Cardiac Rhythm Management
Articles Articles 2011 November

Letter from the Editor in Chief

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John Day, MD, FHRS, FACC
Editor-in-Chief
The Journal of Innovations in Cardiac Rhythm Management
E-mail: JDay@InnovationsInCRM.com
Director of Heart Rhythm Services
Intermountain Medical Center
Salt Lake City, UT

 

John Day, Editor-in-Chief

Dear Readers,

This month, I would like to focus my commentary on the topic of fluoroscopy management during ablation procedures. This issue of the Journal features a highly engaging contribution by Dr. McDaniel, in which he discusses efforts to reduce fluoroscopic exposure in pediatric ablation procedures.

I applaud our pediatric colleagues' efforts to dramatically reduce or even eliminate fluoroscopy in Electrophysiology (EP) procedures. Their desire to avoid fluoroscopy is very understandable given the significant long-term cancer risk in those patients with exposure to ionizing radiation at such a young age. Through the use of 3D mapping systems, many pediatric EP centers have even completely eliminated fluoroscopy from most ablation procedures.

For those of us who perform ablation procedures in the adult world, we have much to learn from our pediatric EP colleagues. Our patients, particularly young women, may also be at increased lifetime risk for cancer. In addition, our risk as operators in these cases may also be increased. Sadly, I would argue that most of the radiation exposure in a typical EP lab is largely unnecessary and, with proper training and utilization of newer technologies, most radiation exposure can be eliminated.

In an effort to minimize unnecessary radiation exposure, the U.S. Food and Drug Administration announced on February 9, 2010, its initiative to reduce this exposure from computed tomography (CT), nuclear medicine studies and fluoroscopy1, the three procedures that are the greatest contributors to total radiation exposure within the U.S. population.

During my EP fellowship training, we often joked that EP fellows seemed to “glow” from our lengthy fluoroscopy procedures. Our attendings often joked that we were their “radiation shields.” At that stage of my life, the consequences of radiation exposure seemed so distant that somehow they were not real. It was an occupational hazard that I felt I had no choice but to accept.

However, later in life as I began my practice, the reality of radiation exposure within EP procedures became very real. Very early in my career, I was referred a 21-year-old woman with symptomatic WPW. It was a particularly difficult posteroseptal pathway that originated from within the coronary sinus. After a long, five-hour case, I was eventually able to ablate the pathway. She did well for a couple of years, but then returned due to a recurrence of her tachycardias. Unfortunately, her accessory pathway had returned and we took her back to the EP lab. Once again, after another long, five-hour case, I was able to successfully ablate her posteroseptal pathway.

I thought all was well until several years later when the patient's surgeon asked me to see her for a pre-operative assessment prior to cancer surgery. My heart sank when I saw her again for this appointment. Could the radiation exposure from her two long ablation procedures have contributed to her cancer? Who would care for her two small children if she did not survive her cancer? While I will never know the answer as to whether the two ablations contributed to her cancer, it did leave an indelible impression that, in considering both the health of my patients as well as my own, I needed to do everything possible to reduce unnecessary radiation exposure.

If we are going to reduce unnecessary radiation exposure, we need to first understand the nomenclature. To begin with, the old terms “rads” and “rems” are out-of-date and no longer used. The new terms are “Greys” (absorbed dose) and “Sieverts” (effective dose equivalent). A Grey is equal to J/kg and a Sievert is equal to a Grey multiplied by radiation weighting factor. In the cath lab, we usually talk in terms of mGy, however, when we talk in terms of total radiation exposure from all sources, mSv is generally used. For example, in the case of a single chest x-ray, it is the approximate equivalent of 1 mGy or 0.1 mSv.

