Mitral valve reconstruction with artificial chordae: how to secure the desired length?

The use of sutures as artificial chordae is widely established in mitral valve reconstruction. After the correct length of the chordae is determined by saline injection, there is a variety of methods to secure that length before tying surgical knots. The following study was performed to analyse the amount of damage posed by applying a Hemoclip or a Pean-clamp, and by using a surgical knot-pusher.

A total of 30 4–0 Gore-Tex-Sutures were tested applying clips or Pean-clamps for length determination. 10 knots were tied by the same surgeon on each suture, pushing the knots either with bare fingers or a knot-pusher. The suture was then mounted into a two-arm Mitsubishi-robot, force was applied and the amount of force leading to breaking the suture was recorded. Spontaneous breaking of the suture was defined to be caused by a force of 1N. Unclamped and unclipped sutures were used as controls.

No difference in breaking forces were found, if a Pean was applied, with or without the use of a knot pusher (Control suture: 36±4.4N; Pean: 37.5±4.7N; Knot-pusher: 38.6±5N; Pean+Knot-pusher 37.5±4.2N). Using a hemoclip significantly decreased the breaking forces to 12.9±14.6N (p<0.01 vs. control). Two sutures broke spontaneously while being mounted into the robot, whereas in no other group spontaneous breaking was recorded.

In mitral valve reconstructive surgery, the use of a knot-pusher, if handled appropriately, does not decrease the breaking-point of artificial chordae. The length can be safely secured by applying a Pean-clamp. Hemoclips should not be used on artificial chordae.