首页|Investigation of Myocardial Bioimpedance at Multiple Frequencies for Cardiac Radiofrequency Ablation: Ex-Vivo Experiments
Investigation of Myocardial Bioimpedance at Multiple Frequencies for Cardiac Radiofrequency Ablation: Ex-Vivo Experiments
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NETL
NSTL
IEEE
Background: Bioimpedance method is used clinically as a surrogate measure of effective tissue heating during cardiac ablation. It does not, however provide information regarding thermal cellular destruction which is the goal of ablation procedures. Objective: This study investigated myocardial impedance (resistance and reactance) at different frequencies in response to the thermal effect and across temperatures where tissue necrosis occurs during ablation. Methods: An ex-vivo experiment bench was designed to heat heart muscle tissue blocks uniformly to different targeted temperatures. Tissue resistance and reactance were recorded at three frequencies of 5 k, 50 k and 250 kHz. Impedance was measured in 3 phases (1) the relationship of tissue impedance with thermal effect at temperatures $.$ Results: Myocardial resistance and reactance demonstrated a strong linear relationship with temperature effect within the tissue (−1.3%/ °C and −1.96%/ °C on average respectively, frequency dependent). At ≥ 65 °C, the reactance was almost abolished (∼0Ω) and stayed flat during the restitution back to 37 °C, potentially indicative of complete necrosis. Time to reactance abolishment was a few seconds for ≥ 75 °C, 17 seconds for 65 °C and few minutes for 55 °C. Conclusion: Myocardial impedance behaviour thermal and necrotic effects were straightforward and observable. Changes in reactance can be used as a potential indicator of cellular necrosis. Significance: Data provided can be used to develop better models and solutions for monitoring the efficacy of cardiac ablation procedures, thus enhancing clinical outcomes.
NETL
NSTL
IEEE
