WBR267
| Author | [[PageAuthor::Ogheneochuko Ajari, MB.BS, MS [1]]] |
|---|---|
| Exam Type | ExamType::USMLE Step 1 |
| Main Category | MainCategory::Embryology, MainCategory::Pathophysiology |
| Sub Category | SubCategory::Cardiology, SubCategory::Pulmonology |
| Prompt | [[Prompt::A 5-week-old female infant who was born a preterm was brought to the hospital with the mother complaining of rapid breathing, diaphoresis and difficulty with feeding. She also mentioned that there has been little weight gain since birth. On examination, the infant has a hoarse cry and cough, with evidence of lower lung infections. Doppler further reveals a left-to-right shunt. Which of the following statements is true about the infant’s condition?]] |
| Answer A | AnswerA::The patency of the ductus arteriosus is primarily controlled by low fetal oxygen tension and the circulation of prostanoids produced from arachidonic acid metabolism. |
| Answer A Explanation | AnswerAExp::Correct- See explanation |
| Answer B | AnswerB::Oxygen-induced constriction of the ductus arteriosus fails in preterm infants potentially due to maturity of oxygen-sensing receptors. |
| Answer B Explanation | AnswerBExp::Incorrect. Oxygen-induced constriction of the ductus arteriosus fails in preterm infants potentially due to immaturity of oxygen-sensing receptors. |
| Answer C | AnswerC::The ductus arteriosus is thought to derive from the embryonic left fourth aortic arch. |
| Answer C Explanation | AnswerCExp::Incorrect. The ductus arteriosus is thought to derive from the embryonic left sixth aortic arch. |
| Answer D | AnswerD::Smooth muscle contraction of the ductus arteriosus results from the activation of the G-coupled prostaglandin receptor EP4 by PGF2. |
| Answer D Explanation | AnswerDExp::Incorrect. Smooth muscle contraction of the ductus arteriosus results from the activation of the G-coupled prostaglandin receptor EP4 by PGE2. |
| Answer E | AnswerE::Within 1 – 5 days after a full-term birth, the ductus arteriosus closes as a result of decreased oxygen tension and increased circulating PGE2 and prostacyclins (PGI2). |
| Answer E Explanation | AnswerEExp::Incorrect. Within 1 – 5 days after a full-term birth, the ductus arteriosus closes as a result of increased oxygen tension and decreased circulating PGE2 and prostacyclins (PGI2). |
| Right Answer | RightAnswer::A |
| Explanation | [[Explanation::The Ductus Arteriosus (DA) is thought to derive from the embryonic left sixth aortic arch.
The DA connects the pulmonary artery to the aorta and it serves to shunt blood away from the lungs into the umbilical placental circulation where gas exchange takes place. At birth, its closure is essential for postnatal adaptation. Its closure is initiated by an increase in oxygen and changes in both the pulmonary and systemic blood pressure. In full-term neonates, the DA routinely closes within the first 5 days post-delivery. In preterm infants, failure of its closure after birth can be associated with an increased incidence of neonatal morbidity.
The patency of the ductus arteriosus is primarily controlled by low fetal oxygen tension and the prostanoids in the blood produced from arachidonic acid metabolism.
Oxygen-induced constriction of the ductus arteriosus fails in preterm infants potentially due to immaturity of oxygen-sensing receptors. Smooth muscle relaxation of the ductus arteriosus results from the activation of the G-coupled prostaglandin receptor EP4 by PGE2.
Using indomethacin or ibuprofen to trigger prostaglandin inhibition – has been the standard strategy to close the DA in predisposed infants, who are particularly preterm. Surgical closure of the DA is another modality of treatment.
Within 1 – 5 days after a full-term birth, the ductus arteriosus closes as a result of increased oxygen tension and decreased circulating PGE2 and prostacyclins (PGI2). |
| Approved | Approved::Yes |
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| Linked Question | Linked:: |
| Order in Linked Questions | LinkedOrder:: |