Vena cava anatomy and variants by Dr. Basanta Regmi

1. VENACAVA: Normal Anatomy and
Congenital Anomalies
Dr. Basant Regmi
 MD Radiodiagnosis (PGY- 1)
 NAMS ,Bir Hospital

2. Topics
 NORMAL ANATOMY
 EMBROLOGY and DEVELOPMENT
 CONGENITAL ANOMALIES

4. Superior vena cava: Gross anatomy
Beginning: at the level of first
right costal cartilage at the level of
T1
Course: Descend vertically
behind the 2nd and 3rd ICS
End: Ends into right atrium at the
level of right 3rd costal cartilage
Length: approx 7cm
Diameter: usually 1.5 cm

5. Tributaries
Rt and Lt Brachiocephalic vein ( origin)
Azygous vein from the posterior aspesct
Small veins draining the pericardium and other
mediastinal structures

6. Relations
Left lateral : aortic arch
and trachea
Right lateral: pleura ,rt
upper lobe,right phrenic
nerve
Anteriorly: thymus ,
manubrium
Posteriorly: azygous vein
Superiorly:
brachiocephalic veins,
superior thoracic aperature
Inferiorly : pericardium ,
right atrium

8. Tributaries
 T8: paired inferior phrenic
veins
 T8: hepatic veins
 L1: right suprarenal vein
 L2: right gonadal vein
 L1-L5: lumbar veins
 L5: common illac veins
(origin)

9. Relation of the abdominal part of
the inferior venacava
Anteriorly:
 first part of duodenum
 common bile duct
 portal vein
 head of pancreas
 right gonadal artery
 root of mesentery
 Right common iliac
artery

10. Posteriorly:
 The lower three lumbar
vertebral bodies
 Their intervertebral disc
 Right psoas major
 Sympathetic trunk
 Right crus of the
diaphragm
 The medial part of the
suprarenal gland
 Right celiac ganglion

11. Right:
 The right ureter
 The second part of the
duodenum
 Medial border of right
kidney
 The right lobe of the liver
Left:
 Aorta
 The right crus of the
diaphragm
 The caudate lobe of the
liver

12. EMBRYOLOGY

13. EMBRYOLOGY
In the fifth week, three pairs of major veins can be
distinguished:
1. Thevitelline veins (omphalomesenteric veins)
carrying blood from the yolk sacto the sinus venosus
2. Theumbilical veins
originating in the chorionic villi, carrying oxygenatedblood to the
embryo
3. Thecardinal veins
draining the body of the embryo proper

14. EMBRYOLOGY
Main components of the venous and arterial systems ina4-mm
embryo (end of the fourthweek).

15. EMBRYOLOGY
Cardinal Veins
Theanterior cardinal veins drains the cephalic part ofthe embryo
Theposterior cardinal veins drains the rest of theembryo
Theanterior and posterior veins join before entering the sinus
horn and form the short common cardinal veins (ducts of Cuvier)
During the fourth week, the cardinal veins form asymmetrical
system

16. EMBRYOLOGY
Development of veins draining upper part ofbody
A. Ducts of Cuvier
B. Subclavianveins
C. Transverse anastomosis
E. Superior venacava
F. Right Brachiocephalic vein
G. Left Brachiocephalic vein
H. Internal Jugular vein
External jugular veinarise
assecondary channel

17. EMBRYOLOGY
Development of Inferiorvenacava
 During the fifth to the seventh week anumber of additional
veins are formed:
1. Thesubcardinal veins, mainly drain the kidneys
2.Thesacrocardinal veins, drain the lower extremities
3. Thesupracardinal veins, drain the body wall by way of the
intercostal veins, taking over the functions of theposterior
cardinal veins

18. EMBRYOLOGY
Development of Inferior venacava
 Green-Subcardinal
 Red-Supracardinal
 Yellow- Subcardinal-
hepatocardinal
anastomosis
 Blue- Hepatocardiac
channel
 White- Supracardinal-
Subcardinal
anastomosis

19. EMBRYOLOGY
Development of Inferiorvenacava
Theanastomosis between the two ( rt and lt) subcardinal
veins forms the left renalvein
Theleft subcardinal vein disappears, and only itsdistal
portion remains asthe left gonadalvein
Theright subcardinal vein becomes the main drainage
channel and develops into the renal segment of theinferior
vena cava

20. EMBRYOLOGY
Development of Inferiorvenacava
Theanastomosis between the sacrocardinal veins forms the
left common iliacvein
Theright sacrocardinal vein becomes the sacrocardinal
segment of the inferior venacava
When the renal segment of the IVCconnects with the
hepatic segment, the IVC(consisting of hepatic, renal,and
sacrocardinal segments) is complete

21. EMBRYOLOGY
Development of Azygosveins and Hemiazygous
veins
The 4th to 11th right intercostal veins empty into the
right supracardinal vein, which together with a
portion of the posterior cardinal vein forms the
azygosvein
Onthe left the 4th to 7th intercostal veins enter into
the left supracardinal vein, and the left supracardinal
vein, then known asthe hemiazygos vein, emptiesinto
the azygosvein

22. .

