Novel Methods to Decrease Radiation Exposure to Operators in the Electrophysiology Lab

The United States Nuclear Regulatory Commission states that the average American receives 620 millirem of radiation per year.¹ However, electrophysiology (EP) professionals may be exposed to more radiation due to the nature of their jobs. Methods currently in 

place to limit the amount of radiation exposure to EP professionals include radiation barrier protection such as lead or lead-like aprons and the use of As Low As Reasonably Achievable (ALARA) principles. However, routine strategies still expose EP workers to higher levels of radiation than may be necessary of their job. Venneri and colleagues found that cardiac catheterization laboratory personnel with an effective dose of greater than 2 milliSievert (mSv; or 200 millirem) in a year had an average individual effective doseof 46 mSv (4600 millirem).² This translated to a median risk of cancer (fatal and nonfatal) of 1 in 192 — a small but non-negligible risk.² Our report hopes to discuss some of the novel methods of radiation protection that can be employed in order to reduce radiation exposure in EP labs. 

A simple solution that was developed to lower radiation exposure to EP operators was the RADPAD^® (Worldwide Innovations and Technologies, Inc.; Figure 1). This product is a sterile, lead-free surgical drape containing barium and bismuth that, when placed 

properly between the image intensifier and the operator, reduces scatter radiation exposure to primary operators.³ Murphy and colleagues found that the radiation exposure to primary operators during complex percutaneous coronary interventions was significantly lower than to operators who did not use the RADPAD.³ However, this product did not protect the entire lab team from secondary radiation leaving the patient. This inspired Dr. Todd J. Cohen to develop the Prometheus^™ line of sterile EP drapes featuring a built-in RADPAD. This sterile, lead-free device is laid over the patient next to the primary beam to block additional scatter radiation.⁴ The Prometheus provides an additional attenuation level of up to 97 percent and thus protects the entire EP team, not just primary operators.⁴ Dr. Cohen also developed a radiation protective head/sweat band that is helpful in reducing radiation applied to the brain; the SR Headband (TZ Medical; Figure 2) is lightweight, disposable, and lead-free, and attenuates 87 percentof scatter radiation at 80 kV.⁵ 

Another method that can be used in the EP arena is remote catheter navigation. Examples of these systems include the Sensei^® X Robotic System (Hansen Medical; Figure 3a), the Niobe^™ system (Stereotaxis; Figure 3b), and the Amigo^® Remote Catheter System (Catheter Robotics; Figure 3c). These systems allow for EP operators to conduct their entire operation procedure from outside the operating suite. Stereotaxis catheters use electromagnetic fields, whereas the other two systems may use a small force sensor to display real-time contact force and guide the catheter.⁶ The Amigo (developed with the assistance of Dr. Cohen) may allow the operator to use standard sheaths and catheters, while the other two systems use specialized sheaths or catheters.⁷ Robotic systems can result in a decrease in the fluoroscopy time required for the procedure.^8-9

Radiation protection cabins also may allow EP doctors the ability to avoid large amounts of radiation exposure. This device protects the primary operator by shielding the entire frontal part of the body. The operator puts his or her hands through holes in a protectivecabin, which allows for easy maneuverability of the operators’ hands for the procedure. Dragusin and colleagues evaluated the Cathpax^® (Lemer Pax; Figure 4) and found that the radiation protection cabin allowed physicians to perform catheter ablations without hindering catheter manipulation and, most importantly, exposed the operator to negligible levels of radiation.¹⁰

There are also methods to non-fluoroscopically map the location of the catheter in the heart. These systems use magnetic sensors or electrical fields in order to create a 3D map. Such systems include the EnSite^™  Velocity^™ Cardiac Mapping System (St. Jude Medical; Figure 5a) and the Carto^® 3 System (Biosense Webster, Inc., a Johnson & Johnson company; Figure 5b). Studies of the Velocity and Carto 3 Systems have been shown to significantly reduce the use of fluoroscopy during procedures.^11-12 

In addition, use of MediGuide^™ Technology (St. Jude Medical; Figure 6), which uses electromagnetic fields to create a live fluoroscopic image¹³, in atrial fibrillation ablations has dramatically decreased fluoroscopy time and radiation exposure;¹⁴ it isimportant to note that MediGuide is an entire system, and a lab must undergo extensive renovations to install it. 

With these novel methods of radiation protection, radiation exposure in the EP lab may become minimal to nonexistent in the near future. This is good news for EP doctors and their entire staff. 

Disclosures: Daniel Kersten and David Gregorius, MS have no conflicts of interest to report regarding the content herein. Todd J. Cohen, MD reports he is the designer of the RADPAD Prometheus^™ line of products (Worldwide Innovations and Technologies, Inc.) and that royalties were received for sales. Dr. Cohen is the inventor of the SR Headband (intellectual property is assigned to Winthrop University Hospital and licensed to TZ Medical), and the inventor (and listed on the patent) ofthe robotic catheter system known as the the Amigo^® RCS (developed by Catheter Robotics). He has no consulting position, corporate position, receives no royalties, and has no equity interest in Catheter Robotics.   

References

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2. Venneri L, Rossi F, Botto N, et al. Cancer risk from professional exposure in staff working in cardiac catheterization laboratory: insights from the National Research Council’s Biological Effects of Ionizing Radiation VII Report. Am Heart J. 2009;157(1):118-124.
3. Murphy JC, Darragh K, Walsh SJ, Hanratty CG. Efficacy of the RADPAD protective drape during real world complex percutaneous coronary intervention procedures. Am J Cardiol. 2011;108(10):1408-1410.
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