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Transpical Implantation of Neochords for Mitral Valve Repair - The Double-Helix Knot.
Mehrdad Ghoreishi, Chetan Pasrija, Brody Wehman, Pete Wilson, James Gammie.
University of Maryland School of Medicine, Baltimore, MD, USA.
OBJECTIVE: Mitral valve (MV) repair using ePTFE neochords is effective and durable. We have developed a new technique to anchor ePTFE neochords to the mitral leaflet on the beating heart using transapical cardiac access and have investigated the force required to pull the implanted suture out of the leaflet.
METHODS: An ePTFE-wrapped needle configured in a preformed knot configuration is positioned on the ventricular side of the targeted mitral leaflet. The needle is advanced across the leaflet and a preformed “double-helix” ePTFE knot is formed on the atrial surface of the leaflet (Figure). The ePTFE suture pair is titrated to an optimal length and secured on the epicardium. The perpendicular tension required to pull the neochords out of the leaflet was measured with a digital force gauge (in Newtons, N). Normal in-vivo forces on marginal MV chordae tendinae are 0.1 - 0.3 N.
RESULTS: 11 porcine hearts were studied. In 7 hearts, the sutures were implanted with the described technique. In 4 hearts, the neochords were secured to the leaflet edge using conventional technique. In 7 hearts, we implanted 11 double-helix knots in anterior leaflets and 6 knots in posterior leaflets. The mean distance from the knots to the edge of the leaflets was 11±6.25 mm in anterior leaflets and 5± 1.67 mm in posterior leaflets. The mean anterior leaflet thickness was 1.4 mm, and the mean posterior leaflet thickness was 1.7 mm. The mean pull out force was 8.58±3.34 N for double-helix-anchored neochords and 8.34±3.29 N for conventional neochords (P = 0.93). The mean pull out force for sutures implanted with double helix technique in anterior leaflets was 8.22±3.64 N and 9.23±2.91 N in posterior leaflets (P = 0.58).
CONCLUSIONS: Transapical neochord implantation with the double-helix preformed knot technique enables rapid and secure anchoring of ePTFE neochords on the beating mitral leaflet. Anchoring security is equivalent to conventional suturing techniques and pull-out forces are 25 - 80 times greater than physiologic forces on marginal chords. 
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