Radiofrequency Thermal Ablation Heat Energy Transfer in an Ex-Vivo Model

Abstract

Little work has been done to consider the temperature changes and energy transfer that occur in the tissue outside the vein with ultrasound-guided vein ablation therapy. In this experiment, a ex-vivo model of the human calf was used to analyze heat transfer and energy degradation in tissue surrounding the vein during endovascular radiofrequency ablation (RFA). A clinical vein ablation protocol was used to determine the tissue temperature distribution in 10 per cent agar gel. Heat energy from the radiofrequency catheter was measured for 140 seconds at fixed points by four thermometer probes placed equidistant radially at 0.0025, 0.005, and 0.01 m away from the RFA catheter. The temperature rose 1.5°C at 0.0025 m, 0.6°C at 0.005 m, and 0.0°C at 0.01 m from the RFA catheter. There was a clinically insignificant heat transfer at the distances evaluated, 1.4 ± 0.2 J/s at 0.0025 m, 0.7 ± 0.3 J/s at 0.0050 m, and 0.3 ± 0.0 J/s at 0.01 m. Heat degradation occurred rapidly: 4.5 ± 0.5 J (at 0.0025 m), 4.0 ± 1.6 J (at 0.0050 m), and 3.9 ± 3.6 J (at 0.01 m). Tumescent anesthesia injected one centimeter around the vein would act as a heat sink to absorb the energy transferred outside the vein to minimize tissue and nerve damage and will help phlebologists strategize options for minimizing damage.

Local application of doxorubicin- loaded Iron oxid nanoparticles and the vascular disrupting agent via the hepatic artery: chemoembolization–photothermal ablation treatment of hepatocellular carcinoma in rats

“…Fe 2 O 3 -PDA-Dox nanoparticles have high absorbance in the near infrared zone and displays excellent in vitro heating when irradiated by NIR with a wavelength of 808 nm [9–11]. Monitoring of the solution temperature with a thermal imager verified the in vitro heating effect of Fe 2 O 3 -PDA-Dox nanoparticles following NIR, and in vivo results showed that the temperature of tumor tissue rose to 63.4 °C after irradiation for 5 min, a temperature sufficient to kill tumor tissue [22, 23]. While the covalent bonds of Fe 2 O 3 -PDA are highly effective at carrying dox [24], the pH-sensitivity of PDA resulted in the release of Dox into simulated tumor tissue at pH 6.5, with 29 and 32% of the Dox content released at 10 and 28 h, respectively.…”

Possible involvement of HSP70 in pancreatic cancer cell proliferation after heat exposure and impact on RFA postoperative patient prognosis

“…Furthermore, some studies move the sight to improve the surgery technical, such as using computational model to set special plan for individual [38] or different organs [39,40]. And also, some researchers considered the influence caused by transferred energy [41]. Moreover, a study elaborated the electromagnetic wave frequency dependence of lung's electrical conductivity effects on heat generation of RFA [42].…”