title: Modelling the heart with the atrioventricular plane as a piston unit.
abstract: Medical imaging and clinical studies have proven that the heart pumps by means of minor outer volume changes and back-and-forth longitudinal movements in the atrioventricular (AV) region. The magnitude of AV-plane displacement has also shown to be a reliable index for diagnosis of heart failure. Despite this, AV-plane displacement is usually omitted from cardiovascular modelling. We present a lumped-parameter cardiac model in which the heart is described as a displacement pump with the AV plane functioning as a piston unit (AV piston). This unit is constructed of different upper and lower areas analogous with the difference in the atrial and ventricular cross-sections. The model output reproduces normal physiology, with a left ventricular pressure in the range of 8-130 mmHg, an atrial pressure of approximatly 9 mmHg, and an arterial pressure change between 75 mmHg and 130 mmHg. In addition, the model reproduces the direction of the main systolic and diastolic movements of the AV piston with realistic velocity magnitude (∼10 cm/s). Moreover, changes in the simulated systolic ventricular-contraction force influence diastolic filling, emphasizing the coupling between cardiac systolic and diastolic functions. The agreement between the simulation and normal physiology highlights the importance of myocardial longitudinal movements and of atrioventricular interactions in cardiac pumping.
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden. Electronic address: elira.maksuti@sth.kth.se.
authors.forename: Elira
authors.initials: E
authors.lastname: Maksuti
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Molecular Medicine and Surgery, Karolinska Institute, Stockholm, Sweden.
authors.forename: Anna
authors.initials: A
authors.lastname: Bjällmark
authors.affiliation: Department of Medical Engineering, School of Technology and Health, KTH Royal Institute of Technology, Stockholm, Sweden; Department of Physiology and Pharmacology, Karolinska Institute, Stockholm, Sweden.
authors.forename: Michael
authors.initials: M
authors.lastname: Broomé
mesh_terms: D001783:Blood Flow Velocity; D001794:Blood Pressure; D003198:Computer Simulation; D004452:Echocardiography; D006321:Heart / Q000502:physiology*; D006801:Humans; D008955:Models, Cardiovascular; D014741:Video Recording
keywords: Atrioventricular interaction; Bond graphs; Cardiac function; Cardiac model; Cardiac pumping; Longitudinal function