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Cardiac cath lab work carries multiple risks
An Italian study adds to the growing list of possible long-term risks to physicians, nurses, and techs in the cardiac cath lab.
Dr. Piccaluga also shared data from several other pertinent recent studies in which she was a coinvestigator. In one, 83 cardiologists and nurses working in cardiac catheterization laboratories and 83 matched radiation-nonexposed controls completed a neuropsychological test battery. The radiation-exposed group scored significantly lower on measures of delayed recall, visual short-term memory, and verbal fluency, all of which are skills located in left hemisphere structures of the brain – the side with more exposure to ionizing radiation during interventional procedures (J Int Neuropsychol Soc. 2015 Oct;21[9]:670-6).
In another study, Dr. Piccaluga and her coinvestigators had participants perform an odor-sniffing test. Olfactory discrimination in the cardiac cath lab staffers was significantly diminished in a pattern that has been identified in other studies as an early signal of impending clinical onset of Alzheimer’s and Parkinson’s diseases (Int J Cardiol. 2014 Feb 15;171[3]:461-3).
And in yet another study, Dr. Piccaluga and her coworkers found that left and right carotid intima-media thickness as measured by ultrasound in cardiac cath lab personnel having high lifetime radiation exposure was significantly greater than in those with low exposure and in nonexposed controls. In the left carotid artery, but not the right, intimal-medial thickness was significantly correlated with a total occupational radiologic risk score.
Moreover, the Italian investigators found a significant reduction in leukocyte telomere length – a biomarker for accelerated vascular aging – in cardiac cath lab staff regularly exposed to ionizing radiation, compared with controls (JACC Cardiovasc Interv. 2015 Apr 20;8[4]:616-27).
All of these findings, she stressed, make a persuasive case for interventional cardiologists doing everything they can to protect themselves from unnecessary radiation exposure at all times.
Dr. Alaide Chieffo
How to best go about accomplishing this was the territory covered by Alaide Chieffo, MD, of San Raffaele Scientific Institute in Milan.
The patient-related factors germane to radiation dose – procedure complexity and body thickness – are outside physician control. But there are plenty of operator-dependent factors, including, for starters, procedural experience. In one classic study, Dr. Chieffo noted, Greek investigators showed that interventional cardiologists’ radiation exposure dose was 60% greater in their first year of practice than in their second year.
Distance from the patient is crucial, she observed, since the patient is the greatest source of radiation to the operator. If the operator is 35 cm from the patient, the radiation exposure is fourfold greater than at a distance of 70 cm. At a distance of 17.5 cm, the exposure intensity is 16-fold greater than at a 70-cm distance. And at 8.8 cm of distance, it’s 64 times greater.
Image acquisition is another key variable within the interventionalist’s control. Cine images entail 12- to 20-times greater radiation doses than those of fluoroscopy, so don’t resort to cine when fluoroscopy will do. Also, reducing the fluoroscopy frame rate from 15 to 7.5 frames per second significantly decreases the amount of radiation released while providing images of adequate quality for many procedures. Tight collimation, the use of manually inserted wedge filters, and thoughtful selection of tube angulations result in less radiation for both patient and physician. It has been shown that tube angulations that expose a patient to intense radiation levels increase the operator’s radiation exposure exponentially. The least-irradiating tube angulations are caudal posteroanterior 0°/30°– angulation for the left coronary main stem, cranial posteroanterior 0°/30°+ for the left anterior descending coronary artery bifurcation, and right anterior oblique views of 40° or more. Left anterior oblique projections are the most radiation intensive, according to a comprehensive study (J Am Coll Cardiol. 2004 Oct 6;44[7]:1420-8), Dr. Chieffo continued.
Panelist Ghada Mikhail, MD, of Imperial College London, said there is some relatively new operator protective gear available. She cited lightweight protective caps, for example, but an audience show of hands indicated almost no one uses them.
“Protectors for the breasts and gonads are available. You can wear them underneath the lead. The extra time to put them on is worthwhile,” she said.
“I think the risk of radiation is completely underestimated,” Dr. Mikhail added. “We have a responsibility to young trainees to teach them about radiation protection, which a lot of institutions and supervisors don’t do. That’s partly because a lot of them don’t know the details.”
All of the speakers indicated they had no financial conflicts regarding their presentations.