Simulation of non-transmural ablation lines that effectively block electrical signal propagation in the heart

Atrial fibrillation (AF), the most common cardiac rhythm disorder, increases patient mortality and social burdens. To achieve a permanent cure for AF, catheter-based radiofrequency ablation destroys the ability of local cardiac tissue to conduct electrical signals, thus terminating the arrhythmia. It is generally assumed that only lesions that penetrate the whole thickness of the heart wall can block the electrical signals. However, there was no in-depth theoretical research on the relationship between ablation depths and electrical signal blocking. We use the Barkley model and the Luo-Rudy model to simulate the spiral activity during AF episodes. We find that, when the ablation depth exceeds a certain critical value, although there is still a tiny slit, the electrical signals cannot pass through, and this phenomenon can be explained by the eikonal equation. Moreover, the slit has a filtering effect. When the height of the slit is within a certain interval, the signal period detected on the other side of the ablation line is almost twice that of the wave source, which is caused by the slow conduction at the slit. In addition, we find that when the ablation line is not deep enough to completely block the passage of the spiral wave, increasing the width of the ablation line can achieve blocking. We simulate two different obstacles caused by the ablation under the no-flux boundary condition constructed by the phase-field method and under the condition of fixed potential, and get different results. The electrotonic leak current may be the main reason for this difference. These results can help clinicians understand the blocking phenomenon in ablation procedures and develop more effective ablation strategies.