Novel implantation of vagus nerve stimulator AspireSR pulse generator: Technical note

Objective To eliminate the need for preoperative evaluation required for the Aspire SR pulse generator and allow for minimum sensitivity settings, thereby providing the most accurate setting for cardiac-based seizure detection (CBSD). Methods Using intraoperative EKG (telemetry) and standard button electrode pads, the left arm (black) pad is moved over the VNS lead site in the neck and the left leg (red) pad is moved over the anticipated location of the pulse generator (three (3) cm lateral to the mid-sternum in the region between V₂ and V₃ in normal 12 lead EKG). After ensuring amplitude is > 0.4 mV, the generator is placed in a pocket at the target location via an anterior axillary incision. Anatomic localization is also described placing the pulse generator between the sternal border and midclavicular line, at the level of the 4th rib/intercostal space. Results Using EKG method a cohort of 56 patients, 55 (98.2%) achieved appropriate heartbeat detection at sensitivity of 1, while 1 (1.8%) was set at 2. Using anatomic method, all 34 patients (100%) achieved appropriate heartbeat detection at sensitivity of 1. These results were sustained at follow-up, with mean absolute differences between heart rate obtained from the AspireSR pulse generator and pulse oximeter < 1 beat across all tested positions. Conclusion Both methods provide a reliable, efficient, and durable way of placing the AspireSR pulse generator with excellent heartbeat detection using the most specific heartbeat detection setting.