Yun K L, Niczyporuk M A, Daughters G T, Ingels N B, Stinson E B, Alderman E L, Hansen D E, Miller D C
Department of Cardiovascular Surgery, Stanford University School of Medicine, Calif.
Circulation. 1991 Mar;83(3):962-73. doi: 10.1161/01.cir.83.3.962.
Contraction of obliquely oriented left ventricular (LV) fibers results in a twisting motion of the left ventricle. The purpose of this study was to assess the effects of acute human cardiac allograft rejection on LV twist pattern and the twist-volume relation.
Tantalum markers were implanted into the LV midwall in 15 transplant recipients to measure time-varying, three-dimensional chamber twist using computer-assisted analysis of biplane cinefluoroscopic images. Twist was defined as the mean longitudinal gradient of circumferential rotation about the LV long axis. When plotted against normalized percent ejection fraction (%EF), the resulting twist-normalized %EF relation could be divided into three phases. In systole, LV twist was linearly related to ejection of blood. In contrast, diastolic untwist was characterized by early rapid recoil with little change in LV volume, followed by more gradual untwisting when the bulk of diastolic filling occurred. During 10 acute rejection episodes in 10 patients, maximum twist, peak systolic twist rate, and the slope of the systolic twist-normalized %EF relation did not change. In contrast, the slope of the early (first 15% of filling) diastolic twist-normalized %EF relation (M(early-dia)) decreased significantly (-0.194 +/- 0.062 [prerejection] versus -0.103 +/- 0.054 rad/cm [rejection], p = 0.0003), resulting in a prolonged tau 1/2 (time required to untwist by 50% [20 +/- 5% versus 28 +/- 5% of diastole], p = 0.0003) and decrease in percent untwisting at 15% diastolic LV filling (62 +/- 11% versus 36 +/- 13%, p = 0.0003). Therefore, a greater proportion of LV untwisting occurred later in diastole during rejection, as reflected by an increase in the slope (M(mid-dia)) of the middle to late (from 15 to 90% filling) diastolic twist-normalized %EF relation (-0.018 +/- 0.009 versus -0.030 +/- 0.010 rad/cm, p = 0.0015). Peak rate of untwist was not affected. With resolution of rejection, M(early-dia) and percent untwist during early diastole returned to baseline levels (p = NS versus baseline). There was also a trend for M(mid-dia) to return toward prerejection values (p = NS versus baseline), but this change did not reach statistical significance compared with rejection values.
Acute cardiac allograft rejection is associated with altered diastolic twist mechanics in the absence of any demonstratable systolic abnormalities. During rejection, myocardial edema and other factors may result in intrinsic changes of the elastic properties of the myocardium, thereby leading to modification of recoil forces responsible for the early, rapid unwinding of the deformed ventricle.
左心室（LV）斜向纤维的收缩导致左心室的扭转运动。本研究的目的是评估急性人类心脏移植排斥反应对左心室扭转模式和扭转-容积关系的影响。
在15例移植受者的左心室中层壁植入钽标记物，通过双平面电影荧光透视图像的计算机辅助分析来测量随时间变化的三维心室扭转。扭转定义为围绕左心室长轴的圆周旋转的平均纵向梯度。当与标准化射血分数（%EF）作图时，所得的扭转-标准化%EF关系可分为三个阶段。在收缩期，左心室扭转与血液射出呈线性相关。相比之下，舒张期解旋的特征是早期快速回弹，左心室容积变化很小，随后在大部分舒张期充盈时解旋更为缓慢。在10例患者的10次急性排斥反应发作期间，最大扭转、收缩期峰值扭转率以及收缩期扭转-标准化%EF关系的斜率没有变化。相比之下，舒张期早期（充盈的前15%）扭转-标准化%EF关系的斜率（M(early-dia)）显著降低（排斥前为-0.194±0.062，排斥时为-0.103±0.054 rad/cm，p = 0.0003），导致tau 1/2延长（解旋50%所需时间[舒张期的20±5%对28±5%]，p = 0.0003），并且在舒张期左心室充盈15%时解旋百分比降低（62±11%对36±13%，p = 0.0003）。因此，在排斥期间，舒张期后期发生左心室解旋的比例更大，这反映在舒张期中后期（从充盈的15%到90%）扭转-标准化%EF关系的斜率（M(mid-dia)）增加（-0.018±0.009对-0.030±0.010 rad/cm，p = 0.0015）。解旋峰值速率不受影响。随着排斥反应的消退，M(early-dia)和舒张期早期的解旋百分比恢复到基线水平（与基线相比p =无显著差异）。M(mid-dia)也有恢复到排斥前值的趋势（与基线相比p =无显著差异），但与排斥值相比，这种变化没有达到统计学显著性。
急性心脏移植排斥反应与舒张期扭转力学改变有关，而无任何可证明的收缩期异常。在排斥反应期间，心肌水肿和其他因素可能导致心肌弹性特性的内在变化，从而导致负责变形心室早期快速展开的回弹力发生改变。
