REVISTA
BRASILEIRA
DE
ANESTESIOLOGIA
PublicaçãoOficialdaSociedadeBrasileiradeAnestesiologia www.sba.com.brCLINICAL
INFORMATION
Anesthesia
for
pulmonary
trunk
aneurysmorrhaphy
Benedito
Barbosa
João
a,b,c,∗,
Ronaldo
Machado
Bueno
b,d,
Guilherme
D’Addazio
Marques
b,
Felippe
Batista
Soares
eaUniversidadeFederaldeSãoPaulo(Unifesp),SãoPaulo,SP,Brazil
bHospitalBeneficiênciaPortuguesa,SãoPaulo,SP,Brazil
cHospitalEuryclidesdeJesusZerbini,SãoPaulo,SP,Brazil
dInstitutodoCorac¸ãodoHospitaldasClínicas---Incor(FMUSP),SãoPaulo,SP,Brazil
eHospitalMunicipaldeSãoJosédosCampos,SãoJosédosCampos,SP,Brazil
Received27January2013;accepted22March2013 Availableonline18March2015
KEYWORDS
Generalanesthesia; Anesthetic: inhalational; Surgery:
aneurysmorraphy
Abstract
Backgroundandobjectives: Theaneurysminthepulmonarytrunkisararedisease.Becauseof itslocation,arupturecanleadtorightventricularfailureandsuddendeath.Aneurysmorraphy isthemostwidelyusedsurgicaltreatmentinthesecases.Theaimofthisstudyistoreporta successfulbalancedgeneralanesthesiaforaneurysmorraphyofpulmonarytrunk.
Casereport: Malepatient,28 years,asymptomatic, diagnosedwithananeurysminthe pul-monary trunk.Accordingtothelocationoftheaneurysmandtheconsequentfailureofthe pulmonary valve,ananeurysmorraphywas indicated,withimplantationofvascular-valvular prosthesis(valvedtube).Weoptedfor abalancedgeneralanesthesia,seekingtopreventan increaseinsystemicandpulmonaryvascularresistances,thusavoidingtocausestressonthe walloftheaneurysmalvessel.
Conclusions: Abalancedgeneralanesthesia,incombinationwithadequateventilationto pre-vent elevation in pulmonary vascular pressure, was appropriate for surgical repair of an aneurysminthepulmonarytrunk.
©2014SociedadeBrasileiradeAnestesiologia.Publishedby ElsevierEditoraLtda.Thisisan openaccessarticleundertheCCBY-NC-NDlicense( http://creativecommons.org/licenses/by-nc-nd/4.0/).
∗Correspondingauthor.
E-mail:[email protected](B.B.João).
http://dx.doi.org/10.1016/j.bjane.2013.03.027
PALAVRAS-CHAVE
Anestesiageral; Anestésico: inalatório; Cirurgia: aneurismorrafia
Anestesiaparaaneurismorrafiadetroncodeartériapulmonar
Resumo
Justificativaeobjetivos: Oaneurismadetroncodeartériapulmonaréumadoenc¸arara.Por sualocalizac¸ão,umarupturapodeconduziràfalênciadoventrículodireitoeàmortesúbita. A aneurismorrafia é otratamentocirúrgico mais usadonesses casos.Oobjetivo foi relatar umaanestesiageralbalanceadaparaaneurismorrafiadetroncodeartériapulmonarfeitacom sucesso.
Relatodocaso:Paciente do sexo masculino, 28 anos, assintomático, diagnosticado com aneurismadetroncodeartériapulmonar.Deacordocomalocalizac¸ãodoaneurismaea con-sequenteinsuficiência daválvulapulmonar,foi indicadaaaneurismorrafiacomimplantede prótesevascular evalvular (tubovalvado).Optou-se pela anestesiageral balanceada, para impedir um aumento nas resistências vasculares sistêmicas e pulmonar e evitar-se, dessa maneira,umestressesobreaparededovasoaneurismático.
Conclusões:Aanestesiageralbalanceada,emassociac¸ãocomumaventilac¸ãoadequadapara evitar elevac¸ãonapressãovascularpulmonar,foiapropriadapara correc¸ão cirúrgicade um aneurismaemtroncopulmonar.
©2014SociedadeBrasileiradeAnestesiologia.PublicadoporElsevierEditoraLtda.Este ´eum artigoOpen Accesssobumalicenc¸aCCBY-NC-ND( http://creativecommons.org/licenses/by-nc-nd/4.0/).
