Basilar ArteryIntracranial AneurysmAneurysmArteriesVertebrobasilar InsufficiencyVertebral ArteryCerebral ArteriesAneurysm, InfectedCerebral AngiographySubarachnoid HemorrhageAortic AneurysmPulmonary ArteryCarotid ArteriesBrain Stem InfarctionsEmbolization, TherapeuticAneurysm, DissectingRenal ArteryVasospasm, IntracranialFemoral ArteryAortic Aneurysm, ThoracicHeart AneurysmMesenteric ArteriesCarotid Artery, InternalTomography, X-Ray ComputedIliac ArteryVasodilationAngiography, Digital SubtractionVasoconstrictionIliac AneurysmCarotid Artery DiseasesMuscle, Smooth, VascularTreatment OutcomeCoronary Artery BypassArterial Occlusive DiseasesBlood Vessel Prosthesis ImplantationSubclavian ArterySplenic ArteryAneurysm, FalseRadial ArteryCoronary AneurysmMammary ArteriesDogsCerebrovascular CirculationStentsVasodilator AgentsAngiographyCircle of WillisMagnetic Resonance AngiographyMiddle Cerebral ArterySerotoninEndovascular ProceduresCeliac ArteryCarotid Artery, CommonBlood Vessel ProsthesisHepatic ArteryBrachial ArteryMesenteric Artery, SuperiorAortic RuptureAorta, AbdominalCoronary VesselsPapaverinePotassium ChlorideRabbitsMuscle ContractionVasoconstrictor AgentsOphthalmic ArteryPicolinesVascular Surgical ProceduresPosterior Cerebral ArterySumatriptanEndothelium, VascularIntracranial Embolism and ThrombosisAortographyIschemic Attack, TransientFollow-Up StudiesUltrasonography, Doppler, TranscranialPopliteal ArteryAcetylcholineTime FactorsIntracranial ArteriosclerosisDilatation, PathologicTemporal ArteriesRetrospective StudiesAneurysm, RupturedRenal Artery ObstructionThoracic ArteriesIntracranial ThrombosisPonsUmbilical ArteriesBronchial ArteriesCerebral InfarctionUlnar ArteryVasomotor SystemMechanical ThrombolysisAnterior Cerebral ArteryVertebral Artery DissectionCoronary AngiographySubclavian Steal SyndromeNitroprussideConstriction, Pathologic