Andersons pediatric cardiology 1123
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pulmonaryartery.Thisreducesthechanceofthewiredroppingintotheright
ventricle,asisoftenthecasewhenanend-holecatheterisused.Amultitrack
catheterislesssuitabletodelineatesupravalvarorsubvalvargradients,asthe
holesofthecatheterarespreadoverseveralmillimeters,whereoneholecould
beabovewhileanotherisatorbelowthesubvalvarnarrowing.
FIG.42.30 Pressuretracingsofsubvalvarpulmonarystenosisobtained
usingapressurewire.Top,Mainpulmonaryarterytracing.Middle,
Withdrawalacrossthepulmonaryvalve.Totheleft,thetracingstillhasa
typicalarterialwaveform,whereastowardtherightitchangestoa
ventricularwaveformwithoutcreatingasignificantgradient.Bottom,After
furtherwithdrawalthroughthesubpulmonaryarea,thepressuregradient
becomesapparent,beingvirtuallyexclusivelylocatedatthesubvalvar
ratherthanthevalvarlevel.
Inpatientswithcriticalpulmonaryvalvestenosisorthosewithseverevalvar
stenosisandreducedrightventricularfunction,crossingofthepulmonaryvalve
itselfmaynotbewelltolerated.Inthesepatientsitisthereforereasonableto
considerjustobtainingarightventricular-to-systemicarterialpressureratioand
delayingcrossingthevalveuntilangiographyhasbeenobtainedandtheballoon
carefullypreppedtobereadytoproceedswiftly,ifrequired.
Rightventricularangiographyshouldbeperformedusingcranialangulation
withsomedegreeofleftanteriorobliqueprojectionaswellaslateralprojection
toprofilethevalve'sannulus.Theangiogramcanmosteasilybeperformedin
theneonatebyagentleinjectionofcontrastbyhandor,inolderchildren,by
usingarightventricularpowerinjection(Fig.42.31).Caremustbetakennotto
infiltratecontrastintothemyocardiumoftherightventricularoutflowtract,as
suchaneventcanbepoorlytolerated.Thevalve'sannulusismeasuredfrom
hingepointtohingepointwhenthevalveisfullyopenandtheannulus
maximallyexpanded(seeFig.42.31).Inselectedpatientswherethereisconcern
aboutdownstreamstenosislocatedwithinthemainorbranchpulmonary
arteries,rotationalangiographywiththree-dimensionalreconstructioncanadd
valuableadditionalanatomicinformation(Fig.42.32).
