fetal circulation.pptx

This presentation is focused on fetal circulation

1. Fetal Circulation By Dr Salman Mustaan

2. Introduction During pregnancy, fetus depends upon its mother for nutrition and oxygen Blood circulation is different than it is after birth All the necessary nutrition, oxygen and life support from mother goes through the placenta and to the fetus through blood vessels in the umbilical cord

3. Circulation Pathway Umbilical vein carries oxygenated blood and arteries carry deoxygenated blood 50% of the umbilical venous blood enters the hepatic circulation 50% bypasses the hepatic circulation and enters inferior vena cava via Ductus Venosus

4. Cont’d Here it mixes with the poorly oxygenated blood from the lower fetal part. This blood enters the right atrium and flows to the left atrium via foramen ovale . From left atrium, it flows into the left ventricle and via ascending aorta goes to the fetal upper body and brain

5. Cont’d Fetal Superior vena cava enters the right atrium, bypasses the left atrium and enters blood into right ventricle From the right ventricle, blood is ejected via pulmonary artery into lungs The major portion of this blood bypasses the lungs and flows right to left through the ductus arteriosus into the descending aorta to perfuse the lower part of the fetal body including flow to the placenta via two umbilical arteries

6. Fetal circulation Three cardiovascular structures are unique to fetal circulation that are important for maintaining parallel circulation: 1. Ductus Venosus 2. Ductus Arteriosus 3. Foramen Ovale

7. Total fetal cardiac output is 450ml/kg/min Approx 65% of fetal blood in descending aorta returns to the placenta. The rest of 35% perfuses the fetal organs and tissues

8. The transition from fetal circulation A fall in pulmonary resistance after the first few breaths Removal of low resistance placental circulation leads to an increase in systemic vascular resistance A fall in pulmonary arterial pressure

9. Cont’d Because pulmonary resistance becomes lower than systemic resistance, the shunt through ductus arteriosus reverses and becomes left to right. The high arterial pressure first constricts and then closes the ductus arteriosus . It becomes Ligamentum arteriosum

10. Cont’d The increased volume of pulmonary blood flow returning to the left atrium from the lungs, increases the left atrial volume and pressure sufficiently to close the foramen ovale . Removal of the placenta from circulation also closes the ductus venosus

11. SUMMARY OF BLEEDING DISORDERS Condition PT APTT BT PLATELETS 1 N N 2 N N N 3 N N N 4 N N 5 N N N 6 N N 7 8 N N N N

12. THANK YOU