Effect of mitral valve strut chord cutting on marginal chord tension

The technique of strut chordaesc (SC) cutting, which was proposed for the correction of ischemic mitral regurgitation, has been shown to be an effective short-term procedure. However, the effects of SC cutting on other chordal tensions are unknown. The study aim was to assess anterior leaflet marginal chord tensions after SC cutting.

Tensions of anterior leaflet marginal chordae were measured before and after the cutting of each strut chord independently, or of both SC together, in an intact porcine mitral valve. The cutting positions were chosen between intermediate and marginal chord branching positions. Transmitral pressures were 120 and 160 mmHg. A total of 12 mitral valves was tested.

At a transmitral pressure of 120 mmHg, anterolateral SC cutting increased the tension of the marginal chord from the anterolateral papillary muscle (from 0.10 +/- 0.02 to 0.29 +/- 0.11 N; p = 0.02), but not from the posteromedial papillary muscle. At a transmitral pressure of 120 mmHg, posteromedial SC cutting significantly increased the tension of the marginal chord from the posteromedial papillary muscle (from 0.08 +/- 0.03 to 0.34 +/- 0.20 N; p = 0.029), but not from the anterolateral papillary muscle. Cutting both SC at a transmitral pressure of 120 mmHg increased the tension of the marginal chord from both the posteromedial papillary muscle (from 0.09 +/- 0.04 to 0.40 +/- 0.26 N; p = 0.001) and from the anterolateral papillary muscle (from 0.11 +/- 0.03 to 0.48 +/- 0.13 N; p <0.000001).

Cutting either of the SC significantly increases the tension of the anterior leaflet marginal chord from the same papillary muscle, but not from the other papillary muscle. Cutting both SCs significantly increases the anterior leaflet marginal chord tensions from both papillary muscles by approximately four-fold.