Andersons pediatric cardiology 363
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FIG.16.7 Incisionsforvideo-assistedthoracoscopicsurgery.Most
proceduresareattemptedwithisolationofthelung,inwhichitispossible
selectivelytodeflatethelungintheoperativethoraciccavity.Twotofour
smallincisionsaremadeasindicateddependingontheproceduretobe
attempted.Theintercostalmusclesaredividedintheribspaceofentry
withelectrocautery.(ModifiedfromSoukiasianHJ,FontanaGP.Surgeons
shouldprovideminimallyinvasiveapproachesforthetreatmentof
congenitalheartdisease.SeminThoracCardiovascSurgPediatrCard
SurgAnnu.2005;185–192.)
OpenSternum
Aftercompletionofalong,complexprocedure,theremaybesignificant
accumulationofextravascularfluidintheheart,lungs,chestwall,andeventhe
peritonealcavity.Reapproximationofthesternumcanresultinasignificant
reductionincardiacoutputduetocompressionoftheheartbyadjacent
structures,combinedwiththediastolicdysfunctionthatistheresultof
myocardialedema.Thisacuterestrictivephysiologyissimilartothatseenwith
tamponade,andhasbeentermedpseudotamponadephysiology.68Becausea
periodofdecreasedcardiacoutputispredictablefollowingcomplexprocedures,
eventhepatientwithinitiallyacceptablehemodynamicsmaydisplay
pseudotamponadephysiologywithinthefirst12hoursfollowingterminationof
CPB.Delayedsternalclosurehasbeenusedcommonlyasameansofavoiding
ormanaginglowcardiacoutputsyndromeinneonatesandsmallinfants
undergoingcomplexprocedures.Otherindicationsfordelayedsternalclosure
includeongoingbleedingthatcannotbeeasilycontrolled.Occasionally,the
sternaledgesmaybestentedopentoincreaseavailablespace.Indicationsforan
opensternumstrategyandtimingofclosurevarygreatly.Forsomeprograms,all
patientsundergoingthefirststageofpalliationforhypoplasticleftheart
syndromeundergodelayedsternalclosure.69,70Forothers,thestrategyisapplied
onanindividualbasis.71Closureisundertakenwhenhemostasishasbeen
achievedandthepatienthasdiuresedandbeenweanedfromthemajorityof
inotropicsupport.Somehaveadvocatedwaitinguntilthepatienthasdiuresedto
thepreoperativeweight.70Whilethesternumisopen,themediastinumis
coveredwitheitherGore-Texorasiliconesheet.Thiscanbesecuredwith
adhesive,savingtheskinedgesfromtheinjuryofsutures.
Materials
Thejobofthecongenitalcardiacsurgeonoftenrequiresreconstructionof
nonexistentstructures.Thematerialsavailableforthistaskincludebiomaterials,
syntheticmaterials,andcombinationsthereof.
Sutures
Suturesarenecessaryforanysurgicaltask.Materialsareusuallyclassifiedas
absorbableornonabsorbable,andasmonofilamentorpolyfilament.Thechoice
ofsuturesdependsonthespecificapplicationandstressesexpectedonthesuture
lineoranastomosis.Vascularanastomosesareconstructedmostcommonlywith
monofilamentsuture.Thesutureglidesthroughthetissueeasily,andthisresults
inminimaldamagetothetissueandimprovedhemostasis.Fortaskssuchas
fascialclosure,absorbablebraidedsuturesarecommonlyusedbecausethey
havealowerlikelihoodoftearingthroughtissue,andwillbereabsorbed,
minimizingtheriskofinfection.
Absorbablesuturespersistinthebodyforalimitedperiodoftime.Amongthe
earliestabsorbablesuturesisgut,createdfromtheintestinesofcowsorsheep.
Usedlesscommonlythaninthepast,thesuturemaybeuseduntreated,orafter
treatmentwithchromiumsalts,aprocessthatincreasesdurability.Moremodern
absorbablesuturesincludepolygalacticacid(Vicryl),andpolyglycolicacid
(Dexon).Thesepolyfilamentbraidedsuturesareabsorbedwithin60to90days.
Theyarecommonlyusedforclosureoffascia,subcutaneoustissue,andskin.
Absorbablesuturesarealsoavailableasmonofilament.Polyglyconate(Maxon),
andpoliglecaprone(Monocryl),haveexcellentstrengthwhencomparedwith
otherabsorbablesutures,andarefrequentlyusedtoclosetheskin.Inadditionto
useinclosingwounds,theyhavebeenusedforvascularanastomoses.
Polydioxanone(PDS)isamonofilamentsuturethathasalongdurationof
absorbabilityandhightensilestrength,withtheadditionaladvantageof
maintainingitsintegrityinthefaceofinfection.Itappearstoinducelessfibrosis
thanpolygalacticacid.Asaresult,itiscommonlyusedforsurgeryoftheairway.
Amongnonabsorbablesutures,oneoftheoldestissilk.Itisconsidered
nonabsorbableandpolyfilament,thoughitisultimatelydegraded.Althoughin
thepastsilkwasusedforvascularanastomoses,todayitisusedforretractionor
toligatesmallvessels.BraidedpolyestersutureswithTefloncoating(Tevdek,
