Truncus arteriosus

Background

Truncus arteriosus anatomy
  • A cyanotic congenital heart defect
  • Blood is pumped through a single truncal valve into a truncal artery which gives rise to the aorta and the pulmonary arteries
  • Associated with large VSD in most patients
  • Incidence ranges from 6 to 10 per 100,000 live births, accounts for 4% of all congenital heart disease [1]

Physiology

  • PVR is high in the newborn infant, so there is little left to right shunting at birth
  • Over first several weeks of life, PVR drops, left to right shunting increases, leading to heart failure
  • Mixing of systemic and pulmonary blood leads to mild to moderate cyanosis
  • Pulmonary vascular obstructive disease may develop in surgically uncorrected patients

Clinical Features

  • Most present within the first weeks of life with
    • Cyanosis
    • Pulmonary congestion and heart failure
      • Poor feeding, lethargy, signs of respiratory distress (tachypnea, costal-sternal retractions, grunting, and nasal flaring), tachycardia, hyperdynamic precordium, and hepatomegaly
    • Cardiovascular findings
      • Loud second heart sound
      • Prominent ejection click at the apex or left sternal border
      • Systolic ejection murmur at the left sternal border
      • Bounding peripheral pulses
      • Increased pulse pressure

Differential Diagnosis

Congenital Heart Disease Types

Evaluation

  • ECG
    • May be normal
    • May have evidence of left or right ventricular hypertrophy
  • Chest x-ray
    • Enlarged cardiac silhouette
    • Increased pulmonary vascular markings
    • May see absent thymus in patients with TA associated with DiGeorge syndrome
  • Echocardiography

Management

  • Stabilize cardiopulmonary function prior to surgery
  • Diuretic therapy, (eg, furosemide) reduce preload, relieve volume overload and pulmonary congestion
  • Inotropic agents (eg, dopamine and dobutamine) improve myocardial contractility
  • ACEI reduces afterload
  • Noninvasive positive pressure ventilation often used in patients with respiratory distress due to pulmonary congestion
  • Supportive care to correct metabolic acidosis, hypoglycemia, and anemia that may contribute to heart failure
  • Prostaglandin E1 if patient also has critical coarctation of the aorta
  • Primary surgical repair during the neonatal period (less than 30 days of age)
    • Improved survival rate at one year of age of >80% vs 15% in uncorrected patients [3]

Disposition

  • Admit

See Also

External Links

References

  1. Reller MD. Prevalence of congenital heart defects in metropolitan Atlanta, 1998-2005. J Pediatr. 2008;153(6):807-13.
  2. Knipe K et al. Cyanotic congenital heart diseases. Radiopaedia. http://radiopaedia.org/articles/cyanotic-congenital-heart-disease
  3. Thompson LD. Neonatal repair of truncus arteriosus: continuing improvement in outcomes. Ann Thorac Surg. 2001;72(2):391-5.