23. Anomalies of the Superior
Venae Cavae

24. Anomaliesof theSVC
Bilateral SVC
1. with normal drainage to rt atrium
2. with unroofed coronary sinus
Left sided SVC
Others minor anomalies:
1. Retroaortic innominate vein
2. congenital aneurysm of SVC
a. fusiform type
b. sacular type

25. 1..a..Bilateral Superior VenaeCavaewith Normal
Drainageto the RightAtrium
 Result from failure of the left anterior and left common
cardinal veins to involute
 Theincidence is 0.3%
 LSVCdrains into RA through CSin 92%
and into LA by unroofed CSin 8%

26. Double SVC
Fig. CT images cranial to caudal depicting the
anomaly.
R SVC = right SVC, LSVC = left SVC, CS =
coronary sinus

27. Double SVC

28. 1..b..Bilateral SVC with anUnroofed CoronarySinus
Common wall between the LA & CS Is absent
Persistent LSVC drains into the leftatrium
In patients with anormal 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 acompletelyunroofed
coronary sinus

29. Bilateral SVCwith anUnroofed CoronarySinus
Diagnostic Features
B. MRimage in acoronal
plane shows complete
unroofing of the CS. LSVC
connects to the roof of the LA
and the CS opening functions
as aLA septal defect (Raghib
defect)

30. 2.Left SVC
 Results from failure of
the embryonic left
anterior cardinal vein to
regress associated with
the regression of right
anterior cardinal vein
 Overall incidence: ranges
from 1 per 330 to 1 per
750 normal individuals
and 1 per 25 patients
with congenital heart
disease

31. Left SVC
 Mostly drain to right atrium
(coronary sinus)
 Most commonly associated
with Atrial septal defect
 Other associated cardiac
anomalies are Single atrium,
VSD, PDA, tetralogy of Fallot

32. Left SVC
Left Sided Superior Vena Cava
A chest radiograph demonstrates abnormal position of the central venous
catheter (red arrow). Blood gas analysis and contrast injection confirmed
catheter position within a left-sided superior vena cava. Ao, aortic knob

33. 3.a.Retroaortic Innominate
Vein
First reported in 1888, and 62 caseshave been
reported till date
Also known as postaortic innominate vein
Anatomy
 Characterized by an abnormal position of the left innominatevein
behind the ascendingaorta
 Normal course of the left innominate vein is from left to right, anterior
to the aorticarch

34. Retroaortic InnominateVein
A: Diagram showing aRAIV associated
with aright aortic arch in a
patient with TOF,RSVC
B: Gadolinium-enhanced MRangiogram
showing aretroaortic innominate vein

35. 3.c. Congenital aneurysm of SVC

36. Anomalies of the Inferior
Vena Cava

37. Congenital anomalies of IVC
1) Left IVC
2) Double IVC
3) Azygos continuation of the IVC
4) Circumaortic left renal vein
5) Retroaortic left renal vein
6) Circumcaval ureter
7) others

38. Left IVC
 Results from the regression
of right supracardinal vein
with persistence of left
supracardinal vein
 prevalence: 0.2-0.5%
 Left IVC ends at left renal
vein – then, crosses
anterior to aorta, uniting
with right renal vein – from
a normal right sided
prerenal IVC

39. Fig. Left IVC
CT images caudal to cranial depict the anomaly

40. Clinical significance
 Potential for misdiagnosis as left sided
paraaortic adenopathy
 Spontaneous rupture of abdominal
aortic aneurysm into left IVC has been
reported
 Transjugular access to the infrarenal
IVC for placement of an IVC Filter may
be difficult

41. Double IVC
 Results from persistence
of both supracardinal
veins
 Prevalence: 0.2-3 %
 Left IVC typically ends at
the left renal vein -
which crosses anterior to
the aorta in the normal
fashion – then joins the
right IVC

42. Fig. Double IVC
CT scan caudal to cranial images depicting the anomaly

43. Clinical significance
 Should be suspected in cases of
recurrent pulmonary embolism
following placement of an IVC filter
 Misdiagnosis as lymphadenopathy

