The sensitivity of ECG contamination to surgical implantation site in brain computer interfaces

Abstract

Background: Brain sensing devices are approved today for Parkinson's, essential tremor, and epilepsy therapies. Clinical decisions for implants are often influenced by the premise that patients will benefit from using sensing technology. However, artifacts, such as ECG contamination, can render such treatments unreliable. Therefore, clinicians need to understand how surgical decisions may affect artifact probability. Objectives: Investigate neural signal contamination with ECG activity in sensing enabled neurostimulation systems, and in particular clinical choices such as implant location that impact signal fidelity. Methods: Electric field modeling and empirical signals from 85 patients were used to investigate the relationship between implant location and ECG contamination. Results: The impact on neural recordings depends on the difference between ECG signal and noise floor of the electrophysiological recording. Empirically, we demonstrate that severe ECG contamination was more than 3.2x higher in left-sided subclavicular implants (48.3%), when compared to right-sided implants (15.3%). Cranial implants did not show ECG contamination. Conclusions: Given the relative frequency of corrupted neural signals, we conclude that implant location will impact the ability of brain sensing devices to be used for "closed-loop" algorithms. Clinical adjustments such as implant location can significantly affect signal integrity and need consideration.

Stimulation related artifacts and a multipurpose template-based offline removal solution for a novel sensing-enabled deep brain stimulation device

“…We demonstrate that sensing LFP signals when stimulation is OFF is not equivalent to sensing when stimulation is ON, which has important implications for both clinical and research applications. Similar to other reports [31,32], simply enabling stimulation (even without delivered current, i.e. the ON-0mA state) introduced artifact not observed when stimulation was OFF.…”

“…ECG artifact has been similarly reported by other groups [31,32], more commonly when the IPG was implanted in the left chest wall [31]. Susceptibility to ECG, as with the PC+S, is likely due to possible insufficiency of connector seals and the use of passive recharge after stimulation, which increases the duration the electrodes are connected to the case for recharging [27].…”

“…QRS interpolation was a modified version of an online repository script for processing signals collected from the Percept [31]. This method identifies the location of QRS complexes, and the artifact is removed by interpolation, where the QRS complex is replaced by the signal immediately preceding and immediately following the identified QRS.…”

“…Recently, the Medtronic Percept PC became the first FDA approved device with the capability to sense LFPs during stimulation [29]. Preliminary reports have highlighted the presence of ECG artifacts, particularly when stimulation is turned ON [31,32] (ON is a device status setting, and can be configured to deliver no current if amplitude is set to 0 mA). Other sources of artifact included movement artifact and those caused by turning stimulation OFF or ON.…”

“…Artifacts caused by ramping (changing stimulation amplitude), as has been seen with the RC+S [27], have not been previously characterized. Two previous studies (pre-print) have noted the presence of ON-stimulation artifact [31,32] and proposed methods for artifact removal (focusing on ECG), though there has not been a direct comparison of multiple methods. Nor has there been a comprehensive comparison of the LFP signal properties recorded when stimulation is ON versus OFF after artifact removal.…”