CHARLOTTESVILLE, Va., – A growing body of research continues to warn of the potential long-term effects of radiation exposure for patients and medical providers during such imaging procedures as x-rays and computed tomography (CT) 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,” says John D. Ferguson, MD, associate professor of cardiology in the UVA School of Medicine. The study, led by Ferguson, appears in the December 2009 issue of Circulation. “Cardiac interventions continue to evolve toward lower risk procedures, and this study is another huge step in that direction.”
More than two million Americans suffer from atrial fibrillation (AF), 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 AF 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 3D 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 in AF patients, 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 UVA 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,” says Brian Annex, MD, chief of the UVA 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,” Annex says.
“This procedure is currently being used in selected patients at UVA Medical Center while ongoing investigations are underway to establish the full spectrum of patients who we hope can receive this type of approach in the near future.”
Images of Patient Undergoing Catheter Ablation for an Abnormal Heart Rhythm Called Atrial Fibrillation Without Use of X-Ray Guidance
|Image A (above) shows a 3D MRI of the left atrium, one of the heart’s upper chambers. The tip of the ablation catheter appears in bright green, and the operator can follow the catheter’s movement on the computer screen. This catheter is used to treat (ablate) abnormal tissue in the heart. The red dots are the areas which have been treated.|
|Image B shows the ultrasound catheter in the heart. The heart’s inner walls appear in white and the blood is black. The catheter’s metal tip reflects the ultrasound and produces a white circle with a white cone shaped shadow behind it. It can be followed very easily. The catheter’s movement within the heart can be monitored in real time without the need for X-ray guidance.|
Sally H. Jones