Hypoplastic left heart syndrome (HLHS) is one of the most complex cardiac defects seen in the newborn and remains probably the most challenging to manage ...HLHSHomeHealthTopicsHHLHSPrintNavigateThisAreaSingleVentricleInterstageClinicNPCQICollaborativeMeettheTeamHypoplasticLeftHeartSyndrome/NorwoodProcedureHypoplasticleftheartsyndrome(HLHS)isoneofthemostcomplexcardiacdefectsseeninthenewbornandremainsprobablythemostchallengingtomanageofallcongenitalheartdefects.Itisoneofagroupofcardiacanomaliesthatcanbegroupedtogetherunderthedescription singleventricle defects.InachildwithHLHS,allofthestructuresontheleftsideoftheheart(thesidewhichreceivesoxygen-richbloodfromthelungsandpumpsitouttothebody)areseverelyunderdeveloped. Themitralandaorticvalvesareeithercompletely"atretic"(closed),ortheyareverysmall.Theleftventricleitselfistiny,andthefirstpartoftheaortaisverysmall,oftenonlyafewmillimetersindiameter. Viewa3-DgraphicsummaryThisresultsinasituationwheretheleftsideoftheheartiscompletelyunabletosupportthecirculationneededbythebody'sorgans,thoughtherightsideoftheheart(thesidethatdeliversbloodtothelungs)istypicallynormallydeveloped.Bloodreturningfromthelungstotheleftatriummustpassthroughanatrialseptaldefect(ASD)totherightsideoftheheart.Therightventriclemustthendoa"doubleduty"ofpumpingbloodbothtothelungs(viathepulmonaryartery)andouttothebody(viaapatentductusarteriosus).Thepatentductusarteriosus,anormalstructureinthefetus,isoftentheonlypathwaythroughwhichbloodcanreachthebodyfromtheheart.Whentheductusarteriosusbeginstoclose,asittypicallydoesinthefirstdaysoflife,thebloodflowtothebodywillseverelydiminish,resultingindangerouslylowbloodflowtovitalorgansandleadingtoshock.Withouttreatment,hypoplasticleftheartsyndromeisuniformlyfatal,oftenwithinthefirsthoursordaysoflife.SignsandSymptomsInfantswithhypoplasticleftheartsyndromecandeveloplife-threateningshockwhentheductusarteriosusbeginstoclose.Inmostcases,however,theductusarteriosusiswidelyopenatthetimeofbirth,supplyingthebloodflowtothebody,and