+ Radiation and ICDs
- As the population ages, the proportion of patients with devices like pacemakers or implantable cardioverter defibrillators (ICDs) is rising.
- The electronics in these devices can be affected by the application of photon or particle radiation, leading to defaults such as:1,2
- Generation of random defibrillation shocks when no shock is needed
- Inhibition of device operation resulting in the device not properly responding to adverse biological signals
- Resetting or reprogramming of the device
- Complete loss of function
- Loss of remote monitoring capabilities
- At conventional daily dose rates (2 Gy/min), 15% of the pacemakers tested had a clinically important failure.3
- Failures at doses as low as 15 cGy have been reported3
+ Identification of pacemakers/ICDs
- Screening all patients is an important step to identify patients with pacemakers/ICDs:
- All patients are asked before planning and before the commencement of the treatment course whether they have a pacemaker/ICD implanted
- Radiation Therapists check the patient's chart for information regarding the presence of pacemaker/ICD
- Radiation therapists are familiar with facility policy regarding these devices.
- If the patient or the documentation indicates the presence of a pacemaker/ICD, the patient’s physician, treatment planning staff and the responsible medical physicist must be made aware of an implanted device, regardless of the treatment area.
- The device’s presence and location is clearly documented
- The model and manufacturer of the device is identified and documented in the patient's chart (if not done already)
- In addition, it is important that the patient clearly understands the risks involved with these devices in radiation therapy:
- Typically, this discussion takes place between the patient and the oncologist and forms an integral part of informed consent
- If there is reason to suspect a device has not been properly identified and documented in the patient’s chart, the treatment is delayed so the Radiation therapist can contact the responsible radiation oncologist to receive further instructions.
- Careful planning can allow for safe and effective radiation therapy in patients with pacemakers/ICDs.
- The plan considers the best method for treating the patient’s disease, while protecting the device
- Radiation therapists consider their facility policy and procedures
- Treatment planning defines the location of the device and the absorbed dose to be received by the pacemaker.
- If the total estimated dose to the device might exceed 2 Gy, its function is checked prior to therapy and monitored over time.4
- The American Association of Physicists in Medicine recommendations suggest the following precautions with regard to pacemakers/ICDs:4
- Radiation to the device is kept as low as reasonably achievable
- A limit of 2 Gy for accumulated dose to the device
- Devices must never be directly irradiated in a conventional radiotherapy setting
- Devices that fall within a requisite treatment area may be surgically moved prior to treatment
- Steps are taken to ensure the availability of the appropriate personnel (i.e., pacemaker technician, nurse, cardiologist, code team) and back-up equipment (e.g., pacing, defibrillating equipment) prior to treatment.5
- Patients and their pacemakers/ICDs are monitored throughout the treatment.
- In some cases, monitoring may require the use of cardiac monitoring equipment (e.g., electrocardiogram) or the presence of specialized personnel (i.e., pacemaker technician, nurse, cardiologist, crash team).
- A dosimeter may also be used to verify the dose received by the device.
- All steps taken to monitor the patient are carefully documented in the patient chart.
- Device function and settings are checked after the radiation therapy is completed.5
- Formal interrogation of the pacemaker/ICD by knowledgeable personnel (cardiologist, pacemaker technician) is carried out when:6
- The device was reprogrammed before the procedure, leaving the device non-functional (e.g., disabling tachycardia detection)
- Patients experience significant intraoperative events including cardiac arrest requiring temporary pacing or cardiopulmonary resuscitation, and those who required external electrical cardioversion
- The device was exposed to electromagnetic interference with a greater probability of affecting device function were undertaken (e.g., exposure to the direct beam)
- Wootton LS, Polf JC, Petersen S, et al. Proton dose perturbations caused by high-voltage leads from implanted cardioverter defibrillators. J Appl Clin Med Phys 2012;13(4):13-22.
- Boston Scientific. A Closer Look: Product Education at a Glance. Therapeutic Radiation and Implantable Pacemakers and Defibrillators. Available at: http://www.bostonscientific.com/templatedata/imports/HTML/CRM/A_Closer_Look/pdfs/ACL_Therapeutic_Radiation_121508.pdf. Accessed October 26, 2012.
- Steidley KD, Steidley, DE. Pacemaker/ICD Irradiation Policies in Radiation Oncology. Available at http://irpa11.irpa.net/pdfs/4e26.pdf. Accessed October 26, 2012.
- Marbach JR, Sontag MR, Van Dyk, Wolbarst AB. Management of Radiation Oncology Patients with Implanted Cardiac Pacemakers. American Association of Physicists in Medicine Report 45. Available at: http://www.aapm.org/pubs/reports/rpt_45.pdf. Accessed October 26, 2012.
- Langer M, Orlandi E, Carrara M, et al. Management of patients with implantable cardioverter defibrillator needing radiation therapy for cancer. Br J Anaesth 2012;108 (5):881-882.
- Stone ME, Salter B, Fischer A. Perioperative management of patients with cardiac implantable electronic devices. Br J Anaesth 2011;107(suppl 1):i16-i26.