Functional and Hemodynamic Assessment of a Novel 3-Dimensional Anatomically Correct Annuloplasty Ring to Correct Functional Tricuspid Regurgitation
Nikolay V. Vasilyev1, Muralidhar Padala2, Haruo Yamauchi1, Bjoern Sill1, Eva M. Delmo Walter1, Vinod H. Thourani2, Jorge H. Jimenez3, Pedro J. del Nido1, Ajit P. Yoganathan3.
OBJECTIVE: Tricuspid regurgitation (TR) is prevalent among mitral valve repair patients, and tricuspid annuloplasty is now recommended. Suture annuloplasty and use of mitral rings on the tricuspid annulus have yielded poor outcomes. We report a novel 3-dimensional tricuspid annuloplasty ring and its functional efficacy in a chronic animal model.
METHODS: Anatomical measurements of the normal tricuspid annulus were obtained from 5 human cadavers; and a ring was designed. First, a prototype was tested ex-vivo in porcine hearts at 120mmHg (n=10). TR was created by excising a 2x5mm section from the free edge of the anterior leaflet, the ring was then implanted. Second, the ring was tested in a similar acute ovine TR model (n=3), the ring was compared against a predicate (Edwards MC3). Finally, in a swine model (n=6), TR was created using annular dilation model. During the initial surgery, 6-12 small (3-5mm) annular incisions were made under cardioscopy on beating heart, and the leaflets were intact. At 4-5 weeks after TR creation, when annular dilatation was confirmed, the ring was surgically implanted. Tricuspid annular diameter, TR grade, and 3D shape data of tricuspid valve were examined by serial echocardiography after TR creation, ring implantation, and every 2 weeks till sacrifice. Animals were sacrificed 4 weeks after the ring implantation.
RESULTS: In the ex vivo heart experiments, acute reduction in TR was evident with complete elimination of TR and favorable leaflet coaptation with the 3D design. In the acute ovine model, similar reduction with no residual TR was measured; wherein the hemodynamic outcomes were either equivalent or better than the predicate device. In a chronic swine model, the tricuspid annulus gradually dilated 4 weeks after annular incisions (22.5±2.5mm to 35.0±3.6mm, 155% of original size) leading to central TR (1.3±1.0 to 2.9±0.8, p=0.002). Following ring implantation, the TR decreased to 1.3±0.8, p=0.02, by the time of euthanasia.
CONCLUSIONS: This study demonstrated the hemodynamic efficacy of a novel 3-dimensional anatomically correct annuloplasty ring to correct functional TR in ex vivo and acute and chronic animal studies. This specific tricuspid valve annuloplasty ring may be a better alternative to the current annuloplasty devices.
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