Schur Rebecca M, Eck Brendan L, Yuan Alex
Cole Eye Institute, Cleveland Clinic, Cleveland, OH, USA.
Department of Ophthalmic Research, Lerner Research Institute, Cleveland Clinic, Cleveland, OH, USA.
Doc Ophthalmol. 2022 Apr;144(2):137-145. doi: 10.1007/s10633-022-09865-z. Epub 2022 Mar 5.
A left ventricular assist device (LVAD) is an implantable cardiac pump that uses a magnetically-levitating rotor to pump blood into circulation for patients with congestive heart failure. The continuous high-frequency motion of the pump can cause significant interference in electroretinography (ERG) recordings. We evaluate filtering methods to improve ERG quality in the presence of LVAD interference.
A patient with an implanted LVAD was referred to our clinic 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 once 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.
High-frequency interference was present in all ERG recordings and corresponded to the speed settings of the pump. 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. By contrast, when recording in low-bandwidth mode, the filter drop-off was not steep enough to completely remove the interference and peak delays were introduced that could not be readily corrected.
LVAD interference in ERG waveforms can be successfully removed using simple digital filters. If post hoc data processing capabilities are unavailable, a large amount of interference can be removed by narrowing the acquisition bandwidth and averaging additional repeats of each stimulus response.
左心室辅助装置（LVAD）是一种可植入式心脏泵，它利用磁悬浮转子为充血性心力衰竭患者将血液泵入循环系统。该泵的持续高频运动会对视网膜电图（ERG）记录造成显著干扰。我们评估滤波方法，以在存在LVAD干扰的情况下提高ERG质量。
一名植入LVAD的患者因疑似视网膜营养不良被转诊至我们的诊所进行ERG检测。根据国际临床视觉电生理学会（ISCEV）标准进行全视野ERG（ffERG）和图形ERG（pERG）检查。记录在全带宽模式下采集一次，然后在低带宽模式下再次采集。进行数字低通和带阻滤波以减轻ERG干扰。还对一名未植入装置的对照受试者进行了后处理评估。
所有ERG记录中均存在高频干扰，且与泵的速度设置相对应。在进行后处理时，低通和带阻滤波器均能抑制干扰，并呈现出可读的ERG，且不影响峰值时间或幅度。相比之下，在低带宽模式下记录时，滤波器的截止不够陡峭，无法完全消除干扰，并且引入了无法轻易校正的峰值延迟。
使用简单的数字滤波器可以成功消除ERG波形中的LVAD干扰。如果没有事后数据处理能力，可以通过缩小采集带宽并对每个刺激反应的额外重复进行平均来消除大量干扰。
