By Hein Heidbuchel
More and more complex procedures in the management of arrhythmias mean an increased risk of radiation exposure for both patients and operators. The lifetime attributable excess cancer risk for operators may be around one in 100 (with recent reports also hinting to an excess risk of brain tumours), the same as for a patient undergoing repetitive complex procedures. Many texts have quantified radiation exposure in electrophysiology, and they have urged electrophysiologists to evaluate the need for and justify the use of radiation exposure. But they largely leave the physicians themselves to implement radiation reduction in their practice. Moreover, there is even a fallacy in using non-fluoroscopic mapping (NFM) technology as it may give rise to a false feeling of having done enough to reduce the radiation dose.
For these reasons, EHRA has compiled a position paper that offers very practical advice on how to reduce exposure to patients and staff. The text deals with
- Customisation of the X-ray system. For example by lowering the frame rate to three per second or even lower, by reducing the dose per frame by a factor of five, and by better collimation
- Workflow adaptations, which could include complete avoidance of cine imaging and recording fluoroscopy instead, avoiding left anterior oblique or anteroposterior imaging if possible as it is associated with higher radiation doses, and giving nurses or anaesthesiologists the right to temporarily halt fluoroscopy
- Using shielding measures (eg table foot mounted lower lead curtains; or a radioprotection cabin that also allows for device implantations).
All these measures can very easily be implemented in the cathlab. In combination, they can result in at least a 10-fold reduction of radiation dose for both patients and staff. In fact, the duration of fluoroscopy becomes a non-relevant term, since even procedures with more than 60 minutes of fluoroscopy can be performed with ≤1500Gy*cm2 or ≤3mSv (ie, less than the yearly natural radiation exposure) if these practical modifications are implemented. When reporting in the literature or to each other, electrophysiologists should not communicate the fluoroscopy duration of their interventions, but the dose area product (DAP) values. Or, they can convert those DAP values to the effective dose (ED), which for adults is: mSv=DAP (Gy*cm2) x 0.20. Thus, a value of 100Gy*cm2 for a cardiac procedure would represent about 20mSv in effective dose.
Non-fluoroscopic mapping technology is powerful, but also requires education to optimise its benefits, which otherwise might be partially lost. These benefits include creating cardiac chamber geometry with multipolar catheters instead of with the mapping catheter and creating chamber geometry without using fluoroscopy.
Upcoming new technology that allows for “virtual fluoroscopy” also has the potential to further dramatically reduce radiation dose, including during device implantations, which nowadays are much more of a concern for radioprotection than complex ablations.
Finally, EHRA suggests other concrete improvements that can be implemented by both physicians and industry in the near future, such as: specially designed lead screens for use during device implantation, triggered fluoroscopy (ie, imaging that is commanded by the electrophysiology system) and sheath visualisation in NFM.
EHRA also urges for better user interfaces for collimation (which now often is not done because of the complexities) and for making asymmetric collimation possible.
As a very practical guide, these recommendations are worth to be read and implemented by both electrophysiological operators in the field (for the sake of their personal health and that of their patients) and by the industry in order to further improve on radioprotection measures that are tailored to the needs of the electrophysiology community. The radiation protection guide is due to be published in EP Europace in Spring 2013.
Hein Heidbuchel, director of the Invasive EP Laboratory at the Department of Cardiovascular Medicine, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium; chair of the Education Committee of EHRA.