Ciaccio Edward J, Coromilas James, Wan Elaine Y, Yarmohammadi Hirad, Saluja Deepak S, Biviano Angelo B, Wit Andrew L, Peters Nicholas S, Garan Hasan
Department of Medicine - Division of Cardiology, Columbia University College of Physicians and Surgeons, New York, NY 10032, USA; ElectroCardioMaths Programme, Imperial Centre for Cardiac Engineering, Imperial College London, London, UK.
Department of Medicine - Division of Cardiovascular Disease and Hypertension, Rutgers University, New Brunswick, NJ, USA.
Comput Methods Programs Biomed. 2020 Nov;196:105666. doi: 10.1016/j.cmpb.2020.105666. Epub 2020 Jul 15.
To validate the predictability of reentrant circuit isthmus locations without ventricular tachycardia (VT) induction during high-definition mapping, we used computer methods to analyse sinus rhythm activation in experiments where isthmus location was subsequently verified by mapping reentrant VT circuits.
In 21 experiments using a canine postinfarction model, bipolar electrograms were obtained from 196-312 recordings with 4mm spacing in the epicardial border zone during sinus rhythm and during VT. From computerized electrical activation maps of the reentrant circuit, areas of conduction block were determined and the isthmus was localized. A linear regression was computed at three different locations about the reentry isthmus using sinus rhythm electrogram activation data. From the regression analysis, the uniformity, a measure of the constancy at which the wavefront propagates, and the activation gradient, a measure that may approximate wavefront speed, were computed. The purpose was to test the hypothesis that the isthmus locates in a region of slow uniform activation bounded by areas of electrical discontinuity.
Based on the regression parameters, sinus rhythm activation along the isthmus near its exit proceeded uniformly (mean r= 0.95±0.05) and with a low magnitude gradient (mean 0.37±0.10mm/ms). Perpendicular to the isthmus long-axis across its boundaries, the activation wavefront propagated much less uniformly (mean r= 0.76±0.24) although of similar gradient (mean 0.38±0.23mm/ms). In the opposite direction from the exit, at the isthmus entrance, there was also less uniformity (mean r= 0.80±0.22) but a larger magnitude gradient (mean 0.50±0.25mm/ms). A theoretical ablation line drawn perpendicular to the last sinus rhythm activation site along the isthmus long-axis was predicted to prevent VT reinduction. Anatomical conduction block occurred in 7/21 experiments, but comprised only small portions of the isthmus lateral boundaries; thus detection of sinus rhythm conduction block alone was insufficient to entirely define the VT isthmus.
Uniform activation with a low magnitude gradient during sinus rhythm is present at the VT isthmus exit location but there is less uniformity across the isthmus lateral boundaries and at isthmus entrance locations. These factors may be useful to verify any proposed VT isthmus location, reducing the need for VT induction to ablate the isthmus. Measured computerized values similar to those determined herein could therefore be assistive to sharpen specificity when applying sinus rhythm mapping to localize EP catheter ablation sites.
为了验证在高清标测期间无室性心动过速（VT）诱发时折返环峡部位置的可预测性，我们采用计算机方法分析窦性心律激动情况，随后通过标测折返性室性心动过速环路来验证峡部位置的实验。
在21个使用犬心肌梗死模型的实验中，在窦性心律和室性心动过速期间，从心外膜边界区以4mm间距进行196 - 312次记录获取双极电图。从折返环的计算机化电激动图中，确定传导阻滞区域并定位峡部。使用窦性心律电图激动数据在折返峡部周围的三个不同位置进行线性回归计算。通过回归分析，计算出均匀性（一种衡量波前传播恒定性的指标）和激动梯度（一种可能近似波前速度的指标）。目的是检验峡部位于由电不连续区域界定的缓慢均匀激动区域这一假设。
基于回归参数，沿峡部出口附近的窦性心律激动均匀进行（平均r = 0.95±0.05）且梯度幅度低（平均0.37±0.10mm/ms）。垂直于峡部长轴穿过其边界时，激动波前传播均匀性较差（平均r = 0.76±0.24），尽管梯度相似（平均0.38±0.23mm/ms）。在与出口相反的方向，即峡部入口处，均匀性也较差（平均r = 0.80±0.22），但梯度幅度较大（平均0.50±0.25mm/ms）。预测沿峡部长轴垂直于最后窦性心律激动部位绘制的理论消融线可防止室性心动过速再次诱发。7/21个实验中出现解剖学传导阻滞，但仅包括峡部侧边界的小部分；因此仅检测窦性心律传导阻滞不足以完全界定室性心动过速峡部。
室性心动过速峡部出口位置在窦性心律期间存在低梯度幅度的均匀激动，但峡部侧边界和峡部入口位置的均匀性较差。这些因素可能有助于验证任何提议的室性心动过速峡部位置，减少为消融峡部而诱发室性心动过速的需求。因此，当应用窦性心律标测来定位心内电生理导管消融部位时，类似于本文所确定的测量计算机化值可能有助于提高特异性。
