Timek Tomasz A, Liang David, Daughters George T, Ingels Neil B, Miller D Craig
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, California 94305-5247, USA.
J Heart Valve Dis. 2008 Mar;17(2):149-54.
A saddle-shaped mitral annulus may optimize anterior leaflet shape and, in theory, reduce leaflet and chordal stress. Although annuloplasty rings alter native annular height and immobilize the posterior mitral leaflet, their effects on anterior leaflet geometry are unknown.
Four radiopaque markers were placed on the central meridian of the anterior mitral leaflet (AML), and eight on the mitral annulus, of 20 sheep. Six animals were then implanted with a Carpentier-Edwards Physio ring, and six a Medtronic Duran flexible ring. Eight animals served as controls. All animals were then studied with biplane 60 Hz videofluoroscopy at 7-10 days after surgery. The angle Theta was calculated as the angle between each AML leaflet marker and the annular septal-lateral diameter, while AML marker excursion was expressed as the difference between maximum and minimum angle Theta during the cardiac cycle. The intrinsic AML shape was described by three angles, each between three consecutive leaflet markers from the mid-septal annular marker to the leaflet edge (Phi1-3, from annulus to leaflet edge).
Hemodynamic parameters differed only in left ventricular pressure, which was higher in control animals. Anterior leaflet excursion during the cardiac cycle for all four leaflet markers did not change with ring annuloplasty. The intrinsic leaflet angles (Phi1-3) were also unaffected by annular fixation, and thus leaflet shape remained unaltered.
Neither semi-rigid nor flexible annuloplasty rings affected anterior leaflet excursion or the intrinsic geometry of the AML at end-systole or end-diastole. These data suggest that, in normal sheep hearts, annuloplasty rings do not alter anterior leaflet shape and hence do not perturb leaflet stress distribution.
鞍形二尖瓣环可优化前叶形状，理论上可减轻瓣叶及腱索应力。尽管瓣环成形环可改变瓣环高度并固定二尖瓣后叶，但其对前叶几何形态的影响尚不清楚。
在20只绵羊的二尖瓣前叶中央子午线上放置4个不透X线的标记物，在二尖瓣环上放置8个。然后给6只动物植入Carpentier-Edwards Physio环，6只植入美敦力Duran柔性环。8只动物作为对照。术后7 - 10天，对所有动物进行双平面60Hz视频荧光透视检查。计算角度Theta，即每个二尖瓣前叶标记物与瓣环间隔 - 侧径之间的夹角，二尖瓣前叶标记物的偏移量表示为心动周期中最大和最小角度Theta之间的差值。二尖瓣前叶的固有形状由三个角度描述，每个角度位于从间隔瓣环标记物到瓣叶边缘的三个连续瓣叶标记物之间（Phi1 - 3，从瓣环到瓣叶边缘）。
血流动力学参数仅在左心室压力方面存在差异，对照动物的左心室压力较高。所有四个瓣叶标记物在心动周期中的前叶偏移量在瓣环成形术后未发生变化。瓣叶固有角度（Phi1 - 3）也不受瓣环固定的影响，因此瓣叶形状保持不变。
无论是半刚性还是柔性瓣环成形环，在收缩末期或舒张末期均不影响前叶偏移或二尖瓣前叶的固有几何形态。这些数据表明，在正常绵羊心脏中，瓣环成形环不会改变前叶形状，因此不会扰乱瓣叶应力分布。
