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Evaluation of a Novel Automated ePTFE Suturing and Coaxial Fastener System for Mitral Chordae Tendineae Replacement: Strength, Feasibility and Healing
Candice Y. Lee, MD1, Jude S. Sauer, MD2, Heather R. Gorea2, Angelo J. Martellaro2, Andrew Sifain, MD1, Peter A. Knight, MD1.
1University of Rochester Medical Center, Rochester, NY, USA, 2LSI SOLUTIONS, Victor, NY, USA.
OBJECTIVE: Mitral valve (MV) chordal replacement remains technically challenging. Automated technology that remotely delivers and accurately secures ePTFE suture could shorten the learning curve and improve the reliability of surgical MV repairs.
METHODS: An IACUC-approved sheep survivor model was developed to perform open MV repairs on the fibrillated hearts of 8 rams; 4 demonstrated feasibility and 4 evaluated healing integrity after 6 months. Cutting 1-2 native chords produced intraoperative mitral regurgitation (MR). An automated suturing device placed a pledgeted ePTFE suture through the papillary muscle. Another ePTFE suture was placed through the leaflet. Both sutures were threaded coaxially in opposite directions through a hollow titanium fastener in the shaft of a hand-activated device. With the fastener positioned against the papillary muscle, saline was infused through the device into the left ventricle, enabling real-time suture length adjustment. When MV competence was observed, a squeeze of the device lever crimped the fastener and trimmed suture tails. Echocardiography and pathologic evaluation confirmed MV competence, repair integrity and healing. Multiple ex vivo animal hearts and two in situ cadaver hearts also had artificial chords successfully placed. A customized fixture simulating intracardiac chordal tensioning quantified the durability of 120 coaxial fastened ePTFE sutures (80 tensioning cycles/minute up to 3 months).
RESULTS: Three sheep were survived for an average of 6.7 months; a fourth died at 6.5 months from unknown causes. At reoperation, epicardial echocardiography demonstrated trace or no MR. The hearts healed well with suture and fasteners nearly completely endothelialized. Study ex vivo, cadaver and survivor heart repairs illustrated MV competence. Simulator testing of fastened ePTFE suture demonstrated no degradation of knot holding forces for a total of over 440 million cycles.
CONCLUSIONS: Using ex vivo, cadaver and survivor sheep hearts, this study demonstrated a new technology enabling easier papillary suture placement, real-time adjustment of chordal suture length during infusion testing and durability of automated fasteners to secure ePTFE sutures for MV repairs. These successful results encourage further exploration.
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