Abdominal aortic aneurysm Flashcards
What is an aneurysm?
Dilation of a vessel by more than 50% of its normal diameter
What is the normal diameter of a vessel?
1.2-2cm
What is the minimum diameter before it is termed an aneurysm?
over 3cm
What is a true aneurysm?
An aneurysm in which all three layers of the vessel wall are intact
What is a false aneurysm?
An aneurysm in which there is a breach in the vessel wall (the surrounding structures act as the vessel wall)
What can cause false aneurysms?
trauma ie needles (medical or non medical), fractures etc
is an abdominal aortic aneurysm a true or false aneurysm?
True
What are the three types of aneurysm?
saccular, fusiform and mycotic
Which type of aneurysm has the highest chance of rupture?
saccular
What accounts for the vast majority of aneurysms?
fusiform
What is a mycotic aneurysm?
It is not a generic problem with the artery wall but an infection. The infection weakens the wall and the aneurysm expands rapidly. It involves all three layers of the artery
What increases your likelihood of getting an Abdominal aortic aneurysm?
-age (older), gender (male), smoking, hypertension
What is the main way a rupture occurs in an AAA?
Dilation of the aneurysm causes stress. Increase in size also causes increase in speed of growth. The bigger the aneurysms get, the more stressed and therefore the more likely the aneurysms are of rupturing.
What causes aneurysms?
damage to the vessel wall mostly caused by atherosclerosis
Are aneurysms genetic?
They can run in families most often on the male side
what percentage of AAA patients have a popliteal aneurysm?
25%
A ruptured AAA is the … most common cause f males in the UK?
7th
What is the ratio of male and females sufferers of AAAs?
9males :1 female
What percentage of AAAs are asymptomatic?
75%
How are asymptomatic AAAs identified?
imaging for other pathology or screening tests
What are the symptoms that can occur alongside AAAs?
- pain
- trashing
- rupture
What is meant by trashing?
clot in lumen from aneurysm which can break off which can go into peripheral vessels.
What is the presentation of an AAA?
- sudden onset epigastric/central pain
- may radiate through to back
- may mimic renal colic
- collapse
What is the presentation of AAA on examination in symptomatic AAA rupture?
-may look well
-hypo/hypertensive
-pulsatile, expansile mass +/- tender
-transmitted pulse
-peripheral pulses
(can sometimes see pulse coming out side of body caused by aneurysm rupture)
What are the outcomes for AAA rupture?
- 75% will not make it to hospital
- ones that rupture in the peritoneal sack dont usually survie
- 50% operative mortality
When should you intervene in a symptomatic AAA?
when there is :
- pain
- trashing
- rupture
When should you intervene in an asymptomatic AAA?
- an AAA of more than 5.5cm in diameter
- rapid expansion of aneurysm (more than 0.5cm in 6 months or more than 1cm in 1 year)
What is the risk of an aneurysm rupturing at less than 5.5cm?
less than 1%
What imaging should you do for an AAA?
- Duplex ultrasound
- CT angiogram
What is the use of a Duplex ultrasound?
- sued in asymptomatic AAA and for surveillance
- it identifies the size of the aneurysm as well as the involvement of the iliac arteries
- does not determine the location of the aneurysm
Why is a CT angiogram scan useful?
Will determine if there is a rupture, allows size, shape, artery involvement to be determined as well as planning of treatment
-A CT angiogram is a CT scan with contrast
What are the methods of treatment for AAA?
- open repair
- endovascular aneurysm repair (EVAR)
What is the principle of an open repair of an AAA?
- laparotomy
- clamp aorta and iliacs
- open aneurysm
- graft inserted
- aneurysm is then closed back over the graft as the graft would damage the bowl if it came into contact with it
(open abdomen, fire the piece of aorta above and below the aneurysm and then clamp it to stop it bleeding. Dacron (Polyester) graft with two different conformations: tube or bifurcated depending on suite of aneurysm.)
What percentage of AAAs are treated this way?
25%
What drug is used in open repair?
Heparin to thin the blood to try and reduce the clot
What are the principles of an EVAR?
- want to exclude the AAA from inside the vessel
- the tube is inserted via the peripheral artery guided by an Xray
What are the advantages of an EVAR over open repair?
- less invasive
- only need 2 1cm cuts in the groin
- preferred by patients
What are the disadvantages of an EVAR?
- lifelong scans needed
- 15-25% of patients will need an adjustment to their EVAR over the rest of their lives
What is acute limb ischemia?
sudden loss of blood supply to a limb
What causes acute limb ischemia?
occlusion of native artery or bypass graft
What are the causes of sudden occlusion?
