Circuit impedance could be a crucial factor influencing radiofrequency efficacy and safety. A myocardial phantom study

Abstract

S225 cant bradycardia. Examination of traces has not revealed any recurrence of heart block. Conclusion: This was an unusual case of severe transient conduction disturbance with unknown cause. Careful consideration is needed before undertaking long-term device therapy in young patients.

Effects of different ablation settings on lesion dimensions in an ex vivo swine heart model: Baseline impedance, irrigant, and electrode configuration

“…Consistent with the results of previous studies, 6,7,10,11 using various statical approaches, our ex vivo experiments progressively demonstrated that at similar AI values, baseline impedance exhibited a strong negative linear correlation with lesion dimensions, particularly lesion depth. Namely, ablation at lower baseline impedance resulted in larger lesion dimensions created by the same level of AI, which could be explained by a simple linear formula, albeit necessitating further investigation under other conditions.…”

“…Consistent with the results of previous studies, 6,7,10,11 also reported a similar conclusion that impedance could influence ablation lesions, however, the impedance values in their experiment were distinctly lower than ours, which were more consistent with the real clinical practice. In addition, our study has revealed a threshold impedance-150 Ω, over which the predictive accuracy of AI seems to be compromised, given that the AI formula prospectively predicted lesion depth with high accuracy of ±1 mm in the context of AI-guided ablation.…”

“…Beyond ablation configurations, impedance may play an essential part in lesion formation. Previous research 6,7 has demonstrated that electric impedance had a substantial influence on lesion size, with the overall value consisting of two components. In contrast to the relatively consistent first component, the second component, baseline impedance, varies greatly between individuals and may be used to effectively create appropriate ablation lesions.…”

“…However, the parameter of impedance is not included in the proprietary formula of AI: (k·$${\int }_{0}^{T}{{CF}}^{a}$$(t)$${P}^{b}$$(t)dt) c , where CF is contact force, P is RF power, T is application time, and a, b, c, and k are constants. Previous studies 6,7 demonstrated that electric impedance has a substantial impact on lesion size, which is comprised of two components. The first component is resistance generated by the tissue and blood volume surrounding the ablation catheter tip, which is relatively constant between individuals and influenced by the amount of contact between the tip electrode and the myocardial tissue.…”