Andersons pediatric cardiology 1064

Whenthevalveisstenotic,thereislimitedexcursionoftheleaflets.Turbulent
flowdistaltothetruncalvalvewillbeevidentoncolorfloworcontinuouswave
interrogation.Theparasternallong-axissectionswilldemonstratetheexpected
fibrouscontinuitybetweentheleafletsofthetruncalvalveandthetruncalleaflet
ofthemitralvalve(seeFig.40.10;Video40.1),thedegreeofdilationoftheleft
ventricle,andtheextentofbiventricularhypertrophy.Restrictionofthe
ventricularseptaldefectwillbeseeninthisview.ContinuouswaveDoppler
interrogationwillrecordadropinpressureacrossthedefect,whichmayeither
befromlefttorightorfromrighttoleft,dependingontheventricularoriginof
thecommontrunk.
Theparasternalshort-axissectiontakenjustabovethelevelofthetruncal
valvedemonstratesthepulmonaryarteriesastheyarisefromthecommontrunk.
Intheso-calledtypeIvariantofcommontrunk,ashortpulmonaryarterial
segmentarisesfromtheleftlateralaspectofthecommontrunkanddividesinto
rightandleftpulmonaryarteries(Fig.40.11;Video40.2).Stenosisattheorigin
oftherightorleftpulmonaryarteries,orpulmonaryarterialhypoplasia,willbe
evidentinthissection.Intheso-calledtypeIIpattern,therightandleft
pulmonaryarteriesarisefromtheposteriorwallofthecommontrunkthrough
separatebutadjacentorifices(Fig.40.12).Inpractice,itisoftendifficultto
distinguishthesepatterns,eveninpostmortemspecimens.Incontrast,thetype
IIIvariantiseasilydistinguished,therightandleftpulmonaryarteriesarising
fromthecommontrunkviatwowidelyseparatedorifices.However,thisvariant
isseenmostfrequentlyinthesettingofpulmonarydominance,withtheaortic
segmentofthecommontrunkbeinghypoplastic.Otherrareroriginsofthe
pulmonaryarteriesmustbeanticipated,includingatresiaorevenabsenceofone
pulmonaryartery.Theparasternalshort-axissectionwillalsoidentifythe
numberoftruncalvalvarleaflets(Fig.40.13;Videos40.3to40.5).Discontinuity
betweenthetricuspidandtruncalvalvarleafletswillbeseeninthiscutwhen
thereisamuscularposteroinferiorrimtotheventricularseptaldefect,expected
infour-fifthsofpatients(Video40.6).Theparasternalshort-axissectionisalso
theplaneusedtointerrogatethecoronaryarteries(Video40.7).

FIG.40.11 Echocardiographicimagedemonstratingtheshortaxisofthe
arterialtrunk(Tr).Theright(RPA)andleft(LPA)pulmonaryarteriesarise
fromashortcommonartery.Thereislaminarflowinbothpulmonary
arteriesthatisofnormalcaliber.

FIG.40.12 Echocardiographicimagetakenfromaparasternalwindow
demonstratingtheseparateoriginoftherightpulmonaryartery.Thereis
laminarflowwithinthepulmonaryarterythatisofnormalcaliber.


FIG.40.13 Echocardiographicimageofthetruncalvalveviewedfroma
parasternalwindow.Inthispatientthevalvewasfunctionallybicuspid.

Theapicalandparasternalfour-chambersectionsalsodemonstratethelarge
subarterialventricularseptaldefectandtheoverridingofthetruncalvalve
(Video40.8).ColorflowDopplerinterrogationwillusuallydemonstrate
biventricularshuntingacrossthedefect.Anytruncalinsufficiencywillbe
evidentinthisview,whereascontinuouswaveDopplerwilldocumentany
systolicgradientshouldthetruncalvalvebestenotic.Thediastolicdropin
pressurebetweenthecommontrunkandtheventricularmasscanbe
demonstratedwhenthereisvalvarinsufficiency.
Thesubcostalsectionsareuniqueintheirabilitytodisplaymostofthe
morphologicfeaturesofcommonarterialtrunk.Thesubcostalparacoronal
sectionsdemonstratetheventricularseptaldefect,thenatureofits
posteroinferiorrim,theoverridingofthecommontrunk(Fig.40.14;Video
40.9),andtheoriginofboththeascendingaortaandthepulmonaryarteries
(Figs.40.15and40.16).Obliquesectionsmayrevealnotonlytheoriginsofthe
pulmonaryarteries,butalsotheintegrityoftheaorticarch(Fig.40.17).Aright

obliquesectionidentifiestheentiretyoftheproximalrightpulmonaryartery,
whereasleftwardrotationcanbeusedtodemonstratethefeaturesoftheleft
pulmonaryartery.Theywillalsopermitidentificationofanystenosisatthe
originsoftheleftandrightpulmonaryarteries,andwillrevealrarefindingssuch
ascrossedoriginsofthepulmonaryarteries.Anteriorangulationdemonstrates
themorphologyofthetruncalvalve,whereascolormappingrevealstheseverity
oftruncalregurgitation(Fig.40.18;Video40.10).Characteristically,