1. Patent Ductus Arteriosus

2. Incidence of PDA Closure of PDA in term infants:
50% by 24 hours
90% by 48 hours
100% by 72 hours
Closure of PDA >30 weeks gestation:
11% remain open after 4 days
Closure of PDA < 30 weeks gestation:
65% remain open after 4 days

3. Regulation of Ductal Closure
Functional closure of lumen:
Occurs within hours after birth due to smooth muscle constriction
Anatomic occlusion of lumen:
Occurs days after birth due to intimal thickening and loss of smooth muscle cells

4. Factors regulating Ductal Relaxation
Increased pulmonary vascular pressure
Vasodilator prostaglandins: PGE1
Nitric oxide

5. Post-natal factors regulating Ductal Closure
Increased Pa02
Decreased PVR
Decreased circulatory concentrations of PGE1
Decreased PGE1 receptors in ductal wall
Increased cortisol concentrations
Cortisol decreases the sensativity of the ductus to vasodilating effects of PGE.

6. Factors Restricting Ductal Closure in Preemies
Decreased intrinsic smooth muscle tone
Higher circulating PGE1 concentrations
Increased sensitivity to vasodilatory effects of PGE1 and NO

7. Hemodynamic and Pulmonary Consequences of PDA
Left to right shunt: increased pulmonary venous pressure, increased pulmonary edema
Decreased blood flow to skin, bone, muscle, GI tract, and kidneys
Rapid increase in pulmonary blood flow leading to pulmonary hemorrhage (risk of surfactant administration)

8. Treatment Indocin prophlaxis
Treatment indocin: closure in 85% patients
Surgical ligation

9. Complications of PDA
BPD
NEC
Feeding intolerance

10. Risks of Indocin Use
Decreased mesenteric, renal, and cerebral blood flow
Oliguria, dilutional hyponatremia
Isolated intestinal perforation (increased risk when combined with postnatal steroids)
NEC?

11. Contraindications to Indocin Use
NEC
Renal failure
Bleeding disorders and severe thrombocytopenia
Hemodynamically insignificant PDA

12. Clinical diagnosis Systolic heart murmur, though may be absent
Hyperdynamic precordium
Bounding peripheral pulses
Wide pulse pressure
Worsening respiratory status

13. Indocin Prophylaxis
Decreases symptomatic PDA and the need for surgical ligation
Decreases Grade III and IV IVH
No change in short or long term mortality
No difference in rates of NEC
Long term neurodevelopmental outcome is not adversely affected