Mitral Annular Remodeling to Treat Functional Mitral Regurgitation: A Pilot Acute Study in a Canine Model

Background: The aim of this study was to evaluate the feasibility and efficacy of the injection of a nonabsorbable substance into the base of the left ventricle (LV) to treat functional mitral regurgitation (MR). Methods: Tyramine-based hyaluronan hydrogel was injected into the base of the LV of the beating heart in a canine model of rapid ventricular pacing-induced functional MR (n = 4). The severity of MR was evaluated by epicardial echocardiography before and after hydrogel injection. Results: The injection improved MR grade from 3.4 +/- 0.8 to 1.3 +/- 0.5 (P = .006) without inducing hemodynamic instability or any evidence of myocardial ischemia. We noted significant decreases in the septal-lateral dimension at the mitral annulus (3.4 +/- 0.4 cm to 2.9 +/- 0.3 cm; P = .039) and MR volume (20.6 +/- 7.3 mm(3) to 5.2 +/- 2.2 mm(3); P = .044). Conclusions: A novel treatment consisting of hydrogel injection into the base of the LV between the 2 papillary muscles was found to be feasible and effective for reducing functional MR in a canine model.