Factors that encourage continued patency of the ductus include prematurity, RDS,
surfactant therapy, hypoxia, anemia, hypervolemia, and high altitude.
In the clinically significant PDA, a murmur may be auscultated and is systolic or
continuous heard best in the left upper sternal border. The baby often has a widened
pulse pressure (>30 mmHg) with corresponding bounding peripheral pulses (palmar
pulses). Additional findings include respiratory insufficiency, hepatomegaly or a
hyperactive precordium. A CXR may show an enlarged heart and increased vascular
markings. Echocardiography is used to confirm a PDA. Its continued presence may
result in heart failure, ventilator dependency, CLD and potential increased susceptibility
to NEC, IVH or CLD.
PDA closure may be accomplished medically or surgically. Indomethacin or ibuprofen
may be administered, but should not be given in patients with creatinine >1.6 mg/dl,
platelet count <50,000, or suspicion of NEC. Surgical ligation is indicated when medical
treatment is unsuccessful or when NSAID administration is contraindicated.
There may be an initial hypertensive episode resulting from closure of the ductus. This
may be followed by potential hypotension, which may require pressor support. Some of
the hypotension observed may be in response to surgical conditions such as
thoracostomy, sedation and paralysis. Additionally, some infants may have low cardiac
output due to alterations following ligation (post ligation syndrome). Pressor support is
therapy for this initial change.