Delhaas T, Arts T, Prinzen F W, Reneman R S
Department of Physiology, University of Limburg, Maastricht, The Netherlands.
Pflugers Arch. 1993 Apr;423(1-2):78-87. doi: 10.1007/BF00374964.
To determine the relation between regional electrical activation time and fiber strain, epicardial electrical activation and deformation were measured in six open-chest dogs at the left ventricular anterior free wall after 15 min of right atrial, left ventricular free wall, left ventricular apex, or right ventricular outflow tract pacing, when end-diastolic pressure was normal or elevated (volume-loading). Regional electrical activation was measured using a 192-electrode brush. Regional subepicardial fiber strain (ef) was measured simultaneously in 16 regions, using optical markers which were attached to the epicardial surface and recorded on video. When relating regional ef during the ejection phase to regional activation time, the best correlation was found when a hemodynamic time reference rather than an electrophysiological one is used. Using the moment of the maximum rate of change of left ventricular pressure as the time reference for electrical activation, regional electrical activation time (t(ea)) and the degree of ef during the ejection phase could be fitted by a linear regression equation ef = a t(ea) + b, in which a = -3.46 +/- 0.73 s-1 an b = -0.28 +/- 0.05. For electrical activation times ranging from -40 to -80 ms, fiber strain was estimated with an accuracy of +/- 0.026 (+/- SE) with this relation. During right atrial pacing, t(ea) and ef were on the average -48 ms and -0.10 respectively. On further investigation, the relation between ef and t(ea) appeared to be influenced by end-diastolic pressure. For normal (1.1 kPa) and elevated end-diastolic pressure (1.8 kPa), the slope of the linear regression line was -3.96 and -2.86 s-1, respectively. Three conclusions may be drawn. Firstly, the time interval between the moment of regional electrical activation and the moment of the maximum rate of change of left ventricular pressure is an index of regional fiber strain. Secondly, it can be concluded from the above equations that electrical asynchrony of more than 30 ms causes non-uniformities in the degree of ef of the order of mean ef during pacing from the right atrium. Finally, differences in fiber strain during asynchronous electrical activation are less pronounced at larger filling pressures.
为了确定局部电激活时间与纤维应变之间的关系，在6只开胸犬的左心室前游离壁进行了测量，分别在右心房、左心室游离壁、左心室心尖或右心室流出道起搏15分钟后，当舒张末期压力正常或升高（容量负荷）时，测量心外膜电激活和变形。使用192电极刷测量局部电激活。使用附着于心外膜表面并记录在视频上的光学标记，同时在16个区域测量局部心外膜下纤维应变（ef）。当将射血期的局部ef与局部激活时间相关联时，发现使用血流动力学时间参考而非电生理时间参考时相关性最佳。以左心室压力最大变化率的时刻作为电激活的时间参考，局部电激活时间（t(ea)）和射血期ef的程度可用线性回归方程ef = a t(ea) + b拟合，其中a = -3.46 +/- 0.73 s-1，b = -0.28 +/- 0.05。对于-40至-80 ms的电激活时间，利用该关系估计纤维应变的准确度为+/- 0.026（+/-标准误）。在右心房起搏期间，t(ea)和ef的平均值分别为-48 ms和-0.10。进一步研究发现，ef与t(ea)之间的关系似乎受舒张末期压力影响。对于正常（1.1 kPa）和升高的舒张末期压力（1.8 kPa），线性回归线的斜率分别为-3.96和-2.86 s-1。可以得出三个结论。首先，局部电激活时刻与左心室压力最大变化率时刻之间的时间间隔是局部纤维应变的一个指标。其次，从上述方程可以得出，超过30 ms的电不同步会导致从右心房起搏期间ef程度的不均匀性，其程度约为平均ef。最后，在较大充盈压力下，异步电激活期间纤维应变的差异不太明显。
