Abstract
Partial heart transplantation (PHT) offers a growth-accommodating alternative to mechanical valve replacement in congenital heart disease. While experience with semilunar valve PHT is expanding, application to atrioventricular valves remains extremely limited. We report the first mitral valve PHT at our institution, focusing on technical considerations and lessons learned. A 12-year-old patient with prior ventricular septal defect closure and supra-annular implantation of a 21-mm mechanical mitral valve due to congenital stenosis developed prosthetic stenosis (mean gradient 18 mm Hg). Evaluation confirmed suitability for mitral valve PHT using an allogenic donor valve. Preoperative CT imaging guided assessment of chordal length, as native papillary muscles were absent. Following removal of the prosthesis, expanded polytetrafluoroethylene sutures were placed on the left ventricular free wall, matched to donor chordal length and anchored near the papillary bases in anticipation of necrosis. The donor valve, retained with a small muscular rim, was secured to the native annulus and tested for competence. An additional suture was placed on the central papillary subhead. Recovery was uneventful, and the patient was discharged on immunosuppression. At four months, MRI demonstrated severe mitral regurgitation (regurgitant fraction 53%) due to anterior leaflet prolapse. The family elected mechanical replacement. Intraoperatively, the transplanted valve showed complete annular integration and tissue viability. Histopathology confirmed papillary necrosis with fibroblast infiltration, while leaflets and chordae remained viable. Mitral valve PHT is feasible and demonstrates valve viability. Durable outcomes may depend on symmetric and balanced reimplantation of the subvalvar apparatus, particularly in patients lacking native papillary muscles.