Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research

González-Suárez, Ana; Pérez, Juan Alberto Tormos; Irastorza, Ramiro M.; Reddy, Vivek Y.; Berjano, Enrique

doi:10.1016/j.cmpb.2021.106546

Cited by 27 publications

(36 citation statements)

References 120 publications

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“…This implies that no conclusion can be drawn from our model about the incidence of steam pops. Despite this limitation, the inclusion of the sudden drop in electrical conductivity around 100 °C as well as the latent heat associated with the phase change, have been shown to be adequate for predicting the lesion sizes in RFCA modeling [ 14 ]. Fourth, the values of electrical conductivity at 500 kHz were taken from the ‘Dielectric properties’ section of the IT’IS Foundation database [ 7 ] (0.281 S/m for myocardium and 0.446 S/m for striated muscle).…”

Section: Discussionmentioning

confidence: 99%

“…The model solved a coupled electric–thermal problem numerically using the Finite Element Method on ANSYS software (ANSYS, Canonsburg, PA, USA). The governing equation for the thermal problem was the Bioheat Equation [ 14 ]:

where ρ is density (kg/m 3 ), c specific heat (J/kg·K), T temperature (°C), t time (s), k thermal conductivity (W/m·K), Q RF the heat source caused by RF power (W/m 3 ), Q p the heat loss caused by blood perfusion (W/m 3 ) and Q m the metabolic heat generation (W/m 3 ). Both Q m and Q p were ignored as these terms are negligible compared to the others [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

“…We previously checked that they were able to provide a Ω = 1 isoline more or less coincident with the 72 °C isotherm for 5 s heating [ 19 ] and more or less coincident with the 55 °C isotherm after 60 s of heating [ 20 , 21 ]. The Ω = 1 isoline was therefore considered to represent the thermal lesion contour, which is equivalent to a cell death probability of 63% [ 14 ].…”

Section: Methodsmentioning

confidence: 99%

“…The model solved a coupled electric-thermal problem numerically using the Finite Element Method on ANSYS software (ANSYS, Canonsburg, PA, USA). The governing equation for the thermal problem was the Bioheat Equation [14]:…”

Section: Governing Equationsmentioning

confidence: 99%

“…where ρ is density (kg/m 3 ), c specific heat (J/kg•K), T temperature ( • C), t time (s), k thermal conductivity (W/m•K), Q RF the heat source caused by RF power (W/m 3 ), Q p the heat loss caused by blood perfusion (W/m 3 ) and Q m the metabolic heat generation (W/m 3 ). Both Q m and Q p were ignored as these terms are negligible compared to the others [14].…”

Section: Governing Equationsmentioning

confidence: 99%

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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%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Governing Equationsmentioning

confidence: 99%

Section: Governing Equationsmentioning

confidence: 99%

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

2022

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Effect of dispersive electrode position (anterior vs. posterior) in epicardial radiofrequency ablation of ventricular wall: A computer simulation study

Irastorza,

Hadid,

Berjano

2024

Numer Methods Biomed Eng

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An epicardial approach is often used in radiofrequency (RF) catheter ablation to ablate ventricular tachycardia when an endocardial approach fails. Our objective was to analyze the effect of the position of the dispersive patch (DP) on lesion size using computer modeling during epicardial approach. We compared the posterior position (patient's back), commonly used in clinical practice, to the anterior position (patient's chest). The model considered ventricular wall thicknesses between 4 and 8 mm, and electrode insertion depths between .3 and .7 mm. RF pulses were simulated with 20 W of power for 30 s duration. Statistically significant differences (P < .001) were found between both DP positions in terms of baseline impedance, RF current (at 15 s) and thermal lesion size. The anterior position involved lower impedance (130.8 ± 4.7 vs. 146.2 ± 4.9 Ω) and a higher current (401.5 ± 5.6 vs. 377.5 ± 5.1 mA). The anterior position created lesion sizes larger than the posterior position: 8.9 ± 0.4 vs. 8.4 ± 0.4 mm in maximum width, 8.6 ± 0.4 vs. 8.1 ± 0.4 mm in surface width, and 4.5 ± 0.4 vs. 4.3 ± 0.4 mm in depth. Our results suggest that: (1) the redirection of the RF currents due to repositioning the PD has little impact on lesion size and only affects baseline impedance, and (2) the differences in lesion size are only 0.5 mm wider and 0.2 mm deeper for the anterior position, which does not seem to have a clinical impact in the context of VT ablation.

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Proactive esophageal cooling during laser cardiac ablation: A computer modeling study

Gomez Bustamante,

Mercado Montoya,

Berjano

et al. 2024

Lasers Surg Med

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Background and ObjectivesLaser ablation is increasingly used to treat atrial fibrillation (AF). However, atrioesophageal injury remains a potentially serious complication. While proactive esophageal cooling (PEC) reduces esophageal injury during radiofrequency ablation, the effects of PEC during laser ablation have not previously been determined. We aimed to evaluate the protective effects of PEC during laser ablation of AF by means of a theoretical study based on computer modeling.MethodsThree‐dimensional mathematical models were built for 20 different cases including a fragment of atrial wall (myocardium), epicardial fat (adipose tissue), connective tissue, and esophageal wall. The esophagus was considered with and without PEC. Laser‐tissue interaction was modeled using Beer–Lambert's law, Pennes' Bioheat equation was used to compute the resultant heating, and the Arrhenius equation was used to estimate the fraction of tissue damage (FOD), assuming a threshold of 63% to assess induced necrosis. We modeled laser irradiation power of 8.5 W over 20 s. Thermal simulations extended up to 250 s to account for thermal latency.ResultsPEC significantly altered the temperature distribution around the cooling device, resulting in lower temperatures (around 22°C less in the esophagus and 9°C in the atrial wall) compared to the case without PEC. This thermal reduction translated into the absence of transmural lesions in the esophagus. The esophagus was thermally damaged only in the cases without PEC and with a distance equal to or shorter than 3.5 mm between the esophagus and endocardium (inner boundary of the atrial wall). Furthermore, PEC demonstrated minimal impact on the lesion created across the atrial wall, either in terms of maximum temperature or FOD.ConclusionsPEC reduces the potential for esophageal injury without degrading the intended cardiac lesions for a variety of different tissue thicknesses. Thermal latency may influence lesion formation during laser ablation and may play a part in any collateral damage.

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Computer modeling of radiofrequency cardiac ablation: 30 years of bioengineering research

Cited by 27 publications

References 120 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 dispersive electrode position (anterior vs. posterior) in epicardial radiofrequency ablation of ventricular wall: A computer simulation study

Proactive esophageal cooling during laser cardiac ablation: A computer modeling study

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