arterial aneurysm Flashcards
What is the definition of an aneurysm?
permanent & irreversible localized dilation of a blood vessel that has atleast a 50% increase in diameter
What is the difference between an aneurysm & arterial ectasia?
aneurysm: > 50% increase in diameter
ectasia: <50% localized arterial dilatation
What are the types of aneurysms according to their wall?
- TRUE: all layers of artery are involved
- FALSE: only fibrous tissue lined from inside by endothelium
- DISSECTING: patch of intima tears & blood forcibly dissects its way between the inner & outer layer of the media
What causes a pseudoaneurysm?
partial tear of arterial wall -> extravasation of blood -> formation of hematoma surrounded by fibrin network connected to lumen
Where does a dissecting aneurysm usually occur?
thoracic & abdominal aorta
What are the 2 morphological types of aneurysms?
SACCULAR
- on one side of the vessel wall
FUSIFORM
- the whole lumen is diffusely enlarged
What arteries are more prone to saccular aneurysms?
peripheral arteries in neck & limb
Which arteries are more prone to fusiform aneurysms?
large internal arteries (aorta)
Which morphological aneurysm type is more dangerous?
saccular is more prone to rupture than fusiform but it spontaneously regresses unlike fusiform
What is the most common locations for a congenital (saccular) aneurysm?
- Circle of Willis causing subarachnoid hemorrhage
- splenic, renal & celiac arteries leading to hemorrhage into peritoneal cavity
- Ehler-Danlos syndrome & Marfan’s Syndrome
What is the most common locations for a congenital (saccular) aneurysm?
- Circle of Willis causing subarachnoid hemorrhage
- splenic, renal & celiac arteries leading to hemorrhage into peritoneal cavity
- Ehler-Danlos syndrome & Marfan’s Syndrome
What is the most common cause of acquired aneurysms & what is the commonest site it occurs in?
atheroscrelosis
INFRA-RENAL ABDOMINAL AORTA
What are the different types of acquired aneurysms?
- degenerative: atherosclerosis
- infective (mycotic): bacterial or fungal emboli may lodge in arterial wall resulting in weakness
- mechanical
What are the types of mechanically acquired aneurysms?
- post-stenotic aneurysms: in association with coarcitation, cervical rib, & popliteal artery entrapment
- traumatic aneurysms: false aneurysms due to pulsating hematoma
What is the commonest site for an aneurysm?
infra-renal abdominal aorta
what is the commonest site for a peripheral true aneurysm?
popliteal artery
What is the commonest site for a false aneurysm?
Femoral artery
What is the commonest site for a false aneurysm?
Femoral artery
What is the usual clinical picture of an aneurysm?
ASYMPTOMATIC
if symptomatic -> swelling
-> pressure manifestations
-> PAIN (impeding rupture)
-> distal ischemia
-> if popliteal artery is easily palpable consider aneurysm
if there are recurrent attacks of acute ischemia affecting distal foot with normal cardiac examination (no AF) what should be suspected?
investigate for popliteal artery aneurysms
What signs are seen upon inspection of a patient presenting with an aneurysm?
- swelling on anatomical course of a main artery
- expansile pulsations
- pulsates synchronously with heart beat
What will be felt upon palpation of an aneurysm?
- smooth cystic swelling
- moves transversely across the line of the artery but not longitudinally
- compressible
- proximal compression of artery -> shrinkage of swelling with loss of pulsations
- distal compression of artery -> increase in tension & pulsations
- palpable thrill
What will be heard upon auscultation of an aneurysm?
audible systolic bruit
What is the difference between an aneurysm & an AV fistula?
ANEURYSM AV FISTULA
- on anatomical site
- distal ischemia
- expansile pulsations
- cystic
- compressible
- palpable thrill - no hyperdynamic circulation - hyperdynamic circulation - no venous hypertension - venous hypertension - proximal compression -> decrease size - proximal compression-> decrease size & Branham's bradycardia - audible bruit is systolic - audible bruit is continuous
What are the complications of an aneurysm?
