title: Investigation of hemodynamics in an in vitro system simulating left ventricular support through the right subclavian artery using 4-dimensional flow magnetic resonance imaging.
abstract: OBJECTIVE
  Left ventricular assist devices are an important treatment option for patients with heart failure alter the hemodynamics in the heart and great vessels. Because in vivo magnetic resonance studies of patients with ventricular assist devices are not possible, in vitro models represent an important tool to investigate flow alterations caused by these systems. By using an in vitro magnetic resonance-compatible model that mimics physiologic conditions as close as possible, this work investigated the flow characteristics using 4-dimensional flow-sensitive magnetic resonance imaging of a left ventricular assist device with outflow via the right subclavian artery as commonly used in cardiothoracic surgery in the recent past.
  
  
  METHODS
  An in vitro model was developed consisting of an aorta with its supra-aortic branches connected to a left ventricular assist device simulating the pulsatile flow of the native failing heart. A second left ventricular assist device supplied the aorta with continuous flow via the right subclavian artery. Four-dimensional flow-sensitive magnetic resonance imaging was performed for different flow rates of the left ventricular assist device simulating the native heart and the left ventricular assist device providing the continuous flow. Flow characteristics were qualitatively and quantitatively evaluated in the entire vessel system.
  
  
  RESULTS
  Flow characteristics inside the aorta and its upper branching vessels revealed that the right subclavian artery and the right carotid artery were solely supported by the continuous-flow left ventricular assist device for all flow rates. The flow rates in the brain-supplying arteries are only marginally affected by different operating conditions. The qualitative analysis revealed only minor effects on the flow characteristics, such as weakly pronounced vortex flow caused by the retrograde flow via the brachiocephalic artery.
  
  
  CONCLUSIONS
  The results indicate that, despite the massive alterations in natural hemodynamics due to the retrograde flow via the right subclavian and brachiocephalic arteries, there are no drastic consequences on the flow in the brain-feeding arteries and the flow characteristics in the ascending and descending aortas. It may be beneficial to adjust the operating condition of the left ventricular assist device to the residual function of the failing heart.
authors.affiliation: Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Bern, Switzerland. Electronic address: bernd.jung@insel.ch.
authors.forename: Bernd
authors.initials: B
authors.lastname: Jung
authors.affiliation: Department of Radiology, Medical Physics, University Hospital, Freiburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Müller
authors.affiliation: Department of Radiology, Medical Physics, University Hospital, Freiburg, Germany.
authors.forename: Waltraud
authors.initials: W
authors.lastname: Buchenberg
authors.affiliation: Institute of Diagnostic, Interventional and Pediatric Radiology, University Hospital Bern, Bern, Switzerland.
authors.forename: Michael
authors.initials: M
authors.lastname: Ith
authors.affiliation: Department of Cardiovascular Surgery, University Hospital Bern, Bern, Switzerland.
authors.forename: David
authors.initials: D
authors.lastname: Reineke
authors.affiliation: Cardiovascular Surgery, Heart Center Freiburg University, Freiburg, Germany.
authors.forename: Friedhelm
authors.initials: F
authors.lastname: Beyersdorf
authors.affiliation: Cardiovascular Surgery, Heart Center Freiburg University, Freiburg, Germany.
authors.forename: Christoph
authors.initials: C
authors.lastname: Benk
mesh_terms: D006353:Heart-Assist Devices; D006439:Hemodynamics; D008279:Magnetic Resonance Imaging / Q000379:methods*; D008955:Models, Cardiovascular; D013348:Subclavian Artery / Q000502:physiology*
keywords: 4D flow MRI; LVAD; aortic hemodynamics; outflow graft