Basilar ArteryVertebrobasilar InsufficiencyPosterior Cerebral ArteryVertebral ArteryCatheters, IndwellingInfarction, Posterior Cerebral ArteryCerebral AngiographyIntracranial AneurysmBrain Stem InfarctionsCathetersCerebral ArteriesArteriesMagnetic Resonance AngiographySubarachnoid HemorrhageCerebrovascular CirculationBrain InfarctionAneurysm, RupturedCerebral InfarctionIntracranial ArteriosclerosisEmbolization, TherapeuticMoyamoya DiseaseVertebral Artery DissectionStrokeTomography, X-Ray ComputedCarotid Artery, InternalAnterior Cerebral ArteryBrain IschemiaMagnetic Resonance ImagingUltrasonography, Doppler, TranscranialTreatment OutcomePulmonary ArteryIschemic Attack, TransientIntracranial EmbolismAngiography, Digital SubtractionCarotid ArteriesArterial Occlusive DiseasesAngiographyCatheterizationRetrospective StudiesCerebrovascular DisordersFollow-Up StudiesConstriction, PathologicFemoral ArteryAneurysm, DissectingCerebral RevascularizationVasospasm, IntracranialMesenteric ArteriesRenal ArteryCatheterization, Central VenousVasodilationBlood CirculationAcute DiseaseProspective StudiesVasoconstrictionStentsCranial Fossa, PosteriorBrainDogsCerebellumRisk FactorsMuscle, Smooth, VascularIliac ArteryRecurrenceRadial ArteryCoronary Artery BypassCatheterization, PeripheralRegistriesVasodilator AgentsCentral Venous CathetersCardiac CathetersTime FactorsPredictive Value of TestsMammary ArteriesSubclavian ArteryCoronary VesselsCarotid Artery DiseasesPulmonary CirculationSerotoninUrinary CatheterizationCircle of WillisMiddle Cerebral ArteryDiffusion Magnetic Resonance ImagingRabbitsExtracorporeal CirculationBrachial ArteryRegional Blood FlowCollateral CirculationVasoconstrictor AgentsPapaverineHepatic ArteryEquipment FailureSplenic ArteryMuscle ContractionEndothelium, VascularCarotid Artery, CommonPotassium ChlorideUrinary CathetersCoronary CirculationAcetylcholineOphthalmic Artery