Mesenteric VeinsMesenteric Vascular OcclusionIschemiaMesenteric Artery, SuperiorMesenteryMesenteric Artery, InferiorPortal VeinCeliac ArterySplanchnic CirculationVeinsVascular DiseasesMesenteric ArteriesPortal SystemSplenic VeinMyocardial IschemiaBrain IschemiaVascular Surgical ProceduresReperfusion InjuryAngiographyTomography, X-Ray ComputedFemoral VeinRenal VeinsEmbolectomyAngioplasty, BalloonEmbolismIntestinesSaphenous VeinVenous ThrombosisAbdominal PainEndovascular ProceduresTime FactorsIliac VeinConstriction, PathologicThrombosisTreatment OutcomeVaricose VeinsHepatic VeinsRetrospective StudiesChronic DiseaseEndarterectomyUltrasonography, Doppler, DuplexAcute DiseaseIschemic PreconditioningVisceraVascular PatencyDigestive System Surgical ProceduresIntestine, SmallStentsPulmonary VeinsPancreaticoduodenectomyIofetamineVena Cava, InferiorJugular VeinsNorepinephrineHypertension, PortalAortic AneurysmLiver CirculationBlood Vessel Prosthesis ImplantationArterial Occlusive DiseasesDogsPortasystemic Shunt, SurgicalAneurysm, DissectingAdrenergic alpha-2 Receptor AntagonistsAngioplastyAmphetaminesEsophageal and Gastric VaricesMuscle, Smooth, VascularRats, WistarUmbilical VeinsMyocardial Reperfusion InjuryRecurrenceAnastomosis, Surgical