Letters to the Editor

In a recent letter to the editor in the Journal of Clinical Oncology, Hoecht, Rosenthal, Sancar, Behrens, and Hinkelbein (2002) described implantable cardiac defibrillator (ICD) malfunctions as a result of exposure to scatter radiation doses that totaled less than 2 Gy. Of interest was that the ICDs were not in the direct radiation therapy field when the incidents occurred. The ICDs in question had converted into “fallback mode, which has a fixed detection area and a fixed pace rate of 50/minutes ventricular sensing-ventricular pacing inhibition” (Hoecht et al., p. 2212). This was reproducible in only one specific manufacturer’s product. However, this unfortunate and potentially serious complication should not be overlooked.