Andersons pediatric cardiology 1084

CardiacCatheterizationandAngiography
Mostcardiologistswouldnotconsidercatheterizationanecessarydiagnostic
procedureforchildrenwithtypicalclinicalfindings.Ifitisundertaken,itis
usuallypossibletoprobetheductfromthepulmonarytrunkandtopassa
catheterthroughthevesselanddowntheaorta.Whenthecatheterapparently
crossesaduct,butturnsinaheadwarddirection,thealertinvestigatorshould
considerthepresenceofanaortopulmonarywindow.Thesizeoftheshuntmay
bedifficulttoquantifybyoximetrybecauseitisdifficulttoobtainatruly
representativesampledistaltothesiteofshunting.Pulmonaryarterialpressureis
usuallynormalorslightlyelevated.Theductcanbevisualizedbyselective
aortographywithinjectionofcontrastmediainthelastpartoftheaorticarch
(Fig.41.13).

FIG.41.13 Lateralarteriogramsshowingvariousductalanatomies.

However,therapeuticcatheterizationiscurrentlythetreatmentofchoicefor
mostchildrenandadultswithapatentduct.Inthisregard,complete
hemodynamicassessmentisimportantpriortoattemptingclosure,particularlyin
theadult.Inpatientswithanelevatedpulmonaryarterialpressure,assessmentof
pulmonaryvascularresistanceanditsresponsetovasodilatingagentsmaybe
helpfulindeterminingsuitabilityofclosure.Assessmentofhemodynamics
duringtemporarytestocclusionwithaballooncathetermayalsobeahelpful
maneuverinassessingadvisabilityofclosureinmarginalcases.69
Angiographydefinestheanatomy.Suchdetailedassessmentisessential
beforeattemptingclosuresothattheproperdeviceandsizecanbechosen.


Importantfeaturesincludetheminimaldiameter(usuallyatthepulmonary
arterialend),thelargestdiameter(usuallyattheaorticampulla),thelengthofthe
duct,anditsrelationshiptotheanteriorborderofthetrachealshadow,thelatter
helpingtoguidepositioningofthedevice.40Otherimagingmodalitiesare

availabletoconfirmthepresenceofductalpatency.Radionuclidescanningcan
beusedtodetectthepresenceofshunting,butanatomiclocalizationislacking.
Magneticresonanceimagingprovidesanatomicdetail70andisparticularly
usefulinthesettingofunusualductalgeometryandinthosewithassociated
abnormalitiesoftheaorticarch(Fig.41.14).71,72Examplesincludethepatient
withaductalaneurysmpresentingasamassinthechest,theductassociated
withavascularring,arightaorticarch,orcervicalarch.Withvelocityencoding
ofcinemagneticresonancesignals,patternsofshuntingcanbedetected.73,74In
theadult,computedtomographycanassessthedegreeofcalcification,an
importantfeatureifsurgicalclosureisconsidered.However,ingeneral,the
simplertechniqueofcross-sectionalechocardiographywithcolorflowDoppler
providessufficientanatomicandhemodynamicdetailtodefinetheanatomyand
itsvariationsandpointsthewaytopropermanagement.


FIG.41.14 Volume-renderedmagneticresonanceimageshowingthe
anatomyoftheaorticarchinaninfantwithhypoplasticleftheartsyndrome.
Ductalanatomy(DA)anditsrelationshiptotheascendingaorta(AAO,
arrow)andleftsubclavianartery(LSCA)areclearlyunderstood.LPA,Left
pulmonaryartery.

DiagnosticProblems
Othercausesofacontinuousmurmurmaycreateconfusion.Thevenoushum
oftencausesdifficultytotheinexperiencedauscultator.Thisnoise,whichcanbe
loud,isusuallybestheardinthesupraclavicularfossa,andalthoughaudible
bilaterally,itisusuallylouderontheright.Avenoushum,whenloud,maybe
transmittedbelowtheclavicleandmaybemisdiagnosedasbeingfromapatent
duct.Thiserrorcanbeavoidedbyexertingpressureovertherootoftheneck,
turningtheheadtotheside,orlyingthechilddown.Thesemaneuversreadily
obliteratethevenoushum,whilehavingnoeffectonthemurmurgeneratedby

ductalflow.Anaortopulmonarywindowrarelycausesacontinuousmurmur
similartothatofpersistentductalpatency.However,moretypicallythe