Annulus upsizing for mitral valve re-replacement in children

Background: Mitral valve replacement remains the last resort for treatment of congenital mitral valve disease. Enlarging the mitral annulus at the time of mitral valve replacement may allow implantation of a larger prosthesis in children. Methods: All mitral valve replacement procedures from 1990 to 2012 were included, and mitral annulus enlargement techniques were analyzed. A control group of patients undergoing replacement of a previously implanted mechanical mitral valve prosthesis was compared with the cohort of patients who underwent annular enlarging procedures. Primary end points were increases in annulus size and Z score, and freedom from paced rhythm. Results: Among 205 mitral valve replacement procedures, 16 (8%) included techniques to upsize the mitral annulus in 15 patients, all but 1 of whom had undergone prior mitral valve replacement. These patients were compared with a control cohort of 53 patients undergoing mitral valve re-replacement without annulus enlargement. The annulus was upsized by 18% ± 11% (compared with 16% ± 20% in controls, P =.5) using open balloon dilation in 4 patients, radial annular incisions in 5 patients, and patch augmentation of the aorto-mitral continuity in 7 patients. The mean valvar diameter Z score increased from -0.2 ± 1.3 to +1.1 ± 1.4 (P <.001), compared with an increase from -0.3 ± 1.2 to 0.9 ± 1.1 in controls (P <.001). During a mean follow-up of 6.5 ± 6.4 years, 4 of 12 patients required permanent pacing in the upsizing group (predominantly with patch augmentation), versus 5 of 53 patients in the control group. Conclusions: In children undergoing mitral valve replacement, various techniques can be used to upsize the mitral annulus and allow implantation of a larger prosthesis. There is a nontrivial risk of heart block with annulus upsizing, which deserves further study.