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
Why was biopsy not possible in the Cizginer et al., (2007) case study?
Patient placed on heparin
What is the prevalence of a retro-aortic left renal vein?
2.1%
How did the patient in the Kondo et al., (2009) case study present?
27 year old man
1 month history of painful swelling in both legs
What was the cause of presentation in the Kondo et al., (2009) case study? What treatment was given?
DVT
Treatment:
- Anticoagulation
- Compression stockings
What did MR angiography show in the Kondo et al., (2009) case study?
Absence of infrahepatic IVC
Dilated renal and lumbar collaterals
Swollen azygos and hemiazygos veins
How did the patient in the Gil et al., (2006) case study present?
14 year old boy
Mass in abdomen
Left leg DVT
What did CT abdomen and pelvis show in the Gil et al., (2006) case study?
Absence of ENTIRE IVC
Enlarged azygos and hemiazygos veins
Cluster of thrombosed collateral veins in right pelvis (abdominal mass)
Hepatic veins directly to right atrium
What is the prevalence of IVC anomalies in healthy individuals?
0.3-0.5%
What is prevalence of IVC anomalies in cardiovascular patients?
0.6-2.0%
What is the prevalence of IVC agenesis in the general population?
0.0005-1%
What is the prevalence of IVC agenesis in young DVT patients?
Up to 5%
What is the prevalence of ICA agenesis?
<0.01%
Is ICA agenesis usually unilateral or bilateral?
Unilateral
What forms the ICA in utero?
3rd aortic arches and cranial parts of dorsal aortae
What is the hypothesised cause of ICA agenesis?
Mechanical insults:
- Pressure
- Excessive folding
- Amniotic bands
After surgery, how did the patient respond in the Gil et al., (2006) case study?
Reduced pelvic venous thrombosis
Development of abdominal well venous plexus
Describe the patient’s case in the Naeini et al., (2005) case study?
38 year old woman with acute right-sided headaches
No neurological deficit
Cerebral angiography:
- No right ICA
- Left vertebral artery direct from aortic arch
What implications can an aberrant ICA have?
Aberrant circle of willis
What effects on the Circle of Willis did the absent right ICA in the Naeini et al., (2005) case study?
Right middle cerebral artery arose from hypertrophies right posterior communicating artery:
- ie. Posterior vertebral supply
Anterior communicating artery from left anterior cerebral artery became right anterior cerebral artery
Right ophthalmic artery from posterior communicating artery
What are anomalous vessels?
Vessels that do not exist
OR
Vessels that do normally exists but have an unusual pathway
What are the implications of anomalous vessels?
May displace other structures
At risk during routine procedures or trauma
May require surgical procedure modification:
- Especially if laparoscopic
Regarding the common carotid artery, what did the Anangwe et al., (2008) study show?
Separate branching of superior laryngeal artery from CCA
Regarding the common carotid artery, what did the Al-Rafiah et al., (2011) study show?
Superior thyroid artery from CCA in 11 CCAs:
- Out of 30 cadavers (therefore 60 CCAs)
- ~18.5% of CCAs
Regarding the common carotid artery, what did the Lemaire et al., (2000) study show?
The superior thyroid artery and lingual artery can arise from a thyrolingual branch of the CCA
What other branches can arise from the CCA?
Occipital artery
Thyroid ima artery
Right vertebral artery
What is the normal level of bifurcation of the CCA? In the Anange et al., (2008) study on a Kenyan population, what was the prevalence of bifurcation at this level?
C3-C4
18 CCAs out of 80
What was the most common level of bifurcation of the CCA in the Anange et al., (2008) study on a Kenyan population?
C3:
- 31 out of 80 CCAs
Where did the anomalous branch of the CCA arise in the case study by Simic et al., (2004)?
From left CCA 2cm above aortic arch that coursed inferiorly
Where did the anomalous branch of the CCA bifurcate in the case study by Simic et al., (2004)?
