Technical Notes & Surgical TechniquesNovel implantation of vagus nerve stimulator AspireSR pulse generator: Technical note

- AspireSR pulse generator uses ictal tachycardia to provide automatic stimulation for termination of seizures.
- Both methods for placement of AspireSR allow use of the most specific heartbeat detection without preoperative testing.
- These methods use electrocardiographic principles to ensure highest possible amplitude of cardiac electrical activity.
- Follow-up showed mean absolute difference in heartbeat detection between device and patient less than one beat per minute.

ObjectiveTo 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).MethodsUsing 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.ResultsUsing 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.ConclusionBoth 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.