Mitral Valve Posterior Leaflet Reconstruction Using Extracellular Matrix: In Vitro Evaluation

Entire Mitral Valve Reconstruction Using Porcine Extracellular Matrix: Adding a Ring Annuloplasty

PURPOSE

This study investigated the implications of inserting a flexible annuloplasty ring after reconstructing the entire mitral valve in a porcine model using a previously investigated tube graft design made of 2-ply small intestinal submucosa extracellular matrix (CorMatrix®).

METHODS

An acute model with eight 80-kg pigs, each acting as its own control, was used. The entire mitral valve was reconstructed with a 2-ply small intestinal submucosa extracellular matrix tube graft (CorMatrix®). Subsequently, a Simulus® flexible ring was inserted. The characterization was based on mitral annular geometry and valvular dynamics with sonomicrometry and echocardiography.

RESULTS

After adding the ring annuloplasty, the in-plane annular dynamics were more constant throughout the cardiac cycle compared to the reconstruction alone. However, the commissure-commissure distance was statistically significantly decreased [35.0 ± 3.4 mm vs. 27.4 ± 1.9 mm, P < 0.001, diff =  - 7.6 mm, 95% CI, - 9.8 to (-5.4) mm] after ring insertion, changing the physiological annular D-shape into a circular shape which created folds at the coaptation zone resulting in a central regurgitant jet on color Doppler.

CONCLUSION

We successfully reconstructed the entire mitral valve using 2-ply small intestinal submucosal extracellular matrix (CorMatrix®) combined with a flexible annuloplasty. The annuloplasty reduced the unphysiological systolic widening previously found with this reconstructive technique. However, the Simulus flex ring changed the physiological annular D-shape into a circular shape and hindered a correct unfolding of the leaflets. Thus, we do not recommend a flexible ring in conjunction with this reconstructive technique; further investigations are needed to discover a more suitable remodelling annuloplasty.

Three dimensional modeling of atrioventricular valves provides predictive guides for optimal choice of prosthesis

Inaccuracies in intraoperative and preoperative measurements and estimations may lead to adverse outcomes such as patient-prosthesis mismatch. We aim to measure the relation between different dimensions of the atrioventricular valve complex in explanted porcine heart models. After a detailed physical morphology study, a cast of the explanted heart models was made using silicon-based materials. Digital models were obtained from three-dimensional scanning of the casts, showing the measured annulopapillary distance was 2.50 ± 0.18 cm, and 2.75 ± 0.36 cm for anterior and posterior papillary muscles of left ventricle, respectively. There was a significant linear association between the mitral annular circumference to anterior–posterior distance (p = 0.003, 95% CI 0.78–3.06), mitral annular circumference to interpapillary distance (p = 0.009, 95% CI 0.38–2.20), anterior–posterior distance to interpapillary distance (p = 0.02, 95% CI 0.10–0.78). Anterior–posterior distance appeared to be the most important predictor of mitral annular circumference compared to other measured distances. The mean length of the perpendicular distance of the tricuspid annulus, a, was 2.65 ± 0.54 cm; b was 1.77 ± 0.60 cm, and c was 3.06 ± 0.55 cm. Distance c was the most significant predictor for tricuspid annular circumference (p = 0.006, 95% CI 0.28–2.84). The anterior–posterior distance measured by three-dimensional scanning can safely be used to predict the annular circumference of the mitral valve. For the tricuspid valve, the strongest predictor for the circumference is the c-distance. Other measurements made from the positively correlated parameters may be extrapolated to their respective correlated parameters. They can aid surgeons in selecting the optimal prosthesis for the patients and improve procedural planning.