Introduction
Aneurysmisthefocaldilatationofavessel.Althoughitmay occurinvesselsofthevenoussystem,1itismorefrequent inarteriesandaffectsitsthreetunics(intima,media,and adventitia). It is classified as fusiform, if symmetric and dilatationinvolvingtheentirecircumference,orsaccular,if asymmetricandonlyapartofthecircumferenceisdilated. Unlike the aorta, which is the most affected by that disease, pulmonary artery aneurysm (PAA) is a rare occurrence.2However,eveninalowpressurecircuitasthe lung,itissubjecttothesamehemodynamicforcesthat pro-motethegrowthoftheaortaorotherarterieswhenaffected byananeurysm.2
The etiological causes of disease may be idiopathic, congenitalheart defects(e.g., patent ductusarteriosus), vasculitis(autoimmune, postinfection or geneticfactors), and connective tissue diseases such as Marfan syndrome, amongothers.3,4
Clinically, it may be manifested by dyspnea, cough, hemoptysis,andchestpain.3However,mostpatients with PAAareasymptomatic.2,5Thediagnosisismadeatrandom byroutinescreening.
Thepresenceofpainisasymptomthatindicates impend-ingrupture.Inthiscase,surgicaltreatmentisrecommended topreventsuddendeath(SD)causedbytheaneurysm rup-tureandrightventricle(RV)failure.6
Evenwhenthereisnopain,butthepulmonarytrunkis involved, therisk of SD is alsohigh for thesame reasons citedabove,andmanyauthorssuggestsurgery.7
We reporta rare case of anesthesiafor surgical treat-mentofpulmonarytrunk aneurysm(aneurysmorrhaphy)in anasymptomaticpatientwithMarfansyndrome.
The purpose of anesthesia was to keep under control bothsystemicbloodpressure(SBP)andpulmonaryarterial pressure(PAP).
Therefore,wesoughttoavoidruptureoftheaneurysm, its disastrous consequences in vascular site, and possible damageaftersurgicalcorrection.
Case
report
Malepatient,28yearsold,white,67kg,1.90m,diagnosed withapulmonarytrunkaneurysm,withoutother comorbidi-ties.
Thepatienthadnosignsorsymptomsofthedisease.The diagnosiswasmadeduringaperiodicmedicalexamination atthecompanywhereheworked.
Intheevaluationofthefirsttests,anincreasedheartsize bythe growthoftheright ventricleandpulmonary artery trunkwasnoticed(Fig.1).The electrocardiogramshowed adeviationoftheQRSaxistotherightandarightbundle branchblock.
A Doppler echocardiography was requested, which revealedmoderatedilatation andhypertrophyoftheright
PAA
RV
Ao
PAA
RV
LV
Figure 2 PAA aneurysm and increasedRV; PAA, pulmonary arterytrunk;RV,rightventricle;Ao,aorta;LV,leftventricle.
ventricle,significantdilationofthepulmonaryarterytrunk anditsbranches,anddysplasiawithseverepulmonaryvalve insufficiency. Mean pulmonary artery pressure was esti-matedat30mmHg(normalreferencevalue:10---18mmHg). After these tests, the patient was sent to the hospi-tal Beneficência Portuguesa (São Paulo, Brasil), where a pulmonary artery computed angiography was performed. The following relevant aspects were observed: aneurys-mal dilatation of the pulmonary artery trunk measuring 5.8cm in diameter; pulmonary valve annulus measuring 3.6cm×3.5cm diameter;medianized heartshowing signs ofrightventricledilatationanditsoutflow.
Withthediagnosisofpulmonaryarteryaneurysm(Fig.2) andpulmonaryvalveannulusdilation(withimpairedvalve), aneurysmorrhaphy was indicated, with synthetic Dacron tube and metal valve implantation in pulmonary position (valvedtube).
Ontheoperationday,thepatientwastakentothe oper-ating room and monitored withelectrocardioscope, pulse oximeter, and noninvasive blood pressure.A large venous accesswasplacedin the right upperlimb andmidazolam (3mg)wasadministeredtoprovideanxiolysis/sedation.At thattime,withnormalvaluesofheartrateandblood pres-sure, dexmedetomidine infusion wasstarted at a dose of 0.5gkg−1h−1for15min,sufficienttimetoleftradialartery
catheterizationinordertoinvasivelymeasurethepressure. Induction of anesthesia started with preoxygenation (100%O2),reductionofdexmedetomidineto0.4gkg−1h−1,
fentanyl 10gkg−1 etomidate 20mg, rocuronium
0.6mgkg−1, and intravenous lidocaine 2mgkg−1. After
therequiredtimefordrugaction,trachealintubationwas performedwithout complications,suchashypertensionor tachycardia. Monitoring wascompleted with capnography andcentralvenouspressure.
