Background - Acute posterolateral ischemia in sheep results in ischemic mitral regurgitation (IMR). While complete ring annuloplasty prevents acute IMR, partial annuloplasty rings may offer a more physiologic repair, but are untested in animal models of IMR. Methods - Radiopaque markers were placed on the LV, mitral annulus (MA), and leaflets in 13 sheep. Seven sheep served as controls, and 6 had a St. Jude Tailor partial flexible ring implanted (29 mm in 5, 31 mm in 1). After 8±1 day, the animals were studied with biplane videofluoroscopy and echocardiography before and during acute posterolateral LV ischemia (balloon occlusion of circumflex artery). Mitral annular area (MAA), septal-lateral annular diameter (SL), annular perimeters, and leaflet edge separation were calculated from 3-D marker coordinates. Results - The average degree of mitral regurgitation increased from 0.0±0.0 to 2.1-0.7 (P=0.0006) in the control group during acute ischemia but remained unchanged in the Tailor group (0.1±0.2 for both conditions). The change in MAA throughout the cardiac cycle before ischemia was 17±4% in control animals, but only 5±2% (P=0.0002) in the Tailor ring group. Unlike the control animals, there was no increase in MAA (5.4±0.8 and 5.5±0.7 cm2, respectively; p=NS) nor dilatation of the muscular annulus (6.2±0.3 and 6.2±0.4, respectively; p=NS) during ischemia with the Tailor ring. Mitral SL dimension increased slightly with ischemia (2.3±0.2 versus 2.2±0.2 cm, P=0.03). Although posterior leaflet motion was limited, as observed with complete rings, normal annular flexion was maintained with the Tailor ring before and during acute ischemia. Conclusions - The Tailor partial annuloplasty ring prevented acute IMR probably by limiting SL diameter dilatation during acute ischemia. In this animal model of acute IMR, a partial, flexible posterior annuloplasty ring is as effective as a complete ring.
|Original language||English (US)|
|Issue number||13 SUPPL.|
|State||Published - Sep 24 2002|
- Mitral valve
ASJC Scopus subject areas
- Cardiology and Cardiovascular Medicine
- Physiology (medical)