At level of aortic arch
What did the branches of the anomalous branch of the CCA anastomose with in the case study by Simic et al., (2004)?
Left branch anastomosed with left pericardiophrenic artery
Right branch anastomosed with right internal thoracic artery
What did the right internal thoracic artery in the patient in the in the case study by Simic et al., (2004) bifurcate into? Where?
Bifurcated into:
- Musculophrenic artery
- Superior epigastric artery
Level of 3rd rib
What did the anomalous vessel in the case study by Simic et al., (2004)?
Left phrenic nerve
Parietal peritoneum
Mediastinal pleura
What are the implications of having an anomalous vessel supplying structures it usually doesn’t, such as that in the case study by Simic et al., (2004)?
Damage to the left CCA in this case would damage structures not normally expecting to be affected by left CCA damage
Chemotherapy or angiographic dye could have unwanted effects due to different dissemination
Radical neck surgery = Unexpected haemorrhage
Regarding the radial artery, what did the study of 100 limbs by Nasr, (2012) find?
8 variant origins
Several different branching patterns
3 modes of termination
What racial differences can be seen regarding the origin of the radial artery?
Axillary origin: - 5% of African people - 2.7% of Caucasians High brachial origin: - 5.9-12.1% of Caucasians - 2.3% of Koreans - 0.33% of the Chinese
Describe the case study by Mannan et al., (2005)?
86 year old male cadaver
Superficial ulnar artery from 3rd part (lateral to pectoralis minor) of axillary artery:
- Ran over forearm flexor muscles
- Anastomosed with ‘normal’ ulnar artery in distal 1/3 of forearm
What are the risks of the variation in the case study by Mannan et al., (2005)?
Risk of accidental damage to:
- Venepuncture
- Acupuncture
Where do the lumbar veins usually run?
Between transverse process and psoas
What variation of a lumbar vein was noted in a case study by Karcaaltincaba and Akata, (2004)?
Right lumbar vein through foramen in L3 pedicle
Left lumbar vein was normal
What did the variation in the case study by Karcaaltincaba and Akata, (2004) mimic and why was this concerning?
An osteolytic lesion
Patient had known rectal cancer
What procedure may be risky if carried out in a patient with the variation noted in the case study by Karcaaltincaba and Akata, (2004)?
Percutaneous vertebroplasty:
- Needle passed through pedicle
What did Schulz and Rothwell, (2011) study?
Plaque formation of the carotids
What did Schulz and Rothwell, (2011) hypothesise might be the cause of some people, with similar risk factors, developing plaques in the carotids and them only developing unilaterally?
Bifurcation patterns of the CCA
What was the method used in the Schulz and Rothwell, (2011) study?
Measure vessel diameters of ICA and ECA and area ratios from angiograms
What were the inter-individual results of the study by Schulz and Rothwell, (2011)?
4-fold variation in outflow;inflow area ratio (0.38 to 1.28)
‘Normal’ ICA diameter ranged from 1/2 of ICA to 1/3 greater
What were the intra-individual results of the study by Schulz and Rothwell, (2011)?
5% calibre difference between ICAs
42% of patients had an outflow:inflow variation of >25% between the 2 sides
What were the conclusions of the study by Schulz and Rothewell, (2011)?
Relationships found between: - Haemodynamics - Bifurcation anatomy - Atheroma Does the shape of vessel affect haemodynamics and hence predict plaque formation?
What did all the 134 patients included in the study on the Circle of Willis by Nathan et al., (1992) have in common?
All treated for anterior communicating artery aneurysm:
- Commonest side for cerebral aneurysm
What were the results and conclusions of the study by Nathan et al., (1992)?
High association between anomalies and cerebrovascular disease:
- 46 patients (34.4%) had anatomical variations of anterior communicating artery
- Compared to ‘normal’ anatomy
Outcome dependent on clinical grade on admission and NOT the anatomical variation
What were the methods of the study by Horikoshi et al., (2002) into aneurysms of the anterior communicating artery?
