NICU:  Cardiovascular:  Patent Ductus Arteriosus

Introduction

Patent Ductus Arteriosus (PDA) is a common cardiac complication in the ICN.  Clinical signs of PDA include hyperactive precordium, wide pulse pressure and bounding pulses, palmar pulses, delayed distal capillary refill, and metabolic acidosis.  A murmur (usually continuous, along the left upper sternal borner and radiating to the back) may not be heard in up to 50% of cases, especially in a large PDA.  Also, murmurs may indicate a different anomaly.

Diagnosis

Definitive Diagnosis is made with a 2 dimensional echocardiogram; this assesses the size of the PDA as well as the degree of shunting across it.  The echo also rules out duct-dependent cyanotic lesions -- PDA closure in this setting may be incompatible with life.

Medical Treatment:

In some cases, the first line of treatment may be fluid restriction.  By reducing the circulating volume, flow across the PDA may be reduced enough to allow natural closure.  Indocin, an antiprostaglandin agent, may also be used.

Pretreatment workup for indocin
Echocardiogram
CBC with differential (to check platelet count and Hct)
Electrolytes, BUN, Creatinine
Close monitoring of urine output

Contraindications to indocin therapy

BUN > 30
Creatinine > 1.5
UOP < 1 cc/kg/hour for the 12 hours prior to therapy
Platelets less than 100,000; stool strongly positive for occult blood
     Platelets can be infused to achieve the desired level before indocin is given
Any bleeding diathesis
Necrotizing enterocolitis

Dosage of Indocin

Monitoring

Follow up the UOP closely and maintain greater than 1-2 cc/kg/hour.  Check the electrolytes, BUN, creatinine, and platelets prior to each dose.  Doses should be 12 hours apart.  For significant drops in UOP, do not give further doses of Indocin at least until the UOP has recovered.

Assessment

Monitor the clinical effect.  A follow-up echo is often done to confirm closure.  Closeure is physiologic at first, then become anatomic after a few days.  Thus a PDA may re-open after Indocin therapy (prior to anatomic closure).