Blood Flow VelocityDiastoleRegional Blood FlowUltrasonography, Doppler, TranscranialCerebrovascular CirculationMiddle Cerebral ArteryUltrasonography, DopplerOphthalmic ArteryCerebral ArteriesPulsatile FlowCoronary CirculationUltrasonography, Doppler, ColorBlood PressureHemodynamicsEchocardiography, DopplerUltrasonography, Doppler, PulsedVascular ResistanceLaser-Doppler FlowmetryHypocapniaSystoleCiliary ArteriesRetinal ArteryEchoencephalographyRheologyUmbilical ArteriesModels, CardiovascularHyperventilationHeart RateMicrocirculationUltrasonography, PrenatalCarbon DioxideHyperemiaDogsAnterior Cerebral ArteryEchocardiographyUltrasonographyArteriesReference ValuesVentricular Function, LeftEchocardiography, Doppler, ColorCoronary VesselsMyocardial ContractionMitral ValveTime FactorsIntracranial PressureGestational AgeFetal HeartVasodilationHeart Rate, FetalCeliac ArteryEchocardiography, Doppler, PulsedHomeostasisAcetazolamideReproducibility of ResultsPregnancyVasodilator AgentsHeartProspective StudiesDoppler EffectOxygenMesenteric Artery, SuperiorFetal Growth RetardationPulmonary CirculationBrainCircle of WillisCarotid Artery, InternalPlacental CirculationCollateral CirculationAtrial Function, LeftHemorheologyTilt-Table TestBlood VolumeHeart VentriclesPosterior Cerebral ArteryCardiac OutputEchocardiography, TransesophagealVasomotor SystemHypotension, OrthostaticSplanchnic CirculationStroke VolumeHypercapniaFlow CytometryDuctus ArteriosusBlood ViscosityVentricular FunctionBlood Circulation TimePostureOxygen ConsumptionPartial PressureObserver VariationPulsePapaverineAnalysis of VarianceSensitivity and SpecificityCoronary AngiographyInfant, NewbornRetinal VesselsUterusVasoconstrictionAdenosine