Section 126.1: Patent Ductus Arteriosus (PDA)

Incidence · Pathophysiology · Clinical manifestations · Echo criteria · Pharmacologic closure (ibuprofen, indomethacin, acetaminophen) · Surgical ligation · Percutaneous closure
❤️ Key fact: 65% of infants <30 wk have PDA; 85% at 24 wk. Hemodynamic significance depends on size + left heart effects.

🫀 Patent Ductus Arteriosus in Preterm Infants: Key Concepts

📊 Incidence
65% at <30 wk, 85% at 24 wk. Spontaneous closure occurs in >90% by discharge.
🩺 Clinical signs
Bounding pulses, wide pulse pressure, hyperdynamic precordium, continuous murmur, pulmonary edema, worsening respiratory failure.
📐 Echo criteria for significant PDA
Size ≥1.5 mm, LA/Ao ratio ≥1.5, left-to-right shunt, retrograde diastolic flow in descending aorta.
💊 Pharmacologic closure
Ibuprofen or indomethacin (COX inhibitors). Acetaminophen alternative. Contraindications: renal failure, thrombocytopenia, NEC, active bleeding.
🔪 Surgical/percutaneous closure
If medical therapy fails or contraindicated. Surgical ligation → post-ligation cardiac syndrome (hypotension). Percutaneous Amplatzer Piccolo Occluder for infants ≥700 g.
⚠️ Indomethacin vs ibuprofen
Indomethacin reduces severe IVH. Ibuprofen has fewer renal side effects. Both equally effective for PDA closure.
⚠️ Contraindications to COX inhibitors: Platelets <50,000, active hemorrhage, severe IVH, NEC/perforation, creatinine >1.8 mg/dL, oliguria.

🔍 Approach to suspected hemodynamically significant PDA in a preterm infant

1
Clinical suspicion – Worsening respiratory failure, increasing O2 requirement, carbon dioxide retention, metabolic acidosis, or failure to wean ventilator.
2
Physical exam – Bounding peripheral pulses, widened pulse pressure, hyperdynamic precordium, continuous or systolic murmur at left upper sternal border, hepatomegaly.
3
Echocardiography – PDA diameter ≥1.5 mm, left atrial to aortic root (LA/Ao) ratio ≥1.5, left ventricular dilation, retrograde diastolic flow in descending aorta, elevated left pulmonary artery velocity.
4
Exclude other causes – Sepsis, pneumothorax, fluid overload, airway issues. Echocardiography also assesses pulmonary hypertension and cardiac function.
5
Assess for contraindications to medical therapy – Renal failure, thrombocytopenia, NEC, active bleeding, severe IVH.

📋 Stepwise management of PDA in preterm infants

1
Conservative management – Fluid restriction (130-140 mL/kg/day), diuretics for pulmonary edema (furosemide 1 mg/kg IV), treat anemia if present. Many PDAs close spontaneously.
2
Pharmacologic closure (first-line) – Ibuprofen (10 mg/kg, then 5 mg/kg at 24 and 48h) or indomethacin (0.1-0.2 mg/kg/dose q12-24h x 3 doses). Acetaminophen (15 mg/kg q6h x 3-7 days) alternative if COX inhibitors contraindicated.
3
Monitor response – Repeat echocardiography after 1-2 days. If PDA persists and still hemodynamically significant, a second course may be attempted (lower success rate).
4
Surgical ligation (if medical therapy fails or contraindicated) – Open thoracotomy. Post-ligation cardiac syndrome (hypotension, low cardiac output) occurs in up to 50% → volume, inotropes (dobutamine, milrinone), hydrocortisone.
5
Percutaneous closure – Amplatzer Piccolo Occluder (FDA approved for ≥700 g). Performed in cardiac catheterization lab. Lower risk of post-ligation syndrome.
📌 Prophylactic indomethacin: Reduces severe IVH and PDA ligation but does not improve long-term neurodevelopment. Avoid concomitant hydrocortisone (increases intestinal perforation).

🧠 Rapid reflex prompts – PDA

📌 Incidence of PDA at 24 weeks GA?
85%. At 30 weeks: 65%.
📌 Echocardiographic criteria for significant PDA?
Diameter ≥1.5 mm, LA/Ao ≥1.5, left-to-right shunt, retrograde diastolic flow in descending aorta.
📌 First-line pharmacologic agent for PDA?
Ibuprofen or indomethacin (equally effective). Ibuprofen has fewer renal side effects.
📌 Contraindications to COX inhibitors?
Creatinine >1.8 mg/dL, platelets <50,000, active bleeding, NEC, spontaneous intestinal perforation.
📌 What is post-ligation cardiac syndrome?
Hypotension 6-12 hours after ductal ligation due to increased afterload and decreased preload; treat with fluids and inotropes.
📌 Newer less invasive PDA closure method?
Percutaneous device closure (Amplatzer Piccolo) for infants ≥700 g.