Armando Hasudungan

Biology and Medicine Tutorials



  • An aneurysm is an abnormal localized dilatation of a blood vessel (>50% of its original diameter)
  • It may be associated with structural abnormalities of collagen and elastin in the vessel wall
  • Prevalence of abdominal aortic aneurysm: Much more common in females (9:1), 4% of men aged 65 (increasing with age).


Anatomy Layers of the vessel, from the inside, the tunica intima, media and adventitia. Surrounding the vessel is extravascular tissue.


True and false
True Aneurysms is dilatation of the vessel wall involving all layers, where as false is dilatation of the vessel due to the leakage of blood through the wall but is contained by the adventitia or surrounding perivascular soft tissue.


Aneurysm: an artery that has enlarged to greater than 1.5 times the expected diameter.
True Aneurysm: The aneurysm is bound by all three layers of the vessel wall (intima, media and adventitia). The wall may be attenuated.
False Aneurysm: Occurs when a blood vessel wall is injured, and the blood is contained by the surrounding tissues creating an apparent dilatation of vessel.
Aortic dissection: occurs when a tear in the tunica intima of the aorta causes blood to flow between the layers of the wall of the aorta, forcing the layers apart.

Types of Aneurysm

Sites of Aneurysm The aorta (infrarenal) is the most common. Iliac, femoral and popliteal arteries are the next most common.


Types of Aneurysm True Aneurysm is abnormal dilatations that involve all the layers of the vessel wall. False Aneurysms (pesudoaneurysm) involve a collection of blood in the outer layer only (adventitia) which communicates with the lumen. Aneurysms can be saccular (dilatation on one side) or fusiform (both sides) which is common in AAA.


True Aneurysms

  • Atheroma
  • Infection (myocotic aneurysm in endocarditis, teritary syphilus -thoracic aneurysm)
  • Connective tissue disorders (Marfan's Disease, Ethers-Donalos)
  • Inflammatory (ie. Takuyasu Aortitis)

False Aneurysms

  • Trauma
  • Iatrogenic causes (ie. femoral cannulation, surgery)

Cerebral Aneurysm

A cerebral aneurysm is an acquired focal abnormal dilation of the wall of an artery in the brain. Intra-cranial aneurysms are most commonly located at branching points of the major arteries at the base of the brain, which course through the subarachnoid space. Cerebral aneurysms can lead to subarachnoid haemorrhage. saccular aneurysm of the middle cerebral artery is the most common

Thoracic Aortic Aneurysm

Often asymptomatic, diagnosed by widened mediastinum of chest x-ray or on CT/MRI. Rupture has high mortality and rare without prior symptoms

Abdominal Aortic Aneurysm

For more Information AAA

Classic ruptured AAA triad: Hypotension/collapse, back/abdominal pain, Palpable/pulsatile abdominal mass.

Often asymptomatic. ~40% are incidental findings (clinical examination, ultrasound, abdominal x-ray). Most common site is aneurysm below the renal arteries. 15% extend down to involve the origins of the common iliac arteries. AAA is associated with other peripheral aneurysm (popliteal). Risk of rupture and mortality increase with the diameter of the aneurysm.

Remember AAA greater then 5.5cm in diameter need some for of intervention


Stenting and Coiling

Complications and Prognosis

  • Rupture
  • Thrombosis
  • Embolism
  • Fistulae
  • Pressure on other structures
Remember Classic triad of ruptured AAA congenital: Hypotension/collapse, back/abdominal pain, Palpable/pulsatile abdominal mass.


Best Practice
Oxford Handbook of Clinical Medicine
Oxford Handbook of Clinical Surgery
Robinson, D., Mees, B., Verhagen, H., & Chuen, J. (2013). Aortic aneurysms Screening, surveillance and referral. RACGP. 42 (6). 365-369.
Summary of Aneurysms