Andersons pediatric cardiology 284

Abstract
Examinationofthefrequencyofcongenitalcardiacdiseasehasvery
importantimplicationsforclinicaldiagnosisandmanagementandfor
studyingtheetiologyandburdenofcongenitalheartdisease.Inthischapter
weexploresomeimportantdefinitionsandetiologicconsiderationsandwe
reviewtheavailableliteratureonthereportedprevalenceofcongenital
heartdisease.Thequestion“howmuchcongenitalheartdisease”continues
toevolveinthefaceofimprovingprenataldiagnosis,optionsforearly
pregnancyterminationandbettersurvivaloutcomes.Moststudiesreporta
prevalenceofcongenitalheartdiseaseof0.2–2%amongnewbornsandthe
variabilityisduetothemethodsusedtoscreenforandtoascertainthe
diagnosis.Theburdenofcongenitalheartdiseaseisnowexpandingtoadult
medicineasmanypatientswithrepairedcongenitalheartdiseaseare
survivingtoadulthood.Asanexample,arecentstudyestimatedthatinyear
2010,therewere2.4millionpeopleintheUnitedStateswithcongenital
heartdisease;ofthem,1.4millionareadultsand300,000hadsevere
disease.Withthegreaterpotentialneedforreoperationandcareduring
follow-up,aneconomicandlogisticalburdencanbeexpectedinthefuture
inadultswithcongenitalheartdisease.

Keywords
Prevalence;incidence;rates;prenataldiagnosis;adultswithcongenital
heartdisease


Introduction
Examinationofthefrequencyofcongenitalcardiacdisease,eitherasarateoras
aproportion,hasimportantimplicationsforthestudyofcongenitalcardiac
malformations,aswellastheirclinicalmanagement.However,thereismuch
confusionandmisuseregardingterminologyandmethodology,withimportant
implicationsfortheaccuracy,validity,andcomparabilityoffindingsreportedin

thepublishedliterature.Knowledgeofhowcriticallytoappraisethesereportsis
importantindefiningtheirvaluewhenappliedtoissuesofdiagnosticlikelihood,
surveillanceandtrends,etiologicassociations,burdenofdisease,and
requirementsforresources.Theseissueshavemorerecentlybeenimpactedby
fetaldiagnosisandtermination,withindividualdecisionsinfluencedby
contemporaryestimatesofprognosisrelatedtothenaturalandmodifiednatural
history.Asmorepatientssurviveintoadulthood,estimatesoftheburdenof
disease,andtherequirementsforresources,havealsoachievedgreater
importance.Thereforethequestionof“howmuchcongenitalcardiacdisease?”
continuestoevolve.Providingthecorrectanswerhasimportantrelevancefor
boththeprovidersofhealthcareandthehealthcaresystemitself.


Definitions
Inconsideringanddiscussingtheprevalenceofcongenitalheartdisease,key
termstobedefinedincludecongenitalcardiacdiseaseitself,frequency,ratio,
proportion,rate,incidence,andprevalence.

CongenitalCardiacDisease
Inexaminingreportsofcongenitallymalformedhearts,itisimportanttoknow
howthelesionsweredefinedandwhatconditionswereincludedorexcluded.
However,thedefinitionsinTable13.1donotaddressallcontroversy.Thereis
nocurrentconsensusastowhetherseveralgroupsoflesionsshouldbe
consideredtorepresentcongenitalcardiacmalformationsbecausetheydonot
manifestclinicallyuntillaterinlife.Theseconditionsincludegeneticconditions,
arrhythmicconditions,primarycardiomyopathies,andstructuraldefectsthatdo
nothavefunctionalimportanceinmany,butnotall,circumstances.
Considerationsregardingtheinclusionorexclusionoftheselesionsare
importantbecausetheselesionsarecommonandtheirinclusionmightinflatea
prevalenceestimate.Comparabilityofpreviousreportshassomewhatsuffered

fromalackofcommonnomenclatureregardingthedescriptionand
classificationofcongenitalheartdefects.Tosomeextent,therehasbeen
importantworkinconsolidatingnomenclaturetowardaninternationally
acceptedstandard,whichmayfacilitatefuturework.1–3
Table13.1
ClinicalDefinitionsUsedinIdentifyingtheFrequencyofCongenitalCardiacDisease
Term
DefinitionandExamples
Congenitalcardiac Agrossstructuralabnormalityoftheheartorintrathoracicgreatvesselsthatisactuallyor
disease
potentiallyoffunctionalsignificance.26Excludesnormalvariantswithoutfunctional
consequence(e.g.,persistentpatencyoftheleftsuperiorcavalvein,orabnormalpatternsof
branchingofthesystemicarteries).
Geneticconditions Presentfromconceptionandmaynothavemanifestcardiovascularconsequencesuntilmuch
laterinlife(e.g.,Marfansyndrome,Williamssyndrome,andhypertrophiccardiomyopathy).
Arrhythmic
Abnormalitiesatthephysiologicorultrastructurallevelthatresultinarrhythmias(e.g.,long
conditions
QTsyndromeandventricularpreexcitation).
Primary
Myocardialstructuralabnormalitieswithageneticormetabolicetiology(e.g.,hypertrophic
cardiomyopathies cardiomyopathyandventricularnoncompaction).
Structuraldefects Defectsthatdonothavefunctionalsignificanceinmany,butnotall,circumstancesor