Comparison of Strength, Consistency, and Speed of COR-KNOT versus Manually Hand-Tied Knots in an Ex Vivo Minimally Invasive Model

Abstract

Objective This study compared the strength, consistency, and speed of prosthetic attachment sutures secured with automated fasteners with those of manual knots using an ex vivo porcine mitral valve annuloplasty model. A novel miniature pressure transducer system was developed to quantify pressures between sutured prosthetic rings and underlying cardiac tissue. Methods Sixteen mitral annuloplasty rings were sewn into ex vivo pig hearts. Eight rings were secured with the COR-KNOT device; and eight rings, with hand-tied knots using a knot pusher. A cardiac surgeon and a surgery resident each completed four manually tied rings and four COR-KNOT rings via a thoracotomy trainer. The total time to knot and cut each ring's sutures was recorded. Suture attachment pressures were measured within (intrasuture) and between (extrasuture) each suture loop using a 0.5 × 2.0-mm microtransducer probe system. Results The suture holding pressures for the COR-KNOT fasteners were significantly greater than for the manually tied knots (median, 1008.9 vs 415.8 mm Hg, P < 0.001). All automated fasteners measured greater than 500 mm Hg, whereas 56% of the hand-tied knots were less than 500 mm Hg, and 14% were less than 75 mm Hg. There was less variation in attachment pressures for the COR-KNOT fasteners than for the hand-tied knots (SD, 401.6 vs 499.3 mm Hg, P = 0.04). Significant time savings occurred with the use of the COR-KNOT compared with manual tying (12.4 vs 71.1 seconds perknot, P = 0.001). Conclusions The novel microtransducer technology provided an innovative means of evaluating cardiac prosthetic anchoring sutures. In this model, mitral annuloplasty ring sutures secured with the COR-KNOT device were stronger, more consistent, and faster than with manually tied knots.