Catheter-Tracking With Non-Fluoro Sensor Reduces Radiation in Atrial Ablations

June 20, 2014

NICE, FRANCE — The use of a visualization and navigation system, MediGuide (St Jude Medical), capable of displaying the position of an ablation catheter on prerecorded fluoroscopic images, significantly limits the total duration of fluoroscopy and radiation exposure during ablation of atrial flutter and atrial fibrillation[1].

The use of the system reduced the total fluoroscopy time 91% in patients undergoing ablation of atrial flutter and 42% for patients undergoing atrial fibrillation compared with standard ablation procedures. In both the atrial-flutter and atrial-fibrillation patients, the use of the MediGuide system did not result in a significant difference in total procedure times.

"The problem with the ablation procedures is that we need fluoroscopy to position the catheters, and there is always a risk of radiation exposure, both to the patient and to the physician and staff," senior investigator Dr Laurent Macle (Montreal Heart Institute, QC) told heartwire at CardioStim 2014 , where he presented the results.

With the MediGuide system, explained Macle, physicians use an acquired image—they press on the pedal and see a prerecorded fluoroscopic image on their monitors—without using any fluoroscopy. There is a sensor in the tip of the catheter that allows it to be overlaid on the acquired fluoroscopic image and be seen.

"It's a real-time acquisition of the fluoroscopy image, and [with the sensor] you can see your catheter moving inside," said Macle. "You can maneuver it inside the heart without using any fluoroscopy."

System Is Safe, Feasible

Dr Laurent Macle

To test the feasibility of the MediGuide system, Macle and colleagues compared the procedural data among 90 patients treated at their center for atrial flutter and 44 patients treated for atrial fibrillation. Of the flutter patients, 48 were treated using the MediGuide system and 42 using standard ablation with fluoroscopy. For those with fibrillation, there was an equal split among those treated with standard ablation and those treated using the MediGuide system. Baseline characteristics between the MediGuide-treated patients and those treated with standard ablation were similar.

Among the atrial-flutter patients, total procedural time was 89 minutes in the MediGuide arm and 82 minutes in conventional-ablation arm, a nonsignificant difference. Total fluoroscopy time, however, was 0.8 minutes among those using the acquired fluoroscopy images with MediGuide and 9.9 minutes for those undergoing conventional ablation. This translated into a significant reduction in radiation exposure.

Similarly, there was also a significant reduction in fluoroscopy time and radiation exposure among the atrial-fibrillation patients treated with the MediGuide system compared with those treated with conventional ablation.

Procedural Data: Atrial Flutter and Fibrillation With and Without MediGuide

Outcome MediGuide ablation Conventional ablation p
Atrial flutter      
Procedure time (min) 89.5 82.5 NS
Total fluoroscopy time (min) 0.8 9.9 <0.0001
Radiation exposure (µGy.m2) 1096 3051 <0.0001
Atrial fibrillation      
Procedure time (min) 168.5 159.5 NS
Total fluoroscopy time (min) 12.5 21.5 <0.0001
Radiation exposure (µGy.m2) 1107 2835 0.0001

To heartwire , Macle said there is a global worry about radiation exposure, especially for interventional cardiologists. Cancers, not to mention orthopedic issues that arise from wearing lead vests for long interventional procedures, especially ablations, are worrisome.

"We also wanted to see where the system was having an impact," he said. What this means is that the use of fluoroscopy was significantly reduced in atrial flutter in positioning the catheter within the coronary sinus, creating the geometry of the right atrium, and ablating the cavotricuspid isthmus. With atrial fibrillation, the MediGuide system had the largest impact in reducing fluoroscopy used in preparation for the procedure.

"The system is much more powerful for flutter than for fib right now," he said. "You still need some fluoroscopy for atrial fibrillation." He suspects, however, that as physicians get better at using the system for atrial-fibrillation ablations, the use of fluoroscopy could be reduced further.

Macle reports consulting fees and research grants from St Jude Medical.

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