Modulating the Baseline Impedance: An Adjunctive Technique for Maximizing Radiofrequency Lesion Dimensions in Deep and Intramural Ventricular Substrate: An Adjunctive Technique for Maximizing Radiofrequency Lesion Dimensions in Deep and Intramural Ventricular Substrate

Background Radiofrequency ablation of intramural ventricular substrate is often limited by insufficient tissue penetration despite high energy settings. As lesion dimensions have a direct and negative relationship to impedance, reducing the baseline impedance may increase the ablation effect on deep ventricular tissue. Methods This study included 16 patients with ventricular tachycardia or frequent ventricular premature complexes refractory to ablation with irrigated catheters. After a failed response to radiofrequency ablation, impedance was modulated by adding or repositioning return patches in an attempt to decrease the circuit impedance. Ablation was repeated at a similar location and power settings, and the effect on arrhythmia suppression and adverse effects were evaluated. Results Six patients with idiopathic ventricular premature complexes originating from the left ventricular summit (n=4) or papillary muscles (n=2), 6 patients with noninfarct related ventricular tachycardia and 4 patients with infarct-related ventricular tachycardia had unsuccessful response to radiofrequency ablation at critical sites (number of applications: 10.4±3.1, power: 42.3±2.9 W, duration: 55.3±25.5 seconds, impedance reduction: 14.6±3.5 Ω, low-ionic solution was used in 81.25%). Modulating the return patches resulted in reduced baseline impedance (111.7±8.2 versus 134.7±6.6 Ω, P