Overcoming High Impedance in the Transitional Area of the Distal Great Cardiac Vein during Radiofrequency Catheter Ablation of Ventricular Arrhythmia.

(1) Background: Radiofrequency catheter ablation (RFCA) is an essential treatment for ventricular arrhythmia (VA). However, high impedance in the transitional area of the distal great cardiac vein (TAODGCV) often leads to ablation failure. This study aimed to explore the factors influencing impedance and identify effective ways to reduce impedance. (2) Methods: A total of 156 patients with VA arising from the TAODGCV received RFCA therapy at our center from October 2009 to August 2021 and were retrospectively analyzed. Local impedance variation during RFCA was monitored, recorded, and analyzed. (3) Results: The impedance increased from the proximal to distal portions of the TAODGCV and decreased by increasing the saline flow rate at the same site. To overcome high impedance, we implemented the following strategies: (1) Reset the upper limit impedance to 300 Ω and accelerate the saline flow rate to 60 mL/min (effective in 118 of 144 patients); (2) turn off the upper limit impedance (effective in eleven of 21 patients); (3) use high-flow-rate irrigation devices (effective in five of 15 patients); and (4) increase the upper limit temperature (effective in six of ten patients). (4) Conclusions: In the TAODGCV, local impedance is mainly influenced by the target site location and saline flow rate. We concluded several methods to overcome the high impedance and contribute to a successful ablation.