Generation of chordae tendineae with polytetrafluoroethylene stents. Results of mitral valve chordal replacement in sheep.

Surgical repair of ruptured or elongated chordae tendineae of the mitral valve is one of the most complex reconstructive techniques in cardiac surgery. Various surgical procedures have been described to repair chordal abnormalities of the anterior leaflet of the mitral valve with unpredictable results. Mitral valve replacement is usually recommended in that situation. This report describes a simple repair technique that we have devised. We resected one or two marginal chordae of the anterior leaflet of the mitral valve in 35 sheep and replaced them with a double-armed, pledget-supported, expanded polytetrafluoroethylene suture. The 30 surviving animals were studied hemodynamically and were electively put to death 3, 6, 9, 18, and 24 months after the operation. Mitral insufficiency did not develop in any of the sheep. All specimens had a normal mitral valve without thrombosis. The polytetrafluoroethylene suture remained pliable and was incorporated into the anterior leaflet and papillary muscle. Scanning and transmission electron microscopy showed that the suture was completely covered by a sheath of tissue with a collagen structure remarkably similar to that of a native chorda. Calcification was not detected in the new chordae. This reproducible and safe technique may considerably simplify the difficult repair of chordal abnormalities.