3140 - Thermal Response of Subcutaneous Implantable Cardioverter-Defibrillators and Leadless Pacemakers during Radiotherapy and Their Resistance to Irradiation
Presenter(s)
M. Stapor-Fudzinska1, M. Dyrbus2, S. Blamek1, M. Tajstra2, and A. Cholewka3; 1Maria Sklodowska-Curie National Research Institute of Oncology, Gliwice, Poland, 2Department of Cardiology, School of Medical Sciences in Zabrze, Medical University of Silesia, Zabrze, Poland, 3Faculty of Science and Technology, University of Silesia, Katowice, Poland
Purpose/Objective(s):
Materials/Methods:
Three sICDs and four LPMs were used in the study. Activated device was placed on a therapeutic table and exposed to open-field irradiation using photons with a nominal energy of 6 MV. The devices were irradiated starting at a dose of 2 Gy (sICDs) and 5 Gy (LPMs), gradually escalating to a total dose of 200 Gy and 330Gy respectively.
Thirteen temperature measurements were taken for each sICD. During the measurements, the ambient temperature was maintained at 23±1 °C. Thermographic images were captured from both the upper (A) and lower (B) sides using a infrared camera (resolution 464×348 px, thermal sensitivity <30 mK, accuracy ±2 °C). Eleven temperature measurements were taken for each LPMs. Thermographic images were taken only from one side because the device was left in the self-prepared insert.
The sICDs were made primarily of titanium. For thermographic evaluation, the emissivity coefficient corresponding to titanium was applied. Temperature analyses included the average temperature over the entire device, the maximum (hot spot) temperature, and localized regions of interest (ROIs) where heating was most pronounced.
Results:
Average devices temperatures remained at approximately 30 °C across irradiation doses. The maximum surface temperature reached 45 °C. These values represented isolated pixels corresponding to areas smaller than 1 mm². All observed variations remained within the physiological range of human thermoregulation (25–45 °C).
A significant decrease in battery life was noted for sICDs (47±21 %). In one of the devices, an unannounced shock was delivered after 28Gy from an open-field irradiation. Reset mode was activated after receiving about 180 Gy.
None of the LPMs showed any major malfunctions or resets.
Conclusion:
Under exposure conditions exceeding those used clinically, sICD and LPMs surface temperatures did not exceed the manufacturer’s specified operating range (25–45 °C). The observed maximal heating affected a small surface areas and would be effectively mitigated in vivo by blood perfusion and tissue heat exchange.
Thermal effects caused by radiotherapy on ICD surfaces do not pose a risk to patient safety.
Irradiation of devices with an open-field demonstrates their resistance to radiation doses higher than those deposited during therapeutic sessions.