Most operators realize that radiation exposure in the cath lab puts them, plus their staff, at risk of potential cancers in the future. What they may not know is that a number of strategies exist to reduce exposure, and many don’t cost a dime.
An invisible danger
Radiation exposure is an occupational hazard for interventional cardiologists, electrophysiologists, other subspecialists and their coworkers. Intellectually they know it, but in day-to-day practice it may not rise to the top tier of priorities, particularly in the bustle of a busy catheterization laboratory. “You can’t touch radiation and the consequences aren’t tangible,” observes Charles Chambers, MD, an interventional cardiologist at Hershey Medical Center in Pennsylvania and a champion of radiation safety for patients and physicians.
The potential health consequences are not immediate. But they are accumulative, a concern that grows as cardiologists take on longer and more complicated cases. And operators who perform diagnostic angiography and PCIs are not the only ones at risk. Percutaneous treatments such as aortic and mitral valve replacements for valvular diseases, radiofrequency ablations for atrial fibrillation and interventions for chronic total occlusions and peripheral artery disease repeatedly expose more cardiologists to radiation for longer durations.
“Procedures are becoming longer and more radiation-intensive,” says Shikhar Agarwal, MD, an interventional cardiologist at the Cleveland Clinic’s Heart and Vascular Institute. “Unless we become very cognizant of the radiation dose to us, some of us may get burned in terms of developing radiation-related diseases. It is critical that we do whatever is necessary to minimize dose to the operators.”
A few years ago that message may have fallen on deaf ears. But the publication of reports describing head and neck cancers in career interventionalists captured the attention of some cardiologists and provided fodder for radiation safety advocates. Many physicians credit Ariel Roguin, MD, PhD, an interventional cardiologist at the Technion-Israel Institute of Technology, for first raising the call of—if not alarm—extreme caution.
In 2012, Roguin and colleagues documented nine cases of brain cancer in interventional cardiologists, and expanded that list to brain and neck cancers in 23 interventional cardiologists, six interventional radiologists and two electrophysiologists (Am J Cardiol 2013;111:1368-1372). Ominously, of the 26 cases where they obtained information on tumor location, 22 occurred on the left side—the side that more frequently is exposed to radiation during interventional procedures.
Start with the source
With today’s digital imaging systems, physicians can customize protocols in ways that could reduce radiation exposure without diminishing image quality. The catch is, they may not know it. Agarwal and his colleagues at the Cleveland Clinic put that idea to the test by instituting measures to lower operator radiation exposure. One component dealt with a change to the default setting in imaging devices.
“The equipment has a big role to play in terms of reducing radiation,” he says. Case in point: Their team cut radiation doses by 22 percent for diagnostic catheterizations and by 32 percent for PCIs by leveraging widely available technology (Circ Cardiovasc Interv online Aug. 5, 2014).
They conducted a retrospective before-after assessment of an initiative that reduced the default fluoroscopic frame rate from 10 to 7.5 frames per second. The program also emphasized the use of low-dose acquisitions, best radiation practices and monthly review of radiation dosimetry of each interventional cardiology fellow by the cath lab director.
The results? Median total air kerma during diagnostic catheterizations after the changes was 625 mGy vs. 798 mGy before and median total air kerma during PCIs was 1,675 mGy vs. 2,463 mGy, respectively.
“We didn’t ask people to conform,” Agarwal notes. “We just said. ‘We are going to make these changes on the equipment. If you think they are not OK then please go back to your practice.’ Most people did not even realize they were doing low-dose fluoroscopy … and low-dose acquisition.”
Some cardiologists balk at making modifications for fear that poor imaging will compromise patient care. The Cleveland Clinic effort did not assess quality head on. Instead they used the success of the PCI as a surrogate, Agarwal says, which was identical in the two periods.
Even just introducing low-dose fluoroscopy can lessen radiation exposure to operators and patients, interventional cardiologists at the Quebec Heart and Lung Institute in Quebec City demonstrated in a randomized trial. In this case, they looked at whether lowering the fluoroscopy rate from 15 to 7.5 frames per second in transradial diagnostic coronary angiographies and PCIs nudged the needle down for radiation exposure (J Am Col Cardiol Cardiovasc Interv 2014;7:567-574).
They reported a relative reduction of 30 percent in the operator dose and a 30 percent drop in patients’ dose-area product. Fluoroscopy time was marginally higher in the 15 frames per second groups.
“When we looked at the procedure time, contrast agents and other parameters, everything was equal,” says Olivier F. Bertrand, MD, PhD, senior author on the paper. “So basically the only thing we reduced was the radiation exposure to the patient and to the operator.”