44. Azygos continuation of the IVC
 Failure to form the right
subcardinal-hepatic
anastomosis, with resultant
atrophy of the right
subcardinal vein
 Prevalence: 0.6%
 The azygos vein joins the SVC
at the normal location (at the
level of T4 posteriorly)
 Dilatation of azygos vein,
azygos arch and the SVC
 Each gonadal vein drain to the
ipsilateral renal vein

45. Clinical significance
 Avoid misdiagnosis as right paratracheal
mass or retrocrural adenopathy
(enlarged azygos vein at the confluence
with the SVC)
 Preoperative knowledge of the anatomy
important in planning cardiopulmonary
bypass and to avoid difficulties in
catheterizing the heart

46. The vessel lying parallel to the Aorta below the level of crus of diaphargm
which is Azygous vein and it is tourtous and draining to the superior venacava

47. Circumaortic left renal vein
 Results from the persistence of
the dorsal limb of the embryonic
left renal vein and of the dorsal
arch of the renal collar
(intersupracardinal anastomosis)
 prevalence: 8.7 %
 Two renal veins are present
 The superior renal vein receives
the left adrenal vein and crosses
the aorta anteriorly
 Inferior renal vein receives the
left gonadal vein and crosses
posterior to the aorta
approximately 1-2 cm inferior the
normal anterior vein

48. Superior left renal vein crosses anterior to the Aorta whereas
inferior left renal vein crosses posterior to the Aorta

49. Circumaortic left renal vein
Fig. Renal vein collar
Selecive injection of upper (anterior) renal vein with retrograde
filling of lower (retroaortic limb)

50. Clinical significance
 Preoperative planning prior to nephrectomy
and in renal vein catheterization for venous
sampling
 Misdiagnosis as retroperitoneal adenopathy

51. Retro aortic left renal vein
 Persistence of the dorsal
arch of the renal collar with
regression of the ventral
arch – single renal vein
passes posterior to the
aorta
 Prevalence: 2.1%

52. Retro aortic left renal vein
Fig. CT scans show the left renal vein (arrow) descending to
cross posterior to the aorta

53. Clinical significance
 Preoperative recognition of the anomaly
 Posterior nutcracker syndrome
 an unusual cause of unexplained episodes of
microscopic or macroscopic hematouria with or
without flank pain in the absence of glomerular
disease.
 Arises due to compression of a retroaortic left renal
vein between the aorta and the vertebral body,
causing venous hypertension, hematuria, and left
gonadal vein varicocele

54. Circumcaval ureter
 Also termed as a retrocaval ureter
 Right supracardinal system fails to
develop, whereas the right
posterior cardinal vein persists
 Almost always on the right side
 Proximal ureter courses posterior
to the IVC, then emerges to the
right of aorta, coming to lie
anterior to the right iliac vessels
 Patient may develop partial
ureteral obstruction or recurrent
urinary tract infections

55. Circumcaval ureter
Fig. CT scans presented from
cranial to caudal show the
anomaly. The right ureter
(arrow) is positioned posterior
to the IVC. The ureter (arrow)
then courses to the left of the
IVC. Finally, the ureter (arrow)
crosses anterior to the
IVC

56. Other anomalies
1.Absence of the infrarenal
IVC or the entire IVC
Fig. absent infrarenal IVC with
collateral flow from the lower
extremities reaching the azygos
system via paravertebral collateral
veins

57. Other anomalies
2.Double IVC with
retroaortic rt renal vein
with hemiazygous
continuation of IVC

58. Other anomalies
 Double IVC with
retroaortic lt renal vein
with azygous
continuation of IVC

59. Conclusion
 Most of these anomalies are clinically silent and they
are often unsuspected and are discovered incidentally
on radiographic studies done for other reasons
 Familarity with the CT apppearances of such
anomalies may aid in the interpretation ,otherwise we
may have potentaially confusing CT images
A working knowledge of these venacava anomalies is
essential for the Interventional Radiologist and the
Vascular Surgeon.

61. Reference
Textbook of Radiology and Imaging, Sutton, 7/e
Congenital anomalies of the Superior vena cava: A CT
study; Cormier et al, Seminars in Roentgenology, vol xxiv
no -2,( April) 1989, pp( 77-83 )
http://www.medecine.uottawa.ca/radiology/assets/documents/chest_cardiac_imaging/a
rticles/Congenital%20Anomalies%20of%20SVC%20-%20A%20CT%20Study.pdf
Spectrum of congenital anomalies of the Inferior vena cava:
Cross sectional imaging findings; Bass et al, RadioGraphics
vol 20, no -3( may-june ) 2000
https://pubs.rsna.org/doi/pdf/10.1148/radiographics.20.3.g00ma09639
Radiopedia .org and Various internet sources