Cardiology

Since the incorporation of fluoroscopy in the cath lab 50 years ago, health risks associated with radiation exposure have been of increasing concern to those who make their living in the lab.

During that time, developments in technology have offset some of these concerns by affording cath lab operators the ability to perform a catheterization with decreased amounts of radiation required to obtain good images.

“The framing rates to visualize images 30 to 40 years ago used to be 30 to 60 frames per second, and now we routinely use 15 — the fluoroscopy during that time was continuous, but now it is pulsed at 7.5 frames per second, so you are shooting fewer frames,” said Thomas Bashore, MD, clinical chief, division of cardiology, Duke University Medical Center, Durham, N.C., in an interview. “The equipment is also a lot better and provides higher resolution images.”

	Thomas Bashore

Nevertheless, increasing demands for catheterizations and extended times in the cath lab have countered the benefits interventionalists experience as a result of these innovations.

“Thirty years ago, we performed a fewer number of cases per day, the cases were generally shorter and the total fluoroscopy times were relatively brief. Now, a busy operator performs six to 10 cases per day, including complex interventions requiring prolonged fluoroscopy exposures,” said James A. Goldstein, MD, director of cardiovascular research and education, William Beaumont Hospital, Royal Oak, Mich., and a founding member of the Multispecialty Occupational Health Group.

Augmenting the concern of overexposure to radiation are the known risks associated with wearing orthopedically burdensome leaded aprons over the long term.

However, despite these safety hazards and the innovations to the imaging modalities themselves, the radiation protection systems have remained virtually unchanged during the past 3 decades.

	James A. Goldstein

“We are still using leaded aprons, glasses and thyroid collars, and small shields we put up from the table or drop down from the ceiling; unfortunately, our heads, arms and legs are incompletely protected,” Goldstein said. “Little has changed in radiation protection, which is disappointing.”

The Nature of the Problem

Occupational health hazards in interventional cardiology have often been referred to as “the cost of doing business” by those who enter the field. For Bashore, this lack of attentiveness to a potentially serious problem can at least be partially explained by the fact that, unlike radiologists, cardiologists do not receive a lot of training in radiation safety.

“Education in radiation safety for radiologists has really helped them understand how much radiation the operators and patients receive. Cardiology has not done a good job with this,” Bashore said.

According to Bashore, most cardiologists have not paid a lot of attention to radiation exposure, “mainly because they have not been focused on the equipment itself but rather on the procedure. Radiologists are much more focused on the actual equipment and how it is best used. It’s only been in the last decade that people in cardiology have started to realize they need to pay more attention to this.”

Part of this realization in recent years has come from research that has highlighted the potential harm of long-term, cumulative radiation exposure. Recently, a study was published in EuroIntervention that brought one of the chief concerns to the forefront.

	Ariel Roguin

In the study, Ariel Roguin, MD, PhD, and colleagues performed an extensive literature search and reported that, among interventional cardiologists, there were nine cases of brain tumors, five that were already published and four new cases. Since the publication, Roguin, who is associate professor at the Technion, Israel Institute of Technology, Haifa, Israel, has regularly received emails of additional cases of malignancies among those in the specialty, which now number at 20.

Although admitting that the collection of cases via email is not scientific, Roguin insisted that interventional cardiologists must be aware of the potential dangers of radiation exposure, even though the risks most likely will never be proved because of the low numbers of epidemiological issues and incidences.

“I can’t prove that our findings are anything more than background noise. However, from those 20 cases we have, I know the side that was involved in 12. In those 12, one was from the right side, one was from the midline and 10 were from the left side, and we work with radiation to our left,” Roguin said. “So is this chance? Maybe. I’m still actively seeking more cases and plan on updating our small data set in the future.”

Despite there not being a “smoking gun” yet in terms of whether there is an actual risk for cancer among those who work in the cath lab, Goldstein, who is also a member of the Cardiology Today Intervention Editorial Board, said the issue of cancer in the cath lab is a serious concern.

“These anecdotal reports of cancer among interventionalists are growing in number,” he said. “But caution must be exercised when interpreting such data. In order to draw firm conclusions, further studies where we really know what the numerator and denominator are will be necessary. Thus, as a scientist, one must look upon such anecdotal cases with a healthy dose of skepticism; however, one cannot ignore the warning such cases are sending.”

	John W. Hirshfeld

John W. Hirshfeld, MD, professor of medicine at the Hospital of the University of Pennsylvania, Philadelphia, agreed that the quality of data currently available is not strong, stressing that there have not been good observational data on whether practitioners have a detectable degree of health effects from their exposure.

