TOF病理生理及术前处理(英文)

TetralogyofFallot

PathophysiologyandMedicalManagementventricularseptaldefectrightventricularoutflowtractobstructionaorticoverriderightventricularhypertrophyContentsIntroductionAnatomyandAssociatedDefectsGeneticsPathophysiologyPhysicalExaminationandotherexaminationsMedicalManagementIntroductionIncidence：3.3per10,000livebirthsThefirstcompletedescriptionofTOFwaspublishedin1888bytheFrenchphysicianEtienne-LouisArthurFallotuntil1945,thefirstsurgicaltreatmentforTOFwasperformedbyAlfredBlalockatJohnsHopkinsUniversityAnatomyandAssociatedDefectsAnatomyandAssociatedDefectsImportantdegreesofobstructionmayalsooccurattheleveloftherightandleftbranchpulmonaryarteriesPulmonaryatresia(PA)ispresentinapproximately7%ofpatientswithTOF.Multiplemajoraortopulmonarycollateralarteries(MAPCAs)areusuallyfoundinthosepatientsAnatomyandAssociatedDefectsAnatomyandAssociatedDefectsMajorassociatedcardiacdefectsarerelativelyuncommoninTOFThemostfrequentlyassociatedlesionsareatrial

septaldefect(ASD),PDA,completeatrioventricular

septaldefect,andmultipleventricularseptaldefectsOtherlesscommondefectsincludepersistentleftsuperiorvenacava,anomalousaorticoriginofthecoronaryartery,andaberrantoriginoftherightorleftpulmonaryarteryGeneticsTheheritabilityofTOFisthoughttobeabout54%accordingtoalargestudybyBoonetalOtherearlyresearchwasabletoshowanassociationofTOFwithDiGeorgesyndrome,Alagillesyndrome,andtrisomies21,18,and13Morerecently,specificmutationshavebeencorrelatedwithTOFincludingamicrodeletioninchromosome22q11(foundin15%ofTOFpatientsandinupto40%ofthosewithTOF/PA),amutationinJagger-1(JAG-1)(foundin1–2%),amutationinNKX2.5(foundin4%),andamutationinzinc-fingerprotein,multi-type2(ZFPM2,foundin4%)PathophysiologyTheinitialpresentationofthepatientwithTOFisdependentonthedegreeofRVOTOMostcommonly,cyanosisismildatbirthandgraduallyprogresseswithageastheobstructionincreasesduetoincreasinghypertrophyoftherightventricularinfundibulumandfailureofgrowthofthehypoplasticpulmonaryvalvePathophysiologyInitially,thepredominantshuntacrosstheVSDmayevenbelefttorightinpatientswithmildobstruction(pinkTOF),andtheclinicalpictureisoneofcongestiveheartfailureCyanosistendstobecomesignificantwithinthefirst6–12monthsoflifeinthesepatientsInsuchsituations,theobstructionisentirelyorpredominantlyattheinfundibularlevelThepulmonaryvalveannulusandthebranchpulmonaryarteriesareusuallyofgoodsizePathophysiologySomepatientsmaydevelopcharacteristichypercyanoticor“tetspells,”whichareperiodsofprofoundsystemichypoxemiatypicallyoccurringinthecontextofcrying,eating,ordefecationRarely,thesehypercyanoticspellscanleadtolossofconsciousness,neurologicinjury,ordeathThesespellsarecharacterizedbyamarkeddecreaseinpulmonarybloodflowandanincreaseintheright-to-leftshuntacrosstheVSDintotheleftventricleandouttheaortaTheprecisepathophysiologyofthesespellsisuncertainbutmayinvolvealterationsinsystemicvascularresistancePathophysiologyAsmallerpercentageofpatientswillpresentwithsignificantcyanosisatorshortlyafterbirthInthisgroup,theoutflowtractobstructionisnearlyalwaysduetoahypoplasticpulmonaryvalveannuluswithorwithoutsevererightventricularinfundibularobstructionorhypoplasiaAlthoughtheperipheralpulmonaryarteriesmayappearhypoplastic,theyaregenerallyadequateinsizewhenthereisTOFwithpulmonarystenosisThesmallappearanceisduetoreducedpressureandflowPathophysiologyPatientswithatresiaofthePVandmainpulmonarytrunkwillbedependentonaPDAorsystemicaortopulmonarycollateralarteriesforpulmonarybloodflowInthelattersituation,thecollateralarteriesmaybesuchthatpulmonaryovercirculationexistsandcongestiveheartfailure(CHF)ispresentPathophysiologyOlderpatientswithuntreatedTOFandlong-standingcyanosiswilldevelopclubbingofthefingersandtoes,dyspnea,exerciseintolerance,brainabscesses,andpolycythemiawithpulmonaryandcerebralthrombosesPhysicalExaminationCyanosisisthemainphysicalfindingThefirstheartsoundisnormal,butthesecondsoundisoftensingleThecharacteristicsystolicmurmurresultsfromtheRVOTOandisusuallymoderateinintensitythemurmurdisappearsinthepresenceofa“tet”spellAthrillisuncommonContinuousmurmurs,bestheardovertheback,willbeheardwithsignificantsystemicaortopulmonarycollateralarteryflowPhysicalExaminationPatientswithabsentpulmonaryvalvesyndromewilloftenexhibitsignsofrespiratorydistressandadiastolicmurmurfromthepulmonaryregurgitationInolderchildrenandadults,clubbingofthefingersandtoesoccurs.Clubbingusuallydevelopsafter6monthsofageandpersistsuntilafteroperativecorrectionElectrocardiogramChestRadiographytheheartsizeisgenerallynormal,andthepulmonaryarterysegmentmaybesmall“boot-shaped”heartTheaorticarchisright-sidedinapproximately25%ofpatientsEchocardiographyThediagnosisisgenerallyeasilyestablishedbyechocardiographyThetypicalmalalignmentVSDwithaorticoverrideandRVOTOiswellvisualizedOften,thelocationoftheLADcanbedeterminedbytransthoracicechobyfollowingtheleftmaincoronaryarteryuntilitbifurcatesIftheanatomyoftheperipheralpulmonaryarteriesisnotwellseen,cardiacMRIorcatheterizationcanbeusefulforclarificationCardiacCatheterizationInthemajorityofpatients,diagnosticcardiaccatheterizationisnotnecessaryCatheterizationismorecommonlyusedforinterventionalproceduresbeforeandafterTOFrepairtoaddressbranchpulmonaryarterystenosesIntherareinstancewhenthecoronaryarteryanatomyisnotwelldelineatedbyechocardiography,cardiaccatheterizationmaybeofbenefitCardiacCatheterizationInTOFwithpulmonaryatresiaandMAPCAs,catheterizationisessentialfordelineatingthepulmonaryarteryandaortopulmonarycollateralanatomyforsurgicalplanningAdultpatientswithrepairedTOFmayrequirecardiaccatheterizationifthereisconcernforcoronaryarterydiseaseorpriortopulmonaryvalvereplacementCardiacMRIItprovidesexcellentdetailandspecificflowdataandcanquantifymyocardialfunctionandpercentageofpulmonaryvalveregurgitationMostcommonly,cMRIisusedinTOFtoprovidefollow-upimagingafterrepairHowever,gadolinium-enhancedMRangiographyisbecomingacriticaladjuncttothepreoperativeworkupofTOFpatientsspecificallywithbranchpulmonaryarteryanomaliesoraortopulmonarycollateralsandcanfunctionasa3D“roadmap”forsurgicalplanningBecausecMRIrequirespatientcooperation(breath-holdingandlyingstill),pediatricpatientsoftenrequiregeneralanesthesiaTherapyMedicalManagementMedicalManagementHypercyanoticspellsresultfromtransientreductionsinpulmonarybloodflowduetoasuddenincreaseinRVOTOand/oradecreaseinsystemicvascularresistance(SVR)Conditionsthatpredisposetohypercyanoticspellsincludedehydration,anemia,increasedcatecholaminelevels,acidosis,fever,oranythingelsethatcandecreasesystemicvascularresistanceMedicalManagementIntheacutesetting,therapyisdirectedat(1)increasingthetotalcardiacoutputbyincreasingbloodvolumewithfluidadministrationorbloodtransfusionadministration(2)treatingacidosiswithsodiumbicarbonateandsupplementaloxygen(3)decreasingthecardiachyperdynamicstatewithsedationandintravenousbeta-blockers(4)increasingsystemicvascularresistancewithposturalchangesorintravenousa-agonists(phenylephrine)administrationMedicalManagementInrarerefractorycases,mechanicalventilationfollowedbyemergentcardiopulmonarybypassandsurgicalinterventionmayberequiredInpatientsinwhomitisdesirabletodelaydefinitiverepair,oralbetablockademaybeusedtodecreasemyocardialcontractilityanddecreasethedynamicinfundibularobstructionHowever,clinicalresponsehasbeenvariable,andoncehypercyanoticspelloccur,planforsurgicalrepairshouldbemadeMedicalManagementInneonateswithTOF/PA,inwhichthepulmonarybloodflowisdependentuponapatentductus,ductalpatencyshouldbemaintainedwithProstaglandinE1,(PGE1)untileithercompleterepairisperformedoruntilastablesourceofpulmonarybloodflowisestablishedPatientswithTOF/PAoftendonothaveapatentductus,andthepulmonarybloodflowisdependentuponMAPCAS,andPGE1isnotnecessary

