Lai David T, Timek Tomasz A, Tibayan Frederick A, Green G Randall, Daughters George T, Liang David, Ingels Neil B, Miller D Craig
Department of Cardiovascular and Thoracic Surgery, Stanford University School of Medicine, Stanford, CA, USA.
Eur J Cardiothorac Surg. 2002 Nov;22(5):808-16. doi: 10.1016/s1010-7940(02)00530-4.
Annuloplasty rings are used to treat ischemic mitral regurgitation (IMR), but their exact effects on 3-D geometry of the overall mitral valve complex during acute left ventricular (LV) ischemia remain unknown.
Radiopaque markers were sutured to the mitral leaflet edges, annulus, papillary muscle tips, and ventricle in three groups of sheep. One group served as control (n = 5), and the others underwent Duran (n = 6) or Physio (n = 5) ring annuloplasty. One week later, 3-D marker coordinates at end-systole were obtained before and during balloon occlusion of the circumflex artery.
In all control animals, acute LV ischemia was associated with: (i) septal-lateral separation of the leaflet edges, which was predicted by lateral displacement of the lateral annulus during septal-lateral mitral annular dilatation; (ii) apical restriction of the posterior leaflet edge, which was predicted by displacement of the lateral annulus away from the non-ischemic anterior papillary muscle; (iii) displacement of the posterior papillary muscle, which was not predictive of either septal-lateral leaflet separation or leaflet restriction; and (iv) mitral regurgitation. In the Duran group during ischemia, the posterior leaflet edge shifted posteriorly due to posterior movement of the lateral annulus, but no IMR occurred. In the Physio group during ischemia, neither the posterior leaflet edge nor the lateral annulus changed positions, and there was no IMR. In both the Duran and Physio groups, displacement of the posterior papillary muscle did not lead to IMR.
Either annuloplasty ring prevented the perturbations of mitral leaflet and annular--but not papillary muscle tip--3-D geometry during acute LV ischemia. By fixing the septal-lateral annular dimension and preventing lateral displacement of the lateral annulus, annuloplasty rings prevented systolic septal-lateral leaflet separation and posterior leaflet restriction, and no acute IMR occurred. The flexible ring allowed posterior displacement of the posterior leaflet edge and the lateral annulus, which was not observed with a semi-rigid ring.
瓣环成形环用于治疗缺血性二尖瓣反流（IMR），但其在急性左心室（LV）缺血期间对整个二尖瓣复合体三维几何结构的确切影响尚不清楚。
在三组绵羊中，将不透射线的标记物缝合到二尖瓣叶边缘、瓣环、乳头肌尖端和心室上。一组作为对照组（n = 5），其他组接受杜兰（Duran，n = 6）或生理（Physio，n = 5）瓣环成形术。一周后，在左旋支动脉球囊闭塞前后获取收缩末期的三维标记物坐标。
在所有对照动物中，急性左心室缺血与以下情况相关：（i）瓣叶边缘的间隔-侧方分离，这可通过间隔-侧方二尖瓣环扩张期间侧方瓣环的侧方移位来预测；（ii）后叶边缘的心尖部受限，这可通过侧方瓣环远离非缺血性前乳头肌的移位来预测；（iii）后乳头肌的移位，这既不能预测间隔-侧方瓣叶分离，也不能预测瓣叶受限；以及（iv）二尖瓣反流。在杜兰组缺血期间，由于侧方瓣环向后移动，后叶边缘向后移位，但未发生IMR。在生理组缺血期间，后叶边缘和侧方瓣环均未改变位置，也没有IMR。在杜兰组和生理组中，后乳头肌的移位均未导致IMR。
两种瓣环成形环均能防止急性左心室缺血期间二尖瓣叶和瓣环（而非乳头肌尖端）三维几何结构的扰动。通过固定间隔-侧方瓣环尺寸并防止侧方瓣环的侧方移位，瓣环成形环可防止收缩期间隔-侧方瓣叶分离和后叶受限，且未发生急性IMR。柔性环允许后叶边缘和侧方瓣环向后移位，而半刚性环则未观察到这种情况。
