Mehringer Noah, Severance Lauren, Park Aaron, Ho Gordon, McVeigh Elliot
Department of Bioengineering, University of California San Diego, La Jolla, CA, USA.
Department of Medicine, University of California San Diego, La Jolla, CA, USA.
J Interv Card Electrophysiol. 2025 Jun 20. doi: 10.1007/s10840-025-02087-8.
Ablation for atrial fibrillation targets an arrhythmogenic substrate in the left atrium (LA) myocardium with therapeutic energy, resulting in a scar tissue. Although a global LA function typically improves after ablation, the injured tissue is stiffer and non-contractile. The local functional impact of ablation has not been thoroughly investigated.
This study retrospectively analyzed the LA mechanics of 15 subjects who received a four-dimensional computed tomography (4DCT) scan pre- and post-ablation for atrial fibrillation. LA volumes were automatically segmented at every frame by a trained neural network and converted into surface meshes. A local endocardial strain was computed at a resolution of 2 mm from the deforming meshes. The LA endocardial surface was automatically divided into five walls and further into 24 sub-segments using the left atrial positioning system. Intraoperative notes gathered during the ablation procedure informed which regions received ablative treatment.
In an average of 18 months after ablation, the strain is decreased by 16.3% in the septal wall and by 18.3% in the posterior wall. In subjects who were imaged in sinus rhythm both before and after the procedure, the effect of ablation reduced the regional strain by 15.3% (p = 0.012). Post-ablation strain maps demonstrated spatial patterns of reduced strain which matched the ablation pattern.
This study demonstrates the capability of 4DCT to capture high-resolution changes in the left atrial strain in response to tissue damage and explores the quantification of a regionally reduced LA function from the scar tissue.
房颤消融术通过治疗能量作用于左心房（LA）心肌中的致心律失常基质，从而形成瘢痕组织。尽管消融术后左心房整体功能通常会改善，但受损组织更僵硬且无收缩能力。消融对局部功能的影响尚未得到充分研究。
本研究回顾性分析了15例接受房颤消融术前和术后四维计算机断层扫描（4DCT）的受试者的左心房力学情况。通过训练有素的神经网络在每一帧自动分割左心房容积，并将其转换为表面网格。从变形网格中以2毫米的分辨率计算局部心内膜应变。使用左心房定位系统将左心房心内膜表面自动分为五个壁，并进一步分为24个亚段。消融过程中收集的术中记录告知哪些区域接受了消融治疗。
消融术后平均18个月，间隔壁应变降低16.3%，后壁应变降低18.3%。在术前和术后均以窦性心律成像的受试者中，消融的影响使局部应变降低了15.3%（p = 0.012）。消融术后应变图显示了应变降低的空间模式，与消融模式相匹配。
本研究证明了4DCT捕捉左心房应变因组织损伤而发生的高分辨率变化的能力，并探索了从瘢痕组织中量化局部左心房功能降低的方法。
