January 13, 2010 — A growing body of research continues to warn of the potentially harmful long-term effects of radiation exposure for patients and medical providers during such imaging procedures as X-rays and computed tomography scans, both of which are traditionally used with certain heart procedures.
Now researchers at the University of Virginia Health System have developed a promising X-ray-free technique to treat a common heart disorder called atrial fibrillation – a breakthrough that could all but eliminate radiation exposure to patients and their medical providers.
"One of the most exciting things about our research is the direct impact on patient care and safety," said Dr. John D. Ferguson, associate professor of cardiology in the U.Va. School of Medicine. The study, led by Ferguson, appears in the December issue of Circulation. "Cardiac interventions continue to evolve toward lower-risk procedures, and this study is another huge step in that direction."
More than 2 million Americans suffer from atrial fibrillation, a condition characterized by an irregular heart rate that can lead to weakness, blood clotting and even stroke.
In order to regulate the heart's rhythm, physicians commonly perform a catheter ablation – a procedure in which doctors use X-ray fluoroscopy to guide a catheter, or flexible tube, to the affected area of the heart. The procedure typically lasts three to four hours, leaving patients and medical providers exposed to significant radiation.
But Ferguson's research team has developed and successfully tested a new technique to perform catheter ablation of atrial fibrillation using an ultrasound catheter (intracardiac echocardiography) and electroanatomic mapping without the use of X-ray fluoroscopy for the entire procedure.
Using an ultrasound catheter within the heart, physicians can obtain high-resolution images of the heart and other key anatomic structures. This provides complete visualization at all times of the catheter's location, allowing physicians to steer the tube to affected target areas while avoiding injury to key cardiac structures.
The novel technique also uses a computer mapping system, which displays in 3-D the image of the heart and the catheter's location and allows physicians to record precise location points along the catheter's path.
And to further eliminate radiation exposure, the new technique uses cardiac MRI instead of CT scans for all required imaging prior to the procedure. Researchers performed the novel technique in a pilot study on 21 consecutive patients referred to the U.Va. Atrial Fibrillation Center.
"Larger studies are needed to confirm the safety of the procedure, but the concept that you can perform complex electrophysiology procedures without any use of X-ray is outstanding," said Dr. Brian Annex, chief of the U.Va. Division of Cardiology.
"This research is a ground-breaking step in our efforts to minimize radiation exposure to all patients. This is a major goal that is especially critical to those most vulnerable – patients who would otherwise require excessive radiation due to weight, women of child-bearing potential, and of course children and younger adults,' he said.
"This procedure is currently being used in selected patients at U.Va. Medical Center while ongoing investigations are under way to establish the full spectrum of patients who we hope can receive this type of approach in the near future."