measured, and 2D echocardiography was used to measure leaflet geometry and kinematics. Results: RF was increased in the FTR condition compared to baseline (27.99±16.24% vs 0%, p<0.0001). URA lowered RF (TSR: 11.28±5.94%, DSR: 4.64±3.46%) while RV- PMA at both ring sizes reduced RF to trace levels (PMA+TSR: 2.87±4.27%, PMA+DSR: 1.25±2.45%) (Fig. 1C). URA restored coaptation to physiological levels in the septal-anterior plane, but not the posterior-anterior plane, whereas PMA restored coaptation to physiological levels or greater in both planes (Fig. 1D1 & 1D2). PMA enabled better leaflet mobility (Fig. 1E1 & 1E2).Conclusion: RV-PMA by drawing the anterior papillary muscle towards the septal and posterior papillary muscle can effectively reduce FTR in this ex vivo model.
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