Mathematical modeling of radiofrequency ablation for varicose veins.

Choi SY, Kwak BK, Seo T - Comput Math Methods Med (2014)

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fig8: Temperature distributions along the interfacial surface in the axial direction between blood and vessel wall for various blood velocities at t = 7 s.
Mentions: Temperature profiles along the interfacial surface between lumen and vessel wall for various blood velocities at time t = 7 s are shown in Figure 8(a). The peak temperature occurs at the tip of the electrode and decreases as the blood velocity increases. As the blood velocity increases, the location of the peak velocity moves to the outflow region. As the blood velocity increases more and more, the energy by the convective heat transfer becomes larger than energy by conductive heat transfer. The region that is influenced by temperature in the case of the stagnant flow occupies approximately 28.5% of the whole geometry. However, the region that is influenced by temperature in the case of continuously moving electrode against the flow direction is about 50%. As the blood velocity increases from 0 to 1, 2, 2.5, and 5 mm/s, the region under the influence of temperature expands between 13.6% and 37.8% depending on the blood velocity compared with the region for the stagnant flow condition. The peak temperature along the venous wall is between 309 K (36°C) and 316.8 K (43.8°C) depending on the blood velocity. Thus, as the blood velocity increases, the peak temperature decreases by the cooling effect of the blood flow and causes lower ablation efficiency.

Bottom Line: The lower the blood velocity, the higher the temperature in the vein wall and the greater the tissue damage.The generated RF energy induces a temperature rise of the blood in the lumen and leads to an occlusion of the blood vessel.The vein wall absorbs more energy in the low pullback velocity than in the high one.

View Article: PubMed Central - PubMed

Affiliation: Department of Radiology and Medical Research Institute, School of Medicine, Ewha Womans University, 1071 Anyangcheon-ro, Yangcheon-gu, Seoul 158-710, Republic of Korea.

ABSTRACT
We present a three-dimensional mathematical model for the study of radiofrequency ablation (RFA) with blood flow for varicose vein. The model designed to analyze temperature distribution heated by radiofrequency energy and cooled by blood flow includes a cylindrically symmetric blood vessel with a homogeneous vein wall. The simulated blood velocity conditions are U = 0, 1, 2.5, 5, 10, 20, and 40 mm/s. The lower the blood velocity, the higher the temperature in the vein wall and the greater the tissue damage. The region that is influenced by temperature in the case of the stagnant flow occupies approximately 28.5% of the whole geometry, while the region that is influenced by temperature in the case of continuously moving electrode against the flow direction is about 50%. The generated RF energy induces a temperature rise of the blood in the lumen and leads to an occlusion of the blood vessel. The result of the study demonstrated that higher blood velocity led to smaller thermal region and lower ablation efficiency. Since the peak temperature along the venous wall depends on the blood velocity and pullback velocity, the temperature distribution in the model influences ablation efficiency. The vein wall absorbs more energy in the low pullback velocity than in the high one.

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