“The field of intervention is just starting to accumulate people who have 25 to 35 years of experience, so we don’t really know the health effects of long-term exposure in the cath lab yet,” Hirshfeld told Cardiology Today Intervention. “There have been some armchair analyses that have looked at what the estimated increased cancer risk is for someone who is occupationally exposed to radiation, and the analyses suggest that they probably have an incremental lifetime risk of about 2%. But your lifetime risk of getting cancer anyway is around 20% to 25%, so the incremental effect of occupational radiation exposure would be difficult to detect with confidence in the small population of career catheterizers.”

Cautionary Measures

For those who are occupationally exposed to radiation, the term ALARA, or “as low as reasonably achievable,” has for decades been the standard for acceptable exposure levels. However, the subjectivity of what is “low” and what is “reasonably achievable” ultimately leads to questions as to how best to apply this principle to practice.

In an attempt to bring more objective measures to radiation exposure, badges are now worn by cath lab operators that collect day-to-day exposure levels. And for those who exceed the monthly levels deemed safe, they are taken out of the cath lab for the remainder of the month.

	Lloyd W. Klein

“Operators are essentially being punished for their exposure. So, not surprisingly, many don’t wear a badge,” said Lloyd W. Klein, MD, professor of medicine, Rush Medical College, Chicago, and a member of the Multispecialty Occupational Health Group. “We’ve created a system in which if you dare to be exposed you will be punished. That has to change or no one will wear their badges.”

Rather than limiting exposure by compromising the operator’s ability to perform their job, others are suggesting ways to fine-tune methodology that will reduce radiation exposure and the resulting consequences. In an editorial published in the American Heart Journal, Bashore offered several recommendations on how to reduce radiation exposure in the cath lab, which include:

• Use fewest magnified views.
• Keep source-to-image distance as narrow as possible.
• Keep the maximal kilovolt potential across the tube as high as practical for good contrast, but keep milliamperes as low as possible to reduce the number of X-rays produced.
• Keep the number of exposures to a minimum.
• Use pulsed fluoroscopy.
• Use lowest framing rate possible.

Although the editorial was published 8 years ago, Bashore said these measures are still pertinent to the practice of interventional cardiology today; however, he added that minimizing time in the room, limiting high-dose fluoroscopy and avoiding extremely angulated views to keep the source-to-image distance narrow are important as well. Added to which, awareness of dose to the patient, he said, can be determined in most laboratories by noting the dose-area-product (total amount of exposure sent to the patient) and an estimate of skin dose that can be derived from the interventional reference point.

In addition, Hirshfeld suggested that operators make sure the equipment is properly calibrated so that it is using the lowest possible dose rate that will produce quality images, and operators be as far from the X-ray tube as possible. “The X-ray intensity goes down as the square of your distance from the source, so if you double your distance from the source, you’ve just decreased your exposure by a factor of four,” he said. “Also, it is important to use the ceiling mounted Plexiglas shields, which stop 90% of the scattered radiation. By using it, you cut the dose rate to the upper body, which is where most of your unprotected structures are, by a factor of 10. Just about all laboratories have them installed, but the operator has to decide to use them.”

Hirshfeld also said the exposure levels for the clinical staff who work in the lab should be minimal.

“Physicians who work in the cath lab need to make sure that staff members are minimally exposed and that they keep their distance from the X-ray source, because most of the time the staff should not have to experience the exposure,” he said. “The physicians can’t get out of where they stand, but nurses and technicians can.”

An ‘Epidemic’ in the Cath Lab

Although techniques and protocols to lower exposure levels have been evolving, surprisingly, radiation protection technologies have been virtually unchanged during the past 30 years. And, unlike the anecdotal reports of harm caused by radiation exposure in the cath lab, the health risks associated with wearing leaded aprons and collars over the long-term are clinically substantiated — to the extent that some are calling it an epidemic.

“It has been well-established that working in the cath lab for 20 or more years and having to work standing up and wearing heavy leaded aprons is associated with an epidemic of orthopedic problems, particularly in the spine but also in the hip, knees and ankles,” Goldstein said. “Almost everyone I know — even our younger colleagues — walk out of the cath lab at the end of a busy day with an aching back.”

To quantify this epidemic, Goldstein, Klein and several others from the Interventional Committee of the Society of Cardiovascular Angiography and Interventions conducted a survey of more than 1,600 members and received responses from 424. Among those who responded, orthopedic problems were prevalent, with 42% experiencing spine problems — of which 70% were lumbosacral and 30% cervical — and 28% experiencing hip, knee and ankle problems.

