Timek Tomasz A, Nielsen Sten L, Lai David T, Tibayan Frederick, Liang David, Daughters George T, Beineke Philip, Hastie Trevor, Ingels Neil B, Miller D Craig
Department of Cardiothoracic Surgery, Stanford University School of Medicine, Stanford, CA 94305-5247, USA.
J Heart Valve Dis. 2004 Mar;13(2):165-73.
Whilst increased 'Alfieri stitch' tension may reduce the durability of 'edge-to-edge' mitral repair, the factors affecting suture tension are unknown. In order to study hemodynamics and left ventricular (LV) and annular dynamics that determine suture tension, the central edge of the mitral leaflets was approximated with a miniature force transducer to measure leaflet tension (T) at the leaflet approximation point.
Eight sheep were studied under open-chest conditions immediately after surgical placement of a force transducer and implantation of radiopaque markers on the left ventricle and mitral annulus (MA). Hemodynamic variables were altered by two caval occlusion steps (deltaV1 and deltaV2) and dobutamine infusion. Three-dimensional marker coordinates were obtained by simultaneous biplane videofluoroscopy to measure LV volume, MA area (MAA) and septal-lateral (SL) annular dimension throughout the cardiac cycle.
At baseline, peak Alfieri stitch tension (0.30 +/- 0.18 N) was observed 96 +/- 61 ms prior to end-diastole coincident with peak annular SL diameter (98 +/- 58 ms before end-diastole). Dobutamine infusion decreased suture tension (from 0.30 +/- 0.18 N to 0.20 +/- 0.12 N, p = 0.01), although peak systolic pressure increased significantly (138 +/- 19 versus 115 +/- 14 mmHg; p = 0.03). A regression model was fitted with the goal of interpreting the hemodynamic and geometric predictors of tension as their influence varied with time: Tt (N) = 0.1916 + 0.2115 x SL (cm) - 0.1996 x MAA/SL (cm2/cm) + ft x LVP (mmHg), where Tt is tension at any time during the cardiac cycle and ft is the time-varying coefficient of LVP.
Tension on the leaflets in the edge-to-edge repair is determined primarily by MA SL size, and paradoxically is lower when the contractile state is enhanced. This indicates that annular and/or LV dilatation increase stitch tension and may adversely affect durability of the repair if concomitant ring annuloplasty is not performed.
虽然增加“阿尔菲里缝合”张力可能会降低“边缘对边缘”二尖瓣修复的耐久性，但影响缝线张力的因素尚不清楚。为了研究决定缝线张力的血流动力学以及左心室（LV）和瓣环动力学，使用微型力传感器使二尖瓣叶的中央边缘靠近，以测量瓣叶靠近点处的瓣叶张力（T）。
对8只绵羊在开胸条件下进行研究，在手术放置力传感器并在左心室和二尖瓣环（MA）植入不透射线标记后立即进行。通过两个腔静脉闭塞步骤（deltaV1和deltaV2）和多巴酚丁胺输注改变血流动力学变量。通过同步双平面荧光透视获得三维标记坐标，以测量整个心动周期中的左心室容积、MA面积（MAA）和间隔-侧方（SL）瓣环尺寸。
在基线时，在舒张末期前96±61毫秒观察到阿尔菲里缝合的峰值张力（0.30±0.18牛），与瓣环SL直径峰值（舒张末期前98±58毫秒）一致。多巴酚丁胺输注降低了缝线张力（从0.30±0.18牛降至0.20±0.12牛，p = 0.01），尽管收缩压峰值显著升高（138±19对115±14毫米汞柱；p = 0.03）。拟合了一个回归模型，目的是解释随着时间变化其影响的张力的血流动力学和几何预测因素：Tt（牛）= 0.1916 + 0.2115×SL（厘米） - 0.1996×MAA/SL（平方厘米/厘米）+ ft×LVP（毫米汞柱），其中Tt是心动周期中任何时间的张力，ft是LVP的时变系数。
边缘对边缘修复中瓣叶上的张力主要由MA SL大小决定，矛盾的是，当收缩状态增强时张力较低。这表明瓣环和/或左心室扩张会增加缝线张力，如果不进行伴随的瓣环成形术，可能会对修复的耐久性产生不利影响。
