Abstract
Purpose :
A left ventricular assist device (LVAD) is an implantable cardiac pump that uses a magnetically-levitating rotor to pump blood into circulation in patients with congestive heart failure. In a patient with an implanted LVAD, the high-frequency pump rotation introduces significant interference in electroretinography (ERG) recordings. We evaluate filtering methods to improve ERG quality in the presence of LVAD interference.
Methods :
A patient with an implanted LVAD was referred for ERG testing on suspicion of a retinal dystrophy. Full-field ERG (ffERG) and pattern ERG (pERG) were performed according to ISCEV standards. Recordings were acquired in full-bandwidth mode and again in low-bandwidth mode. Digital low-pass and band-stop filtering were performed to mitigate ERG interference. Post-processing was also evaluated in a control subject with no implanted device.
Results :
High-frequency interference corresponding to the speed of the pump was present in all recordings (Fig. 1). When applied in post-processing, both low-pass and band-stop filters suppressed the interference and presented readable ERGs without affecting peak times or amplitudes (Fig. 2). By contrast, when recording in low-BW mode, the filter drop-off was not steep enough to remove the interference and peak delays were introduced that could not be readily corrected.
Conclusions :
LVAD interference in ERGs can be successfully removed using simple digital filters. If post-hoc data processing capabilities are unavailable, a large amount of interference can be suppressed with a lower acquisition bandwidth and additional recordings of each stimulus response.
This abstract was presented at the 2022 ARVO Annual Meeting, held in Denver, CO, May 1-4, 2022, and virtually.