Description of extra-cranial aneurysms

1. EXTRA CRANIAL ANEURYSMS
DR. MBIINE RONALD

2. OUTLINE
• Definition
• Classification of aneurysms
– Aortic aneurysms
• Thoracic aorta
• Abdominal aorta
– Carotid
– Iliac
– Popliteal
• Dissecting Aneurysms

3. Definition
• Permanent dilatation of a localised segment of an
arterial system.
• Dilatation of arterial lumen by more than 50% of
its luminal diameter.
• TRUE:
– Localised dilatation of an arterial wall at a weakened
area. Involves all three layers of the arterial wall.
• FALSE/TRAUMATIC:
– Haematoma cavity communicating with the injured
artery. Contains a single layer of fibrous tissue as a
wall of the sac.

4. TRUE ANEURYSMS
• Fusiform
• Saccular
• Dissecting

5. Dissecting aneurysm
• Dilatation of an artery formed by formation of
a false channel between the intima and media
by blood.
• Occurs when blood is forced through a
ruptured flap of intima

6. Aetiology
• Degenerative: Atheromatous, most common
aetiology
• Traumatic
• Infective:
– Syphilitic
– Mycotic(bacterial)
– Tubercolosis
• Collagen diseases: Marfan’s syndrome,
polyarteritis nodosa, Ehler-Danlos syndrome
• Congenital: Berry aneurysms

7. Pathogenesis

8. Clinical features
• Swelling exhibiting:
– Pulsatile expansion
– Smooth surface
– Warm
– Compressible
– Swelling reduces in size when compressed
proximally
– May have a thrill and systolic bruit

9. • Distal pulses have reduced volume compared
to the contra-lateral pulses.
• Symptoms as a result of pressure on the
surrounding structures.

10. Differential diagnoses
• Pyogenic abscess
• Vascular tumours
• Pulsating tumours: Sarcomas
– Pulsating secondaries
• Pseudocysts of the pancrea
• AV fistula

11. COMPLICATIONS
• Rupture
• Pressure compression
• Thrombosis
• Ischaemia in the distal areas.

12. Investigations
• XRAY:
– May show calcifications of the swelling and erosion of
subjacent bone.
• USS:
– May confirm diagnosis
• Duplex USS, Doppler USS
• CT SCAN:
– Shows the size of the aneurysm.
– CT Angiograms
• Investigations related to aetiology: RBS, lipid profile

13. Abdominal aortic aneurysm
• Commonest type of extra abdominal
aneurysm.
• 2% population have aneurysms at autopsy
• 95% rule: are atheromatous and lie below
renal arteries.
• Symptoms dependent on size.
– Discomfort and abdominal pain usual symptoms.

14. epidemiology
• Most patients between 45-85 years
• Affects males more with ratios between 1:4 to
1:15 in M:F

15. Pathophysiology
• The aortic wall contains smooth muscle cell
matrix, elastin, collagen. The elastin in the tunica
media is the load bearing part, with collagen in
the adventitia as a safe net to provide tensile
strength.
• In the infra renal area, elastin is markedly
reduced, the absence of vasa vasorum further
compound this problem. The presence of
atherosclerotic instability of this region cause the
infra renal AA to be most prone to aneurysm
formation.

16. • Aortic smooth muscles cells and macrophages
produce the matrix metallo proteinases
(MMP) and these cause proteolysis of the
aortic medial wall with resultant elastin and
collagen degradation and increase in diameter.
• Collagen degradation in the adventitia causes
rupture.

