Embryology of Heart part 2 by Dr Jasleen.pptx

Embryology of heart - systemic veins

1. EMBRYOLOGY OF PULMONARY AND SYSTEMIC VEINS BY- DR JASLEEN KAUR DNB SS REGISTRAR PAEDS CARDIO INDRAPRASTHA APOLLO HOSPITAL

2. Umbilical Vitelline The Developing Venous System Sinus V enosus Cardinal

3. LSVC occurs in 0.3% to 0.5% of the normal population In 65% of cases, left brachiocephalic vein is also missing 4% of patients with CHD have an LSVC Usually drains to the coronary sinus

4. Embryology The respiratory system develops as an evagination from the foregut at 26 days. The venous plexus surrounding the early lung buds drains into the cardinal and umbilico- vitelline veins - part of the splanchnic (systemic) venous system.

5. Embryology cont. VENOUS SYSTEM OF THE EMBRYO The right cardinal venous system develops into the right SVC whereas the left cardinal venous system mostly disappears and may potentially develop into left SVC (<1% of individuals). The umbilicovitelline veins develop into the IVC,portal venous system and ductus venosus.

6. Embryology cont. In the embryo,the primordia of the lungs,larynx and tracheobronchial tree are derived from a division of the foregut.So,during early stage of development,lungs are enmeshed by the vascular plexus of the foregut (splanchnic plexus). At this stage lungs has no direct connection with the heart.There are multiple connections with the splanchnic plexus i.e, umbilicovitelline and cardinal venous systems . Edwards JE. Mayo Clin Proc 1953;28:441-452

7. A: At 27 to 29 days of gestation, the primordial lung buds are enmeshed by the vascular plexus of the foregut (the splanchnic plexus). At this stage, there is no direct connection to the heart. Instead, there are multiple connections to the umbilicovitelline and cardinal venous systems. A small evagination can be seen in the posterior wall of the left atrium to the left of the developing septum secundum In early stage of embryo,the lung buds are enmeshed by the vascular plexus of the foregut (splanchnic plexus). A small evagination arises in the posterior wall of the left atrium to the left of the developing septum secundum.It forms the common pulmonary vein.

8. By the end of the 1 st month of gestation common pulmonary vein establishes connection between the pulmonary venous plexus and the sinoatrial portion of the heart. Connection b/w pulmonary venous plexus and the splanchnic venous plexus are still patent.

9. The connection b/w pulmonary venous plexus and splanchnic venous plexus involutes. Common pulmonary vein incorporates into the left atrium so that individual pulmonary veins connect separately and directly to the left atrium.

10. Embryology

11. 𝗈 PAPVC results from failure to establish a normal connection between one or more of the pulmonary veins with the CPV before the connections with the splanchnic venous system have regressed.

12. 𝗈 TAPVC results from failure to establish a normal c o n n e cti o n b e t w e e n t h e pu lm o n a r y v e n o u s pl e x u s & the CPV before the connections with splanchnic venous system have regressed .

13. Embryology Atresia of the common pulmonary vein and cor triatriatum. When there is stenosis of connection between common pulmonary vein and left atrium,the common pulmonary vein dilates and k/a COR TRIATRIATUM.

14. Darlings classification 𝗈 The most common classification system was originally described by Darling et al. in 1957. consists of four types Type I (Supracardiac TAPVC ): 45% of cases. Both right and left pulmonary veins join a common pulmonary venous confluence behind the heart that drains via a vertical vein to the undersurface of the left innominate vein and then to the Right atrium. Type II ( Cardiac TAPVC) : 25% of cases. The pulmonary venous confluence connects to the coronary sinus, & then to the RA via the coronary sinus ostium.

