Initial Clinical Experience With Partial Heart Transplantation for Mitral Valve Replacement: An Experimental Approach

BACKGROUND: Mitral valve replacement in children is limited by the need for anticoagulation, lack of growth potential, and high reoperation rates. Partial heart transplantation (PHT) offers a living, growth-capable alternative. Although successfully applied to semilunar valves, its use in the atrioventricular position has not been described. This study reports the initial 2 cases of mitral PHT and evaluates early technical and physiologic outcomes. METHODS: Two pediatric patients underwent mitral PHT at separate institutions under institutional review board approval. In both cases, donor mitral valves with preserved subvalvular apparatus were implanted orthotopically. Procedural details, postoperative echocardiographic findings, and histopathologic analyses were reviewed to assess function, graft integrity, and mechanisms of failure. RESULTS: Both cases demonstrated technical feasibility, immediate valve competence, and early postoperative recovery. One patient maintained mild to moderate regurgitation at 8 months; the second patient had progressive regurgitation within 2 months, necessitating re-replacement. Histopathologic analysis revealed excellent graft integration and preserved leaflet and annular architecture but evidence of papillary muscle necrosis, consistent with ischemic injury and subsequent change in chordal length as the likely mechanism of regurgitation. CONCLUSIONS: Mitral PHT is technically feasible but remains an experimental approach. Early experience demonstrates successful implantation and biologic integration while identifying papillary muscle ischemia as a key limitation. Future refinements include the use of artificial chordae and careful selection of patients.