MORPHOLOGYPreductal coarctation ischaracterizedbycircumferentialnarrowingoftheaorticsegmentbetweentheleftsubclavianarteryandtheductusarteriosus;theductustypicallyispatentandisthemainsourceof(unoxygenated)blooddeliveredtothedistalaorta.Thepulmonarytrunkisdilatedtoaccommodatetheincreasedbloodflow;becausetherightsideoftheheartnowperfusesthebodydistaltothenarrowedsegment(“coarct”),therightventricletypicallyishypertrophied.
Inthemorecommon“adult” postductal coarctation, theaortaissharplyconstrictedbyatissueridgeadjacenttothenonpatentligamentumarteriosum(
Fig.11.6 ).Theconstrictedsegmentismadeupofsmoothmuscleandelasticfibersderivedfromtheaorticmedia.Proximaltothecoarctation,theaorticarchanditsbranchvesselsaredilatedandtheleftventricleishypertrophied.
Clinical manifestations depend on the severity of the narrowing and the patency of the ductus arteriosus.
Preductal coarctation with a PDA usually presents early in life, classically as cyanosis localized to the lower half of the body; without intervention, most affected infants die in the neonatal period.
Postductal coarctation without a PDA usually is asymptomatic, and the disease may remain unrecognized well into adult life. Classically, there is upper-extremity hypertension paired with weak pulses and relative hypotension in the lower extremities, associated with symptoms of claudication and coldness. Exuberant collateral circulation “around” the coarctation often develops through markedly enlarged intercostal and internal mammary arteries; expansion of the flow through these vessels can lead to radiographically visible “notching” of the ribs.
In most cases, significant coarctations are associated with systolic murmurs and occasionally palpable thrills. Balloon dilation and stent placement or surgical resection with end-to-end anastomosis (or replacement of the affected aortic segment by a prosthetic graft) yields excellent results.
Congenitalheartdiseaserepresentsdefectsofcardiacchambersorthegreatvessels;theseeitherresultinshuntingofbloodbetweentheright-andleft-sidedcirculationorcauseoutflowobstructions.Lesionsrangefromrelativelyasymptomatictorapidlyfatal.Environmental(toxicorinfectious)andgeneticcausesbothcontribute.
MalformationsassociatedwithLeft-to-rightshuntsarethemostcommonandincludeASDs,VSDs,andPDA.Shuntingresultsinright-sidedvolumeoverloadthateventuallycausespulmonaryhypertensionand,withreversalofflowandright-to-leftshunting,cyanosis(Eisenmenger syndrome).
MalformationsassociatedwithRight-to-leftshuntsincludetetralogyofFallotandtranspositionofthegreatarteries.Theselesionscauseearly-onsetcyanosisandareassociatedwithpolycythemia,hypertrophicosteoarthropathy,andparadoxicalembolization.
Obstructivelesionsincludeformsofaorticcoarctation;theclinicalseverityoftheselesionsdependsonthedegreeofstenosisandthepatencyoftheductusarteriosus.