ThemechanicalventilationwasadjustedtoFiO2of60%,
witha frequency of 12 breaths per minute, tidal volume of7mLkg−1,andpositiveend-expiratorypressure(PEEP)of
3cmH2O,inordertomaintainEtCO2between30---32mmHg.
Maintenanceofanesthesiawasachievedwith1% isoflu-rane, dexmedetomidine (0.4gkg−1h−1), and additional
doses of fentanyl to complete 20gkg−1. Midazolam and
rocuronium were administered again during cardiopul-monarybypass (CPB), withanother supplemental dose of musclerelaxantattheendofCPB.
Epsilon-aminocaproic acid, an antifibrinolytic, was infusedatadoseof100mgkg−1inthefirsthourofsurgery,
followedby10mgkg−1h−1inordertoinhibitfibrinolysisand
reducesurgicalbleeding.
Withventilatoryadjustments describedabove, mainte-nance of blood gas values within normal limits, and the useddrugs,wesought topreventanyeventthatpromotes increased systemic or pulmonary arterial blood pressure8 thatcouldincreasetheriskofaneurysmruptureuntilCPB. CPB was performed with moderate hypothermia, and aneurysmorrhaphywithreplacementbyvascularprosthesis andmetallicprostheticvalvewasuneventful.
At the end of CPB, the possible RV dysfunction as a result of the ischemia period----reperfusion on a dilated/hypertrophic ventricle----was prevented by the choiceofpositiveinotropicandvasodilatormilrinone.
Theinitialbolusofthisinotropic9wassuppressedandan infusionof0.5gkg−1min−1ofthedrugwasstartedstillin
CPB.ThisdosewascontinueduntilaftertheendofCPBand protamineadministration.Maintenancewasthenreducedto 0.3gkg−1min−1foranotherhourand,becausecontractile
performance wasvery satisfactory, the drug infusion was stopped.Discontinuationofmilrinonewasmadetoavoida possiblehypotensionasaresultofthisdrugsynergismwith dexmedetomidine.
Thepatientremainedstableuntiltheendofsurgeryand wastakentotheICUintubatedandwithcontinuousinfusion ofdexmedetomidine.
Discussion
The tendency of any aneurysm is to continue gradually dilating.Dilationleadstoastressonthevesselwall,a deter-miningfactorforitsrupture.10Pulmonaryarteryaneurysmis araredisease2,7andthereisnoguidelinefortreatment.11-13 Therapy may vary from conservative7,12 to surgical2,3 accordingto the aneurysmlocationor in the presence of painasasymptom,forexample.3The invasiveprocedures rangefromlobectomyandembolizationinmoredistal arter-iestopneumonectomywhenthemainpulmonaryarteryis involved.2,3
failure and sudden death. Aneurysmorrhaphy is the most commonlyusedsurgeryinsuchcases.2
Pulmonaryarterytrunkaneurysmorrhaphyisperformed understernotomyandwithcardiopulmonarybypass(CPB). However,itdoesnotdifferfrommanyofthecardiac surger-iesroutinelyperformed.
Thespecificsurgicaltimeofthesetypesofcardiovascular procedures(sternotomy,pericardiotomy,aortamanagement andcannulation,amongothers)isapotentstimulustothe sympatheticnervoussystemandmayraisebloodpressure. Asaresult,accordingtoLaplace’slaw,anincreasedblood pressure(orincreasedvesseldiameter)exacerbatesthe ten-sionontheaneurysmwallmakingitunstableandproneto rupture.2,14,15
Regardingpulmonaryarteryaneurysm,besidesthe con-cern with hypertension, an additional challenge arises: preventing an increase in pulmonary vascular resistance (PVR).Anincreasedresistanceinthissitewouldbe trans-mittedtothepulmonarytrunk,withconsequentadditional stressonaneurysmandincreasedRVafterload.
Inthecasereportedhere,weavoidthefactorsthatcould contributetoincreasedPVR,suchashypoxia,decreasedpH (hypercapnia/respiratory and metabolic acidosis),8 adren-ergicandnociceptivestimuli.
Tidalvolume(TV)andPEEPwerereduced(TV=7mLkg−1
andPEEP=3cmH2O), becausethese factors when
exces-sive during mechanical ventilation may cause pulmonary hyperdistensionand, consequently, increase in pulmonary vascular resistance.16 Compensation with FiO
2 (60%) and
respiratoryrate(12bpm)weresufficientforeffective oxy-genationcontrolandCO2elimination.
