Gu Kaihao, Yan Shengjie, Wu Xiaomei
Centre for Biomedical Engineering, School of Information Science and Technology, Fudan University, Shanghai, China.
Academy for Engineering and Technology, Fudan University, Shanghai, China.
Int J Hyperthermia. 2022;39(1):120-133. doi: 10.1080/02656736.2021.2022220.
Traditional computer simulation studies of radiofrequency catheter ablation (RFCA) usually neglect the anisotropy in myocardial electrical conductivity (MEC), which is likely an essential factor in governing the ablation outcome. Here, a numerical study of lesion characteristics during RFCA based on an anatomy-based model incorporating fiber orientation was performed to investigate the anisotropy in MEC.
A three-dimensional thorax model including atria, blood, connective tissue, muscle, fat, and skin was constructed. The myocardial fiber was established through a rule-based method (RBM) based on the anatomical structure of the heart. The anisotropic MEC were 0.40 and 0.28 S m in longitudinal and transverse directions, respectively. The ablation result was compared with the isotropic scenario where the isotropic MEC was the average of the anisotropic conductivities as 0.34 S m.
The complexity of fiber architecture varied with that of the local anatomical structure. At RF power of 20 W for 30 s, the tissue temperature and lesion volume were reduced by 2.8 ± 0.1% and 6.9 ± 0.5%, respectively, under anisotropic MEC around the ostium of the pulmonary vein and left atrial appendage. Those for the posterior wall and roof of the left atrium, and the inside of the superior vena cava were 1.9 ± 0.3% and 5.6 ± 1.2%, respectively.
Anisotropy in MEC has a greater reduction effect on lesion volume than on tissue temperature during RFCA; this effect tends to be restrained at positions with more uniform fiber distributions and can be enhanced where significant variation in fiber architecture occurred.
传统的射频导管消融术（RFCA）计算机模拟研究通常忽略心肌电导率（MEC）的各向异性，而这可能是决定消融结果的关键因素。在此，基于包含纤维方向的解剖学模型对RFCA期间的损伤特征进行了数值研究，以探讨MEC的各向异性。
构建了一个包括心房、血液、结缔组织、肌肉、脂肪和皮肤的三维胸部模型。通过基于心脏解剖结构的基于规则的方法（RBM）建立心肌纤维。纵向和横向的各向异性MEC分别为0.40和0.28 S m。将消融结果与各向同性情况进行比较，各向同性MEC为各向异性电导率的平均值0.34 S m。
纤维结构的复杂性随局部解剖结构的复杂性而变化。在肺静脉口和左心耳周围的各向异性MEC下，在20 W射频功率下持续30 s，组织温度和损伤体积分别降低了2.8±0.1%和6.9±0.5%。左心房后壁和顶部以及上腔静脉内部的降低幅度分别为1.9±0.3%和5.6±1.2%。
在RFCA期间，MEC的各向异性对损伤体积的降低作用比对组织温度的降低作用更大；这种作用在纤维分布更均匀的位置往往受到抑制，而在纤维结构发生显著变化的位置会增强。
