Fetal circulation (for mbbs)

This is a presentation I had made for giving a seminar on Fetal Circulation in the first year of my MBBS course in Maharashtra.
Please share it with your juniors and colleagues.Thank You
Presentation By Tashif Jilani

1. FETAL CIRCULATION - By Tashif (60) Afaque (73) Suraj (64 ) Sonali (79) Yash (76)

2. SUBTOPICS:- Tashif – Introduction and Process of Fetal Circulation Afaque -Shunts and Pecularities of Fetal Circulation Suraj - Changes in Fetal Circulation after Birth Sonali -Congenital Heart Anomalies-1 Yash - Congenital Heart Anomalies-2

3. What is Fetal Circulation?

4. Placental Role in Foetal Circulation: The circulatory system of the mother is not directly connected to that of the fetus, so the placenta functions as the respiratory center for the fetus as well as a site of filtration for plasma nutrients and wastes.

5. • Foetal Lungs: Pulmonary vascular resistance is the resistance offered to blood through lungs. The resistance is very high in fetus because of the non-functioning of fetal lungs. Because of this high pressure, the blood is diverted from pulmonary artery into aorta.

6. UMBILICAL ARTERY It is a paired artery that is found in the pelvic and abdominal region of the fetus which extends into the umblical cord. Supplies de-oxygenated blood from the fetus to the placenta. They surround the urinary bladder and then carry all the de-oxygenated blood out of the fetus.

7. STEPS:- The oxygenated blood ,from the placenta (where gaseous exchange takes place,and not the lungs),travels through the UMBILICAL VEIN . UMBILICAL VEIN joins with LEFT BRANCH OF PORTAL VEIN . Divides into 2 parts:- a) INDIRECT PATH OF IVC :Through substance of liver b) DIRECT PATH TO IVC :Through DUCTUS VENOSUS (DV) to IVC .Thus, DV is for BYPASSING hepatic circulation.

8. 4)The IVC takes the oxygenated blood to the right atrium .By the valve of the IVC ,this blood is directed towards the Foramen Ovale . Here,it is divided into 2 portions:- A)Most of it passes through foramen ovale into left atrium B)The rest of it gets mixed up with the blood returning to the Right atrium through the SVC ,and passes into the R ight ventricle .

9. 5)From the Right Ventricle ,the blood passes forward(mostly deoxygenated) and enters the pulmonary trunk. Here,it can take 2 paths :- 1)A small part of it,then reaches back to the left atrium through pulmonary vein 2)But a large part of it, is made to bypass (pulmonary bypass) or is short circuited or is given a short cut, BY THE DUCTUS ARTERIOSES , into the Aorta.

10. THE LEFT SIDE OF THE HEART (FINAL FEW PROCESSES TO COMPLETE THE CIRCULATION)

11. Left Atrium:- It has received blood from the from these 2 sources :- A)The oxygenated blood from the right atrium B)Small amount of deoxygenated blood from the lungs The blood in the left atrium is therefore, fairly rich in oxygen. This blood now passes to the LEFT VENTRICLE and then to the AORTA . Now,the Aorta has received blood from 2 sources: (a) Left Ventricle (Having Oxygen Rich Blood (75%) (b) Ductus Arterioses .(Having Moderately Oxygenated Blood) (50%)

12. The A orta, passes the oxygen rich blood (which it received from left ventricle),through the Carotid and Subclavian Arteries ,to supply the HEAD,NECK AND THE BRAIN,AND THE UPPER EXTRIMITIES . The rest of the blood gets mixed with the moderately oxygenated blood coming from the Ductus Arterioses . The parts of the body, that are supplied by branches of the aorta ,arising distal to its junction with the Ductus Arteriousus ,therefore,receive blood with only moderate oxygen content.

13. STEPS:- The oxygenated blood ,from the placenta (where gaseous exchange takes place,and not the lungs),travels through the UMBILICAL VEIN . UMBILICAL VEIN joins with LEFT BRANCH OF PORTAL VEIN . Divides into 2 parts:- a) INDIRECT PATH OF IVC :Through substance of liver b) DIRECT PATH TO IVC :Through DUCTUS VENOSUS (DV) to IVC .Thus, DV is for BYPASSING hepatic circulation.

14. 4)The IVC takes the oxygenated blood to the right atrium .By the valve of the IVC ,this blood is directed towards the Foramen Ovale . Here,it is divided into 2 portions:- A)Most of it passes through foramen ovale into left atrium B)The rest of it gets mixed up with the blood returning to the Right atrium through the SVC ,and passes into the R ight ventricle .