缺氧发作的治疗膝胸位/蹲踞：下肢体静脉血回流减少，心室水平右向左分流减少；下肢血供减少，下肢肌肉生成静脉血量减少；升高SVR补充血容量：补液，输血吗啡镇静，抑制呼吸中枢，缓解喘息症状碳酸氢钠纠正酸中毒，减轻对呼吸中枢的刺激作用吸氧；必要时呼吸机辅助通气升高外周血管阻力：去氧肾上腺素，间羟胺PGE1？急诊手术普萘洛尔：急性发作：减慢心率？预防缺氧发作：稳定血管反应性，预防SVR突然下降？Thanks！IndicationsforandTimingofOperationAtbirth,mostpatientswithTOFhavesatisfactorysystemicarterialoxygensaturationandrequirenospecificinterventionProgressionofhypoxemiawillultimatelyoccur,andwhentheoxygensaturationfallsbelow75–80%,operativeinterventionisrecommendedTheoccurrenceofhypoxemicspellsisalsogenerallyanindicationforoperation,althoughinselectcases,medicalmanagementwithpropranololmaybeusedtodelaysurgeryIndicationsforandTimingofOperationInpatientsnotmeetingspecificindications,electivecompleterepairisgenerallyrecommendedby1yearofageandinmostcentersby3–6monthsofageSingle-stagecompleterepaircanbesafelyperformedandispreferredIndicationsforandTimingofOperationHowever,somesurgeonspreferaninitialpalliativesystemic-to-pulmonaryarteryshuntifthepatientbecomescyanoticinearlyinfancy,inordertodeferdefinitiverepairuntilthechildisolder,usually6–12monthsAmodifiedBlalock-Taussig(BT)shuntmayalsobeindicatedinpatientsthatarecyanoticorarehavinghypercyanoticepisodesbutalsohaveconcomitantconditions,likeintracranialhemorrhageorseveresepsisthatcontraindicatethe