Regardingthe anesthetictechnique:‘‘almost any com-binationofanestheticsandvasoactivedrugs hasfavorable studiesandenthusiasticadvocateswhopromoteitsuse’’.17 There is no consensus amonganesthesiologists about the mostappropriate technique for pulmonary trunk aneurys-morrhaphy.Hereweoptedforbalancedgeneralanesthesia, as this modality has been routine in our service for cardiovascular surgery and results in good hemodynamic control.
Isoflurane, the inhaled agent chosen, has two desir-ablecharacteristics, among others,for thecase reported here: first, it attenuates, by anesthetic precondition-ing, the ischemia-reperfusion injury due to CPB;18 and second, it reduces pulmonary vascular resistance19 (althoughwithlessintensityinpatientswithoutpulmonary hypertension).20
We also used dexmedetomidine, a potent ␣2
-adrenoceptor agonist (␣2-receptors consist of three
subtypes: ␣2a, ␣2b e ␣2c) with sympatholytic, sedative,
amnesicandanalgesicproperties.21Itsselectivityregarding receptors␣1 and␣2comparedtoclonidine,acongener,is
eighttimeshigher.
In 2006, But et al.,22 evaluating the effects of dexmedetomidineinpatientswithpulmonaryhypertension (PH)undergoingcardiacsurgery,concludedthat dexmedeto-midine, in addition to reducing the need for fentanyl, attenuated the increase in systemic vascular resistance index and pulmonary vascular resistance. It reduced the meanarterial pressure,mean pulmonary arterypressure, and pulmonary wedge capillary pressure compared to placebogroupvalues.
Inourcase,thepressurewasnotmeasuredinthemore distalpulmonarycapillariesasinthepatientsstudiedbythe authorscitedabove.Themeanpulmonary arterypressure (increased)couldonlybestudiedintheaneurysmalareaby Dopplerechocardiographicexamination.
However,evenwithoutbeingabletotellifthepressure in the arterial bed distal tothe aneurysmwasincreased, theadministrationofadrugcapableofreducingthe adren-ergicresponse23 andpossiblypulmonaryvasculatureblood pressure22 allowedthe inclusionofthisagentin the anes-thesia.
The bolus dose of dexmedetomidine (1gkg−1) is
pur-poselyexcluded.Itisassumedthatduetotheeffecton␣2b receptorsonvascularsmoothmuscle,thebolusloadingdose resultsinanincreaseinbloodpressure21,whichwouldbe undesirableinpatientswithaneurysms.Muchoftheadverse effectsofthisdrugoccurduringorshortlyaftertheloading dose(bolus),21soweoptedforaninfusionof0.5gkg−1h−1
for15minandthenreduceitto0.4gkg−1h−1.
Continuousinfusionofdexmedetomidinewasmaintained until the first hours of the patient arrival in the inten-sive care unit (ICU). Thereby, we seek to extubate the patientundertheagentsafesedationandavoidrespiratory depression21 andincreasedbloodpressure.
The team was also concerned about the possibility of RV dysfunction after CPB. The right ventricle was hyper-trophic/dilated,therefore,moresusceptibletoinadequate protectionbycardioplegicsolution,despiteallcareabout the volume and injection time of cardioplegia. It was known beforehand that the time of aortic clamping dur-ingcardiopulmonarybypass(heartischemia)wouldbefrom moderatetoprolonged,duetothesizeofthesurgery,and thiscouldaffectthemyocardium.
To avoid a poor performance of the RV at the end of CPB,dilatethepulmonaryvasculature,andreducepressure onthesurgicalsutures(prosthesisandaneurysmorrhaphy), weoptedformilrinone,apositiveinotropicvasodilatorand inhibitorofphosphodiesteraseIII(PDEIII).
PhosphodiesteraseIII is an enzyme found in myocytes, bloodvessels,24sarcoplasmicreticulum,andplatelets.25 Mil-rinone inhibitsPDE IIIandreducesthehydrolysis ofcyclic AMP(withlesseffectoncyclicGMP).
Inmyocardium,thisactionresultsinincreased intracel-lularionizedcalciumandheartcontractileforcemediated bythecyclicAMP.
In the smooth muscle of blood vessels, it causes a decrease in the concentration of intracellular calcium, resulting in intense vasodilation.26 The vasodilator action of milrinone on pulmonary vasculature independent of  -receptors and may even exceed the action of -agents, includingisoproterenol,hemostpotentofall.27
Conflicts
of
interest
Theauthorsdeclarenoconflictsofinterest.
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