17. Classified
• Asymptomatic
• Symptomatic
• Symptomatic ruptured

18. Asymptomatic AAA
• In case of an incidental finding of AAA, surgery
is only done if diameter is >55mm
• Aneurysms less than 55mm,require regular
follow up.
• Found during routine examination or USS

19. Symptomatic AAA (without rupture)
• Commonly present as back or abdominal pain
• Groin or thigh pain due to nerve compression
• Pressure symptoms
• Rule of 80’s:
– 80% of patients with AAA will be dead within a
year if they don’t have surgery.
– 80% of patients with AAA will be alive if they have
surgery
• Inflammatory aneurysm in 5%

20. • May present as an
– Aortocaval fistula:
• Presenting as high output cardiac failure
• With continuous bruit in the abdomen
• Severe lower limb ischaemia (Steal phenomenon)
– Aorto-enteric fistula:
• Aneurysm erodes into the fourth part of the
duodenum.
• Presents as GI bleeds.

21. • The risk of operation:
• Hypertension
• Chronic airway disease
• Recent myocardial infarction
• Impaired renal function

22. Complications
• Rupture
• Infection
• Thrombosis, with embolism
• Distal ischaemia/gangrene
• Aortocaval fistula
• Aortoenteric fistula
• Erosion of vertebra
• Spinal cord ischaemia and thrombosis

23. DDX of an unruptured AAA
• Retroperitoneal mass
• Pancreatic pseudocyst
• Mesenteric ischaemia, acute pancreatitis and
perforated duodenal ulcer may mimic an AAA

24. Treatment plan
• Investigation
– Blood investigations
– Imaging
• USS
• CT
• Angiography
• Duplex USS

25. Non Surgical management
• For low risk AAA
– Age below 70 years
– No cardiac disease
– Non inflammatory aneurysm
– Diameter less than 5.5cm
– If growth rate is less than 0.5cm/year
• Risk factor modification:
– Quit smoking, alcohol
– Control of BP, Elastase inhibitors e.g NSAIDS.
• Periodic size measurement using USS every
6months

26. Surgical management
• Indications for surgery:
– Asymptomatic aneurysm greater than 5.5cm
– Growth rate greater than 0.5cm/year
– Painful and tender aneurysm
– Thrombosed aneurysm, aneurysm with distal
emboli

27. Ruptured abdominal Aortic aneurysm
• 1% risk of rupture if diameter is >5.5cm
• 20% risk if diameter is >7cm
• 20% rupture anteriorly into peritioneal cavity.
• 80% rupture posteriorly into retroperitioneal
space.
• 50% mortality

28. Clinical features
• Absence of femoral pulses with a palpable
mass in the abdomen.

29. • DX and treatment need to be rapid in order to
achieve the best results.
• Typically pt has a tender palpable mass in
setting of hypotension.
• Clinical diagnosis.
• CT scan may have additional benefit if dx is in
doubt. USS not requirement to dx Ruptured
AAA.

30. • Once dx is made;
– IV large bore access is obtained.
– Blood for grouping, xmatching
– Fluid resuscitation. Target SBP should not exceed
100mmHg.
– Urinary catheter is passed.
– If patient is stable, surgery maybe defered until
crossmatched blood is availed. In the unstable,
surgery is done even without blood.

31. • Treatment of ruptured aneurysm is Emergency
surgery and not resuscitation and monitoring.

32. PRINCIPLES
• Early identification
• Immediate resuscitation
• Maintenance of systolic blood pressure
• Urinary catheter
• Cross match six units of blood
• Rapid transfer to the operating room

34. Work up
• Full blood count
• Electrolytes
• Liver function tests
• Coagulation tests and
• Blood lipid estimation
• Cross-match
– if surgery is contemplated within a few days.

35. IMAGING
• CXR
• ECG, ECHO
• Isotope ventriculography
• Pulmonary function
• CT SCAN: Best for assessing aneurysm
morphology.
• MRI
• Digital subtraction angiogram
• Spiral CT scan

39. Surgical Approach
• Open Surgical method
– Endo-aneurysmorrhaphy with intraluminal graft
placement.
• Endoluminal procedure
– Endovascular aneurysm repair(EVAR)
– Aorta accessed via common femoral arteries which
are exposed surgically.
– Under radiological control, delivery system guided
into aorta and an endovascular prosthesis is placed.
Usually Dacron or PTFE.

