AnalgesicsAnalgesics, OpioidReceptors, Opioid, muRisk AssessmentReceptors, OpioidPharmacovigilanceSleep, REMReceptors, Opioid, deltaRisk ManagementReceptors, Opioid, kappaOpioid PeptidesRisk FactorsAnalgesics, Non-NarcoticCardiovascular DiseasesHeart Valve Prosthesis ImplantationAortic Valve StenosisMorphineNarcotic AntagonistsCardiac Surgical ProceduresPainAnalgesiaNaloxonePain MeasurementPredictive Value of TestsSleep DeprivationOpioid-Related DisordersTime FactorsElectroencephalographyTreatment OutcomeNaltrexoneSleepSleep StagesSeverity of Illness IndexWakefulnessPain, PostoperativeEnkephalinsCardiac CatheterizationTramadolNarcoticsProspective StudiesEnkephalin, Ala(2)-MePhe(4)-Gly(5)-Drug ToleranceBuprenorphineFollow-Up StudiesEndorphinsROC CurveRetrospective StudiesEnkephalin, D-Penicillamine (2,5)-United StatesFentanylPrognosisRiskLogistic ModelsCohort StudiesDynorphinsPhenacetinBrain WavesAcetaminophenElectromyographyPain ThresholdHydromorphoneElectrooculographyRats, Sprague-DawleyEnkephalin, LeucineMorphinansDextropropoxypheneCodeineArousalInjections, SpinalEnkephalin, Leucine-2-AlanineHyperalgesiabeta-EndorphinAnti-Inflammatory Agents, Non-SteroidalMeperidinePain ManagementPentazocineDose-Response Relationship, DrugMethadoneBenzeneacetamidesPain, IntractableDiprenorphineRats, WistarButorphanolAnesthetics, LocalHydrocodoneChronic PainHypothalamusPolysomnographyOxymorphoneMorphine DerivativesDouble-Blind MethodDipyroneAnalgesia, EpiduralLevorphanolAnalgesia, Patient-ControlledBenzomorphansBupivacaineOxycodoneNociceptorsAlfentanil