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Circuit Impedance Could Be a Crucial Factor Influencing Radiofrequency Ablation Efficacy and Safety: A Myocardial Phantom Study of the Problem and Its Correction
Author(s) -
BHASKARAN ABHISHEK,
BARRY M.A.,
POULIOPOULOS JIM,
NALLIAH CHRISHAN,
QIAN PIERRE,
CHIK WILLIAM,
THAVAPALACHANDRAN SUJITHA,
DAVIS LLOYD,
MCEWAN ALISTAIR,
THOMAS STUART,
KOVOOR PRAMESH,
THIAGALINGAM ARAVINDA
Publication year - 2016
Publication title -
journal of cardiovascular electrophysiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.193
H-Index - 138
eISSN - 1540-8167
pISSN - 1045-3873
DOI - 10.1111/jce.12893
Subject(s) - medicine , imaging phantom , radiofrequency ablation , ablation , cardiology , radiology , biomedical engineering
RF Lesion Size and Overheating Are Dependent on Circuit Impedance Background Circuit impedance could affect the safety and efficacy of radiofrequency (RF) ablation. Aim To perform irrigated RF ablations with graded impedance to compare (1) lesion dimensions and overheated dimensions in fixed power ablations (2) and in power corrected ablations. Methods Ablations were performed with irrigated Navistar Thermocool catheter and Stockert EP shuttle generator at settings of 40 W power for 60 seconds, in a previously validated myocardial phantom. The impedance of the circuit was set at 60 Ω, 80 Ω, 100 Ω, 120 Ω, 140 Ω, and 160 Ω. The lesion and overheated dimensions were measured at 53 °C and 80 °C isotherms, respectively. In the second set of ablations, power was corrected according to circuit impedance. Results In total, 70 ablations were performed. The lesion volume was 72.0 ± 4.8% and 44.7 ± 4.6% higher at 80 Ω and 100 Ω, respectively, compared to that at 120 Ω and it was 15.4 ± 1.2%, 28.1 ± 2.0%, and 38.0 ± 1.8% lower at 140 Ω, 160 Ω, and 180 Ω, respectively. The overheated volume was four times larger when impedance was reduced to 80 Ω from 100 Ω. It was absent at 120 Ω and above. In the power corrected ablations, the lesion volumes were similar to that of 40 W/120 Ω ablations and there was no evidence of overheating. Conclusion The lesion and overheated dimensions were significantly larger with lower circuit impedance during irrigated RF ablation and the lesion size was smaller in high impedance ablations. Power delivery adjusted to impedance using a simple equation improved the consistency of lesion formation and prevented overheating.