Impact Of An Automated Titration Algorithm On Battery Longevity In An Implantable Neurostimulation System For Treatment Of Chronic Heart Failure

Abstract

Background Autonomic Regulation Therapy (ART) using chronic vagus nerve stimulation (VNS) is a promising new therapy for patients with heart failure (HF) who remain symptomatic despite standard care. In the ANTHEM-HF Pilot Study, a therapeutic VNS intensity was successfully achieved in patients with HFrEF using manually-programmed VNS up-titration. In the ANTHEM-HF Pilot Study (NCT01823887), the mean stimulation parameters were 2.4 ± 0.6 mA amplitude, 5 Hz frequency, 250 µs pulse width, and 23% duty cycle. A TitrationAssist algorithm has been developed for automatically intensifying VNS in small increments to a programmable target and capable of adjustments using a hand-held programmer or magnet. While this algorithm has the potential of dramatically reducing the number and duration of clinic visits for VNS titration, the impact of implementing TitrationAssist on device longevity has not been determined. Methods Current draw was measured from 32 VITARIA pulse generators (LivaNova USA, Houston, USA) with TitrationAssist activated. Testing was performed with a 3000 Ω load at programmed stimulation settings of 250 µsec pulse width, pulse frequency of 5 or 10 Hz, output current of 2.0 or 3.0 mA, and duty cycle of 23% (nominal), 33%, and 50%. The measured data was used in a standard longevity estimate process to determine the minimum longevity reached by at least 95% of devices with 95% confidence. The design requirement for battery longevity was >5 years at 10 Hz / 2.5 mA / 23%. Results Current draw was successfully measured from all 32 pulse generators and used to calculate device longevity. Device longevity, expressed in years, is shown in the table, and exceeds the system longevity requirement. At the expected stimulation parameters of 2.0-3.0 mA amplitude, 5 Hz frequency, 250 µs pulse width, 23% duty cycle, device longevity is expected to be in the range of 7-9 years. Device longevity was not significantly affected by the activation of the TitrationAssist algorithm. Conclusions At the expected stimulation parameters, VITARIA pulse generator battery longevity was determined to be 7-9 years. This exceeds the design requirement and suggests that ART can be titrated using TitrationAssist and chronically delivered without frequent generator replacement. Autonomic Regulation Therapy (ART) using chronic vagus nerve stimulation (VNS) is a promising new therapy for patients with heart failure (HF) who remain symptomatic despite standard care. In the ANTHEM-HF Pilot Study, a therapeutic VNS intensity was successfully achieved in patients with HFrEF using manually-programmed VNS up-titration. In the ANTHEM-HF Pilot Study (NCT01823887), the mean stimulation parameters were 2.4 ± 0.6 mA amplitude, 5 Hz frequency, 250 µs pulse width, and 23% duty cycle. A TitrationAssist algorithm has been developed for automatically intensifying VNS in small increments to a programmable target and capable of adjustments using a hand-held programmer or magnet. While this algorithm has the potential of dramatically reducing the number and duration of clinic visits for VNS titration, the impact of implementing TitrationAssist on device longevity has not been determined. Current draw was measured from 32 VITARIA pulse generators (LivaNova USA, Houston, USA) with TitrationAssist activated. Testing was performed with a 3000 Ω load at programmed stimulation settings of 250 µsec pulse width, pulse frequency of 5 or 10 Hz, output current of 2.0 or 3.0 mA, and duty cycle of 23% (nominal), 33%, and 50%. The measured data was used in a standard longevity estimate process to determine the minimum longevity reached by at least 95% of devices with 95% confidence. The design requirement for battery longevity was >5 years at 10 Hz / 2.5 mA / 23%. Current draw was successfully measured from all 32 pulse generators and used to calculate device longevity. Device longevity, expressed in years, is shown in the table, and exceeds the system longevity requirement. At the expected stimulation parameters of 2.0-3.0 mA amplitude, 5 Hz frequency, 250 µs pulse width, 23% duty cycle, device longevity is expected to be in the range of 7-9 years. Device longevity was not significantly affected by the activation of the TitrationAssist algorithm. At the expected stimulation parameters, VITARIA pulse generator battery longevity was determined to be 7-9 years. This exceeds the design requirement and suggests that ART can be titrated using TitrationAssist and chronically delivered without frequent generator replacement.