Early experiences with tachycardia‐triggered vagus nerve stimulation using the AspireSR stimulator

Abstract

Many epilepsy patients treated with vagus nerve stimulation additionally use an “on‐demand” function, triggering an extra stimulation to terminate a seizure or diminish its severity. Nevertheless, a substantial number of patients are not able to actively trigger stimulations by use of a magnet, due to the absence of an aura or inability for voluntary actions in the early phase of a seizure. To address this need, a novel implantable pulse generator, the AspireSR VNS system, was developed to provide automated ictal stimulation triggered by a seizure‐detecting algorithm. We report our experience with three patients in assessing the functionality of ictal stimulation, illustrating the detection system in practice. Detection of ictal tachycardia and variable additional detections of physiological tachycardia depended on the individual seizure‐detecting algorithm settings.

Recent Advancement of Technologies and the Transition to New Concepts in Epilepsy Surgery

“…In addition to the Normal Mode and the Magnet Mode, the Model 106 (AspireSR) obtained the AutoStim Mode to automatically deliver an additional stimulation, triggered by a cardiac-based seizure-detection algorithm (SDA). [32][33][34][35][36] Thence, the closed-loop system has been added to the primary open-loop system. The Model 106 always monitors heart rate, and determines the baseline heart rate as a moving average of the instantaneous heart rate over the previous 5 minutes and the foreground heart rate as a moving average of the most recent 10 seconds.…”

Ictal heart rate changes and the effects of vagus nerve stimulation for patients with refractory epilepsy

“…Clinical research has shown that the AspireSR VNS system is effective in detecting IT and provides automated on-demand stimulation, and improves the sensitivity and specificity of ictal stimulations. 9 – 11 However, no studies have evaluated whether VNS therapy on patients with epilepsy who have ictal bradycardia (IB) or normal HR may be ineffective or less ineffective than on patients with IT. It is very important to screen out candidates who potentially will not benefit from VNS to avoid unnecessary, invasive procedures and to improve the overall clinical efficacy of VNS treatments.…”

“…Furthermore, the tolerability of additional tachycardia-based stimulation was good in this report, and two out of three patients showed an improvement in seizure frequency. 9 Hampel et al has reported a sensitivity of 92% and a specificity of 13.5% for the seizure detection algorithm in a single patient and has also reported a significant decrease in seizure duration as a result of closed-loop VNS with the AspireSR. 11 In addition, a prospective multicenter study of cardiac-based seizure detection to activate VNS demonstrated the ability to detect seizures based on cardiac changes that were as low as a 20% above the baseline HR with high sensitivity.…”

“…These manifestations include changes in HRV, IT, IB, atrioventricular block, and asystole. 13 The latest research has shown that patients with IT during seizures demonstrate good responses to VNS therapy, 9 – 11 yet, its mechanism of action in treating epileptic seizures remains unclear.…”

“…It has been shown that patients with epilepsy with IT during seizures have good responses to VNS therapy, 9 – 11 and its treatment mechanism may be related to a hypersensitive ABR. We presume that the treatment mechanism of VNS in patients with epilepsy with IT, IB, and normal HR during seizures all involve ABR with different sensitivities.…”