Andersons pediatric cardiology 1559

EndocrineDisorders
DiabetesMellitus
Theannualincidenceoftypes1and2diabetesmellitus(DM)diagnosedpriorto
age19yearshasbeenincreasingoverthelastfewdecades.From2011to2012,
theincidenceoftype1DMwas21.7casesper100,000youthsperyear,andthe
incidenceoftype2DMwas12.5casesper100,000youthsperyear.Therewere
significantvariationsacrossracialandethnicgroupsforbothtypes1and2.132
Cardiovascularcomplicationsareusuallymanifestlaterinthedisease,andthey
areexceedinglyrareinchildhood.133
However,thepediatriccardiologistwillencounteranincreasingincidenceof
congenitalcardiacmalformationsintheoffspringofdiabeticmothers.
Congenitalstructuralcardiacanomaliesoccurin3%to6%ofpregnancies
complicatedbyinsulin-dependentdiabetes,withapredominanceofconotruncal
abnormalities.Becausethesedefectsoccurearlyingestationandareassociated
withpoorlycontrolledDM,withhigherHbA1cincreasingtherisk,
preconceptioncounselingandtreatmentareveryimportant.134
Themostfrequentneonatalcardiaccomplicationofmaternaldiabetesis
hypertrophiccardiomyopathy,135producedbyelevatedlevelsofinsulinand
insulin-likegrowthfactorI.Themostobviouscomplication,however,is
macrosomia.Evenintheabsenceofcongenitalcardiacdisease,infantsof
diabeticmothershaveahostofproblems.Thissyndromeisseenbothinmothers
withestablisheddiabetesandinthosewhodevelopthediseaseduring
pregnancy.Thebabieshaveacharacteristicappearance,withhighbirthweight,
plumpness,andpuffyplethoricfacies.Theyarejittery,owingtohypoglycemia
secondarytohyperinsulinism.Theorgans,includingtheheart,areenlarged.The
babiesarefrequentlytachypneic,butthismaynotbeofcardiacetiology.
Respiratorydistresssyndromeisquitecommon.Cardiacmurmursarefrequent.
Approximatelyone-thirdhaveradiologiccardiomegaly.TheECGisrarely
diagnostic.
Indiabetes-relatedcardiachypertrophy,theECGshowsthickeningoftheright
andleftventricularwallstogetherwiththeseptum.Indeed,theventricular

septumisusuallythickerthanthefreewalls.Septalthicknessisgenerallymost
pronouncedinthoseinfantswithCHF.136Spontaneousimprovementafterbirth
isusual,andspecifictreatmentofthehypertrophiccardiomyopathyisrarely


needed.Diureticsmustbeusedjudiciously,asthethickenedmyocardium
requiresahighpreload,andβ-blockadeissometimesadvisedtohelpdiastolic
dysfunction,butthebenefithasnotbeenproven.Theclinicaland
echocardiographicsignsofhypertrophiccardiomyopathyusuallyresolveover
theearlyweeksoflife,butmyocardialthickeningcantakeupto6monthsto
resolve.137Moreimportantthandiagnosisandtreatmentisprevention.Itis
suggestedthatthemostseverelyaffectednewbornsarethoseinwhommaternal
controlofdiabeteshasbeenpoor.138,139

PituitaryGigantismandAcromegaly
Adenomasofthepituitarythatsecretegrowthhormonescausegigantismin
growingchildrenandacromegalyinadults.Cardiovascularcomplicationsare
commonandleadingcontributorstothemorbidityandmortalityofacromegaly.
Hypertension,earlycoronaryarterydisease,valvedisease,arrhythmias,and
acromegaliccardiomyopathyhaveallbeendescribed.140Acromegalic
cardiomyopathyresultsfromelevatedlevelsofgrowthhormoneandthe
resultantelevatedlevelsofinsulin-likegrowthfactor1.Thecardiomyopathyis
characterizedbybiventricularandconcentricinvolvement,whichisprogressive
andmayleadtoCHFwithmyocardialfibrosis.Theseverityofdiseaserelatesto
theageofthepatient.Treatmentwithsurgeryorsomatostatinanalogues,which
reducegrowthhormonelevels,isbeneficialintermsofclinicalsymptomsand
indexesofmyocardialmorphologyandphysiology.141

DisordersofThyroidFunction
Hypothyroidism

CongenitalHypothyroidism.
Congenitalhypothyroidismhasmanyetiologies.Themostcommoncauseis
congenitalthyroiddysplasia,presentinapproximately1in6000livebirths.
Therearerarercauses,includingendemicdeficiencyofiodine,diminished
responsivenesstothyrotrophininfamilialgoiter,andadministrationof
antithyroiddrugstopregnantmothers.Thecardiacfeaturesofcretinismarenot
dramatic.Normaltoslowheartratesandradiologiccardiomegalyareusuallythe
onlymanifestations.Theenlargedcardiacsilhouetteisusuallycausedby
pericardialeffusion,whichisanextremelycommonfeature(affecting


approximatelyhalfofthesepatients142),butitisrarelyhemodynamically
important.Cardiacperformanceisusuallywellpreserved.Abnormalitiesof
heartrateandthepericardialeffusionsresolvewhensubstitutiontreatmentofthe
hypothyroidismissuccessful.
JuvenileHypothyroidism.
Aswithcongenitalforms,juvenilehypothyroidismhasmultipleetiologies.Itis
generallytheresultofautoimmunethyroiditisorHashimotodisease.Growth
retardationisthemostcommonformofpresentationandcanleadtodelayed
sexualmaturation.Cardiacsignsandsymptomsarefewandcardiacfailureis
veryrare.Bradycardia,lowpulsepressure,poorperipheralcirculation,and
nonspecificmurmursmaybepresent.Pericardialeffusionswithnoevidenceof
pericarditisoccurinsomepatients.Tamponadeisrarelyseenbecauseoftheslow
rateoffluidaccumulation.Abouthalfofthepatientswithpericardialeffusions
haveassociatedpleuraleffusions.Establishmentofaeuthyroidstatereversesthe
cardiacmanifestations.

Hyperthyroidism
JuvenileHyperthyroidism.
Themostcommoncauseofjuvenilehyperthyroidismisdiffusetoxicgoiter,also

knownasGravesdisease.ThisisanautoimmunediseaseinwhichIgG
immunoglobulins,whichstimulateexcessiveproductionofthyroidhormones,
canbedemonstrated.Itismorecommoningirls,witharatiooffemalestomales
ofapproximately5to1.Itsgreatestincidenceisbetweentheagesof11and19
years,anditisrarelyseeninchildrenundertheageof3years.Cardiovascular
issuesarepresentatpresentationinapproximatelyone-quarterofthese
patients.143Otherpresentingsymptomsincluderestlessness,poorperformanceat
school,irritability,lossofweight,andoccasionallydiarrhea.Onexamination,
patientshavewarmskinandafinetremorisvisibleinoutstretchedhands.
Enlargementofthethyroidglandisalwayspresent,andbruitsareoftenaudible
overtheenlargedglandbecauseofitsincreasedvascularity.Exophthalmosis
commonbutisnotmarked.Cardiovascularinvolvementissecondarytoan
increasedadrenergicdriveandtodirectmyocardialstimulationbythyroid
hormones.Thepulseisfastwithawidepulsepressure.Thesystolicblood
pressureisincreased,andtheapicalimpulseishyperdynamic.Onauscultation,