<prompt> True statement about ductus Arteriosus isIt undergoes anatomic closure within 24 hours of birthForms the ligamentum venosum in later lifeIt is induced to close by high levels ofprostaglandinsMay cause a machinary murmur by its patency.  <response>: This question deals with the changes in blood circulation that occur at birth :Closure of Ductus arteriosusThe closure occurs almost immediately after birth by contraction of its muscular wall, mediated by bradykinin. i.e.Physiological closure.Anatomic closure occurs by proliferation of intima, and may take from 10-21 days not in 24 hrs. as given in choice A.After obliteration, it forms ligamentum arteriosum. not the ligamentum venosum as given in choice IDLigamentum venosum, on the other hand, is formed by closure of the ductus venosus.In neonates with congenital heart defects, till surgery is undertaken, PGE1 Alprostadil is used to maintain patency of ductus arteriosus.Therefore prostaglandins maintain patency of ductus arteriosus, and not induce it to close as given in choice C.Prostaglandins maintain patency of ductus arteriosusNSAIDs - help in early closure of ductus arteriosusShunt murmur is a continuous machinery murmur.The murmur is best heard at the 2nd left intercostal space and is also well heard below the left clavicle, where it maintains its continuous machinery character. 