title: The looped heart does not save energy by maintaining the momentum of blood flowing in the ventricle.
abstract: Previous studies suggested that the reconstruction or maintenance of physiological blood flow paths in the heart is important to obtain a good outcome following cardiac surgery, but this concept has no established theoretical foundation. We developed a multiscale, multiphysics heart simulator, based on the finite element method, and compared the hemodynamics of ventricles with physiological and nonphysiological flow paths. We found that the physiological flow path did not have an energy-saving effect but facilitated the separation of the outflow and inflow paths, so avoiding any mixing of the blood. The work performed by the ventricular wall was comparable at slower and faster heart rates (physiological vs. nonphysiological, 0.864 vs. 0.874 J, heart rate = 60 beats/min; and 0.599 vs. 0.590 J, heart rate = 100 beats/min), indicating that chiral asymmetry of the flow paths in the mammalian heart has minimal functional merit. At lower heart rates, the blood coming in the first beat was cleared almost completely by the ninth beat in both models. However, at high heart rates, such complete clearance was observed only in the physiological model, whereas 27.0% of blood remained in the nonphysiological model. This multiscale heart simulator provided detailed information on the cardiac mechanics and flow dynamics and could be a useful tool in cardiac physiology.
authors.affiliation: Department of Human and Engineered Environmental Studies, Graduate School of Frontier Sciences, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba, Japan. nabe@sml.k.u-tokyo.ac.jp
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Watanabe
authors.forename: Seiryo
authors.initials: S
authors.lastname: Sugiura
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Hisada
mesh_terms: D003198:Computer Simulation; D003326:Coronary Circulation; D004734:Energy Metabolism; D020342:Finite Element Analysis; D006339:Heart Rate; D006352:Heart Ventricles / Q000033:anatomy & histology; D006439:Hemodynamics; D006801:Humans; D008953:Models, Anatomic; D008955:Models, Cardiovascular; D012039:Regional Blood Flow; D013314:Stress, Mechanical; D016277:Ventricular Function, Left / Q000502:physiology*; D017725:Ventricular Pressure