Cardiovascular Variation Flashcards
How did a duplicated SVC appear on CXR in the case study by Singh et al., (2005)?
Widened mediastinum
Why are incidence rates for duplicated SVC often inaccurate?
Often a silent variation
What clinical issues arise in duplicated SVC?
Can be mistaken for lymphatics during radiography
Suspicious mass
Surgery; excessive bleeding if sectioned during:
- Hilar lymphadenectomy
- Cardiac surgery
What precedes the development of the axial system?
Complex capillary and reticular plexus
What veins develop above the developing heart?
Pre-cardinal veins
Bilateral anterior cardinal veins
What veins develop below the developing heart?
Post-cardinal veins
Bilateral posterior cardinal veins
What structures form the SVC?
Right pre-cardinal/anterior cardinal vein
Right common cardinal vein
Right horn sinus venosus (posterior primitive right atrium)
What do the pre-cardinal veins, post-cardinal veins and the common cardinal veins form?
Veins of heart
SVC
Tributaries to SVC
What does the right supracardinal vein form?
Azygous vein
What does the left supracardinal vein form?
Hemiazygous vein
Accessory hemiazygous vein
How does a duplicated SVC arise?
If left anterior cardinal vein (left pre-cardinal vein) doesn’t regress
What percentage of aortic arch duplications are:
A) Right dominated
B) Left dominated
C) Co-dominated?
Right dominated = 70% (abnormal arch often bigger)
Left dominated = 25%
Co-dominated = 5%
Describe the structure of a right dominant duplicated aortic arch?
Large right and small left arches:
- Arise from ascending aorta
- Form a vascular ring around trachea and oesophagus
What are the clinical implications of a right dominant duplicated aortic arch?
Vascular ring can cause:
- Respiratory distress in babies if tight and compressing trachea
- Asthma-like symptoms/silent in adults if loose ring
In a duplicated aortic arch, what implications does this usually have from the branches of the aortic arch?
Right common carotid artery and right subclavian artery arise separately from right aortic arch instead of from the brachiocephalic trunk
What forms the dorsal aortae in humans?
Primitive gill arteries which are modified
Where do the dorsal aortae extend and meet with?
Extend caudally
Meet with umbilical arteries
How many dorsal aortae are there initially?
2
What do the two ventral aortae fuse to form and where?
Aortic sac
Just cranial to truncus arteriosus
How does the truncus arteriosus form and when?
A lengthening of the connection between the bulbus cordis (primitive heart) and the 1st aortic arches
End of week 4
How does the cranial end of the truncus arteriosus connect to the dorsal aortae?
6 pairs of aortic arches
What does the truncus arteriosus become?
Ascending aorta
What aortic arches usually regress?
I
II
V
What does the 3rd pair of aortic arches form?
On both sides:
- Proximal internal carotid artery
- Part of common carotid artery
What does the 4th pair of aortic arches form?
On right = Right subclavian artery
On left = Arch of aorta:
- Between left common carotid and ductus arteriosus
What does the 6th pair of aortic arches form?
On right = Proximal right pulmonary artery
On left:
- Left pulmonary artery
- Ductus arteriosus
When do the two dorsal aortae fuse and what do they form?
In week 4
Single definitive descending aorta (T4-L4)
What results in a double aortic arch?
Distal part of right dorsal aorta persists
What are the alternate names for Chromosome 22q11 deletion?
DiGeorge syndrome
CATCH22
What is Chromosome 22q11 deletion associated with?
Congenital heart disease Isolated conotruncal anomalies: - Tetralogy of Fallot - Transposition of great vessels - Aortic arch anomalis
What are isolated conotruncal anomalies essentially?
Cardiac outflow tract anomalies
Under normal conditions, where do neural crest cells migrate from?
Hindbrain
Under normal conditions, where do neural crest cells migrate to?
The caudal 3 pharyngeal arches via circumpharyngeal region
Under normal conditions, some neural crest cells continue migrating beyond the usual final destination. What do these form? What are these cells therefore responsible for?
Outflow tract of developing heart
Cells are responsible for aortic arch formation by becoming smooth muscle cells in tunica media of persistent arteries
What does incomplete migration of neural crest cells result in?
