Performance and healing of an expanded polytetrafluoroethylene multichordal device at 6 months after repair of mitral leaflet flail in swine.

OBJECTIVE: Repairing a prolapsed mitral valve that involves multiple cusps is procedurally complicated and carries a higher risk of failure when performed with individual neochordae. Inserting multiple neochordae into the papillary muscle, sizing, and aligning them in a manner that can restore coaptation is challenging. A multichordal mitral valve apparatus (MitraPatch) with a single neopapillary muscle section, 4 neochordae with each chord ending in a neoleaflet section, was developed. In this study, the 6-month outcomes of using this apparatus to repair mitral prolapse in swine is reported. METHODS: Seven pigs (n = 7) with prolapse from mitral chordal transection were repaired with the device. One pig was used to develop the procedure, and 6 swine received the implant and were survived to 150 days (n = 4) and 180 days (n = 2), with monthly echocardiographic examinations. All hearts were explanted for gross necropsy and detailed histopathology. RESULTS: Severe mitral regurgitation (MR) was observed after chordal transection in all pigs. Repairing the valve with the device reduced MR to none-or-trace levels in 3 swine, grade 1 in 3 swine, and 1 to 2+ in 1 swine immediately after surgery. In the pigs with none/trace/grade 1 MR, the device was intact and coaptation was fully restored as observed on serial echocardiograms. The device was intact, without dehiscence, stretching, or fibrosis at termination. The neoleaflet and neopapillary sections of the device elicited a host response, which is on track to produce living valve replacement tissue, but we cannot tell how controlled this might be several years later. In the pig with grade 1 to 2+ MR, accidental transection of both marginal and strut chordae in that region was observed at death, with dehiscence of the device at the site of its insertion into the leaflet. CONCLUSIONS: The anatomic principles that guide this multichordal design appear to be valid, with good hemodynamic performance and a controlled host response at 6 months.

Use of a New Expanded Polytetrafluoroethylene Multichordal Mitral Apparatus (MitraPatch) to Repair Complex Mitral Valve Lesions.

OBJECTIVE: We report a new expanded polytetrafluoroethylene multichordal mitral apparatus (MitraPatch) to simplify mitral repairs involving multiple cusps and sought to describe the surgical technique and demonstrate the efficacy of the device. METHODS: MitraPatch was laser cut from a single sheet of expanded polytetrafluoroethylene and mounted on a custom-designed handle. Surgical technique to deploy the apparatus on the native mitral valve was developed in ex vivo porcine hearts. Hemodynamic efficacy of repairing mitral prolapse and regurgitation was assessed in ex vivo hearts and in five 30-day chronic swine, with histopathology in an additional swine at 120 days after implantation. RESULTS: In ex vivo heart studies, leaflet coaptation was restored from 0 mm at the posterior prolapsing segment to 8.1 ± 2.2 mm after repair with the MitraPatch (P < 0.05) and to 10.2 ± 1.3 mm after the repair of the anterior leaflet (P < 0.05). In in vivo studies, valve function at 30 days was considered good, with none to trace regurgitation. Device was flexible, without tissue overgrowth or dehiscence. At 120 days, complete endothelialization was observed. CONCLUSIONS: The multichordal MitraPatch can potentially simplify complex mitral valve repairs involving multiple leaflet cusps, possibly enabling an optimal mitral repair even by surgeons without the focused high-volume experience.

Pre-clinical Experience with a Multi-Chordal Patch for Mitral Valve Repair.

Surgical repair of flail mitral valve leaflets with neochordoplasty has good outcomes, but implementing it in anterior and bi-leaflet leaflet repair is challenging. Placing and sizing individual neochordae is time consuming and error prone, with persistent localized flail if performed incorrectly. In this study, we report our pre-clinical experience with a novel multi-chordal patch for mitral valve repair. The device was designed based on human cadaver hearts, and laser cut from expanded polytetrafluoroethylene. The prototypes were tested in: (stage 1) ex vivo hearts with leaflet flail (N = 6), (stage 2) acute swine induced with flail (N = 6), and (stage 3) two chronic swine survived to 23 and 120 days (N = 2). A2 and P2 prolapse were successfully repaired with coaptation length restored to 8.1 ± 2.2mm after posterior repair and to 10.2 ± 1.3mm after anterior repair in ex vivo hearts. In vivo, trace regurgitation was seen after repair with excellent patch durability, healing, and endothelialization at euthanasia. A new device for easier mitral repair is reported, with good early pre-clinical outcomes.