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Management of pacemakers and ICDs in radiotherapy



Introduction

Radiotherapy can influence the functioning of pacemakers and implantable cardioverter-defibrillators (ICDs). ICDs offer the same functionality as pacemakers but are also able to deliver a high-voltage shock to the heart if needed. The risk of potentially life-threatening malfunctioning of these devices when exposed to electromagnetic interference or ionizing radiation is well recognized. Modern ICDs show a large variation in their sensitivity to radiation, and seem to be more sensitive to radiation than pacemakers. Electromagnetic effects are usually not considered to be a source of concern.


Important Principles

Current management guidelines are mostly based on in vitro studies due to lack of in vivo data. Theses studies showed that most cardiac devices had some kind of malfunction related to RT, some of which could have lead to serious consequences and require reprogramming. Factors determining the impact of RT on implanted devices include: type of device, proximity of the device to the beam, type and energy of the beam, total dose received, and shielding of the device. Clinical recommendations concern to monitor the ECG and have pacemaker/ICD-qualified personnel stand by at every fraction, to have standard cardiopulmonary resuscitation equipment directly available and intensive device follow-up during and/or RT.


Introduction to References

Although the newest generation of pacemakers exhibits a variety of defects, AAPM Task Group 34 guidelines still seem to be valid. Guidelines for ICDs are provided in the publications of Hurkmans et al. and Gelblum et al.