Abnormal communication between an artery and vein
- Primary = congenital
- o Secondary = trauma, inflammation or healed ruptured aneurysm
- Fistulas may cause shunting of blood, bypassing circulations and increasing venous return, therefore increasing cardiac output.
- May predispose to heart failure.
- May be seen in Pagets disease of the bone, where increased blood flow through bones may eventually lead to heart failure.
- Found in 2% postmortems
- Most common intracranial aneurysm
- Small saccular aneurysms in the cerebral vessels
- Frequently occur at branch points in the circle of Willis.
- Commonly seen in patients with coarctation of the aorta and polycystic renal disease.
- Asymptomatic until they rupture.
Predisposing factors to rupture:
When they rupture:
- More common in males.
- Sudden onset of severe headache.
- Rupture leads to subarachnoid haemorrhage (p/c: severe occipital ‘thunderclap’ headache, vomiting, confusion, reduced/LOC, causes 1-7% of all strokes).