Mesenteric VeinsMesenteric Vascular OcclusionPortal VeinMesenteric ArteriesMesenteric Artery, SuperiorSplenic VeinPortal SystemPancreaticoduodenectomySplanchnic CirculationIliac VeinMesenteric Artery, InferiorVeinsHypertension, PortalVenous ThrombosisHepatic VeinsTomography, X-Ray ComputedArteriesVena Cava, InferiorGastrointestinal HemorrhageThrombosisPancreatic NeoplasmsTreatment OutcomeRenal VeinsMuscle, Smooth, VascularFemoral VeinCeliac ArterySaphenous VeinSuperior Mesenteric Artery SyndromeVasoconstrictionNorepinephrinePulmonary ArteryRenal ArteryVisceraCerebral ArteriesFemoral ArteryVasodilationVaricose VeinsCarotid ArteriesVena Cava, SuperiorSuperior ColliculiPulmonary VeinsDogsBasilar ArteryMuscle ContractionTime FactorsVasoconstrictor AgentsBiological FactorsIofetamineJugular VeinsVasodilator AgentsEndothelium, Vascular