title: Effect of high altitude exposure on the hemodynamics of the bidirectional Glenn physiology: modeling incremented pulmonary vascular resistance and heart rate.
abstract: The considerable blood mixing in the bidirectional Glenn (BDG) physiology further limits the capacity of the single working ventricle to pump enough oxygenated blood to the circulatory system. This condition is exacerbated under severe conditions such as physical activity or high altitude. In this study, the effect of high altitude exposure on hemodynamics and ventricular function of the BDG physiology is investigated. For this purpose, a mathematical approach based on a lumped parameter model was developed to model the BDG circulation. Catheterization data from 39 BDG patients at stabilized oxygen conditions was used to determine baseline flows and pressures for the model. The effect of high altitude exposure was modeled by increasing the pulmonary vascular resistance (PVR) and heart rate (HR) in increments up to 80% and 40%, respectively. The resulting differences in vascular flows, pressures and ventricular function parameters were analyzed. By simultaneously increasing PVR and HR, significant changes (p <0.05) were observed in cardiac index (11% increase at an 80% PVR and 40% HR increase) and pulmonary flow (26% decrease at an 80% PVR and 40% HR increase). Significant increase in mean systemic pressure (9%) was observed at 80% PVR (40% HR) increase. The results show that the poor ventricular function fails to overcome the increased preload and implied low oxygenation in BDG patients at higher altitudes, especially for those with high baseline PVRs. The presented mathematical model provides a framework to estimate the hemodynamic performance of BDG patients at different PVR increments.
authors.affiliation: Group of Biomedical Engineering, Universidad de los Andes, Bogotá, Colombia.
authors.forename: Carolina
authors.initials: C
authors.lastname: Vallecilla
authors.affiliation: Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Dr., Atlanta, GA 30332, USA.
authors.forename: Reza H
authors.initials: RH
authors.lastname: Khiabani
authors.affiliation: Department of Cardiovascular Surgery, Fundación Cardioinfantil, Bogotá, Colombia.
authors.forename: Néstor
authors.initials: N
authors.lastname: Sandoval
authors.affiliation: Division of Cardiology, Children׳s Hospital of Philadelphia, Philadelphia, PA, USA.
authors.forename: Mark
authors.initials: M
authors.lastname: Fogel
authors.affiliation: Group of Biomedical Engineering, Universidad de los Andes, Bogotá, Colombia; Research Department, Fundación Cardioinfantil, Bogotá, Colombia.
authors.forename: Juan Carlos
authors.initials: JC
authors.lastname: Briceño
authors.affiliation: Wallace H Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 313 Ferst Dr., Atlanta, GA 30332, USA. Electronic address: ajit.yoganathan@bme.gatech.edu.
authors.forename: Ajit P
authors.initials: AP
authors.lastname: Yoganathan
mesh_terms: D000531:Altitude; D006328:Cardiac Catheterization; D002675:Child, Preschool; D015331:Cohort Studies; D018729:Fontan Procedure / Q000379:methods; D006330:Heart Defects, Congenital / Q000503:physiopathology*; D006339:Heart Rate; D006352:Heart Ventricles / Q000503:physiopathology; D006439:Hemodynamics; D006801:Humans; D007223:Infant; D008955:Models, Cardiovascular; D010100:Oxygen / Q000737:chemistry; D014655:Vascular Resistance / Q000502:physiology*
chemical_list: D010100:Oxygen
keywords: Congenital heart disease; Fontan; Mathematical modeling; Pulmonary vascular resistance; Univentricular heart