R → L shunts cause cyanosis

•  Children squat to increase SVR and decrease R → L shunts

•  Cyanosis – can lead to polycythemia, strokes, brain abscess, endocarditis

•  Eisenmenger’s syndrome: shift from L → R shunt to R → L shunt

•  Sign of increasing pulmonary vascular resistance (PVR) and pulmonary HTN; this condition is generally irreversible

  L → R shunts cause CHF – manifests as failure to thrive, ↑ HR, tachypnea, hepatomegaly; CHF in children – hepatomegaly 1st sign

  L → R shunts (CHF) – VSD, ASD, PDA

  R → L shunts (cyanosis) – tetralogy of Fallot

  Ductus arteriosus – connection between descending aorta and left pulmonary artery (PA); blood shunted away from lungs in utero

  Ductus venosum – connection between portal vein and IVC; blood shunted away from liver in utero

  Fetal circulation to placenta – 2 umbilical arteries

  Fetal circulation from placenta – 1 umbilical vein

  Ventricular septal defect (VSD)

•  Most common congenital heart defect

•  L → R shunt

•  80% close spontaneously (usually by age 6 months)

•  Large VSDs – usually cause symptoms after 4–6 weeks of life, as PVR ↓ and shunt ↑

•  Can get CHF (tachypnea, tachycardia) and failure to thrive

•  Medical Tx: diuretics and digoxin

•  Usual timing of repair:

•  Large VSDs (shunt > 2.5) – 1 year of age

•  Medium VSDs (shunt 2–2.5) – 5 years of age

•  Failure to thrive – most common reason for earlier repair

  Atrial septal defect (ASD)

•  L → R shunt

•  Ostium secundum – most common (80%); centrally located

•  Ostium primum (or atrioventricular canal defects or endocardial cushion defects); can have mitral valve and tricuspid valve problems; frequent in Down’s syndrome

•  Usually symptomatic when shunt > 2 → CHF (SOB, recurrent infections)

•  Can get paradoxical emboli in adulthood

•  Medical Tx: diuretics and digoxin

•  Usual timing of repair – 1–2 years of age (age 3–6 months with canal defects)

  Tetralogy of Fallot (4 parts)

•  VSD, pulmonic stenosis, overriding aorta, right ventricular (RV) hypertrophy

•  R → L shunt

•  Most common congenital heart defect that results in cyanosis

•  Medical Tx: β-blocker

•  Usual timing of repair – 3–6 months of age

•  Repair: RV outflow tract obstruction (RVOT) removal, RVOT enlargement, and VSD repair

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