The Optimal Suture Technique for Mitral Valve Replacement in an Ex Vivo Animal Model

Objective: This study compared and evaluated three suture methods in order to find the method with the best durability for mitral valve replacement. The methods evaluated are horizontal mattress suture with subanular pledgets, horizontal mattress suture with supraanular pledgets and continuous running suture. Methods: Thirty hearts were explanted from newly terminated pigs. The hearts were randomized in the three groups. After an atriotomy, the mitral valve was cut out, and a patch was sutured into its place. An air pump model was connected to a balloon which was placed in the left ventricle through aorta and continuously filled with air to a maximum of 300 mmHg. The peak pressure at rupture was noted. If no rupture occurred before reaching 300 mmHg, the suture was found competent. Results: Two out of ten hearts in the continuous running suture-group had myocardial rupture within a pressure of 300 mmHg. In the remaining eight hearts there were no ruptures within 300 mmHg. In the two groups sutured with horizontal mattress with pledgets placed either subanular or supraanular, no rupture of myocardium occurred. When comparing continuous running suture with the horizontal mattress with subanular pledgets or the horizontal mattress with supraanular pledgets, the 1-sided Fishers’ exact was 0.237. At 5% significance level, there was no difference between the three suture methods. Conclusion: There was no statistically significant difference between the durability of the three suture methods, though rupture was only evident in the continuous running suture line. Since it is the surgeon’s choice to select the optimal suture technique, our study should be a reminder for the surgeon to reflect on the suturing factors that have an influence on successful mitral valve replacement.