41. Complications following surgery
• Open Surgery:
– Respiratory:
• Lobar consolidation
• Atelectasis
• Shock lung
– Cardiac:
• Ischaemia
• Infarction
– GIT:
• Colonic ischaemia due to lack of collateral blood supply.
• Occurs in 10% of cases.
– Renal failure
– Infection of the graft
– Haemorrhage
– Graft leak

42. • Neurological:
– Sexual dysfunction
– Spinal cord ischaemia
• Aortoduodenal fistula
– Rare but treatable
– Suspect if haematemesis and melaena occur years
following surgery.
• These complications are less in the minimally
invasive procedures.

43. • In the Endovascular technique
– Endo leaks may occur.
– Prosthetic migration
– Thrombosis
– Rupture
• 20% of patients need a secondary procedure
to correct the endoleaks or prosthetic
migration, thrombosis or rupture.

44. THORACIC ANEURYSMS
• Classified into:
– Ascending aortic aneurysms
– Aortic arch aneurysms
– Descending aortic aneurysms
– Thoraco-abdominal aneurysms
• Hypertension most implicated risk factor.
• Atherosclerosis is an aetiological factor
• 20% have concurrent AAA

46. PERIPHERAL ANEURYSMS
• Popliteal aneurysms:
– 70% of all peripheral aneurysms
– 2/3 bilateral
– 1/3 accompanied by abdominal AA

47. Presentation
• Popliteal aneurysms present as a swelling
behind the knee or
• May also present with symptoms caused by
complications, such as
– severe ischaemia following thrombosis or
– distal ischaemic ulceration as a result of emboli.
– Such symptomatic aneurysms require urgent
surgery with/out intra-arterial thrombolysis

48. • Asymptomatic popliteal aneurysms require
elective surgical intervention to prevent future
development of symptoms.
• Surgery necessary if aneurysm exceeds 25mm
• Imaging involves:
– USS
– CT Scan
• Management:
– Inlay graft
– Bypass with ligation of the aneurysm

49. • Femoral aneurysms
– Uncommon
– Usually treated conservatively after ruling out
other synchronous aneurysms
• Iliac aneurysms
– Usually associated with aortic aneurysms
– Operation is indicated, with bypass and exclusion
of the aneurysm by ligation above and below the
dilatation.

50. Carotid artery aneurysms
• Less than 4% of peripheral aneurysms
• Common site is the Common carotid artery bulb.
• 10% bilateral
• Swelling in neck at level below mandible
• May have horners syndrome
• DDX:
– Carotid body tumour
– Neck abscess
– Neurofibroma from the vagus nerve

51. Arterial venous fistula
• May be traumatic, surgically created or
congenital
• The veins undergo arterialisation (thickening
of the wall) with dilatation of the lumen and
development of a tortuous pattern.
• These may have an effect on the cardiac
output if they are large.

52. • May present as a pulsatile swelling with
detectable bruit as well as machinery murmur.
• Proximal compression causes collapse of the
swelling.
• Duplex scan and angiography confirms the
lesion with fast venous filling

53. Management of arteriovenous fistula.
• Embolisation is the best treatment mordality
• Surgery done for severe deformity or serious
haemorrhage.
• Ligation of feeding artery on its own not
adequate

54. DISSECTING ANEURYSMS
• Not an aneurysm but an aortic dissection.
Occurs through the media of the aorta after
splitting through the intima.
• Aetiology:
– Hypertension
– Cystic medial necrosis
– Marfan’s syndrome
– Trauma

55. • Always seen in the thoracic aorta, common in
the ascending aorta(70%)
• May open distally to form a double barrel
aorta.

58. Presentation
• Severe chest pain
• Features of ischaemia due to blockage of
different vessels
• TREATMENT:
– Antihypertensives
– Surgery:
• Dacron graft reconstruction of the aorta under
cardiopulmonary bypass.

59. END