MR angiograms:
- 131 patients with cerebral aneurysms
- 440 patients without
What is Type A anatomy as described by Horikoshi et al., (2002)?
Nonvisualised unilateral A1 segment:
- The A1 segment is the horizontal segment from its origin from the ICA to the anterior communicating artery
What is Type P anatomy as described by Horikoshi et al., (2002)?
A ‘foetal’ type of posterior cerebral artery
Why is there a close correlation between aneurysm development in the ACoA and anterior cerebral artery asymmetry?
Increased shear stress due to increased blood flow
What does Type P anatomy predispose to and why?
ICA aneurysm
Increased ICA flow proximally to PCoA turbulence
In what individuals does Type P anatomy occur more?
Women:
- 21% (vs 9.7% in men; without aneurysms)
- 20.4% (vs 4.6% in men; with aneurysms)
In what individuals is Type A anatomy more common?
Men without aneurysms
What type of anatomy is predominant in ACoA aneurysms?
Type A:
- 61.3% (p<0.001)
What aneurysms are more common in males?
Middle cerebral artery
ACoA
What aneurysms are more common in females?
ICA
Vertebrobasilar artery
What were the methods used in the Bugnicourt et al., (2009) study into the Circle of Willis and migraine?
MR angiography of:
- 27 patients with migraines without aura
- 24 patients with migraines with aura
- 72 controls
What did the results of the Bugnicourt et al., (2009) study show?
Incomplete Circle of Willis in:
- 49% of sufferers
- 18% of controls
What were the conclusions of the Bugnicourt et al., (2009) study?
Incomplete Circle of Willis associated with migraine
No difference +/- aura
What were the methods used in the Cucchiara et al., (2013) study into the Circle of Willis and migraine?
MR angiography and arterial spin perfusion MRI of:
- 61 patients with migraines without aura
- 56 patients with migraines with aura
- 53 controls
What did the results of the Cucchiara et al., (2013) show?
Incomplete Circle of Willis in:
- 73% of patients with aura
- 67% of patients without aura
- 51% of controls
What were the conclusions of the Cucchiara et al., (2013) study?
Incomplete Circle of Willis associated with migraine with aura vs. controls
No significant difference between those without aura and controls
Why did Cucchiara et al., (2013) hypothesise individuals with incomplete Circle of Willis have migraine?
Increased asymmetry in hemispheric cerebral blood flow:
- Specifically in posterior cerebral artery territory
Regarding brachiocephalic trunk variation, what did Iterezote et al., (2009) find?
Out of 110 cadavers 1 had a brachiocephalic trunk anomaly:
- 3.4cm long and 1.9cm diameter
- Completely anterior to trachea
- Off on a right trajectory
Regarding brachiocephalic trunk variation, what did Comert et al., (2004) find?
Innominate artery (brachiocephalic trunk) arose on left of trachea before crossing and bifurcating into:
- Right CCA
- Right subclavian artery
What was the sequelae of the variation found by Comert et al., (2004)? How could it be avoided?
Serious haemorrhage on percutaneous tracheostomy
Diagnostic USS
When 104 uraemic patients underwent US imaging for central line insertion, what IJV variations were seen by Lin et al., (1998)?
19 variations in right IJV
17 variations in left IJV
Unilateral in 18 patients
Bilateral in 9 patients
What was the sequelae of the variations found by Line et al., (1998)?
27 patients had variations that would make IJV lines difficult on external landmarks only
What is the incidence of IJV duplication?
4 per 1,000 unilateral neck dissections
How can IJV duplication vary?
Can be unilateral/bilateral
Vessels can vary in:
- Size
- Height of duplication
What structure is related to IJV duplication?
CN XI running between duplicated parts of IJV
What clinical implications can IJV duplication have?
Cervical node clearance during oncological surgery
What are the potential embryological origins of IJV duplication?
