title: Evaluation of a morphological filter in mean cardiac output determination: application to left ventricular assist devices.
abstract: A morphological filter (MF) is presented for the determination of beat-to-beat mean rotary left ventricular assist device (LVAD) flow rate, measured using an implanted flow probe. The performance of this non-linear filter was assessed using LVAD flow rate (QLVAD) data sets obtained from in silico and in vivo sources. The MF was compared with a third-order Butterworth filter (BWF) and a 10-s moving average filter (MAF). Performance was assessed by calculating the response time and steady state error across a range of heart rates and levels of noise. The response time of the MF was 3.5 times faster than the MAF, 0.5 s slower than the BWF, and had a steady state error of 2.61 %. It completely removed pulsatile signal components caused by residual ventricular function, and tracked sharp transient changes in QLVAD better than the BWF. The use of a two-stage MF improved the noise immunity compared to the single-stage MF. This study showed that the good performance characteristics of the non-linear MF make it a more suitable candidate for embedded real-time processing of QLVAD than linear filters.
authors.affiliation: Innovative Cardiovascular Engineering and Technology Laboratory, The Prince Charles Hospital, Brisbane, QLD, Australia. m.stevens2@uq.edu.au
authors.forename: Michael Charles
authors.initials: MC
authors.lastname: Stevens
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Bradley
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Wilson
authors.forename: David Glen
authors.initials: DG
authors.lastname: Mason
mesh_terms: D000465:Algorithms; D000818:Animals; D002302:Cardiac Output / Q000502:physiology*; D003198:Computer Simulation; D006339:Heart Rate / Q000502:physiology; D006353:Heart-Assist Devices; D017711:Nonlinear Dynamics; D012756:Sheep; D012815:Signal Processing, Computer-Assisted; D016277:Ventricular Function, Left / Q000502:physiology*