Interventional echocardiographs: more exposed to radiation in the cath lab

UNITED STATES – Interventional echocardiographers have become an increasingly important part of the structural cardiology team, but they could pay the price in terms of radiation exposure, according to a new study.

The results show that interventional echocardiographers receive three times higher radiation doses at head level during left atrial appendage closure (LAAO) and 11 times higher doses during TEER (edge-to-edge transcatheter repair) of the mitral valve than interventional cardiologists.

“Over the past five to ten years there has been exponential growth in these two procedures, TEER and LAAO, and while that’s very interesting, I think there hasn’t been as much research done to protect these people,” said the lead author on DRDavid A McNamara, MD, MPH, Spectrum Health, Grand Rapids, Michigan, at | Medscape Cardiology. The study was published on July 7th JAMA network open[1].

Which protection levels?

Previous studies have largely focused on radiation exposure and mitigation efforts during coronary interventions, but the room configuration for LAAO and TEER and the shielding techniques used to mitigate radiation exposure are very different, he noted.

A 2017 study found that radiation exposure for imaging specialists was significantly higher than for structural cardiologists and varied by type of procedure.

For the current study, Dr. McNamara, a trained echocardiographer, and his colleagues presented data on 30 LAAO procedures and 30 consecutive TEER procedures performed at their facility between July 2016 and January 2018.

Interventional imagers, interventional cardiologists, and sonographers all wore a lead skirt, apron, and thyroid protection, as well as a dosimeter to collect radiation data.

Interventional cardiologists stood immediately to the side of the treatment table and used a ceiling-to-ceiling upper-body lead umbrella and a table-to-floor lower-body lead umbrella. The echocardiograph stood at the patient’s head and used a movable accessory screen that was raised to a height that allowed the imager to extend his arms over the screen to fully manipulate a transesophageal echocardiography probe.

The median duration of fluoroscopy was 9.2 minutes for LAAO and 20.9 minutes for TEER. The mean air kerma* was 164 mGy and 109 mGy, respectively.

*Kerma is a measure of the kinetic energy transferred from radiation to matter.

Interventional echocardiographers received a mean radiation dose of 10.6 µSv per case, compared to 2.1 µSv for interventional cardiologists. The result was similar for TEER (10.5 µSv versus 0.9 µSv) and LAAO (10.6 versus 3.5 µSv; P<0.001 for all).

Interventional echocardiographers were 7.5 times more likely than interventional cardiologists to receive a radiation dose greater than 20 µSv (P < 0.001).

“It wasn’t the association but its magnitude that surprised us,” McNamara noted.

The team was pleasantly surprised to find that sonographers, a “very understudied group,” received significantly lower mean radiation doses during LAAO procedures (0.2 µSV) and TEER (0.0 µSv; P<0.001 for both). as interventional imaging devices. .

The average distance from the radiation source was 26 cm (10.2 in) for the echocardiograph, 36 cm (14.2 in) for the interventional cardiologist, and 250 cm (8.2 ft) for the sonograph.

“These people [les échographistes] were much further away than the doctors performing these procedures, which may explain their very low rates. This is something we can use to refine our mitigation techniques towards physicians and all other cath lab members in the room,” said Dr. McNamara.

New more protection systems

the dr Sunil Raothe brand new President of the Society for Cardiovascular Angiography and interventions (SCAI), said, “This is a really important study because it expands the potential occupational hazards beyond what we traditionally consider for the team performing the interventional procedures…we need to recognize that the procedures we do in the cath lab.” perform have changed.”

“Showing that our colleagues are exposed to 3 to 10 times more radiation is really important information to spread. I think that’s a kind of call to action,” said Dr. Rao, a professor of medicine at Duke University in Durham, North Carolina, told | Medscape Cardiology.

However, he noted that practices have changed somewhat since the study and that interventional cardiologists who work with imaging doctors are more aware of radiation exposure.

“When I talk to our colleagues who perform structural heart procedures, they make sure they don’t step on the fluoro pedal while the echocardiograph is manipulating the TE probe,” Rao said. “The echocardiograph often uses much larger shielding than described in the study, and remember that radiation exposure decreases exponentially with distance, so they bounce back during fluoroscopy. . »

Although the volume of TEER, LAAO and tricuspid procedures will continue to increase, Dr. Rao said the cardiologist’s radiation exposure during imaging will be reduced through greater use of next-generation imaging systems with dose-reduction capabilities and better shielding strategies.

He noted that several of SCAI’s best practice documents draw readers’ attention to radiation safety and that SCAI is creating a path for imaging cardiologists to become members of the community, which has traditionally been reserved for interventionists.

However, imaging and cardiology societies have not yet approved standardized safety procedures for interventional imaging equipment, and national registries do not routinely collect radiation exposure information.

“Currently, there are neither the budgets nor the interest at the national level to do such work, so it has to be done locally,” said Dr. rao “The best point of contact for these types of issues, I think, is the head of the cath lab and the heads of the cath lab nurses, who really should work hand-in-hand to ensure radiation safety is at the top of the priority list. »

The study was funded by the Frederik Meijer Heart & Vascular Institute, Spectrum Health and Corindus. Funding sources played no role in the design and conduct of the study; collection, management, analysis and interpretation of data; Manuscript preparation, review and approval; and the decision to submit the manuscript for publication. The lead author Dr. Ryan Madder says he has received research support, speaker honoraria and grants and serves on the Corindus Advisory Board. No other conflicts of interest were reported.

The article originally appeared on entitled Interventional imaging systems take center stage and more radiation. Translated by Stephanie Lavaud.

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