A premature infant in respiratory distress is found to have a continuous “machinery” murmur over the precordium. The following is/are true:
- The most likely diagnosis is coarctation of the aorta
- If large pulmonary arteries are noted, a patent ductus is likely
- To discriminate between a and b, prostaglandin administration can be used which will constrict the patent ductus arteriosus
- If a ductus if found, operative repair should be delayed until the respiratory symptoms improve to reduce mortality rates
- Normal ductus closure depends on increased oxygen saturation in the pulmonary artery
Medicine
b. If large pulmonary arteries are noted, a patent ductus is likely
e. Normal ductus closure depends on increased oxygen saturation in the pulmonary artery
A continuous “machinery” murmur is characteristic of patent ductus arteriosus typically seen in the premature infant. Normal closure of the ductus is prompted by a fall in pulmonary vascular resistance that increases the left-to right shunt and oxygen levels from the aorta. Indomethacin can cause ductus closure by cyclooxygenase inhibition which decreases endogenous prostaglandins. Prostaglandin infusion would keep the ductus open. Operative closure can be done safely in even the smallest neonates and usually promptly relieves the respiratory distress.
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