Andersons pediatric cardiology 179
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vascularanastomosesinthesecondtrimesterofpregnancy.235
Theeffectsonbloodpressureandcardiacfunctioninchildrenof10yearsof
agearereassuringwithnormalbloodpressuresrecordedandnoimportant
abnormalitiesofcardiacfunctionappreciatedusingechocardiographic
methods.236,237However,interestingdifferencesintherestingstateand
responsivenessofthemicrocirculationbetweenmonochorionicanddichorionic
twinshavebeenreported,suggestingthatvascularprogrammingoccursevenin
monochorionictwinswithbalancedintertwintransfusion.238
VascularProgrammingFollowingFetal
Coarctation
Coarctationoftheaortacanbediagnosedinthefetus.Bothanhypoplasticarch
andacoarctationshelfcanbevisualizedandquantifiedusingultrasound.35,239A
continuousDopplerpatternofflowintheisthmusmayberecordedandreflects
alteredpatternsofflowwhichsuggestanobstruction(Video6.13,Fig.6.25).
Studiesofendothelialfunctioninnormotensiveyoungadultsundergoingrepair
ofthecoarctationasneonatesandinfantshavedemonstratedreducedendothelial
dependentandindependentfunctionconfinedtotheprecoarctationsite
comparedwithnormalcontrols.Thisimpliesthatearlyalterationofflowinfetal
lifemayprogramlaterfunctioninspiteofearlyandadequatesurgical
repair181,240andprovideaplausibleexplanationforhypertensionin
approximatelyone-thirdofadultswhohaveundergonecoarctationrepairin
infancyorchildhood
FIG.6.25 ContinuousDopplerpatternofflowintheisthmusreflecting
alteredpatternsofflowthatsuggestarchobstructioninfetallifeand
possibleprogrammingoftheresponsesofthearterialtreeinadultlife.
Summary
Noninvasivemeasurementofthedevelopingcirculationinthehumanfetushas
becomeareality.
Dopplerultrasoundtechnologynowenablesserialexaminationofthehuman
fetusfromthefirsttrimester,allowingustoobservenoninvasively
developmentalchangesincardiovascularfunction,myocardialmaturation,and
theresponsestostructuralandfunctionaldiseasestates.Morequantitativeand
automatedmeasuresofmyocardialfunction,organperfusion,volumeflow,and
ventricularvolumesenableabetterappreciationofcardiacoutputandorgan
flowsinhealthanddisease.Thedevelopingarterialtreecanbeexaminedby
pulsewavevelocityanditsendothelialresponsesmeasured.Thelinkbetween
theuterineenvironment,maternaldisease,andfetalcardiovascularresponses
andlonger-termpathologysuchashypertensionisnowbettercharacterized.
Earlydetectionofcardiovascularabnormalitiesmaypermittheinitiationof
interventionalstrategiesbeforebirthandinearlychildhoodthatcouldreverse
theprogressiontoclinicallyimportantdisease.
