4. Persistent ductus arteriosus

Question 1

Functions of ductus arteriosus?

Answer 1

During the fetal period ductus arteriosus forms a normal junction
between aorta and the pulmonary artery.

Question 2

During this period?

Answer 2

During this period blood flows form the pulmonary
artery to the aorta. This duct is closed immediately after birth. The closure occurs as a result of a
change in the pressure relations and partly due to the active contraction of this duct which follows
changes in oxygen saturation in the blood. In cases of a patent ductus arteriosus which persists even
after birth the blood flows form aorta to the pulmonary artery. This flow is continuous during the
whole cardiac cycle.

Question 3

Blood flow?

Answer 3

The blood flow is faster during systole. This is why we can usually hear a very typical systole-diastolic
murmur which is marked as a machinery or continuous murmur. When the amount of blood flowing
through the duct is large, pulmonary hypertension and shunt would be later irreversible
(hypertension is fixed by fixed vascular obstruction) and more over becomes reversed. Blood then
flows from the pulmonary artery back to the descending aorta.