Suture tie-down forces and cyclic contractile forces after undersized tricuspid annuloplasty using a Tri-Ad Adams tricuspid annuloplasty ring in an ovine model

Abstract

OBJECTIVES This study evaluated suture tie-down forces and cyclic contractile forces after undersized tricuspid annuloplasty using a hybrid band. METHODS Downsized tricuspid annuloplasty was planned in adult male sheep using eight force transducers attached from the septal to the anterior annular areas of the ring (segments 1 and 2, flexible septal; segments 3 and 4, semi-rigid posterior; segments 5 and 6, semi-rigid anterior; segments 7 and 8, flexible anterior). Cyclic contractile forces were analyzed at three different levels of peak right ventricular pressure: 30, 50, and 70 mmHg. RESULTS Eight 5-year-old male Corriedale sheep (average body weight = 66.8 kg) were used. The average suture tie-down force was 4.42 (standard deviation: 2.32) N. When the forces were compared, it was lowest in the flexible anterior area and highest in the flexible septal area (p < 0.001). With right ventricular pressure of 30 mmHg, the average cyclic contractile forces was lowest at segment 3 (0.07 [standard deviation: 0.07] N) and highest at segment 7 (0.15 [standard deviation: 0.08] N). The cyclic contractile forces were 0.12 (standard deviation: 0.1) N, 0.09 (standard deviation: 0.12) N, 0.14 (standard deviation: 0.1) N, and 0.13 (standard deviation: 0.09) N in the flexible septal, semi-rigid posterior, semi-rigid anterior, and flexible anterior parts, respectively (p = 0.208). As the peak right ventricular pressure increased to 50 and 70 mmHg, the cyclic contractile forces of each area increased significantly (p < 0.001). Despite this increase, the cyclic contractile forces remained low (0.1 and 0.3 N), and differences in cyclic contractile forces between segments and between annular areas showed similar patterns. CONCLUSIONS The flexible end of the hybrid band reduces the cyclic contractile forces and might prevent annular tears after ring tricuspid annuloplasty, and the risk of tear would be low even in the septal area.