Congenital Heart Disease, Cyanotic



  • Aberrant embryonic development results in mixing of deoxygenated and oxygenated blood returning to systemic circulation by 2 mechanisms:
    • Right-to-left intracardiac shunt
    • Anatomic defects of the aortic root
  • Subtypes: 5 T's, 2 E's, single ventricle:
    • Tetralogy of Fallot (TOF):
      • Ventricular septal defect (VSD)
      • Right ventricular (RV) outflow obstruction
      • Overriding aorta
      • RV hypertrophy (RVH)
    • Transposition of the great arteries (TGA):
      • Aorta arises from RV and pulmonary artery from left ventricle (LV)
    • Tricuspid atresia:
      • No outlet from right atrium to RV
      • Obligatory atrial level connection
    • Truncus arteriosus:
      • Single arterial trunk for systemic, pulmonic, and carotid circulations
    • Total anomalous pulmonary venous return (TAPVR):
      • Pulmonary veins drain into systemic venous circulation
      • Supracardiac, cardiac, infracardiac, or mixed
    • Ebstein anomaly of tricuspid valve:
      • Abnormal and displaced tricuspid valve divides RV resulting in poor RV function
    • Eisenmenger syndrome:
      • Complication in longstanding acyanotic heart disease with L→R shunts
      • Pulmonary vascular resistance reaches suprasystemic levels; R→L shunt
    • Single ventricle physiology:
      • Total mixing of systemic and venous return
  • Subdivide by amount of pulmonary blood flow:
    • Decreased in TOF and tricuspid atresia
    • Increased in TGA, truncus, and TAPVR


For most forms, cause is unknown:
  • Genetic cause: Chromosome 22 deletion in DiGeorge syndrome (conotruncal defects; TOF, truncus; also coarctation of aorta)
  • Environmental/teratogenic: TGA seen more often in infants of diabetic mothers

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