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

OBJECTIVES: This study evaluated suture tie-down forces and cyclic contractile forces (CCFs) after undersized tricuspid annuloplasty using a hybrid band. METHODS: Downsized tricuspid annuloplasty was planned in adult male sheep using 8 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). CCFs were analysed at 3 different levels of peak right ventricular pressure (RVP): 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 (SD): 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 the RVP of 30 mmHg, the average CCFs was lowest at segment 3 [0.07 (SD: 0.07) N] and highest at segment 7 [0.15 (SD: 0.08) N]. The CCFs were 0.12 (SD: 0.1) N, 0.09 (SD: 0.12) N, 0.14 (SD: 0.1) N and 0.13 (SD: 0.09) N in the flexible septal, semi-rigid posterior, semi-rigid anterior and flexible anterior parts, respectively (P = 0.208). As the peak RVP increased to 50 and 70 mmHg, the CCFs of each area increased significantly (P < 0.001). Despite this increase, the CCFs remained low (0.1 and 0.3 N), and differences in CCFs between segments and between annular areas showed similar patterns. CONCLUSIONS: The flexible end of the hybrid band reduces the CCFs and might prevent annular tears after ring tricuspid annuloplasty, and the risk of tear would be low even in the septal area.