Problems in the changes of the vascular shunts after

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Unformatted text preview: Foramen ovali : closes : by adhesion of upper part of septum primum to the lower part of septum secundum • septum primum inferior to the foramen ovali : fossa ovalis • Lower margin of septum secondum/crista dividens : limbus • Ductus arteriosus : ligamentum arteriosum • Umbilical arteries : the medial umbilical ligaments : superior vesical arteries. Problems in the changes of the vascular shunts after birth: Patent ductus arteriosus. - functional closure ---soon after birth in full term infants - if patent -- shunts aortic blood into pulmonary trunk - common congenital anomaly associated with maternal rubella infection during early pregnancy - common in premature infants and infants born at high altitudes-due to hypoxia and immaturity Embryological basis of PDA – failure of D.A to involute. Possible causes - failure of muscular wall to contract to form ligamentum arteriosum - large pressure differences in pulmonary and aortic blood pressures, Eg. Coarctation of aorta, transposition of great arteries pulmonary stenosis,etc. - hypoxia, prematurity, high altitude - prostaglandins - relaxes smooth muscle. - bradykinin - contraction of smooth muscle Patent foramen ovali. Embryological basis Failure of upper part of septum primum to fuse with lower part of septum secondum Atrial septal defects will be discussed in detail – In the lecture on development of the heart. What is lunate impression? Impression on the left atrial aspect of the site of oval foramen. Bless you. To God be the glory....
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