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An Automated Coaxial Fastener to Secure ePTFE Suture for Mitral Valve Repair and Results from an Innovative Testing Method Demonstrating its Durability
Angelo J. Martellaro1, Jude S. Sauer, MD1, Candice Y. Lee, MD2, Peter A. Knight, MD2.
1LSI SOLUTIONS, Victor, NY, USA, 2University of Rochester Medical Center, Rochester, NY, USA.

OBJECTIVE: While suture and knot integrity is critical to surgical outcome, testing techniques quantifying tensile strength over time are not well established. Better analytics are required for the safe introduction of new technologies to fasten suture. Ergonomic mechanical fasteners that reliably secure ePTFE suture could advance mitral valve repair. This study presents a new automated coaxial titanium fastener technology for mitral chordal replacement and results from an innovative testing method demonstrating its durability.
METHODS: Ten hand-operated devices created 120 samples of hollow titanium fasteners crimped around two closed ePTFE suture loops coaxially oriented in opposite directions. Each fastener secured together one CV4 suture loop attached to a spring on a stationary lower plate and one CV5 suture loop attached to a mobile upper plate. With both plates submerged in saline, a motorized fixture moved the upper plate up and down to repeatedly cycle suture tension from approximately 0.050 to 0.150 kgf at 80 “beats” per minute. Seven different time intervals were evaluated, from 0 cycles (baseline) to 10,500,000 cycles (3 months); Table 1. Following completion of each time interval’s tension cycling, suture loops were pulled apart to measure fastener holding strength.
RESULTS: All fasteners demonstrated excellent ePTFE suture holding forces (mean: 0.688 ± 0.104 kgf, range: 0.505 to 0.912 kgf). Over 440,000,000 suture tensioning cycles were conducted for a cumulative cycling time of over 3,835 days. There was no statistically significant difference in average fastener strength between a shorter duration group (baseline, 1, 3 and 7 days) compared to a longer duration group (1, 2 and 3 month group; 0.680 vs. 0.696 kgf, p = 0.41).
CONCLUSIONS: This new approach to testing cardiac sutures under simulated physiologic conditions holds promise for comparative studies. This research demonstrated that titanium coaxial fasteners used to secure ePTFE suture retain supra-physiologic strength for at least 3 months without any apparent degradation over time. These results encourage further exploration of coaxial titanium fasteners in surgical therapy for mitral valve disease.

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