CN XI development
Bony hypothesis at jugular foramen
What IJV variations were noted in the case study by Nayak, (2006)?
Left duplicated IJV
Left anterior jugular vein communicated with anterior division of left IJV
Double jugular venous arch:
- Formed venous circle anterior to isthmus of thyroid
What is the radial artery used for?
Blood gas analysis
Forearm flaps
Bypass surgeries
How can the radial artery be tested?
Allen test
Doppler US
Regarding the superficial palmar arch, what percentage of hands had a complete arch according to Loukas et al., (2005)?
90%
There are 5 types of complete superficial palmar arch, types III and IV have a median artery. What usually happens to this artery?
Regresses
From where does the princeps pollicis artery usually arise and in what percentage of hands?
It is the 1st palmar metacarpal branch of the radial artery in 80% of hands
What investigations were carried out in the Ozkan et al., (2006) study?
Aortofemoropopliteal angiography (for PAD) OR Renal angiography (for renovascular hypertension)
What were the results of the Ozkan et al., (2006) study?
98% of main renal arteries arise between upper L1 and lower L2:
- 74% of accessory renal arteries also arise here
76% of people had 1 renal artery on each side
What variations were seen in the Ozkan et al., (2006) study?
Multiple renal arteries in 24%
Bilateral multiple renal arteries in 5%
Pre-hilar division in 8%
What racial differences are seen in renal artery variations?
More common in African populations (37%)
Less common in Indian populations (17%)
Out of 701 organ donors and general surgery patients, how many had hepatic artery variations according to Gruttadauria et al., (2001)?
296 (42.22%)
What variations of the hepatic artery were noted by Gruttadauria et al., (2001)?
Replaced or accessory right hepatic artery from SMA
Replaced or accessory left hepatic artery from LGA
Hepatic artery from coeliac axis and one of above
Early hepatic artery bifurcation
14 previously unreported variations also
What hepatic artery variation was noted in the Pulakunta et al., (2008) case report?
Hepatic artery proper entered fissure for ligamentum venosusm
Accessory hepatic artery from SMA entered porta hepatis
What lobe of liver is donated in living donors?
Right lobe
If the left CCA arises as a variant instead of from aortic arch, what changes need to be made for access?
Adaptation of surgical technique
Scan first
What vessel variation was noted in a case study by De-Giorgio et al., (2011)?
Anomalous right coronary artery origin from left coronary cusp
What were the pathological sequelae of the variation noted by De-Giorgio et al., (2011)?
1.08cm right coronary artery aneurysm (vessel 0.5cm)
Why did the pathology noted in the case by De-Giorgio et al., (2011) arise?
Functional stenosis of RCA between aorta and pulmonary trunk:
- Acute angle to aortic lumen resulting in haemodynamic changes and compressive trauma
What is thoracic outlet syndrome?
Compression of brachial plexus and/or subclavian vessels
What variation described by Konuskan et al., (2005) resulted in thoracic outlet syndrome?
Left subclavian artery perforated left scalene anterior muscle
What variation was noted in a case study by Yoo et al., (2003)?
Persistent vitelline artery remnant Fibroadipose band: - From posterior leaflet of mesentery - To anterior leaflet of mesentery - Constricted and twisted ileal loop
How did the patient with the variation noted by Yoo et al., (2003) present?
Small bowel (ileal) obstruction
What usually happens to the vitelline arteries supplying the yolk sac?
1 regresses
1 remains and becomes SMA
How do vein patterns form?
Individual environment in developing tissue
What does the PatientSecure system at NYU Langone Medical Centre do?
Vein pattern analysis:
- Reduces errors
- Helps ID unconscious patients
Apart from vein pattern, what other biometric systems exist?
Fingerprints
Iris scan
What reliability issues arise with biometric systems?
False positives and negatives
How easy to mimic?
Vein pattern analysis requires living tissue
