New protocol reduces children’s radiation exposure during cardiac procedures

A protocol that uses continuous real-time radiation monitoring, low-dose imaging programs and requires physician awareness of radiation dose, significantly reduced radiation exposure during electrophysiology procedures and catheter ablations to diagnose and treat heart arrhythmias in children, according to research presented at the American Heart Association’s Scientific Sessions 2010.

Invasive cardiac electrophysiology is used to diagnose and treat abnormal heart rhythms, or arrhythmias, which can range from the benign to the life-threatening.

In the study, researchers looked at boys and girls at an average age of 14.5 years who underwent electrophysiology procedures to diagnose and treat arrhythmias. In the procedures, doctors use fluoroscopy, which is a continuous X-ray, to visually guide catheters in the heart which are inserted through blood vessels in the groin or neck that lead to the heart.

The downside of this imaging is that it exposes patients to a continuous flow of radiation, said Akash R. Patel, M.D., lead author of the study and an electrophysiology fellow in the Division of Cardiology at The Children’s Hospital of Philadelphia in Pa. “Radiation exposure in pediatric electrophysiology procedures is not insignificant. We compared the radiation exposure of 70 children who had undergone the procedures before we began the protocol to that of 61 children who had the procedures after we instituted the protocol.”

The new protocol uses a low dose fluoroscopy setting and continuous real-time monitoring of radiation exposure. When the radiation dose registers at certain levels, the physician is notified so that the he or she can adjust the fluoroscopy cameras to minimize exposure.

The researchers found significantly reduced radiation exposure among children whose procedures were performed using the new protocol, including:

  • 22 percent reduction in the time that the X-ray machine was on
  • 52 percent reduction in the dose of X-ray entering the skin, which helps to prevent skin injury
  • 51 percent reduction in median effective dose, which correlates with the lifetime increased risk of cancer from radiation exposure.

“While we did not measure what these lower doses mean in the long run, we presume, for example, that reducing the effective dose will decrease the child’s lifetime increased cancer risk from radiation exposure,” Patel said.

“The public should be aware of radiation exposure from electrophysiology procedures, and physicians and hospitals should be vigilant in implementing protocols aimed at reducing radiation exposure from these procedures. This is especially important in children to minimize their risk of radiation-induced cancer because they should live for many decades after their procedures.”

Co-authors are: Jamie Ganley, B.S.; Xiaowei Zhu, M.S., Jonathan J. Rome, M.D.; Maully Shah, M.B.B.S.; and Andrew C. Glatz, M.D. Author disclosures are on the abstract.

The Children’s Hospital of Philadelphia funded the study.

Contact information: Dr. Patel can be reached at (267) 425-6296 and [email protected]

(Please do not publish contact information.)

(Note: Actual presentation time is 9 a.m., CT, Monday, Nov. 15, 2010.)

Also Note These News Tips also for release at 11 a.m. CT, Sunday, Nov. 14, 2010:

Abstract 11390/P1029 — Imaging teams’ radiation exposure during percutaneous interventions higher than fluoroscopic operating teams

Radiation exposure to imaging teams during percutaneous intervention for adult structural heart disease is higher than that of fluoroscopic operating teams — suggesting that imaging team members may need additional radiation protection measures.

Percutaneous adult structural heart disease intervention is a family of invasive procedures that includes closing patent foramina ovalae, atrial septal defects, paravalvular leaks and transfemoral aortic valve implantations. It is currently a small but increasing part of cardiac interventional practice, researchers said.

Such procedures often require fluoroscopic guidance by an operating team and ultrasonic guidance by an imaging team working together. This study was an observational study of ionizing radiation exposure to both operators and imagers during percutaneous interventions for adult structural heart disease.

Fluoroscopic operating team members typically stand to the right of patients undergoing the procedures and imaging team members stand on the left. While all staff are required to wear protective lead aprons and thyroid collars, additional shielding is only provided for the operating team.

Researchers examined how the radiation dose received by fluoroscopic operators differs from that received by the imaging team by measuring radiation exposure during percutaneous procedures for four months. They found greater radiation doses for those standing on the left of patients, which are the imaging personnel.

This may have implications for both radiation protection and the use of noninvasive imaging during these procedures to reduce the reliance on X-ray technology, researchers said.

Rodney De Palma, M.B.B.S, M.R.C.P.; University Hospital of Lausanne, Lausanne, Switzerland; [email protected].

(Note: Actual presentation time is 9 a.m., CT, Monday, Nov. 15, 2010.)

Abstract 17486 — Radiation exposure from cardiac imaging after heart attack more likely to cause cancer in women than men

Women who have had a heart attack, regardless of age, face a higher risk of cancer associated with exposure to low-dose ionizing radiation from heart imaging procedures than male heart attack patients.

Researchers measured the effects of age and gender on low-dose ionizing radiation-associated risk of cancer in heart attack patients who had been exposed to the radiation from cardiac imaging procedures. Studying a database of 56,606 male and 26,255 female heart attack patients between 1996 and 2006 in Quebec, they found:

  • For women, the median age was 71.7 years, low-dose ionizing radiation exposure was 3.7 millisieverts (mSv) per year, and 3,545 new cancers were observed over 4.2 years.
  • For men, the median was 59.7 years, low-dose ionizing radiation exposure was 4.1 mSv/year, and 8,475 new cancers were observed over 4.8 years.
  • The interaction between gender and low-dose ionizing radiation was significant, but it wasn’t between age and low-dose ionizing radiation.
  • For every 10 mSv increase in low-dose ionizing radiation, the risk of cancer increased by 4.4 percent in womem and 2.1 percent in men.

Jonathan Afilalo, M.D., M.Sc.; Division of Cardiology, SMBD-Jewish General Hospital/McGill University, Montreal, Quebec, Canada; (687) 935-4619; [email protected].

(Note: Actual presentation time is 9 a.m., CT, Tuesday, Nov. 16, 2010.)

Author disclosures are on the abstracts.

Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing the science content. Revenues from pharmaceutical and device corporations are available at www.heart.org/corporatefunding.

NR10-1139 (SS10/Patel)

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