title: Cavopulmonary assist for the univentricular Fontan circulation: von Kármán viscous impeller pump.
abstract: OBJECTIVE
  In a univentricular Fontan circulation, modest augmentation of existing cavopulmonary pressure head (2-5 mm Hg) would reduce systemic venous pressure, increase ventricular filling, and thus substantially improve circulatory status. An ideal means of providing mechanical cavopulmonary support does not exist. We hypothesized that a viscous impeller pump, based on the von Kármán viscous pump principle, is optimal for this role.
  
  
  METHODS
  A 3-dimensional computational model of the total cavopulmonary connection was created. The impeller was represented as a smooth 2-sided conical actuator disk with rotation in the vena caval axis. Flow was modeled under 3 conditions: (1) passive flow with no disc; (2) passive flow with a nonrotating disk, and (3) induced flow with disc rotation (0-5K rpm). Flow patterns and hydraulic performance were examined for each case. Hydraulic performance for a vaned impeller was assessed by measuring pressure increase and induced flow over 0 to 7K rpm in a laboratory mock loop.
  
  
  RESULTS
  A nonrotating actuator disc stabilized cavopulmonary flow, reducing power loss by 88%. Disk rotation (from baseline dynamic flow of 4.4 L/min) resulted in a pressure increase of 0.03 mm Hg. A further increase in pressure of 5 to 20 mm Hg and 0 to 5 L/min flow was obtained with a vaned impeller at 0 to 7K rpm in a laboratory mock loop.
  
  
  CONCLUSIONS
  A single viscous impeller pump stabilizes and augments cavopulmonary flow in 4 directions, in the desired pressure range, without venous pathway obstruction. A viscous impeller pump applies to the existing staged protocol as a temporary bridge-to-recovery or -transplant in established univentricular Fontan circulations and may enable compressed palliation of single ventricle without the need for intermediary surgical staging or use of a systemic-to-pulmonary arterial shunt.
authors.affiliation: Section of Cardiothoracic Surgery, Department of Surgery, Indiana University School of Medicine and James Whitcomb Riley Hospital for Children, Indianapolis, Ind 46202, USA. rodefeld@iupui.edu
authors.forename: Mark D
authors.initials: MD
authors.lastname: Rodefeld
authors.forename: Brandon
authors.initials: B
authors.lastname: Coats
authors.forename: Travis
authors.initials: T
authors.lastname: Fisher
authors.forename: Guruprasad A
authors.initials: GA
authors.lastname: Giridharan
authors.forename: Jun
authors.initials: J
authors.lastname: Chen
authors.forename: John W
authors.initials: JW
authors.lastname: Brown
authors.forename: Steven H
authors.initials: SH
authors.lastname: Frankel
mesh_terms: D001794:Blood Pressure; D003198:Computer Simulation; D018729:Fontan Procedure / Q000009:adverse effects / Q000295:instrumentation*; D018610:Heart Bypass, Right / Q000009:adverse effects / Q000295:instrumentation*; D006330:Heart Defects, Congenital / Q000503:physiopathology / Q000601:surgery*; D006353:Heart-Assist Devices; D006439:Hemodynamics; D018056:Hemorheology; D006801:Humans; D008955:Models, Cardiovascular; D011474:Prosthesis Design; D012039:Regional Blood Flow; D013314:Stress, Mechanical