Department of Mechanical Engineering, Michigan State University, East Lansing, MI, USA.
Department of Medicine, University of California, San Diego, La Jolla, CA, USA.
Comput Biol Med. 2023 May;157:106766. doi: 10.1016/j.compbiomed.2023.106766. Epub 2023 Mar 15.
Cryoballoon ablation (CBA) is a cryo-energy based minimally invasive treatment procedure for patients suffering from left atrial (LA) fibrillation. Although this technique has proved to be effective, it is prone to reoccurrences and some serious thermal complications. Also, the factors affecting thermal distribution at the pulmonary vein-antrum junction that are critical to the treatment success is poorly understood. Computer modeling of CBA can resolve this issue and help understand the factors affecting this treatment. To do so, however, numerical challenges associated with the simulation of advection-dominant transport process must be resolved. Here, we describe the development of a thermal-hemodynamics computational framework to simulate incomplete occlusion in a patient-specific LA geometry during CBA. The modeling framework uses the finite element method to predict hemodynamics, thermal distribution, and lesion formation during CBA. An incremental pressure correction scheme is used to decouple velocity and pressure in the Navier-Stokes equation, whereas several stabilization techniques are also applied to overcome numerical instabilities. The framework was implemented using an open-source FE library (FEniCS). We show that model predictions of the hemodynamics in a realistic human LA geometry match well with measurements. The effects of cryoballoon position, pulmonary vein blood velocity and mitral regurgitation on lesion formation during CBA was investigated. For a -70C cryoballoon temperature, the model predicts lesion formation for gaps less than 2.5 mm and increasing efficiency of CBA for higher balloon tissue contact areas. The simulations also predict that lesion formation is not sensitive to variation in pulmonary vein blood velocity and mitral regurgitation. The framework can be applied to optimize CBA in patients for future clinical studies.
冷冻球囊消融（CBA）是一种基于冷冻能量的微创治疗程序，适用于患有左心房（LA）房颤的患者。尽管该技术已被证明有效，但它容易复发，并且存在一些严重的热并发症。此外，对于影响治疗成功的肺静脉-窦交界处热分布的因素了解甚少。CBA 的计算机建模可以解决这个问题，并帮助了解影响这种治疗的因素。然而，要做到这一点，必须解决与主导对流传输过程模拟相关的数值挑战。在这里，我们描述了开发一个热-血液动力学计算框架的情况，以模拟 CBA 期间患者特定 LA 几何形状中的不完全闭塞。该建模框架使用有限元方法来预测 CBA 期间的血液动力学、热分布和病变形成。使用增量压力校正方案来解耦纳维-斯托克斯方程中的速度和压力，同时还应用了几种稳定技术来克服数值不稳定性。该框架是使用开源 FE 库（FEniCS）实现的。我们表明，真实人体 LA 几何形状的血液动力学模型预测与测量结果吻合良好。研究了冷冻球囊位置、肺静脉血流速度和二尖瓣反流对 CBA 期间病变形成的影响。对于-70°C 的冷冻球囊温度，模型预测在间隙小于 2.5mm 时会形成病变，并且在更高的球囊组织接触面积下，CBA 的效率会提高。模拟还预测，病变形成对肺静脉血流速度和二尖瓣反流的变化不敏感。该框架可应用于优化未来临床研究中的患者 CBA。
