Patent ductus arteriosus

Background

Patent ductus arteriosus in a heart after birth.

The fetal circulatory system showing with the normally open ductus arteriosus prior to birth (visible in upper right).

• Ductus arteriosus is a blood vessel connecting main pulmonary artery to proximal descending aorta
  • Shunts blood from right ventricle to bypass fetus's non-functioning lungs in utero
• In PDA, ductus fails to close after birth
• Second most common congenital heart disease
• Approximately 1 in 1600 to 5000 live births in the US.

Pathophysiology

• Ductus arteriosus shunts blood from the pulmonary artery to the aorta bypassing the lungs while in utero
• Normally closes soon after birth via complex process
  • Regulated by oxygen tension and decreases in prostaglandin E2
  • Becomes ligamentum arteriosum
• In PDA, ductus fails to close
  • Results in shunting of blood between aorta and pulmonary artery
  • Some oxygenated blood from high-pressure aorta shunts to lower pressure pulmonary artery
  • A large shunt can cause increased fluid return to lungs and increased lung pressure, leading to pulmonary hypertension
• Some congenital heart defects, such as transposition of the great arteries, are incompatible with life 'without a PDA; may be necessary to allow oxygenated and deoxygenated blood to mix
  • In these cases prostaglandins are used to keep the ductus arteriosus open.

Clinical Features

Phonocardiograms of common cardiac murmurs.

• Continuous machine like heart murmur
• Differential cyanosis (cyanosis of lower extremities and not the upper extremities)
• Dyspnea
• Tachycardia
• Widened pulse pressure
• Congestive heart failure
• Failure to thrive

Differential Diagnosis

• Acute pericarditis
• Aortopulmonary Septal Defect
• Coarctation of the Aorta
• Coronary artery fistula
• Pediatric acute respiratory distress syndrome
• Sinus of valsalva aneurysm
• Pediatric tachycardia
• Pulmonic valvular stenosis
• Sickle cell anemia
• Tetralogy of Fallot with absent pulmonary valve

Congenital Heart Disease Types

• Cyanotic
  • Tetralogy of fallot
  • Total anomalous pulmonary venous return
  • Transposition of the great arteries
  • Tricuspid atresia
  • Truncus arteriosus
  • Ebstein anomaly
  • Hypoplastic left heart syndrome
• Acyanotic
  • AV canal defect
  • Atrial septal defect (ASD)
  • Ventricular septal defect (VSD)
  • Cor triatriatum
  • Patent ductus arteriosus (PDA)
  • Pulmonary/aortic stenosis
  • Coarctation of the aorta
• Differentiation by pulmonary vascularity on CXR
  • Increased pulmonary vascularity
    • Large ASD
    • Large VSD
    • Total anomalous pulmonary venous return
    • Transposition of the great arteries
    • Truncus arteriosus
  • Decreased pulmonary vascularity
    • Tetralogy of fallot
    • Rare heart diseases with pulmonic stenosis

Evaluation

Echocardiogram of a stented persisting ductus arteriosus. The aortic arch and the stent leaving it are seen. The pulmonary artery is not visable.

Echocardiography demonstrating PDA

Chest x-ray and CT showing clips visible from past treatment of patent ductus arteriosus.

• Careful physical examination demonstrating characteristic machine-like murmur
• Echocardiography
  • MRA and Cardiac CT can also be used as diagnostic tools
• Laboratory tests usually not helpful

Management

• Spontaneous closure common
• If significant respiratory distress or impaired oxygen delivery, therapy usually required

Medical Therapy

• IV indomethacin: usually effective when administered in the first 10-14 days of life.
  • <48 hour old: start 0.2mg/kg IV x 1, then 0.1mg/kg q12-24h x 2
  • 2-7 days old: Start 0.2mg/kg IV x 1, then 0.2mg/kg q12-24h x 2
  • > 7 days old: Start 0.2mg/kg IV x 1, then 0.25mg/kg q12-24h x 2

Surgical Therapy

• Offered if medical therapy fails
  • Cardiac catheterization and catheter closure
  • Surgical ligation

Disposition

• Stable, asymptomatic patients can be discharged home with cardiology follow-up
• Symptomatic patients and patients requiring treatment should be admitted with cardiology consultation

Medication Dosing

Indomethacin 0.2mg/kg IV x1, then 0.1-0.25mg/kg q12-24h x2 (dose varies by age) IV

See Also

• Congenital Heart Disease