The effects of ring annuloplasty on mitral leaflet geometry during acute left ventricular ischemia

Background: The perturbed mitral leaflet geometry that leads to acute ische mic mitral regurgitation during acute left ventricular ischemia has not bee n quantified, nor is it known whether annuloplasty rings affect these detri mental changes in leaflet geometry. Methods: Radiopaque markers were implanted on both mitral leaflets and arou nd the anulus in 3 groups of sheep: one group without rings served as the c ontrol group (n = 7); the others underwent Duran (n = 6: Medtronic Heart Va lve Division, Minneapolis, Minn) or Carpentier-Edwards Physio (n = 5; Baxte r Cardiovascular Division, Santa Ana, Calif) ring annuloplasty. After recov ery, 3-dimensional marker coordinates were obtained by means of biplane vid eofluoroscopy before and during acute posterolateral left ventricular ische mia. Leaflet geometry was defined by measuring distances between annular an d leaflet markers and perpendicular distances to the leaflet markers from a best-fit annular plane. Results: In all control animals, left ventricular ischemia was associated w ith acute ischemic mitral regurgitation and apical displacement (away from the annular plane) of the posterior leaflet edge and base markers by 0.6 +/ - 0.4 mm (P = .01) and 0.7 +/- 0.2 mm (P < .001), respectively. The distanc e between the posterior leaflet markers and the mid-posterior anulus did no t change significantly during ischemia. The anterior leaflet edge marker ex tended 1.0 +/- 0.5 mm (P = .01) away from the mid-anterior anulus during is chemia, but compared with its nonischemic position, the anterior leaflet wa s not displaced apically away from the annular plane. In all animals in the Duran and Physio groups, leaflet geometry was unchanged during ischemia, a nd acute ischemic mitral regurgitation was not detected. Conclusion: Acute ischemic mitral regurgitation was associated with restric ted motion of the posterior leaflet and extension of the anterior leaflet. Annuloplasty rings prevented these geometric perturbations of the mitral le aflets during acute left ventricular ischemia and preserved valvular compet ence.