Transapical neochord implantation: is tension of artificial chordae tendineae dependent on the insertion site?

OBJECTIVE

Transapical chordae tendineae replacement is a promising new approach for mitral leaflet prolapse. However, animal studies have raised concerns that the tension of the transapically fixated artificial neochordae might be greater than the tension in the neochordae attached to papillary muscle tips, thereby reducing repair durability.

METHODS

In eight 80-kg pigs, the primary anterior leaflet chordae were replaced by a 5-0 polytetrafluoroethylene neochord using a miniature in-line force transducer. The neochord was attached first to the anterior papillary muscle and, on a second cardiac bypass, transapically to the left ventricle apex. Occlusion of the inferior vena cava was performed to examine the effect of left ventricle pressure changes on neochord tension to adjust the crude data to 95 mm Hg. The maximum slope of the chordal tension curve was calculated to compare curve patterns. The data are presented as the mean ± standard deviation.

RESULTS

The following tension was measured in the neochordae during papillary muscle and transapical fixation, respectively: peak tension (crude, 0.39 ± 0.32 vs 0.50 ± 0.25 N, P = .17; adjusted, 0.41 ± 0.30 vs 0.46 ± 0.27 N, P = .22), mid-systolic tension (crude, 0.19 ± 0.12 vs 0.19 ± 0.15 N, P = .96; adjusted, 0.28 ± 0.16 vs 0.19 ± 0.11 N, P = .12). There was a significantly lower maximum slope (dF/dtmax) of the neochord tension curves after papillary muscle fixation compared with transapical fixation (7.4 ± 6.9 vs 10.3 ± 7.7 N/s, P = .028).

CONCLUSIONS

Overall, the chordal insertion site had little influence on the tension in the artificial neochordae compared with the interindividual variation. However, abnormal tension fluctuations in the transapically fixated neochordae might predispose to leaflet tears and early repair failure.