Influence of HeartMate 3™ on Bispectral Index™ monitor: a retrospective observational study

Electroencephalogram-derived monitors are affected by various artifacts. HeartMate 3™ operates at frequency bands that overlap with those used for calculating the electromyographic index (EMG) and bispectral index (BIS) on the Bispectral Index™ monitor. This study investigated whether HeartMate 3 elevates these values, a change not predicted with HeartMate II™. This retrospective observational study included data from patients who underwent HeartMate 3 or II implantation between April 2008 and December 2023 as extracted from our institutional database. Patient-wise median EMG and BIS were compared between the pre-LVAD period (from the start of surgery to initiation of cardiopulmonary bypass) and the post-LVAD period (from the end of cardiopulmonary bypass to end of surgery). Data were obtained from 33 and 43 patients who underwent HeartMate 3 and HeartMate II implantation, respectively. Patients with HeartMate 3 implantation showed significant elevation in the EMG (pre-LVAD, mean ± standard deviation, 26.1 ± 1.0 dB; post-LVAD, 39.5 ± 2.8 dB; P < 0.001) without a significant change in the BIS (pre-LVAD, 44.5 ± 8.1; post-LVAD, 45.5 ± 7.1; P = 0.35). In contrast, patients with HeartMate II implantation did not show significant changes in either the EMG (pre-LVAD, 26.1 ± 1.2 dB; post-LVAD, 27.1 ± 4.1 dB; P = 0.16) or BIS (pre-LVAD, 45.1 ± 9.2; post-LVAD, 43.0 ± 8.1; P = 0.071). HeartMate 3 significantly elevates EMG. Anesthesiologists should be aware of this to appropriately interpret EMG elevation in patients with HeartMate 3.Trial registration: Japan Registry for Clinical Trials identifier: jRCT1030230549 (date of registration: January 10, 2024.