Ring annuloplasty prevents delayed leaflet coaptation and mitral regurgitation during acute left ventricular ischemia

Objective: Incomplete mitral leaflet coaptation during acute left ventricul ar ischemia is associated with end-diastolic mitral annular dilatation and ischemic mitral regurgitation. Annular rings were implanted in sheep to inv estigate whether annular reduction alone is sufficient to prevent mitral re gurgitation during acute posterolateral left ventricular ischemia. Methods: Radiopaque markers were inserted around the mitral anulus, on papi llary muscle tips, and on the central meridian of both mitral leaflets in t hree groups of sheep: control (n = 5), Physio ring (n = 5) (Baxter Cardiova scular Div, Santa Ana, Calif, and Duran ring (n = 6) (Medtronic Heart Valve Div, Minneapolis, Minn). ATter 8 +/- 1 days, animals were studied with bip lane videofluoroscopy before and during left ventricular ischemia. Annular area was calculated from 3-dimensional marker coordinates and coaptation de fined as minimal distance between leaflet edge markers. Results: Before ischemia, leaflet coaptation occurred just after end-diasto le in all groups (control 17 +/- 41, Duran 33 +/- 30, Physio 33 +/- 24 ms, mean +/- SDI P > .2 by analysis of variance). During ischemia, regurgitatio n was detected in all control animals, and leaflet coaptation was delayed t o 88 +/- 8 ms after md-diastole (P = .02 vs preischemia). This was associat ed with increased end-diastolic annular area (8.0 +/- 0.9 vs 6,7 +/- 0.6 cm (2), P = .004) and septal-lateral annular diameter (2.9 +/- 0.1 vs 2.5 +/- 0.1 cm, P = .02), Mitral regurgitation did not develop in Duran or Physio s heep, time to coaptation was unchanged (Duran 25 +/- 25 ms, Physio 30 +/- 4 8 ms [both P > .2 vs preischemia]), and annular area remained fixed. Conclusion: Mitral annular area reduction and fixation with an annuloplasty ring eliminated delayed leaflet coaptation and prevented mitral regurgitat ion during acute left ventricular ischemia after ring implantation.