Updated: 9/6/2020

Transposition of Great Vessels

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  • A neonatal boy is born to a 37-year-old mother via normal spontaneous vaginal delivery. His mother has type 2 diabetes and hypertension. Since birth, he has had trouble feeding, seems to be constantly tachypneic, and has increasingly blue lips. He is immediately given prostaglandin E, and an echocardiogram is obtained, revealing transposition of the great vessels. He is scheduled for surgical repair.
  • Clinical definition
    • a congenital heart defect in which the aorta leaves the right ventricle and the pulmonary trunk leaves the left ventricle, resulting in the complete separation of the systemic and pulmonary circulations
  • Epidemiology
    • demographics
      • male > female
      • present at birth
      • most common cyanotic lesion presenting immediately after birth
    • risk factors
      • maternal diabetes
      • maternal smoking
      • advanced maternal age
  • Etiology
    • failure of neural crest cells to migrate
  • Pathogenesis
    • failure of the aorticopulmonary septum to spiral results in complete separation of the systemic and pulmonary circulations 
    • infants survive only if a shunt between the two circulations exist, to mix oxygenated blood into the systemic circulation
      • patent ductus arteriosus (PDA)
      • ventricular septal defect (VSD)
      • atrial septal defect (ASD)
      • patent foramen ovale (PFO)
  • Associated conditions
    • VSD
    • coarctation of the aorta
  • Prognosis
    • infants experience severe cyanosis and tachypnea as the ductus arteriosus closes in the newborn period
  • Symptoms
    • early and progressive cyanosis that does not correct with oxygen
    • signs of heart failure
      • tachypnea
      • sweating
      • poor feeding
  • Physical exam
    • cardiac
      • loud and single S2 heart sound 
      • may have a soft systolic ejection murmur
      • may have harsh holosystolic murmur if patients have VSD
    • central cyanosis
  • Radiography
    • indication
      • for all patients
    • recommend views
      • chest
    • findings 
      • cardiomegaly
      • egg-on-a-string appearance
        • narrowed mediastinum
  • Echocardiography
    • indication
      • performed as a diagnostic test
      • most specific test
    • findings
      • pulmonary trunk arising from the left ventricle
      • aorta arising from the right ventricle
  • Making the diagnosis
    • based on clinical presentation and echocardiography
    • in some cases, patients may be diagnosed prenatally with fetal echocardiography
  • Tetralogy of Fallot
    • distinguishing factor
      • tet spells (cyanosis) that are resolved when placed in knee-chest position
  • Medical
    • prostaglandin E1
      • indication 
        • for all neonates
      • mechanism of action
        • maintains a patent ductus arteriosus for adequate lower extremity perfusion
  • Operative
    • balloon atrial septostomy (Rashkind procedure)
      • indication
        • for all patients
        • performed for temporary mixing prior to definitive surgical repair
    • arterial switch surgical repair
      • indication
        • for all patients as definitive treatment
        • commonly performed in the first month of life
  • Heart failure
  • Sudden cardiac death
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