Ocular Radiation Exposure of the Primary Operator Performing Selective Coronary Angiography From a Radial Artery Approach

An Interview With Richard Casazza, MAS

Dr Richard Casazza shares background and insights on his article, "Ocular Radiation Exposure of the Primary Operator Performing Selective Coronary Angiography From a Radial Artery Approach."

My name is Richard Casazza. I'm the Chief Special Procedures Technologist at Maimonides Medical Center in Brooklyn, New York. I've been doing this for 25 years now; I speak at several conferences, particularly regarding radiation exposure and the radial artery approach, and it's something I love to do.

Given the increasing implementation of the radial approach, why do you think it has taken until now for anyone to evaluate the impact of radiation on the operator when performing from this approach?

In a recent study, the NCDR reported the radial approach as around 60% for percutaneous coronary interventions. So, radiation from a radial artery approach in particular is something very interesting to study. There have been some studies in the past; however, they haven’t really focused specifically on a radial artery approach in terms of comparing the amount of exposure from the left eye to the right eye. Historically, we've seen cataracts in interventional cardiologists, predominantly in the left eye, subcapsular changes, and the obvious reason is because the left eye is in closer proximity to the patient and the x-ray tube. So, I just thought that this would be a great study to quantify the amount of radiation that both eyes get, see why we've seen these changes in the past, and apply that to a radial artery approach.

Based on your findings, what do you see as the most practical and effective combination of protective strategies that can realistically be adopted in catheterization labs?

Our study found about 3 to 4 times the amount of exposure to the left eye compared to the right. There's different data out there regarding ways to protect your eyes. With the leaded glasses, the data varies; the data say they can protect anywhere between 35% and 90%. The only study that showed a big difference was with the use of a full lead visor—that's where they really saw differences. However, there comes a trade-off, because that is a little bit heavier. I've actually worn one before and it's definitely heavier, so there is an orthopedic element involved.

Probably the best and most practical way is having a ceiling-mounted lead shield retrofitted with a lead skirt in addition to using lead glasses. I'm on social media a lot, and I watch how people use these lead shields. There's no real benefit of getting significant reductions, like a 90% reduction, if you're not using that lead shield properly. I see online all the time people have the lead shield all the way out to the side, in the back, sometimes not even using it. So, the actual best way in a standard cardiac catheterization laboratory is using the lead glasses in addition to using the lead shield, but using that shield properly where you're effectively blocking that scatter radiation, which is placing that shield abutted to the patient so you really limit that scatter radiation, especially to the eyes.

You noted that your study was single center, and that factors such as operator height or shield placement may influence results. What follow-up studies do you believe are the most needed to build on your findings and ensure safer working conditions?

This study really quantified the amount of exposure to each eye. I think it would be important to have some type of registry or some type of follow-up—especially for interventional cardiologists who are in the latter part of their careers and have received radiation for many years—to see if there's recurring subcapsular changes. Probably the biggest radiation-induced illness that an interventional cardiologist would face would be some type of glioblastoma or left-sided glioblastoma. However, the one that we're most likely to see, because the thresholds are much higher for the brain than for the eyes, are radiation-induced cataracts.

So, following up or having some type of registry or survey where we can follow these interventional cardiologists, especially later into the career, would be beneficial. It would even be better if we follow them early to later and found the prevalence and the significant factors that were or weren't causing cataract changes for these people, may it be some type of shielding or some type of reduced dose rate. These findings would be interesting and beneficial to see who's doing what right and what wrong and really quantify and discern who was getting these subcapsular changes and why.

A more recent paper by your group focuses on the influence of subclavian tortuosity on operator radiation exposure. Are there any other approaches or circumstances about which operators should be particularly mindful when it comes to their or their patient's exposure to radiation?

Subclavian tortuosity in and of itself is probably the biggest anatomical obstacle that we face from a radial artery approach. In an upcoming study comparing left and right radial approaches, we found that, in patients with subclavian tortuosity, we found less exposure using the left radial approach. And, in our initial clinical trial, we found lower ocular radiation exposure using a left radial artery approach. This is probably because of a better aorto-subclavian junction entry angle into the aorta, as well as better shielding, using a left radial approach.

On top of that, there's more ominous implications. Professor Rashid out of Keele University found higher in-hospital stroke using the right radial approach. There was even 1 study, I believe it was done in Argentina, where they measured the amount of silent cerebral artery infarcts pre- and post-cardiac catheterization using MRI, and they found that an independent predictor of those CVAs was the use of the right radial artery approach.

So, when it comes to subclavian tortuosity, we should really be mindful about how difficult and how pronounced it is. And we should probably have some type of threshold to determine when to use a different access site, particularly to avoid these CVAs as well as reduce the amount of exposure that patients and operators are getting. Procedures involving subclavian tortuosity take longer to perform, and especially if your shield isn't in the right spot, we will see a higher amount of exposure, just because we are taking longer with these procedures.

Ocular Radiation Exposure of the Primary Operator Performing Selective Coronary Angiography From a Radial Artery Approach

Operator Radiation Dose Comparing Left Radial Artery and Right Radial Artery Approaches Among Patients With Subclavian Tortuosity