Figure 13.

Schematic diagram of the problems associated with catheter ablation for atrial fibrillation. (A): Normal electrical conduction through the atrial wall. The red lines represent the electrical conduction in all diagrams. (B): Following the completion of the catheter ablation, immediate post-procedure testing shows complete conduction block due to the endocardial lesions. However, undetectable at this time, is the presence of both dead myocardium and damaged, but viable, adjacent tissue. Electrophysical testing at this time can be misleading because neither the dead tissue nor the adjacent damaged, but viable, tissue is capable of conducting electrical activity. (C): in some cases, the viable tissue will recover with time and resume its ability to conduct electrical activity. This recovery of the damaged, but viable, tissue leaves lesions that are neither contiguous (i.e., lesions with “gaps”) nor uniformly transmural. (See Figure 12). (D): such non-transmural, non-contiguous lesions result in resumption of electrical conduction across the desire line of conduction block and failure of the catheter ablation procedure.