Computer modeling and ex vivo experiments with a (saline-linked) irrigated electrode for RF-assisted heating

BioMedical Engineering OnLine

Enrique Berjano²  Macarena Trujillo³  Juan J Perez¹  Javier Arenas² 

[1]Bioelectronic Research Group (I3BH) (Building 7 F), Universitat Politècnica de València, Camino de Vera 46022, Valencia, Spain

[2]Biomedical Synergy, Electronic Engineering Department (Building 7 F), Universitat Politècnica de València, Camino de Vera 46022, Valencia, Spain

[3]Instituto Universitario de Matemática Pura y Aplicada, Universitat Politècnica de València, Camino de Vera 46022, Valencia, Spain

关键词: Saline-linked technology;    Radiofrequency-assisted resection;    Radiofrequency ablation;    Mathematical modeling;    Irrigated electrode;    Computer modeling;   

Others  :  1084185
DOI  :  10.1186/1475-925X-13-164

 received in 2014-10-08, accepted in 2014-12-05,  发布年份 2014

【 摘 要 】

Background

Externally irrigated radiofrequency (RF) electrodes have been widely used to thermally ablate tumors in surface tissue and to thermally coagulate the transection plane during a surgical resection. As far as we know, no mathematical model has yet been developed to study the electrical and thermal performance of these electrodes, especially the role of the saline layer that forms around the electrode.

Methods

Numerical models of a TissueLink device model DS3.0 (Salient Surgical Technologies, Portsmouth, NH, USA) were developed. Irrigation was modeled including a saline layer and a heat convection term in the governing equation. Ex vivo experiments based on fragments of bovine hepatic tissue were conducted to obtain information which was used in building the numerical model. We compared the 60°C isotherm of the computer results with the whitening contour in the heated samples.

Results

Computer and experimental results were in fine agreement in terms of lesion depth (2.4 mm in the simulations and 2.4 ± 0.6 mm in the experiments). In contrast, the lesion width was greater in the simulation (9.6 mm vs. 7.8 ± 1.8 mm). The computer simulations allowed us to explain the role of the saline layer in creating the thermal lesion. Impedance gradually decreased as heating proceeded. The saline was not observed to boil. In the proximity of the electrode (around 1 mm) the thermal lesion was mainly created by the RF power in this zone, while at a further distance the thermal lesion was created by the hot saline on the tissue surface by simple thermal conduction. Including the heat convection term associated with the saline velocity in the governing equation was crucial to verifying that the saline layer had not reached boiling temperature.

Conclusions

The model reproduced thermal performance during heating in terms of lesion depth, and provided an explanation for: 1) the relationship between impedance, electrode insertion depth, and saline layer, and 2) the process of creating thermal lesions in the tissue with this type of electrode.

【 授权许可】

   
2014 Arenas et al.; licensee BioMed Central Ltd.

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