ORLANDO, FLA. — New data suggest that product labeling stating that capsule endoscopy is contraindicated in patients with implantable pacemakers or defibrillators may be unnecessary, Manish S. Patel, M.D., reported at the annual meeting of the American College of Gastroenterology.
The scant data that are available do not support the contraindication. In several case series, no complications or loss of images have been reported in 18 patients with either implantable pacemakers or implantable cardioverter defibrillators (ICDs) who underwent capsule endoscopy, noted Dr. Patel, of Eastern Virginia Medical School, Norfolk.
The basis for the contraindication stems from concern that the 100- to 472-kHz radiofrequency band used by the PillCam SB capsule (formerly called the M2A capsule) might interfere with the operation of pacemakers and ICDs, which use the 100- to 175-kHz band.
Electromagnetic interference from the environment has the potential to inhibit pacing, trigger inappropriate pacing, cause a spurious ICD discharge, cause physical damage to the device'scircuitry, and reset the device to a different mode, possibly causing asynchrony and hemodynamic instability.
The number of people in the United States who have implantable pacemakers is expected to rise from about 2·4 million in 2004 to 3·2 million in 2008. Similarly, the number of individuals with implantable cardioverter defibrillators (ICDs) may rise from 460,000 in 2004 to 1 million in 2008.
Dr. Patel and his colleagues tested two pacemakers (AT501 and KDR901) and one ICD (7274 Marquis DR) manufactured by Medtronic Inc. and one pacemaker (1296 Insignia) and one ICD (A155 Vitality AVT) made by Guidant Corp. Together, the five devices represent 80% of the U.S. and world market for implantable pacemakers and ICDs, Dr. Patel said.
The investigators placed each device in an electrode gel bath at distances of 2, 6, 12, and 18 cm away from a PillCam SB capsule in a random sequence in three 30-second trials at each distance. In a separate set of similar trials, the pacemakers and defibrillators were attached to standard unipolar and bipolar pacing and defibrillation leads. During each set of trials, Dr. Patel and his associates varied the output of each device from a “nominal” to its most sensitive setting at each distance.
An electrophysiologist who was blinded to all of the test parameters did not detect any abnormalities in atrial or ventricular electrograms recorded from a Virtual Interactive Patient (model 9595, Medtronic) during any trial.
“This study shows that there is no interaction between capsule endoscopy and pacemakers and defibrillators, which is consistent with clinical observational reports,” Dr. Patel said.