What is the diagnosis and treatment for a child with a continuous machinery murmur heard best at the second left intercostal space?

Patent Ductus Arteriosus: Diagnosis and Management

A child with a continuous machinery murmur heard best at the second left intercostal space that is widely transmitted over the precordium most likely has a patent ductus arteriosus (PDA), which requires echocardiographic confirmation and may need closure depending on hemodynamic significance.

Diagnostic Approach

• The classic "machinery" or "continuous" murmur heard best at the second left intercostal space is the hallmark physical finding of patent ductus arteriosus 1, 2
• This characteristic murmur occurs due to continuous blood flow from the aorta to the pulmonary artery throughout both systole and diastole 2
• Wide transmission across the precordium suggests significant left-to-right shunting through the PDA 1, 2
• Echocardiography is indicated as a Class I recommendation for any child with a loud or abnormal murmur to confirm the diagnosis 1

Diagnostic Confirmation

• Two-dimensional echocardiography with Doppler assessment is essential for:
  • Confirming PDA diagnosis 1, 3
  • Determining the size and shape of the ductus 3
  • Assessing hemodynamic significance (direction and magnitude of shunt) 1, 2
  • Evaluating for associated cardiac anomalies 1
  • Measuring left atrial and ventricular dimensions to assess volume overload 4

Management Approach

• Management decisions depend on patient age, PDA size, and hemodynamic impact 2, 3:

For Hemodynamically Significant PDA:

• Transcatheter closure is the preferred first-line treatment for most children beyond the neonatal period 3

  • Less invasive than surgery
  • Shorter hospital stay
  • Excellent safety profile

• Surgical ligation may be considered when:

  • Transcatheter closure is technically not feasible 3
  • PDA anatomy is unfavorable for device closure 3
  • There is significant pulmonary hypertension requiring careful assessment 5

Special Considerations:

• In patients with pulmonary arterial hypertension and PDA:

  • Consider PDA closure if pulmonary artery pressure is >2/3 of systemic pressure with net left-to-right shunt (Qp:Qs >1.5) 5
  • Avoid PDA closure in patients with Eisenmenger physiology (right-to-left shunting) 5

• For preterm infants with PDA:

  • Medical management with prostaglandin inhibitors (indomethacin or ibuprofen lysine) may be attempted first 2, 6
  • Surgical intervention may be necessary if medical management fails 7

Complications and Follow-up

• Untreated, hemodynamically significant PDA can lead to:

  • Left heart volume overload 4
  • Congestive heart failure 2
  • Pulmonary hypertension 3
  • Rare complications like AV block have been reported 4

• Regular follow-up with a cardiologist is recommended after PDA closure to monitor for:

  • Resolution of left heart volume overload 4
  • Improvement in cardiac function 3
  • Development of any late complications 5

Pitfalls to Avoid

• Don't mistake PDA for other causes of continuous murmurs such as:

  • Aortopulmonary window
  • Coronary arteriovenous fistula
  • Ruptured sinus of Valsalva aneurysm 1, 3

• Avoid delaying diagnosis and treatment in symptomatic patients, as prolonged volume overload can lead to irreversible pulmonary hypertension 5, 3

• Don't close a PDA in patients with ductal-dependent congenital heart lesions where the PDA is providing essential pulmonary or systemic blood flow 1, 5