15. 5)From the Right Ventricle ,the blood passes forward(mostly deoxygenated) and enters the pulmonary trunk. Here,it can take 2 paths :- 1)A small part of it,then reaches back to the right atrium through pulmonary vein 2)But a large part of it, is made to bypass (pulmonary bypass) or is short circuited or is given a short cut, BY THE DUCTUS ARTERIOSES , into the Aorta.

16. THE LEFT SIDE OF THE HEART (FINAL FEW PROCESSES TO COMPLETE THE CIRCULATION)

17. Left Atrium:- It has received blood from these 2 sources :- A)The oxygenated blood from the right atrium B)Small amount of deoxygenated blood from the lungs The blood in the left atrium is therefore, fairly rich in oxygen. This blood now passes to the LEFT VENTRICLE and then to the AORTA . Now,the Aorta has received blood from 2 sources: (a) Left Ventricle (Having Oxygen Rich Blood) (b) Ductus Arterioses .(Having Moderately Oxygenated Blood)

18. The A orta,passes the oxygen rich blood (which it received from left ventricle),through the Carotid and Subclavian Arteries ,to supply the HEAD,NECK AND THE BRAIN,AND THE UPPER EXTRIMITIES . The rest of the blood gets mixed with the moderately oxygenated blood coming from the Ductus Arterioses . The parts of the body, that are supplied by branches of the aorta ,arising distal to its junction with the Ductus Arteriousus ,therefore,receive blood with only moderate oxygen content.

19. 1. Ductus Venosus : The Ductus Venosus shunts the portion of left umblical vein blood flow directly to the inferior vena cava. Allows oxygenated blood from the placenta to bypass the liver.

20. 2. Ductus Arteriosus: Also called Ductus Botalli . Connects the pulmonary artery to the proximal descending aorta. It allows most of the blood from the right-ventricle to bypass the fetus ’ fluid-filled non-functioning lungs.

21. 3. Foramen Ovale : It is an opening in the intra-atrial septum. It allows the blood to enter the left atrium from the right atrium It is also called False Septi .

22. More oxygenated blood for the upper limb.Hence,the length of the upper limb is more than lower limbs in fetus. Sphincteric action at the junction of left umbilical vein and ductus venosus regulates oxygen content of IVC and excessive load on heart. PECULARITIES OF FETAL CIRCULATION:-

23. Admixture of oxygenated and deoxygenated blood takes place in the Liver terminal part of IVC both atria and distal part of arch of aorta. Transseptal blood flow throughout fetal life through ostium primum and foramen ovale . Pecularities ( Cotd ..)

24. Changes in the Circulation at birth

25. Soon after birth,several changes takes place in the fetal blood vessels . This leads to establishment of the adult type of circulation.The changes are as follows:- CONTRACTION OF THICK MUCLE WALL :- The muscle in the wall of the umbilical arteries contracts immediately after birth,and occludes their lumen.This prevents loss of fetal blood into the placenta. Circulatory Changes at Birth

26. The lumen of the umbilical vein and the ductus venosus is also occluded,but this takes a few minutes after birth,so that all the fetal blood that is in the placenta has time to drain back to the fetus. The ductus arteriosus is occluded,so that all blood from the right ventricle now goes to the lungs,where it is oxygenated.

27. The pulmonary vessles increases in size,and consequently,a much larger volume of blood reaches the left atrium from the lungs . As a result,the pressure inside the left atrium is generally increased. Simaltaneously,the pressure in the right atrium is diminished because blood from the placenta no longer reaches it. The net result of these pressure changes is that the pressure in the left atrium now exceeds that in the right atrium causing valve of the foramen ovale to close.

28. The vessels that are occluded soon after birth are,in due course,replaced by fibrous tissue,and form the ligaments as show in the following table:-

29. Fetal Structure Adult Remnant Foramen ovale Fossa ovalis  of the heart Ductus arteriosus Ligamentum arteriosum Left umbilical vein   Extra-hepatic portion Ligamentum teres hepatis Intra-hepatic portion (ductus venosus ) Ligamentum venosum Left and right umbilical arteries   Proximal portions Umbilical branches of internal iliac arteries Distal portions Medial umbilical ligaments

30. CONGENITAL ANOMALIES Patent Foramen Ovale Patent Ductus Arteriosus Ventricular Septal Defect Aortic Valve Stenosis Pulmonary Valve Stenosis Coarctation of Aorta

31. Patent Foramen Ovale Patent Ductus Arteriosus

32. Ventricular septal defect Coarctation of Aorta

33. References:- https://medlineplus.gov / https:// my.clevelandclinic.org/health https:// www.heart.org/en/health-topics https://openmd.com / https:// www.webmd.com/default.htm https:// www.uptodate.com/home https://search.medscape.com/search/?q=atrial%20septal%20defect