title: Characterization of left ventricle function by analysis of pressure responses to steps in rotational speed of the Hemopump.
abstract: Optimizing the procedure of weaning the left ventricle from a left ventricular assist device requires the determination of the momentaneous condition of the left ventricle. In sheep, a method was developed to momentaneously quantify the left ventricular condition. The left ventricular pump condition was quantified by the time-varying parameters elastance and resistance. They were determined from perturbations in the left ventricular pressure of two subsequent beats induced by changes in flow of the assist device. The end-diastolic volume of the ventricle was estimated without directly measuring ventricular volume. Maximum elastance and resistance were 201.3 +/- 32.7 [Pa/ml] and 12.3 +/- 1.6 [Pa.s/ml], respectively (mean +/- SE). The ventricular time constant, defined by the ratio of resistance of elastance, was 84.6 +/- 17.1 [ms] (mean +/- SE).
authors.affiliation: Institute for Biomedical Technology, University of Twente, Enschede, The Netherlands.
authors.forename: E E
authors.initials: EE
authors.lastname: Kunst
authors.forename: J A
authors.initials: JA
authors.lastname: Van Alsté
authors.forename: T
authors.initials: T
authors.lastname: Arts
authors.forename: H B
authors.initials: HB
authors.lastname: Boom
mesh_terms: D000818:Animals; D004548:Elasticity; D006353:Heart-Assist Devices; D011312:Pressure; D012756:Sheep; D016277:Ventricular Function, Left