Radiation therapists must identify patients with cardiac implantable electronic devices (CIEDs) and ensure the appropriate protocol is followed
Radiation and CIEDs
- As the population ages, the proportion of patients with devices like cardiac implantable electronic devices (CIEDs) is rising.
- The electronics in these devices can be affected by the application of photon or particle radiation, leading to defaults such as1,2:
- 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 failure3.
- Failures at doses as low as 15 cGy have been reported3
Identification of CIEDs
- Screening all patients is an important step to identify patients with CIEDs:
- All patients are asked before planning and before the commencement of the treatment course whether they have a CIED implanted
- Radiation Therapists check the patient’s chart for information regarding the presence of a CIED
- Radiation therapists are familiar with facility policy regarding these devices.
- If the patient or the documentation indicates the presence of a CIED, 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 and Medical Physicist to receive further instructions.
Planning
- Careful planning can allow for safe and effective radiation therapy in patients with CIEDs.
- 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 CIED.
- If the total estimated dose to the device might exceed 2 Gy, its function is checked prior to therapy and monitored over time4.
- Photon energy should be kept to less than 10MV to avoid possible neutron damage to the CIED.5
- The American Association of Physicists in Medicine recommendations suggest the following precautions with regard to the CIEDs4:
- 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 treatment6.
Monitoring
- Patients and their CIEDs 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.
Post-therapy
- Device function and settings are checked after the radiation therapy is completed6.
- Formal interrogation of the CIED by knowledgeable personnel (cardiologist, pacemaker technician) is carried out when7:
- 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)
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References
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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.
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Boston Scientific. A Closer Look: Product Education at a Glance. Therapeutic Radiation and Implantable Pacemakers and Defibrillators. Available from: http://www.bostonscientific.com/templatedata/imports/HTML/CRM/A_Closer_Look/pdfs/ACL_Therapeutic_Radiation_121508.pdf. [Accessed 26 Oct 2012]
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Steidley KD, Steidley, DE. Pacemaker/ICD Irradiation Policies in Radiation Oncology. Available from: http://irpa11.irpa.net/pdfs/4e26.pdf. [Accessed 26 Oct 2012]
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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 from: http://www.aapm.org/pubs/reports/rpt_45.pdf. [Accessed 26 Oct 2012]
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Grant JD, Jensen GL, Tang C, et al. Radiotherapy-induced malfunction in contemporary cardiovascular implantable electronic devices: clinical incidence and predictors. JAMA Oncology. 2015;1(5):624-632.
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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.
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Stone ME, Salter B, Fischer A. Perioperative management of patients with cardiac implantable electronic devices. Br J Anaesth. 2011;107(suppl 1):i16-i26.