Vessel malformation
What did the Momma et al., (1996) study investigate?
Isolated aortic anomalies in 22q11 deletion
Describe case 1 in the Momma et al., (1996) study
Isolation of innominate (brachiocephalic) artery
Describe case 2 in the Momma et al., (1996) study
Right high stenotic aortic arch
Left patent ductus arteriosus
Left descending aorta (vascular ring)
Aberrant left subclavian artery
Describe case 3 in the Momma et al., (1996) study
Right high aortic arch
Right patent ductus arteriosus
Left pulmonary artery stenosis
Describe case 4 in the Momma et al., (1996) study
Isolation of right subclavian artery
Describe case 5 in the Momma et al., (1996) study
Right high aortic arch
Left patent ductus arteriosus
Left descending aorta
Aberrant left subclavian artery
Described the duplicated IVC anomalies in the case study by Natsis et al., (2010)
Left IVC crossed aorta at L2 and joined right IVC at L1
Right renal vein -> Right IVC at L1
Left renal vein -> Left IVC at L2
Left suprarenal vein -> Left IVC
Duplicated left testicular vein -> Common vessel -> Left renal vein
What is the normal aformation of the IVC?
Common iliac veins join at L5
What is the prevalence of duplicated IVC? What does this make the anomaly?
0.2-3.0%
Most common IVC anomaly
What is Type I IVC duplication?
Same calibre trunks and pre-aortic trunk
What is Type II IVC duplication?
Same calibre trunks (narrow) but larger pre-aortic trunk
What is Type III IVC duplication?
Asymmetric trunks:
- Right IVC has larger calibre than left IVC
What study described the types of IVC duplication?
Natsis et al., (2010)
What are the four segments of a normal IVC?
Hepatic
Suprarenal
Renal
Infrarenal
What forms the hepatic part of the IVC?
Vitelline veins (which drain yolk sac)
Why is there usually left variation of the hepatic part of the IVC?
There is (usually) only 1 liver
What form the prerenal/suprarenal part of the IVC?
Hepatic part
Right subcardinal vein
What forms the renal part of the IVC?
Supra-subcardinal anastomosis
Post-subcardinal anastomosis
What forms the infrarenal part of the IVC?
Right supracardinal vein
What do the posterior cardinal veins form?
Iliac veins
How does a duplicated IVC arise?
If both supracardinal veins persist
What can duplicated IVC be misdiagnosed as?
Lymphadenopathy
In a patient with duplicated IVC, what implications was this found to have in a case study by Hashmi and Smarolf, (2007)?
Patient suffered bilateral PEs 1 month after surgery for foot trauma IVC filter planned: - Venograms taken = Double IVC Left IVC small diameter: - Filter insertion difficult
Describe the case study by Hardwick et al., (2011). (IVC interruption)
69 year old female: - Non-smoker - Cough for 3 months - Normal physical exam CXR = Large mass in right lung CT chest: - 5cm mass - Invasion into very large azygous vein
What were the variations seen in the Hardwick et al., (2011) case study?
IVC interrupted so drained into swollen azygous then into SVC
Hepatic veins directly into right atrium
How does an interrupted IVC arise?
Failure of fusion of prerenal and hepatic segments
What is the incidence of interrupted IVC and why is this questionable?
1 in 5000
Usually silent variation
How did the patient in the Cizginer et al., (2007) study present?
26 year old male
1 week history of abdominal pain radiating to testes
What did abdominal CT show in the Cizginer et al., (2007) case study?
Para-aortic mass near renal hilum
Thrombosis of infrarenal segment of IVC
What did axial gradient echo steady state imaging show in the Cizginer et al., (2007) case study?
Suprarenal IVC absent
Dilated azygous vein
What did contrast-enhanced MR venogram show in the Cizginer et al., (2007) case study? What did these mimic?
Infrarenal IVC thrombosed
Retro-aortic left renal vein distended and thrombosed
Both mimicked a mass
What other structures were thrombosed in the Cizginer et al., (2007) case study?
All iliac veins
Right femoral vein
What veins were dilated in the Cizginer et al., (2007) case study?
Inferior mesenteric veins
Lumbar veins