Mitral valve annulus tension and the mechanism of XXXX : an in-vitro study.

@entity2701 @entity384 @entity299 @entity63
BACKGROUND AND AIM OF THE STUDY: The mitral annulus mechanics associated with @entity384 in pathologies such as mitral valve (MV) prolapse, @entity63 and dilative @entity299 remain unknown. The study aim was to investigate @entity2701 ( @entity2701 ) in the dilated annulus and in the displaced papillary muscles due to these pathological conditions. METHODS: Ten porcine MVs were harvested and mounted on a MV closure test rig with the papillary muscles held in the slack, normal, and taut positions. The MV annulus tissue rested on top of a plastic ring on which it could slide freely. The annulus was held by strings in the periphery during valve closure under hydrostatic trans-mitral pressure. The string tensions were measured, and further divided by string spacing to obtain the @entity2701 . Three annuli of normal, 25% dilated and 50% dilated annulus sizes were used. RESULTS: The @entity2701 was lowest at the commissural segment of the annulus, but increased towards the anterior and posterior segments, with a greater increase towards the anterior segment than towards the posterior. The @entity2701 increased with the increase of the apical PM displacement from the slack to normal, and then taut position in the commissural segment of the annulus. Although the @entity2701 increased with annulus area, the increase was less pronounced in the commissural segment than in the anterior and posterior segments. CONCLUSION: There is a significant difference in @entity2701 values between a normal and prolapsed MV, and between a normal MV and a MV with displaced papillary muscles. This difference suggests that @entity384 is a consequence and MV counteraction of imbalanced annular mechanics between the @entity2701 and myocardial force.
