Effect of anisotropy in myocardial electrical conductivity on lesion characteristics during radiofrequency cardiac ablation: a numerical study

Gu, Kaihao; Yan, Shengjie; Wang, Xiaomei

doi:10.1080/02656736.2021.2022220

Cited by 6 publications

(4 citation statements)

References 41 publications

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“…Finally, the results including the thermal anisotropy hardly showed any differences in size with respect to the isotropic model, regardless of the power setting, which suggests that this factor has an insignificant impact. Although the recent study by Gu et al [ 25 ] assessed the effect of electrical anisotropy on lesion size after RFCA, the literature does not suggest that electrical anisotropy is important in the myocardium and muscle [ 10 , 11 ].…”

Section: Discussionmentioning

confidence: 99%

In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle

2022

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Beating heart (BH) and thigh muscle (TM) are two pre-clinical models aimed at studying the lesion sizes created by radiofrequency (RF) catheters in cardiac ablation. Previous experimental results have shown that thermal lesions created in the TM are slightly bigger than in the BH. Our objective was to use in-silico modeling to elucidate some of the causes of this difference. In-silico RF ablation models were created using the Arrhenius function to estimate lesion size under different energy settings (25 W/20 s, 50 W/6 s and 90 W/4 s) and parallel, 45° and perpendicular catheter positions. The models consisted of homogeneous tissue: myocardium in the BH model and striated muscle in the TM model. The computer results showed that the lesion sizes were generally bigger in the TM model and the differences depended on the energy setting, with hardly any differences at 90 W/4 s but with differences of 1 mm in depth and 1.5 m in width at 25 W/20 s. The higher electrical conductivity of striated muscle (0.446 S/m) than that of the myocardium (0.281 S/m) is possibly one of the causes of the higher percentage of RF energy delivered to the tissue in the TM model, with differences between models of 2–5% at 90 W/4 s, ~9% at 50 W/6 s and ~10% at 25 W/20 s. Proximity to the air–blood interface (just 2 cm from the tissue surface) artificially created in the TM model to emulate the cardiac cavity had little effect on lesion size. In conclusion, the TM-based experimental model creates fairly similar-sized lesions to the BH model, especially in high-power short-duration ablations (50 W/6 s and 90 W/4 s). Our computer results suggest that the higher electrical conductivity of striated muscle could be one of the causes of the slightly larger lesions in the TM model.

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Section: Discussionmentioning

confidence: 99%

In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle

2022

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“…Under the condition of AC,

can be considered as the second-order tensor of each node in the FEA, with [ 21 ]

where

, and

are the myocardial transverse electrical conductivity (perpendicular to the fiber orientation); longitudinal electrical conductivity (parallel to the fiber orientation); unit matrix; and direction cosine

of the fiber orientation on each node acquired previously, respectively.…”

Section: Methodsmentioning

confidence: 99%

“…In this study,

is considered as myocardial IC (

), four groups of myocardial AC corresponding to IC are obtained according to the various anisotropy ratios

, and the IC is obtained by averaging the AC in the transverse and longitudinal directions [ 21 ], i.e.,

to compare the effect of AC with a different size and anisotropy ratio on the ablation characteristics generated by PFA in LA. According to the type of myocardium, the anisotropy ratio of myocardial electrical conductivity in groups 1 and 2 are derived from the literature on normal myocardium, and groups 3 and 4 are derived from the literature on myocardium with AF.…”

Section: Methodsmentioning

confidence: 99%

Effect of Anisotropic Electrical Conductivity Induced by Fiber Orientation on Ablation Characteristics of Pulsed Field Ablation in Atrial Fibrillation Treatment: A Computational Study

