title: Microcirculatory alterations after orthotopic pig-to-baboon heart transplantation.
abstract: BACKGROUND
  Whilst macrohemodynamic function of porcine xenografts transplanted into baboons has been assessed perioperatively, the ability of the xenograft to maintain systemic microcirculatory perfusion has not been investigated after pig-to-baboon xenotransplantation so far.
  
  
  METHODS
  We investigated the sublingual microcirculation of six baboons undergoing orthotopic transplantation of hCD46-transgenic pig hearts using orthogonal polarization spectral imaging. Microvascular measurements were performed after induction of anesthesia, in the early phase of cardiopulmonary bypass (CPB), during reperfusion of the porcine heart and 1 h after the xenograft had resumed its life-supporting function. Microvascular blood flow was analyzed semiquantitatively and the number of visualized cell-to-cell interactions was counted.
  
  
  RESULTS
  The proportion of continuously perfused microvessels was 97 (96 to 97) % at baseline and 95 (94 to 97) % in the early phase of CPB. It decreased significantly (P < 0.05) during CPB to 89 (84 to 91), and alterations were still present (P < 0.05) when CPB was terminated and the xenograft had taken over systemic perfusion 83 (81 to 85) %. The microcirculatory changes correlated with the lactate levels (y = 18.1-0.18 x; r(2) = 0.55; P < 0.001), but no correlation with macrohemodynamic parameters was found.
  
  
  CONCLUSIONS
  Microvascular blood flow is altered after orthotopic pig-to-baboon heart transplantation, despite systemic hemodynamic parameters being well maintained by the porcine xenograft. These changes are moderate but persist after termination of CPB. Further studies need to elucidate whether these changes are transient or add to the mortality associated with cardiac xenotransplantation.
authors.affiliation: Department of Anaesthesiology, Ludwig-Maximilians University Munich, Munich, Germany. andreas.bauer@med.lmu.de
authors.forename: Andreas
authors.initials: A
authors.lastname: Bauer
authors.forename: Vivian
authors.initials: V
authors.lastname: Renz
authors.forename: Heiko
authors.initials: H
authors.lastname: Baschnegger
authors.forename: Jan-Michael
authors.initials: JM
authors.lastname: Abicht
authors.forename: Andres
authors.initials: A
authors.lastname: Beiras-Fernandez
authors.forename: Paolo
authors.initials: P
authors.lastname: Brenner
authors.forename: Eckart
authors.initials: E
authors.lastname: Thein
authors.forename: Michael
authors.initials: M
authors.lastname: Schmoeckel
authors.forename: Bruno
authors.initials: B
authors.lastname: Reichart
authors.forename: Frank
authors.initials: F
authors.lastname: Christ
mesh_terms: D000818:Animals; D030801:Animals, Genetically Modified; D016027:Heart Transplantation; D006439:Hemodynamics / Q000502:physiology*; D006801:Humans; D051916:Membrane Cofactor Protein / Q000235:genetics; D008833:Microcirculation / Q000502:physiology*; D009060:Mouth Floor / Q000098:blood supply*; D010215:Papio; D013552:Swine; D014183:Transplantation, Heterologous
chemical_list: D051916:Membrane Cofactor Protein