Biomechanical characteristics of different methods of neo-chordal fixation to the papillary muscles

Several techniques have been described for neo-chordal fixation to the papillary muscles without any reported clinical differences. The objective of this study is to compare in vitro the biomechanical properties of four of these common techniques.

We studied the biomechanical properties of expanded polytetrafluoroethylene neo-chordal fixation using four techniques: nonknotted simple stitch, nonknotted figure-of-eight stitch, knotted pledgeted mattress stitch, and knotted pledgeted stitch using commercially available prefabricated loops. Neo-chordae were submitted to a total of 20 traction-relaxation cycles with incremental loads of 1, 2, and 4 N. We calculated the elongation, the force-strain curve, elasticity, and the maximum tolerated load before neo-chordal failure.

The elongation of the neo-chordae was lowest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and he commercially prefabricated loops (p < .001). Conversely, the elastic modulus was highest in the simple stitch followed by the figure-of-eight, the pledgeted mattress, and the prefabricated loops (p < .001). The maximum tolerated load was similar with the simple stitch (28.87 N) and with the figure-of-eight stitch (31.39 N) but was significantly lower with the pledgeted mattress stitch (20.51 N) and with the prefabricated loops (7.78 N).

In vitro, neo-chordal fixation by nonknotted simple or nonknotted figure-of-eight stitches resulted in less compliance as opposed to the use of knotted pledgeted stitches. Fixation technique seemed to influence neo-chordal biomechanical properties, however, it did not seem to affect the strength of the suture when subjected to loads within physiological ranges.