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

缺氧發(fā)作的治療膝胸位/蹲踞：下肢體靜脈血回流減少，心室水平右向左分流減少；下肢血供減少，下肢肌肉生成靜脈血量減少；升高SVR補(bǔ)充血容量：補(bǔ)液，輸血嗎啡鎮(zhèn)靜，抑制呼吸中樞，緩解喘息癥狀碳酸氫鈉糾正酸中毒，減輕對(duì)呼吸中樞的刺激作用吸氧；必要時(shí)呼吸機(jī)輔助通氣升高外周血管阻力：去氧腎上腺素，間羥胺PGE1？急診手術(shù)普萘洛爾：急性發(fā)作：減慢心率？預(yù)防缺氧發(fā)作：穩(wěn)定血管反應(yīng)性，預(yù)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