- embolism (clot commonly comes from heart)
- atheroembolism (narrowing of vessel can cause clots or some of the plaque can come off and embolise)
- arterial dissection (tear of the intima can cause narrowing of the arteries)
- trauma (dislocating knew can cause dissection of artery behind the knee)
- extrinsic compression
What are the clinical features of acute limb ischemia?
- pain (excruciating)
- pallor (white)
- pulseless
- perishingly cold
- paraesthesia
- paralysis
- no prior history of claudication
- known cause of embolism ‘
- full complement of pulses in other leg
What is the pain like in acute limb ischemia?
- severe, sudden onset, resistant to analgesia
- can have leg muscle tenderness with tight compartment which indicates muscle necrosis
What is the pallor like in acute limb ischemia?
- white initially
- then mottled (purple blue) as capillaries fill with stagnent deoxygenated blood
- then non blanching mottling
What is meant by blanching?
touch it and it goes white then comes back to colour
What are the effect of acute limb ischemia after 0-4 hours?
- white foot
- painful
- sensorimotor deficit
- Salvageable
What are the effect of acute limb ischemia after 4-12 hours?
- mottled
- blanches on pressure
- partially reversible
What are the effect of acute limb ischemia after 12 hours?
- fixed mottling
- non blanching
- compartments tender/red
- paralysis
- Non salvageable
After 12 hours should you perfuse the leg?
No, there is a lot of dead tissue and if you perfused the limb you would simply be washing the toxins into the rest of the body and most likely kill the patient
What is the management plan for Acute limb ischemia?
- ABC (resuscitate and investigate)
- FBC, U/Es, CK, Coag +/- troponin
- ECG (check for MI or dysrhythmia)
- CXR (check for underlying malignancy
-Give anticoagulants but not too much as need anaesthetics
If the limb is salvageable what are the options?
-embolectomy +/-
-fasciotomies +/-
thrombolysis
If the limb is not salvageable what are the options?
-palliation or amputation
What is the risk of dying in hospital due to an embolus?
30% risk of dying in hospital if have embolus due to underlying cause of embolus
Why might an intra operative angiogram be needed in an embolectomy?
Underlying artery disease (especially in elderly patients) so the embolectomy catheter not passing down artery so need intra operative angiogram
How is an embolectomy carried out?
- tie off the two ends of the artery
- small incision to the artery
- insert the balloon catheter
- blow it up
- pull out the clot
- pull out the clot from the artery
What is diabetic foot sepsis?
tissue ulceration, necrosis and gangrene caused by diabetes related complications
What are the diabetic foot problems that can cause susceptibility to diabetic foot sepsis?
- diabetic neuropathy (cant feel trauma)
- peripheral vascular disease (lack of blood)
- infection
What is the most significant problem with diabetes?
Foot problems in diabetics account for more hospital admissions than any other long term complication of diabetes
What are the chances of losing the second leg after losing one leg in diabetes?
50% chance of losing their other leg within the first 5 years of the 1st
What is the main risk factor for limb loss?
diabetes
What can diabetic foot sepsis result from?
- simple puncture wound
- infection from the nail plate or inter-digital space
- from a neuro-ischemic ulcer
Why is diabetic foot sepsis a problem?
- within the foot the intrinsic muscles of the digits are confined within rigid compartments
- infection tracks in the soft tissues into these rigid compartments
- the build up of pus cannot escape
What can the build up of pus cause?
increase pressure in the compartments leading to impaired capillary blood flow and further ischemia and further tissue damage
What are the 5 foot compartments from superficial to deep?
- interosseous compartments
- lateral compartments
- medial compartments
- calcaneal compartments
- central compartments
What are some systemic clinical findings of diabetic foot sepsis?
- pyrexia
- tachycardia
- tachypnoea
- confusion
- Kussmauls breathing (very acidotic, they try to blow CO2 out to raise pH)
What are the local clinical findings of diabetic foot sepsis?
- swollen affected digit
- swollen forefoot
- tenderness
- ulcer with pus extruding
- erythema, may track up limb
- patches of rapidly developing necrosis
- crepitus in soft tissues of the foot
What is crepitus in the foot caused by?
Crepitus is a sign of gas, the gas is from the bugs
What antibiotics would you be using?
Those to treat:
- gram +ve cocci
- gram -Ve bacilli
- anaerobes
How do you treat diabetic foot sepsis?
- rapid surgical debridement of infected tissue
- wound open to encourage drainage
What surgical interventions can be done for diabetic foot sepsis?
- Remove all infection from site should take 15 mins
- Then come back to do a definitive procedure such as a Guillotine amputation
What is the aftercare for diabetic foot problems?
-adequate footwear and education on foot care