Zang

et al. 2022

JCDD

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Pulsed field ablation (PFA) is a promising new ablation modality for the treatment of atrial fibrillation (AF); however, the effect of fiber orientation on the ablation characteristics of PFA in AF treatment is still unclear, which is likely an essential factor in influencing the ablation characteristics. This study constructed an anatomy-based left atrium (LA) model incorporating fiber orientation and selected various electrical conductivity and ablation targets to investigate the effect of anisotropic electrical conductivity (AC), compared with isotropic electrical conductivity (IC), on the ablation characteristics of PFA in AF treatment. The results show that the percentage differences in the size of the surface ablation area between AC and IC are greater than 73.71%; the maximum difference in the size of the ablation isosurface between AC and IC at different locations in the atrial wall is 3.65 mm (X-axis), 3.65 mm (Z-axis), and 4.03 mm (X-axis), respectively; and the percentage differences in the size of the ablation volume are greater than 6.9%. Under the condition of the pulse, the amplitude is 1000 V, the total PFA duration is 1 s, and the pulse train interval is 198.4 ms; the differences in the temperature increase between AC and IC in LA are less than 2.46 °C. Hence, this study suggests that in further exploration of the computational study of PFA in AF treatment using the same or similar conditions as those used here (myocardial electrical conductivity, pulse parameters, and electric field intensity damage threshold), to obtain more accurate computational results, it is necessary to adopt AC rather than IC to investigate the size of the surface ablation area, the size of the ablation isosurface, or the size of the ablation volume generated by PFA in LA. Moreover, if only investigating the temperature increase generated by PFA in LA, adopting IC instead of AC for simplifying the model construction process is reasonable.

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“…Singh and Melnik 2020), several models have been introduced to assess the irreversible cellular damage and estimate the resulting lesion size. As irreversible damage is expected for temperatures above 50 °C (Haines 2011), the simplest approach is the use of the 50 °C isotherm contour to identify the lesion boundary (Petras et al 2019, Ahn and Kim 2021, Gómez-Barea et al 2022, Gu et al 2022. This approach is typically overestimating the myocardial lesion size (Haines 2011, Liu et al 2018 and does not allow a physiologically accurate assessment of the lesion, particularly in the case of dynamic catheter-tissue interactions.…”

Section: Introductionmentioning

confidence: 99%

Calibration of a three-state cell death model for cardiomyocytes and its application in radiofrequency ablation

et al. 2023

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Objective. Thermal cellular injury follows complex dynamics and subcellular processes can heal the inflicted damage if insufficient heat is administered during the procedure. This work aims to the identification of irreversible cardiac tissue damage for predicting the success of thermal treatments.Approach. Several approaches exist in the literature, but they are unable to capture the healing process and the variable energy absorption rate that several cells display. Moreover, none of the existing models is calibrated for cardiomyocytes. We consider a three-state cell death model capable of capturing the reversible damage of a cell, we modify it to include a variable energy absorption rate and we calibrate it for cardiac myocytes.Main results. We show how the thermal damage predicted by the model response is in accordance with available data in the literature on myocytes for different temperature distributions. When coupled with a computational model of radiofrequency catheter ablation, the model predicts lesions in agreement with experimental measurements. We also present additional experiments (repeated ablations and catheter movement) to further illustrate the potential of the model.Significance. We calibrated a three-state cell death model to provide physiological results for cardiac myocytes. The model can be coupled with ablation models and reliably predict lesion sizes comparable to experimental measurements. Such approach is robust for repeated ablations and dynamic catheter-cardiac wall interaction, and allows for tissue remodeling in the predicted damaged area, leading to more accurate in-silico predictions of ablation outcomes.

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Effect of anisotropy in myocardial electrical conductivity on lesion characteristics during radiofrequency cardiac ablation: a numerical study

Cited by 6 publications

References 41 publications

In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle

In-Silico Modeling to Compare Radiofrequency-Induced Thermal Lesions Created on Myocardium and Thigh Muscle

Effect of Anisotropic Electrical Conductivity Induced by Fiber Orientation on Ablation Characteristics of Pulsed Field Ablation in Atrial Fibrillation Treatment: A Computational Study

Calibration of a three-state cell death model for cardiomyocytes and its application in radiofrequency ablation

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