Methods: Posterior quadrangular resection and sliding leaflet techniques were simulated in 24 cases in bovine heart. In all cases, posterior mitral leaflet indentations were closed with 5-0 silk sutures. The indentational chords were left untouched in group 1 (n=12), and were resected in group 2 (n=12). The coaptation lines between anterior and posterior leaflets were assessed in both groups. Presence of tethering chords in posterior leaflet was investigated while the mitral valve competence was tested under the pressure of 170 cmH₂O (125 mmHg).

Results: While coaptation lines were asymmetric in all cases in group 1, no asymmetric coaptation line was detected in group 2 (p<0.001). It was determined that the asymmetric coaptation lines in group 1 were caused by the primary chords supporting the intentionally closed indentations during the procedure.

Conclusion: It can be suggested that after closing the indentations, the primary chords supporting these indentations function as secondary chords which restrain leaflet mobilization in sliding posterior leaflet technique.