Impact of reductive tricuspid ring annuloplasty on right ventricular size, geometry and strain in an ovine model of functional tricuspid regurgitation

Abstract

Objectives Reductive ring annuloplasty of the tricuspid annulus represents the contemporary surgical approach to functional tricuspid regurgitation (FTR). We set out to investigate the influence of moderate reductive tricuspid ring annuloplasty on tricuspid regurgitation and right ventricular (RV) size, geometry, and strain in an ovine model of chronic functional tricuspid regurgitation. Methods Eight healthy Dorsett male sheep (62.8 + 2kg) underwent a left thoracotomy for placement and tightening of pulmonary artery band to at least double proximal pulmonary artery blood pressure. After 8 weeks of recovery, animals underwent sternotomy, epicardial echocardiography, and sonomicrometry crystal implantation. Six crystals were place around tricuspid annulus, and 13 on right ventricular free wall epicardium along 3 parallels defining three wall regions (basal, mid, and lower), and one on the RV apex. All animals underwent beating heart implantation of 26 mm MC3 annuloplasty ring during a second CPB run after baseline data acquisition. Simultaneous haemodynamic, sonomicrometry, and echocardiography data were acquired at Baseline and after reductive tricuspid ring annuloplasty (TRA). Results Implantation of reductive ring annuloplasty resulted in 47 ± 7% annular area reduction (996 ± 152 mm vs 516 ± 52mm2, p = 0.0002) and significantly decreased RV end-diastolic volume (185 ± 27 vs 165 ± 30 ml, p = 0.02). TRA effectively reduced FTR grade (3.75 ± 0.6 vs 0.3 ± 0.5, p = 0.00004) and had little influence on RV function, cross-sectional area, radius of curvature, or free wall regional strains. Conclusion In adult sheep with 8 weeks of pulmonary artery banding and functional tricuspid regurgitation, tricuspid annulus reduction of 47% with prosthetic ring annuloplasty effectively abolished FTR while maintaining regional right ventricular function and strain patterns.