July 1, 2025

Wongchadakul P., Datta A.K.and Rattanadecho P.“Tissue poromechanical deformation effects on steam pop likelihood in 3-D Radiofrequency Cardiac Ablation” Journal of Biological Engineering 2023, https://doi.org/10.1186/s13036-023-00365-5 Impact Factor: 6.248, Q1 Abstract Radiofrequency Cardiac Ablation (RFCA) is a common procedure that heats cardiac tissue to destroy abnormal signal pathways to eliminate arrhythmias. The complex multiphysics phenomena during this procedure need to be better understood to improve both procedure and device design. A deformable poromechanical model of cardiac tissue was developed that coupled joule heating from the electrode, heat transfer, and blood flow from normal perfusion and thermally driven natural convection, which mimics the real tissue structure more closely and provides more realistic results compared to previous models. The expansion of tissue from temperature rise reduces blood velocity, leading to increased tissue temperature, thus affecting steam pop occurrence. Detailed temperature velocity, and thermal expansion of the tissue provided a comprehensive picture of the process. Poromechanical expansion of the tissue from temperature rise reduces blood velocity, increasing tissue temperature. Tissue properties influence temperatures, with lower porosity increasing the temperatures slightly, due to lower velocities. Deeper electrode insertion raises temperature due to increased current flow. The results demonstrate that a 5% increase in porosity leads to a considerable 10% increase in maximum tissue temperature. These insights should greatly help in avoiding undesirable heating effects that can lead to steam pop and in designing improved electrodes.

Wongchadakul P., Ashim K D. and Rattanadecho P. “Natural convection effects on heat transfer in a porous tissue in 3-D radiofrequency cardiac ablation”International Journal of Heat and Mass Transfer Vol 204, 2023 (123832) Scopus, Q1 : Impact Factor 5.431 Abstract Radiofrequency Cardiac Ablation (RFCA) is a non-surgical procedure to destroy abnormal pathways caus- ing cardiac arrhythmias within the cardiac chamber. RF energy from electrodes contacting the cardiac tissue generates heat, raising tissue temperature and ablating it. Success of the procedure, as in avoiding complications like steam pops, requires its comprehensive mechanistic understanding. Using a 3-D porous media-based model of the cardiac tissue and surrounding chamber blood, with coupled fluid flow, heat transfer (including evaporation and thermally driven natural convection), and resistive heating, provided a more complete picture of the thermal ablation process. Circulation of blood due to buoyancy-driven natural convection reduces the non-uniformity of temperatures, by reducing temperatures initially in the target region but increasing them in the later stages, compared to when natural convection effects are not included. Thus, natural convection affects possible steam pop occurrence differently over the time for the procedure. The more complete picture of the RFCA procedure provided here by the detailed physics-based model can benefit with increased accuracy and thus reduced re-ablation (thus higher success rates), and reduced costs for catheter design and development.

Wongchadakul P., Rattanadecho P., and Wessapan T. “Simulation of Temperature Distribution in Different Human Skin Types Exposed to Laser Irradiation with Different Wavelengths andLaser Irradiation Intensities” Songklanakarin Journal of Science and Tenochlogy, vol 41 (3) pp.529-538 May-Jun 2019 Impact Factor 0.47 (Q3) Abstract In modern medical facilities, laser technology is becoming more important in aesthetic and medical applications. However, inappropriate laser irradiation can result in harmful effects such as thermal burn injury. This occurs because thermal response of the skin due to laser irradiation is not well understood. In this study, the thermal response of skin to laser radiation was investigated under the effects of wavelength, laser intensity, and incident time. The transient bioheat model was considered and solved numerically using the finite element method. This study demonstrated that the skin temperature distribution depends strongly on the wavelength, intensity, and skin color type. The amount of energy absorption is significantly higher in the shorter wavelength range and with increasing intensity. Further, a darker skin color results in higher laser absorption. The obtained values provide an indication of the limitations that must be considered during laser-induced thermotherapy.

Wessapan, T., Rattanadecho, P. and Wongchadakul, P.”Effect of body position on natural convection within anterior of the human eye during exposure to electromagnetic fields” Numerical Heat Transfer; Part A: Applications, VolDOI:10.1080/10407782.2015.1109352, pp.1014-1028, 2016. Impact Factor: 2.96 (Q1) Abstract Heating is the main biological effect of the electromagnetic (EM) fields to human eye. This study intends to focus attention on the differences in the heat transfer characteristics of the human eye induced by EM fields in different body positions. The effect of three different body positions – sitting, supine, and prone – on natural convection of aqueous humor (AH) in the anterior chamber of the eye is systematically investigated. The specific absorption rate (SAR) value, fluid flow, and the temperature distribution in the eye during exposure to EM fields are obtained by numerical simulation of EM wave propagation. In this study, the frequencies of 900 and 1,800 MHz are chosen for the investigations. The heat transfer model used in this study is developed based on natural convection and porous media theories. The results show that the AH temperature inside the anterior chamber is the highest in the supine position at both frequencies. It is found that during exposure to EM fields, body position plays an important role on AH natural convection and the heat transfer process within the anterior chamber and its periphery in the front part of the eye. However, the body position has no significant effect on temperature distribution for the middle part of the eye. The obtained results provide information on the body position and thermal effects from EM fields exposure.