Intracranial Arterial DiseasesConstriction, PathologicCarotid StenosisCerebral Arterial DiseasesArterial Occlusive DiseasesIntracranial ArteriosclerosisAortic Valve StenosisCoronary StenosisRenal Artery ObstructionSpinal StenosisTracheal StenosisCerebral AngiographyMagnetic Resonance AngiographyAngioplasty, BalloonPyloric StenosisAngiography, Digital SubtractionMitral Valve StenosisPulmonary Valve StenosisIliac ArteryStentsArteriosclerosis ObliteransAngiographyVertebrobasilar InsufficiencyStrokeIschemic Attack, TransientUltrasonography, Doppler, TranscranialCoronary AngiographyRenal ArteryRecurrenceBlood Flow VelocityCollateral CirculationPredictive Value of TestsTomography, X-Ray ComputedFollow-Up StudiesCarotid Artery DiseasesArteriesCerebrovascular DisordersCerebral ArteriesUltrasonography, Doppler, ColorSensitivity and SpecificitySeverity of Illness IndexAspirinCarotid ArteriesModels, CardiovascularCerebrovascular CirculationHemodynamicsProspective StudiesAortic Stenosis, SubvalvularRetrospective StudiesAortic Stenosis, SupravalvularBrain IschemiaRisk FactorsRegional Blood FlowCarotid Artery, InternalEndarterectomy, CarotidTime FactorsUltrasonography, Doppler, DuplexReproducibility of ResultsLaryngostenosisAortic ValveTricuspid Valve StenosisDiscrete Subaortic StenosisTreatment OutcomeBlood PressurePyloric Stenosis, HypertrophicHeart Valve Prosthesis ImplantationCatheterizationEsophageal StenosisAngioplastyGraft Occlusion, VascularCardiac CatheterizationCoronary DiseaseCoronary CirculationCoronary VesselsEchocardiographyFractional Flow Reserve, MyocardialCalcinosisVascular PatencyHeart Valve ProsthesisPostoperative ComplicationsHypertension, RenovascularArteriovenous Shunt, SurgicalCoronary Artery DiseaseEndarterectomyEchocardiography, DopplerRheumatic Heart DiseaseLumbar VertebraePulmonary Veno-Occlusive DiseaseCarotid Artery, ExternalDecompression, SurgicalObserver VariationUltrasonography, DopplerAortic Valve InsufficiencyAngioplasty, Balloon, CoronaryPulmonary Subvalvular StenosisSpinal CanalUltrasonography, InterventionalMitral ValveBronchial DiseasesUltrasonography