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Patent Ductus Arteriosus

In the uterus, the foetus has a vessel, called the Ductus Arterious (DA), that connects the aorta to the pulmonary artery. The function of this is to allow blood to flow from the RV outflow into the aorta, in order to bypass the pulmonary circulation. Normally, after birth, the DA stops functioning after 1-3 days, and closes within the first 2-3 weeks. In those with a PDA, this vessel stays open after 4 weeks.


A key risk factor here is Prematurity.

Heart cross section with patent ductus arteriosus - BrownCow (https://commons.wikimedia.org/wiki/File:Patent_ductus_arteriosus.svg)

The DA staying patent leads to:

  • Left-to-Right shunt as blood flows from aorta into pulmonary arteries - This causes Pulmonary HTN → RH strain and hypertrophy

  • The increasing blood flow returning from the pulmonary circulation leads to LV hypertrophy as well


It presents with:

  • Continuous crescendo-decrescendo machine-whirring murmur

  • SOB on exertion

  • Poor feeding and weight gain

  • LRTIs


Management:

  • If asymptomatic, the PDA is closely monitored with regular Echo's

  • If symptomatic:

    • Medical – NSAIDs

    • Surgical repair


N.B. Prostaglandins keep the DA open, therefore, NSAIDs are used to close it as they inhibit prostaglandin synthesis.




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