Annulus upsizing for mitral valve re-replacement in children

Abstract

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. 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. 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. 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.