title: Dynamic regulation of atrial coronary blood flow in healthy adult pigs.
abstract: BACKGROUND
  There are several indications for a mismatch between atrial oxygen supply and demand during atrial fibrillation (AF), but atrial coronary flow regulation has not been investigated extensively.
  
  
  OBJECTIVE
  The purpose of this study was to characterize the dynamic regulation of atrial coronary flow in pigs.
  
  
  METHODS
  In anesthetized open-chest pigs, Doppler flow probes were placed around left atrial (LA) and left ventricular (LV) branches of the circumflex artery. Pressures and work indices were measured simultaneously. Systolic and diastolic flow contribution, flow response kinetics, and relationship between pressures, work, and flow were investigated during sinus rhythm, atrial pacing, and acute AF.
  
  
  RESULTS
  During atrial systole, LA flow decreased. Only 2% of total LA flow occurred during atrial systole. Pacing with 2:1 AV block and infusion of acetylcholine revealed that atrial contraction itself impeded atrial coronary flow. The response to sudden changes in heart rate was slower in LA compared to LV. Both LA and LV vascular conductance were positively correlated with work. After the cessation of acute AF, the LA showed a more pronounced phase of supranormal vascular conductance than the LV, indicating a period of atrial reactive hyperemia.
  
  
  CONCLUSIONS
  In healthy adult pigs, atrial coronary flow is impeded by atrial contraction. Although atrial coronary blood flow is positively correlated with atrial external work, it reacts more slowly to changes in rate than ventricular flow. The occurrence of a pronounced hyperemic phase after acute AF supports the notion of a significant supply-demand mismatch during AF.
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Kelly A
authors.initials: KA
authors.lastname: van Bragt
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Hussein M
authors.initials: HM
authors.lastname: Nasrallah
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Marion
authors.initials: M
authors.lastname: Kuiper
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Arne
authors.initials: A
authors.lastname: van Hunnik
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Nico H L
authors.initials: NH
authors.lastname: Kuijpers
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands.
authors.forename: Ulrich
authors.initials: U
authors.lastname: Schotten
authors.affiliation: Department of Physiology, Faculty of Medicine, Maastricht University, The Netherlands. Electronic address: s.verheule@maastrichtuniversity.nl.
authors.forename: Sander
authors.initials: S
authors.lastname: Verheule
mesh_terms: D000818:Animals; D001281:Atrial Fibrillation / Q000473:pathology / Q000503:physiopathology; D016279:Atrial Function, Left / Q000502:physiology; D003326:Coronary Circulation / Q000502:physiology; D003331:Coronary Vessels / Q000000981:diagnostic imaging / Q000503:physiopathology; D004195:Disease Models, Animal; D004562:Electrocardiography / Q000379:methods; D006325:Heart Atria / Q000000981:diagnostic imaging / Q000503:physiopathology; D006352:Heart Ventricles / Q000000981:diagnostic imaging / Q000503:physiopathology; D006439:Hemodynamics; D009200:Myocardial Contraction / Q000502:physiology; D013552:Swine; D014463:Ultrasonography
keywords: Atrial contraction; Atrial coronary flow; Atrial fibrillation; Ischemia; Vascular function