15. Type III (Infracardiac TAPVC) : 21% of cases. The pulmonary venous confluence drains inferiorly via a vertical vein to the portal vein or hepatic veins & then to the RA. Type IV (Mixed Type ) : <10% of cases. Left pulmonary veins drain to the LIV , & right pulmonary veins to the coronary sinus Darling RC et.al. Lab Invest.1957;6:44-64

16. EMBRYOLOGY OF SYSTEMIC VEINS

17. EMB R Y O L O G Y OF SYSTEMIC VEINS In the fifth week, three pairs of major veins can be distinguished: The vitelline veins (omphalomesenteric veins) carrying blood from the yolk sac to the sinus venosus The umbilical veins originating in the chorionic villi, carrying oxygenated blood to the embryo The cardinal veins draining the body of the embryo proper

18. EMB R Y O L O G Y OF SVC Development of veins draining upper part of body Ducts of Cuvier Subclavian veins Transverse anastomosis Superior venacava Right Brachiocephalic vein Left Brachiocephalic vein Internal Jugular vein External jugular vein arise as secondary channe l

19. Anomalies of the SVC Bilateral SVC with normal drainage Bilateral SVC with an Unroofed Coronary Sinus Absent Right SVC in Visceroatrial Situs Solitus Left Atrial or Biatrial Drainage of Right SVC

20. ANOMALIES OF THE SUPERIOR VENA BI L A TE R AL S U PER I OR VE N AE C A V A WI T H NORMAL DRAINAGE TO THE RIGHT ATRIUM

21. LEFT A TRI A L OR BI A TRIAL DRAI N AGE OF RIGHT SVC

22. Bilateral SVC with an Unroofed Coronary Sinus Anatomy Common wall between the LA & CS absent Persistent LSVC drains into the left atrium In patients with a normal inter atrial septum, the orifice of the unroofed CS will function as an interatrial communication Visceral heterotaxy with asplenia exhibits the highest incidence of bilateral SVCs with a completely unroofed coronary sinus

23. EMB R Y O L O G Y OF IVC Development of Inferior venacava During the fifth to the seventh week a number of additional veins are formed: The subcardinal veins, mainly drain the kidneys The sacrocardinal veins, drain the lower extremities The supracardinal veins, drain the body wall by way of the intercostal veins, taking over the functions of the posterior cardinal veins

24. EMB R Y O L O G Y Development of Inferior venacava Green- Subcardinal Red- Supracardinal Yellow- Subcardinal- hepatocardinal anastomosis Blue- Hepatocardiac channel White- Supracardinal- Subcardinal anastomosis

25. EMB R Y O L O G Y Development of Inferior venacava The anastomosis between the subcardinal veins forms the left renal vein The left subcardinal vein disappears, and only its distal portion remains as the left gonadal vein The right subcardinal vein becomes the main drainage channel and develops into the renal segment of the inferior vena cava

26. EMB R Y O L O G Y Development of Azygos veins

27. EMB R Y O L O G Y Development of Azygos veins The 4thto 11th right intercostal veins empty into the right supracardinal vein, which together with a portion of the posterior cardinal vein forms the azygos vein On the left the 4th to 7th intercostal veins enter into the left supracardinal vein, and the left supracardinal vein, then known as the hemiazygos vein, empties into the azygos vein

28. EMB R Y O L O G Y .

29. Anomalies of the Inferior Vena Cava Interrupted Inferior Vena Cava Bilateral Inferior Vena Cavae Inferior Vena Cava drainage to the Left Atrium

30. Interrupted Inferior Vena Cava Anatomy Absence of the hepatic segment of the IVC with azygos continuation into the right or left Rarely the infrahepatic segment of the IVC may continue to both right and left SVC via bilateral azygos veins One of the characteristics of the polysplenia syndrome Also has been reported in patients with normal hearts and rarely in patients with asplenia

31. Bilateral Inferior Venae Cavae Anatomy Bilateral suprahepatic IVCs (i.e., a normal IVC and a contralateral hepatic vein) a frequent finding in cases of visceral heterotaxy with asplenia Bilateral suprahepatic IVCs also can occur rarely in patients with normal visceral situs The left-sided hepatic vein in those cases drains into a normal coronary sinus Do not produce any hemodynamic disturbance

32. Inferior Vena Cava Drainage to the LA Anatomy During fetal life, about half of the IVC blood that enters the RA is directed toward the LA with the help of two venous valves: the eustachian valve & valve of the foramen ovale A left atrial IVC also occur in cases in which all the systemic and all the PVs drained into a left-sided atrium

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