Vascular surgery introductory lecture Flashcards
What causes chronic limb ischaemia?
Atherosclerosis causing stenosis of peripheral arteries
What are risk factors for chronic limb ischaemia?
Smoking Diabetes Hypertension Stroke IHD Hyperlipidaemia Renovascular disease
How does chronic limb ischaemia present?
Intermittent claudication- cramping pain in calf, thigh or buttock after walking for a given distance (the claudication distance) and relieved by rest
What is considered ‘best medical therapy’ for chronic limb ischaemia?
- Stop smoking
- Treat hypertension and high cholesterol (prescribe statin even in patients who’s cholesterol is currently normal)
- Prescribe an antiplatelet agent to prevent progression and reduce cardiovascular risk
- Exercise- esp. supervised exercise programs. Reduce symptoms of claudication by improving collateral blood flow
What are the ‘Six P’s of acute limb ischaemia? Which of these are late changes?
- Pallor
- Pulselessness
- Pain
- Perishing with cold
- Parasthesia (late change)
- Paralysis (late change)
What is the significance of the 6 P’s in acute limb ischaemia?
If a patient presents with all 6 P’s including the late changes, there is SIX HOURS to act before the patient is at serious risk of losing the limb
What are the main causes of acute limb ischaemia?
- Thrombosis in situ (40%): more likely in patients with known vasculopathy
- Emboli (38%)
- Graft/angioplasty occlusion
- Trauma
Ideally, surgical intervention should be immediate upon presentation of acute limb ischaemia. However, sometimes no immediate intervention is available, e.g. if patient presents in the middle of the night. How should such cases be managed?
May be a case for heparinisation (stops clot propagating) and waiting till morning. This is often better for patients as surgeons generally operate better by day
If there is evidence of gangrene, administer antibiotics
What defines critical limb ischaemia?
Advanced stage acute or chronic limb ischaemia defined as the combination of evidence of ischaemia together with any of ischaemic rest pain, non-healing ulcers, or gangrene.
CLI is the point at which the lack of blood flow has crossed a threshold, threatening the sustainability of the limb
What is the difference between wet and dry gangrene?
Wet:
- Tissue death and infection (associated with discharge) occurring together
- Acute emergency
- Requires antibiotics and often amputation
- No clear demarcation between gangrenous area and perfused area
Dry:
- Necrosis in the absence of infection
- Not an acute emergency- can often be left alone e.g. if just a toe has try gangrene it can be safest to leave it to fall off
- Clear demarcation between gangrenous and perfused tissue
How does critical limb ischaemia present?
- Pain at rest, often with onset at night
- Gangrene
- Iscaemic (arterial) ulceration
What are the reconstruction options in critical limb ischaemia?
- Thrombolysis
- Angioplasty
- Bypass
What is the Fontaine classification for peripheral arterial disease?
- Asymptomatic
- Intermittent claudication
- Ischaemic rest pain
- Ulceration/gangrene
What signs might be seen on examination in a patient with peripheral arterial disease?
- Absent femoral, popliteal or foot pulses
- cold, white leg(s)
- Atrophic skin
- Punched out ulcers
- Postural/dependent colour change
- In severe ischaemia
- Vascular (Buerger’s angle) 15s
What is Buerger’s test?
Patient lies flat on couch- look at the colour of their feet
Lift the legs in the air and see if they go pale- the angle at which the feet go pale is Buerger’s angle
Let the legs dangle over the edge of the bed and see if they go red and then bright red
If feet go pale and then red this is a positive Buerger’s test and is a sign of ischaemia
What is an ABPI? What is a normal value for an ABPI? What is the range of ABPI which indicates peripheral artery disease? What is the range of ABPI which indicates critical limb ischaemia?
Ankle-brachial pressure index.
Normal: 1-1.2
PAD: 0.5-0.9
CLI: <0.5
What is indicated by buttock claudication?
Iliac disease
Where is claudication felt when there is femoral disease?
The calf
What are the drawbacks of thrombolysis to treat critical limb ischaemia?
- Contraindications for thrombolysis e.g. bleeding risk, recent surgery etc
- Thrombolysis of a whole limb takes 24-36 hours. Thus if a patient presents with “6 P’s” and has 6 hours before they lose their limb, there is not enough time to thrombolyse
What is PTA? When might this be used as a treatment of critical limb ischamnia? What are the drawbacks?
Percutaneous transluminal angioplasty
Used for disease limited to a single arterial segment
5 year patency is only 55% in femoral artery and 79% in iliac vessels
N.B. stents can be used to maintain patency