Aneurysms and dissections Flashcards
aneurysms are
-Aneurysms are dilatations of the aorta due
to weakening of the wall
dissections are
-Dissections (also called dissecting aneurysms)
lead to widening of the vessel as the result
of blood dissecting through the wall of the
vessel
aneurysms most commonly occur
in the abdominal aorta distal to the renal arteries
causes of aneurysms
- atherosclerotic weakening of the wall of the aorta
2.also occur as a result of infection, vasculitis, or structural abnormalities
-syphilis: aneurysms of the ascending (thoracic) aorta
-genetic abnormalities of collagen, elastin: ascending
aorta
how do dissections occur?
as a result of blood passing through a tear in the intima
-dissections split the vascular media and create a false
vascular channel
dissections most commonly occur in
thoracic aorta
dissections are most commonly associated with?
hypertension
death from dissections are caused by?
hemopericardium and cardiac tamponade
what is a true aneurysm?
bounded by generally complete but attenuated arterial wall components
what is a false aneurysm?
- (pseudoaneurysm) – widening due to extravascular hematoma that communicates with the lumen (dissection)
atherosclerosis as a cause of aneurysms
-usually positioned below the renal arteries and above the
bifurcation of the aorta
-often associated with dilatations of the iliac arteries
-may affect origins of the renal, superior, and inferior
mesenteric arteries
-thinning and destruction of media resulting from
ulceration of atherosclerotic areas
-cylindrical aneurysms which may rupture
-increased diameter increases risk; 50% mortality
-risk of rupture for small aneurysm 2%
-develop after 50; much more common in men
-familial (other than atherosclerosis or
hypertension)
consequences of abdominal aneurysms
-rupture - peritoneal cavity or retroperitoneal
tissues
-impingement on an adjacent structure
-occlusion of a vessel be either direct pressure or
mural thrombus
-vertebral branches that supply the spinal cord
-embolism from the atheroma or mural thrombus
-abdominal mass that simulates a tumor
berry aneurysms
congenital weakness of arterial wall (usually CNS)
-outpoouching
-usually sporadic
-sometimes associated with autosomal dominant
(adult form) polycystic kidney disease
-also associated with Ehlers-Danlos syndrome
-most common around circle of Willis
-anterior communicating artery(40%)>middle
cerebral artery (34%)>junction of
carotid/posterior communicating artery (20%)
-bifurcations of cerebral arteries
vasculitic aneurysms
-Kawasaki, Wegener’s, temporal arteritis, Takayasu’s etc
mycotic aneurysms
Salmonella gastoenteritis
thoracic aorta aneurysms
- syphilitic
- genetic tissue disorders – Marfan’s, Ehlers-Danlos, etc.
- bicuspid aortic valve