- rupture
- pressure effects on
nerves -> pain, paralysis, sensory changes
veins -> edema & congestion
bones -> erosion
viscera -> obstruction - infection & suppuration (rupture & fatal secondary hemorrhage)
- consolidation (coagulation)
What are the complications of a dissecting aneurysm?
- pressure of false lumen on true lumen with ischemic manifestations
- internal rupture -> spontaneous cure
- external rupture -> severe fatal hemorrhage
- proximal propagation -> aortic valve incompetence
- distal propagation -> renal, iliac, or femoral arteries -> obstruction of their lumens
What is the gold standard for diagnosis of aneurysm?
duplex
- detects size & mural thrombus
What is the gold standard for pre-op preparation of aneurysm?
Multi-slice CT
- shows sac, feeding artery & collateral vessels
When should conservative management be used?
in small asymptomatic aneurysms
What are the indications of surgical treatment?
- symptomatic aneurysm (painful or ischemic)
- large aneurysms
- rapidly enlarging aneurysms
- uncontrolled hypertensive patient
- if asymptomatic popliteal artery aneurysm exceeds 2 cm in diameter
What are the surgical options for surgical intervention for an aneurysm?
- excision & grafting
(ideal if local conditions permit it)
(excision is hazardous if dense adhesions are present) - ligation & bypass
(excluded sac will later thrombose & shrink) - excision & ligation
(only in small arteries that have many collaterals) - exclusion graft (
stent inserted inside graft without removing sac)
How is femoral pseudoaneurysm treated?
ultrasound guided fibrin injection
What is the clinical picture of an abdominal aortic aneurysm without rupture?
PAIN
may be due to - spinal erosion (prolonged compression)
- expanding aneurysm
- pain in thigh & groin due to nerve compression
EMBOLIZATION TO PERIPHERAL ARTERIES
What is the best screening & diagnostic method for an abdominal aortic aneurysm?
ABDOMINAL US (replacement for duplex)
What is the best method of investigation for pre op preparation of abdominal aortic aneurysm?
abdominal CT & MRI
when should angiography be used?
- pre-operatively to delineate the proximal & distal extent to decide what stent size should be used
What are the indications for surgery in an abdominal aortic aneurysm?
- symptomatic aneurysms
- asymptomatic aneurysms -> over 5.5cm
- > 4-5cm with evidence of more than 0.5 enlargement in 6 months or more than 1cm in a year
What are the types of surgeries used in abdominal aortic aneurysms?
- open surgical technique
- endovascular aortic aneurysm repair (EVAR)
How is EVAR preformed & what are its advantages?
access to aorta is via femoral arteries
- lower morbidity
- under local anesthesia
- small groin incision
- day case with short recovery time
What are the disadvantages of EVAR?
- less durability (5 years vs 25 years with open)
- expensive
- endoleak
What are the types of endoleak?
I -> incomplete seal or ineffective seal at end of stent graft
II -> retrograde branch flow from collateral vessels
III -> inadequate or ineffective sealing of overlapping graft joints or rupture of graft fabric
IV -> porosity of graft fabric
V -> no clear evidence
what are the complications of an AAA rupture?
- less than 50% of patients survive to reach the hospital
- anterior rupture: into peritoneal cavity
- posterior rupture: into retroperitoneal space (more fatal)
- rupture into IVC: large AV fistula
- rupture into duodenum: upper GIT bleeding
What is the clinical picture of an AAA rupture?
- sudden severe back pain & chest pain that could be confused with MI
- pulsatile mass palpable in the abdomen
- femoral pulses in one or both groins may be diminished
What is the clinical picture of an AAA rupture?
- sudden severe back pain & chest pain that could be confused with MI
- pulsatile mass palpable in the abdomen
- femoral pulses in one or both groins may be diminished
How is a ruptured AAA managed?
operation immediately when cross matched blood is available & EVAR used if available
What is the most common surgical intervention for small arteries?
grafting
