Extravascular implantable cardioverter and leadless pacemaker interactions

Abstract Background Traditional cardiac pacing and defibrillation devices rely on leads connected to a subcutaneous pulse generator, which can result in complications such as vascular damage, infection, or lead failure. Advances in technology have led to the development of leadless pacemakers, which combine the battery, circuitry, and electrodes into a single self-contained unit, and extravascular implantable cardioverter-defibrillators (ICDs), which position electrodes outside the vasculature. These innovations offer promising alternatives for patients requiring both defibrillation and pacing, particularly those unable or unwilling to accommodate traditional leads. However, the interactions between extravascular ICDs and leadless pacemakers remain largely unexplored and currently lack regulatory approval for combined use. Objective This study evaluates the interactions between leadless pacemakers and extravascular ICDs to assess their simultaneous operation. Methods In-silico simulations, saline-tank experiments, and Monte Carlo simulations were conducted to evaluate device interactions, focusing on ventricular fibrillation (VF) detection during pacing conditions. Results VF detection was unaffected by pacing pulse widths ≤0.24 ms, with a pacing pulse-to-VF amplitude ratio of ≤2 considered safe. Wider pulse widths or higher outputs progressively increased the risk of VF undersensing. Experiments confirmed that pacing pulses ≤3V and ≤0.24 ms minimally impacted VF detection. Proximty of device affected pacing pulse amplitude sensed by the ICD, but pacemaker orientation did not. Monte Carlo simulations indicated a 0-4% probability of undesired interactions under clinically relevant conditions. Conclusion Extravascular ICDs and leadless pacemakers may safely coexist with a low observed risk of VF undersensing in our study. Further clinical studies are needed to confirm these findings.