Just how much radiation exposure is involved with EP ablation procedures? A typical SVT ablation has been reported to be 5–20 mSv2. An atrial fibrillation ablation procedure has been reported to be 50 mSv in a man3. To put this into perspective, the annual background radiation exposure is 3 mSv and OSHA limits radiation workers to 50 mSv/year. If a patient, particularly a larger patient, undergoes two atrial fibrillation ablation procedures as well as 15 mSv from a pre-procedure chest CT, the patient has possibly been exposed to more than 100 mSv. While this may seem like a lot, we as physician operators received anywhere from 1/280 to 1/460 the patient dose (with the left hand receiving most of the radiation exposure)4. As you can see, over the course of a year or lifetime, the EP also has significant radiation exposure. Unfortunately, with radiation, there is no threshold for radiation risk and all radiation exposure is lifetime cumulative. People, patients or physicians alike, exposed to a total of 100 mSv have a one in 100 lifetime risk of solid cancer or leukemia5.

Given this significant radiation exposure, what specific things can we do to avoid unnecessary radiation exposure to our patients and to ourselves? The goal really should be “As low as reasonably achievable,” or ALARA, as it is well known among radiation workers. What has really amazed me is how low you can actually go and, in the process, actually achieve a more efficient and safer procedure if this becomes a priority. Minimizing fluoroscopy requires a conscious effort to learn a new skill set. For example, at our center, with the physician and staff focused on reducing unnecessary radiation, our radiation exposure has decreased by approximately 50 percent each year. Currently, for a typical AF ablation procedure, our fluoroscopy times are less than five minutes. With the fluoroscopy unit programmed to deliver the lowest dose possible (FL- EP setting on Siemens) with an extremely low pulse rate (three pulses/sec, “low fluoroscopy” is considered 15 p/s). With these settings, our typical AF patient is exposed to less than 10 mGy or 1 mSv. During this same period of time, our procedure times have continued to decrease dramatically. Our goal is to no longer require fluoroscopy for AF procedures within the next year and no longer wear lead.

In order to help implement a protocol for eliminating unnecessary radiation exposure, I have listed our approach to ALARA.

1. Make sure fluoroscopy is programmed at the very lowest setting possible. For our Siemens system, it is the “FL- EP” setting.
2. Turn your pulse rate down as low as possible. This is a process that takes time. Over the last three years, we have gone from 15 p/s to 7.5 p/s and then from 6 p/s to 4 p/s until we arrived at our current pulse rate of 3 p/s.
3. Learn to trust intracardiac echo and especially your 3D map. As you learn to create and trust accurate 3D maps, there is no longer a need for fluoroscopy, and your case times will significantly drop.
4. We do as much as possible in the AP view. In the LAO view, there is a longer attenuation path for the x-ray beam, which results in more radiation exposure. We also optimize the positioning of the x-ray tube/receptor and never use magnification or cine.
5. Maximize shielding at all levels.
6. Maximize your distance from the x-ray tube in order to take advantage of the inverse square law.
7. Track the radiation dose delivered with each case (mGy or mSv). Fluoroscopy times do not even begin to tell the radiation exposure. As you track your radiation exposure outcomes, your unnecessary exposure will go down significantly.

The concept of reducing fluoroscopy will also be highlighted at the upcoming AF Ablation Innovations conference next month, which I believe will be beneficial for clinicians of all experience levels. In addition to interactive lectures focused on this topic, the conference features a live ablation procedure performed without fluoroscopy by Dr. Vivek Reddy, whose experiences in this procedure will surely provide for an excellent presentation and discussion. To learn more about the conference please visit www.AfibInnovations.com.

I would like to thank our contributing authors for sharing their expertise in the manuscripts featured in this issue, and I welcome your continued manuscript submissions highlighting innovative experiences and techniques within the Journal.

References

  1. New York Times February 9, 2010 “FDA to Increase Oversight of Medical Radiation”.
  2. Europace 2006;8(6):443–448.
  3. Circulation 2004;110(19):3003–3010.
  4. Europace 2006;8(6):443–448.
  5. Health Risks from Exposure to Low Levels of Ionizing Radiation: BEIR VII – Committee to Assess Health Risks from Exposure to Low Levels of Ionizing Radiation, National Research Council ISBN: 978-0-309-09156-5, (2006).

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