A case report of an unusual cause of increased impedance after generator exchange

Remote monitoring has emerged as a complement to in-person care for patient with cardiac implantable electronic devices (CIEDs). It provides the care team with information about device integrity, programming issues, or other medical data (i.e. arrhythmias) and since 2015 has been recognized as a part of standard management by the Heart and Rhythm Society for all patients with CIEDs. However, while it can provide invaluable information to providers, the volume of generated data can increase the risk of oversight. We present a novel case of apparent device malfunction that on closer scrutiny was obvious, but provides a lesson in the mechanisms by which data can be artifactual.

A 62-year-old male presented after his cardiac resynchronization therapy-defibrillator (CRT-D) alerted him that his device was at an elective replacement interval (ERI). He underwent an uncomplicated generator exchange; however, 2 weeks later, a remote alert showed that his device was at ERI and all impedances were above the upper limit. Device interrogation the following day demonstrated that the new device was functioning appropriately and his home monitor had in fact paired with his old generator. He obtained a new home monitor, and subsequent remote transmissions have demonstrated that his device is functioning appropriately.

This case demonstrates the importance of careful review of details from home-monitoring data. While concerning for device malfunction, there could be alternative causes when alerts are generated by remote monitoring. To our knowledge, this is the first report of this mechanism of alert via a home-monitoring device and should be considered when reviewing unusual remote download data.