Background and aim of the study: Although, in theory, the mitral annulus with the Duran flexible ring should change size and shape during the cardiac cycle, no clinical reports are available of such flexibility several years after surgery. The study aim was to evaluate mitral annulus flexibility at medium-term follow up after surgery.

Methods: Eleven patients (mean age 60+/-8 years) were enrolled for this study. All were in sinus rhythm and had less than mild residual mitral regurgitation. The mean time between study and mitral valve repair was 6.0+/-2.4 years. Three sizes of Duran ring were used (three size 27, six size 29, and two size 31). All patients were studied with transesophageal echocardiography. The mitral annulus was reconstructed 10 times around a single axis of rotation during the cardiac cycle, using published methods. The area, circumferential length and shape of the mitral annulus were analyzed at various times during the cardiac cycle.

Results: A significant change in mitral annular area occurred during the cardiac cycle; the maximum to minimum reduction was 23+/-8% (p <0.001). The area and circumferential length of the mitral annulus in patients with size 29 Duran rings changed from 8.2+/-1.3 to 6.2+/-1.3 cm2 (p <0.001) and from 11.8+/-1.1 to 9.9+/-0.8 cm (p <0.001), respectively. Three-dimensional reconstruction of the mitral annulus showed it to retain its non-planar shape, but the shape to change significantly during the cardiac cycle.

Conclusion: The mitral annulus with a Duran ring remained flexible and retained its non-planar configuration at six years after implantation.