title: Sensorless cardiac phase detection for synchronized control of ventricular assist devices using nonlinear kernel regression model.
abstract: Recently, driving methods for synchronizing ventricular assist devices (VADs) with heart rhythm of patients suffering from severe heart failure have been receiving attention. Most of the conventional methods require implanting a sensor for measurement of a signal, such as electrocardiogram, to achieve synchronization. In general, implanting sensors into the cardiovascular system of the patients is undesirable in clinical situations. The objective of this study was to extract the heartbeat component without any additional sensors, and to synchronize the rotational speed of the VAD with this component. Although signals from the VAD such as the consumption current and the rotational speed are affected by heartbeat, these raw signals cannot be utilized directly in the heartbeat synchronization control methods because they are changed by not only the effect of heartbeat but also the change in the rotational speed itself. In this study, a nonlinear kernel regression model was adopted to estimate the instantaneous rotational speed from the raw signals. The heartbeat component was extracted by computing the estimation error of the model with parameters determined by using the signals when there was no effect of heartbeat. Validations were conducted on a mock circulatory system, and the heartbeat component was extracted well by the proposed method. Also, heartbeat synchronization control was achieved without any additional sensors in the test environment.
authors.affiliation: Graduate School of Engineering, Tohoku University, Sendai, Japan. hirohashi@yoshizawa.ecei.tohoku.ac.jp.
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Hirohashi
authors.affiliation: Faculty of Symbolic Systems Science, Fukushima University, Fukushima, Japan. a-tanaka@sss.fukushima-u.ac.jp.
authors.forename: Akira
authors.initials: A
authors.lastname: Tanaka
authors.affiliation: Cyberscience Center, Tohoku University, Sendai, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Yoshizawa
authors.affiliation: Graduate School of Engineering, Tohoku University, Sendai, Japan.
authors.forename: Norihiro
authors.initials: N
authors.lastname: Sugita
authors.affiliation: Graduate School of Engineering, Tohoku University, Sendai, Japan.
authors.forename: Makoto
authors.initials: M
authors.lastname: Abe
authors.affiliation: Graduate School of Engineering, Gunma University, Maebashi, Japan.
authors.forename: Tsuyoshi
authors.initials: T
authors.lastname: Kato
authors.affiliation: Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Shiraishi
authors.affiliation: Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Miura
authors.affiliation: Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
authors.forename: Tomoyuki
authors.initials: T
authors.lastname: Yambe
mesh_terms: D006321:Heart / Q000502:physiology*; D006333:Heart Failure / Q000628:therapy*; D006339:Heart Rate; D006353:Heart-Assist Devices; D006801:Humans; D008955:Models, Cardiovascular; D012044:Regression Analysis
keywords: Sensorless; Synchronized control; Ventricular assist device