MRCP UK EXAMINATIONS

Detailed explanation-1: -In postnatal circulation, when the baby takes its first breath, pulmonary resistance decreases, and blood flow through the placenta ceases. Blood commences flowing through the lungs, and the pressure on the left side becomes higher than on the right. As a result, the shunts mentioned above close.

Detailed explanation-2: -Prostaglandin E1 (PGE1) is used to keep the ductus arteriosus patent and can be life‐saving in neonates with ductal‐dependent cardiac lesions. PGE1 is used to promote mixing of pulmonary and systemic blood flow or improve pulmonary or systemic circulations, prior to balloon atrial septostomy or surgery.

Detailed explanation-3: -An increase in the baby’s blood pressure and a significant reduction in the pulmonary pressures reduces the need for the ductus arteriosus to shunt blood. These changes promote the closure of the shunt. These changes increase the pressure in the left atrium of the heart, which decrease the pressure in the right atrium.

Detailed explanation-4: -Ductus arteriosus. protects lungs against circulatory overload. allows the right ventricle to strengthen. Ductus venosus. fetal blood vessel connecting the umbilical vein to the IVC. blood flow regulated via sphincter. Foramen ovale.