Phung Thien-Khoi N, Moyer Christian B, Norton Patrick T, Ferguson John D, Holmes Jeffrey W
Department of Biomedical Engineering, University of Virginia, Charlottesville, VA.
Department of Radiology, University of Virginia, Charlottesville, VA.
Pacing Clin Electrophysiol. 2017 Jun;40(6):648-654. doi: 10.1111/pace.13086. Epub 2017 May 5.
Atrial fibrillation (AF) is often treated with catheter ablation, which induces scar formation to isolate misfiring electrical signals in the left atrium. Successful ablation restores sinus rhythm at the cost of replacing viable myocardium with scar. The impact of ablation scar on mechanical function of the left atrium is poorly understood.
We used a computational model to simulate various ablation patterns and determine their effect on atrial global and regional mechanical function.
A coupled finite-element and hemodynamic circuit model of the left atrium that represents the regional and global mechanics in paroxysmal AF patients was modified to simulate different ablation patterns: step-wise pulmonary vein isolation (PVI), wide area circumferential ablation (WACA), and a posterior ablation developed by nContact, Inc (Morrisville, NC, USA). Atrial pressure-volume relationships and regional wall motion were compared among the models.
Ablation increased passive stiffness and decreased active work performed by the atrium. Active emptying volume decreased with increasing scar by up to 44% (11 mL) at a scar volume of 31%. At matched scar volumes, WACA decreased active emptying more severely than PVI and nContact. Similarly, wall motion was depressed most in the WACA model because WACA involved portions of the lateral wall with higher baseline motion.
Simulated ablation depressed atrial mechanical function to an extent that depended on both scar volume and location, primarily through reducing active emptying. Placing ablation scar in regions with high baseline motion resulted in greater depression of active function, while ablation of the posterior wall was less disruptive.
心房颤动（AF）常采用导管消融治疗，通过诱导瘢痕形成来隔离左心房中异常放电的电信号。成功的消融以瘢痕取代存活心肌为代价恢复窦性心律。消融瘢痕对左心房机械功能的影响尚不清楚。
我们使用计算模型模拟各种消融模式，并确定它们对心房整体和局部机械功能的影响。
修改了一个代表阵发性房颤患者局部和整体力学的左心房有限元与血流动力学耦合电路模型，以模拟不同的消融模式：逐步肺静脉隔离（PVI）、大面积环形消融（WACA）以及由美国北卡罗来纳州莫里斯维尔的nContact公司开发的后壁消融。比较各模型之间的心房压力-容积关系和局部壁运动。
消融增加了心房的被动僵硬度，降低了心房的主动做功。随着瘢痕增加，主动排空容积减少，在瘢痕容积为31%时，减少幅度高达44%（11 mL）。在瘢痕容积匹配时，WACA比PVI和nContact更严重地降低了主动排空。同样，WACA模型中的壁运动抑制最为明显，因为WACA涉及基线运动较高的侧壁部分。
模拟消融使心房机械功能降低，降低程度取决于瘢痕容积和位置，主要是通过减少主动排空。将消融瘢痕置于基线运动较高的区域会导致主动功能的更大抑制，而后壁消融的干扰较小。