“Because of these orthopedic problems, there has been a large percentage of cath lab operators who miss work or even change careers,” Klein said. “To be direct about this, hospitals don’t really expect people to spend their whole careers in the cath lab. They expect radiation technologists and nursing staff and physicians to retire in their 50s and go on and do more general medicine. They just keep producing new and younger radiologists and technicians, while the older ones go out and become sales reps, head nurses, chiefs of cardiology and so on. It really wasn’t until the interventional era of the last 5 to 10 years that a large number of people are truly spending their careers being an interventional cardiologist and retiring as one.”

This can partly explain why there has been little change in lab design over the decades, Klein said, although he added that three additional factors are also at fault:

“First, those who operate the labs don’t mind if there is periodic turnover because it keeps cost down. Second, those who work in the lab are constantly new and don’t think hazards will happen to them. And third, those who have experience suggest that anyone who is concerned about these problems shouldn’t work there.

“So, when one takes a complete look at how the cath lab is run, it’s fair to say that if we ran mines or factories like this, we’d all be in jail,” he said.

A Call for Change

Due to the multifaceted concerns of working in the cath lab, many interventional cardiologists are calling for a complete revolutionizing of the current work environment in favor of a more technologically advanced, user-friendly design.

One way that some propose would limit occupational radiation exposure in the future is robotic-assisted PCI. This technology would potentially allow the operator to direct the movement of catheters and wires while standing several meters away from the patient and the source of radiation.

In a 2011 study, Klein, Goldstein and other members from the Multispecialty Occupational Health Group forecasted the cath lab of the future, and highlighted robotic-assisted PCI as one of the possible game-changers.

“Robotics would be the ultimate answer if it works,” Klein said. “However, I don’t expect that the transformation to robotic-assisted PCI will happen in my lifetime. People don’t want to go under the knife in the first place, and if they’re going to go under the knife they want the knife to be in the hand of a human being that they select; and as long as that attitude exists, we’re not going to get into robotic-assisted PCI.”

There are also some more fundamental issues that must be addressed as well.

“Robotic-assisted PCI is not very practical right now. There are little data supporting its use and the techniques to use it effectively still need to be worked out,” Hirshfeld said.

Consequently, some are advocating for measures that have the potential to improve working conditions in the short term. However, those too are not without their set of challenges to overcome.

“Ultimately, you have to get the lead off the shoulders and backs and get it within the room so that it is protecting everyone,” Klein said. “But in order to do that we have to make manufacturers change their designs.”

According to Goldstein, during the past 5 years, the Multispecialty Occupational Health Group has met with industry, including the major companies that manufacture X-ray systems, with the intent of convincing them to do just that. “We communicated to them that the present environment is unacceptable, and that it’s time for industry to change it.”

Although the large amount of capital required to develop new cath lab technology has shown to be a significant obstacle, the challenge is further compounded by the fact that change must also reach the hospital level as well.

“Hospitals have to be willing to spend [the money],” Klein said. “Unfortunately, it’s much easier for them to replace doctors who get orthopedic problems than to spend the money.”

Although this may have been the economically correct answer up until recently, the number of procedures being performed currently and the amount of training and experience it takes to do them effectively and efficiently indicates that operators’ careers are not going to be 15 to 20 years long but rather 30 to 40 years long, Klein said.

“Suddenly, we’re no longer moveable parts and replaceable pieces. Now, once you train a nurse to work the equipment in the lab and assist, it’s not so easy or cheap to replace them, and as a result the finances and economic decisions change. It won’t be economically feasible to just treat people like they have a limited career,” he said.

Yet, one important change that has taken place, which has the potential to lead to future improvement in working conditions, is the transition away from the mindset that a hazardous work environment is just part of “doing business.”

“Surely we can create a better environment. That is what the Multispecialty Occupational Health Group is working toward,” Goldstein said. “The societies and their members need to advocate to industry, and subsequently hospitals, the need for better solutions and a safer place to work.” – by Brian Ellis

References:

Bashore TM. Am Heart J. 2004;147:375-378.

Goldstein JA. Catheter Cardiovasc Interv. 2004;63:407-411.

Hirshfeld JW. Circ Cardiovasc Interv. 2011;4:216-218.

Klein LW. Cath Cardiovasc Interv. 2009;73:432-438.

Klein LW. Cath Cardiovasc Interv. 2011;77-447-455.

Roguin A. EuroIntervention. 2012;7:1081-1086.

Disclosure: Drs. Bashore, Hirshfeld, Klein and Roguin report no relevant financial disclosures; Dr. Goldstein has equity in Eco Cath Lab Systems, a company designing novel radiation shielding products that are not yet available.