Risk of occurrence of electromagnetic interference from the application of transcutaneous electrical nerve stimulation on the sensing function of implantable defibrillators.

BACKGROUND: Transcutaneous electrical nerve stimulation (TENS) is an established method for pain relief. But electrical TENS currents are also a source of electromagnetic interference (EMI). Thus, TENS is considered to be contraindicated in implantable cardioverter-defibrillator (ICD) patients. However, data might be outdated due to considerable advances in ICD and cardiac resynchronization therapy (CRT) filtering and noise protection algorithm technologies. The aim of this pilot safety study was to re-evaluate the safety of TENS in patients with modern ICDs. METHODS AND RESULTS: One hundred and seven patients equipped with 55 different models of ICD/CRT with defibrillators from 4 manufacturers underwent a standardized test protocol including TENS at the cervical spine and the thorax, at 2 stimulation modes-high-frequency TENS (80 Hz) and burst-mode TENS (2 Hz). Potential interference monitoring included continuous documentation of ECG Lead II, intracardiac electrograms and the marker channel. Electromagnetic interference was detected in 17 of 107 patients (15.9%). Most frequent were: interpretations as a premature ventricular beats (VS/S) in 15 patients (14%), noise reversion in 5 (4.6%) which resulted in temporary asynchronous pacing in 3 (2.8%), interpretation as ventricular tachycardia/ventricular fibrillation in 2 (1.9%), and premature atrial beat in 2 (1.9%) patients. Electromagnetic interference occurrence was influenced by position (chest, P < 0.01), higher current intensity (P < 0.01), and manufacturer (P = 0.012). CONCLUSION: Overall, only intermittent and minor EMI were detected. Prior to the use of TENS in patients with ICDs, they should undergo testing under the supervision of a cardiac device specialist.

P-wave detection performance of the BioMonitor III, Confirm Rx and Reveal Linq implantable loop recorders.

INTRODUCTION: Rhythm interpretation of EGMs recorded by implantable loop recorders (ILRs) is facilitated in cases when p-waves are visible. The three most commonly used ILRs (BioMonitor III, Confirm RX and Reveal Linq) vary in size, electrode placement and filter algorithms. Therefore, p-wave visibility and amplitude on EGM may vary according to the implanted device. MATERIAL AND METHODS: Consecutive patients were included after ILR implantation. P-wave visibility and amplitude were evaluated in sinus rhythm on 30-s EGMs with standard resolution (25 mm/mV for Biotronik and St. Jude, 30 mm/mV for Medtronic) and after maximum magnification. Additionally, baseline characteristics and p-wave amplitude in lead II on the surface-ECG were documented. RESULTS: 148 patients with either BioMonitor III (n = 48), Confirm Rx (n = 51) or Reveal Linq (n = 49) ILRs were included. With standard resolution, p-waves were visible in 40 patients (83%) implanted with BioMonitor III, 36 patients (71%) with Confirm Rx and in 35 patients (71%) with Reveal Linq ILRs (p = 0.267). After maximum magnification, p-waves could not be identified in 6 patients with Confirm Rx ILR (12%) and 1 patient in both BioMonitor III and Reveal Linq ILR (2%; p = 0.051). The Biomonitor III showed higher p-wave amplitudes compared to the Confirm Rx (0.050 mV (0.040-0.070) vs. 0.030 mV (0.020-0.040); p < 0.001) and the Reveal Linq ILR (0.050 mV (0.040-0.070) vs. 0.030 mV (0.020-0.040); p < 0.001). CONCLUSION: P-wave amplitudes were higher in patients with Biomonitor III. This did not lead to higher p-wave visibility compared to the Confirm RX ILR or the Reveal Linq ILR.