Be aware & be adaptable
Simple changes in habits and approaches can make a difference in radiation exposure. The Cleveland Clinic initiative, for instance, included monthly feedback reports to inform cardiologists of their radiation dosimetry. “On a monthly basis, when you are told you must cut your radiation down, you become cognizant of that,” Agarwal says.
While that approach may alter future behavior, it cannot correct what has already occurred. Instead, operators need feedback in real time. Enter RadiCure, an auditory feedback system designed and tested on 14 interventional cardiologists at the VA North Texas Health System in Dallas. In a randomized study, cardiologists showed that use of a wearable warning bleeper lowered radiation exposure to operators by about one third.
The study, which was presented at the 2014 Society for Cardiovascular Angiography and Interventions scientific session, randomized 505 patients who underwent coronary angiography or PCI into two groups: one with operators wearing the Bleeper Sv (Vertec Scientific) and one without the device. The device would bleep at 15-minute intervals when background radiation remained in a normal range and increase in frequency and intensity if radiation increased. Operators could respond as they pleased; for instance, they could step back from the table or adjust the intensifier.
Operator exposure was significantly lower in the bleeper group compared with the control group, at 0.9 mrem vs. 1.4 mrem for the first operator and 0.5 mrem vs. 0.7 mrem for the second operator. That translated into a 36 percent relative reduction for the first operator and a 29 percent relative reduction for the second operator.
“Radiation is something you don’t visualize and feel,” says Emmanoulos Brilakis, MD, VA North Texas cath lab director and the study’s senior researcher. “This is one way to actually understand you are getting radiated and remind you, and being reminded you realize the adverse consequences and change your behavior.”
Consider your options
Changing an approach for PCI procedures also offers opportunities for lowering operator dose, but it may require an adjustment period for physicians and staff. In the long run, though, sacrificing familiarity for a short time may pay off with long-term health benefits. In an effort to expand the use of radial PCI, one cardiology group provided yet another incentive for operators to try left radial access during PCIs: It cut operator radiation exposure by nearly half.
“My intention was to show that the left radial approach was as effective as the right and can be an alternative,” says Luis A. Guzman, MD, medical director for the cath lab and peripheral program at the University of Florida College of Medicine in Jacksonville. Patients with prior bypass surgeries are not good candidates for right radial access, so being adept at left access gives operators an option to a transfemoral approach for these patients. “Now [there is] the bonus that it appears to be associated with less radiation exposure, which was not something I was expecting.”
He and colleagues designed a study that randomized 100 patients to either a left or right radial access catheterization performed by five operators with varying degrees of experience (J Am Coll Cardiol Intv 2014;7:810-816). They assessed and compared radiation exposure and operator discomfort.
Success rates were identical. With right radial access, operators received a median head exposure of 12 mrems compared with 6.12 mrems from the left. Thyroid median exposure was also lower, too, at 18.7 mrems vs. 10.1 mrems. “It was striking across the board with every operator,” Guzman says. “Every operator was his own control.”
Operators reported more discomfort during access with the left radial approach, often in cases where the patient was obese, but not during procedures. But now that they have practiced left-side techniques, they are more likely to perform a left-access radial PCI, he observes. Staff, who initially resisted because preparation differed for a left-access procedure, also have become proficient and receptive to the option.
Guzman speculates that a finger–trap system they use to move the left arm over the groin area provides the safety advantage. The setup mimics positioning in a transfemoral procedure and possibly confers the same radiation protection as a femoral-access PCI.
Think long term
Cath labs require operators and staff periodically to undergo radiation safety training, but these educational messages may fade over time unless they are reiterated. Some radiation safety experts see early career interventionalists as the linchpin for change. They may be the easiest to teach current best practices. And precautions they take now may allow for long and successful careers, particularly as doses go up with increasingly complex procedures.
The Cleveland Clinic initiative specifically targeted fellows, who may be more flexible and open to change than senior cardiologists. “The fellows are standing at the head of the table, operating the fluoroscopic buttons,” Agarwal points out. “If you tell the fellows, who are more malleable, to change, then they can cut the radiation down without even talking with the staff.”
Chambers sees an opportunity for the profession as a whole to be proactive. By raising awareness among colleagues and self-imposing evidence-based best practices now, cardiologists not only can reduce risks to patients, staff and themselves but also pre-empt dictates from nonphysicians who don’t understand the cath lab environment or culture.
He recommends that every cath lab embed within its quality improvement program a radiation safety component that includes training, equipment standards, monitoring and follow-up. “If you institute a practice in the lab of radiation consciousness, it works,” he says. “The equipment and procedures are out there, they just have to be properly used.”