Peripheral Vascular Diseases

• Atherosclerosis = hardening of the arteries

  
• Claudication = pain in the leg on walking due to blocked or narrowed arteries
• Critical ischaemia = ischaemia which is bad enough to threaten loss of the limb (amputation)
• Acute ischaemia = sudden onset of ischaemia in the leg
• How to diagnose vascular claudication - key questions:

  • Does this pain ever occur standing still or sitting
  • No - because muscles would be using excessive amounts of oxygen so lactic acid wouldn't be generated
  • Is it worse if you walk uphill or hurry
  • Yes - because generating lactic acid
  • What happens to it if you stand still
  • It goes away; oxygen debt is repaid and lactic acid is washed away
  • Where do you get the pain or discomfort
  • Claudication pain is typically in the calf, atypically in the buttock or thigh - not in foot or toes
• How to diagnose vascular claudication:

  • Typical history
  • Examination - absent pulses
  • Exclusion of other conditions (eg arthritis in hip or knee)
  • Ankle-brachial pressure index < 0.9
  • Hand-Held Doppler
  • "Blood pressure in legs"
  • Duplex Doppler U/S
  • CT/MR angiography
• Vascular "history":

  • MI/angina/heart failure
  • Stroke/TIA
  • Diabetes
  • Smoking and other risk factors
  • Social circumstances/quality of life
  • Medications
• Untreated claudication - after 5 years:

  • 20% die of myocardial infarction
  • 10% die of other causes (smoking, cancer, stroke etc)
  • 3% amputation
• Lifestyle modification:

  • Smoking - biggest risk factor, so should be main focus
  • Exercise
  • Weight reduction
  • Improved diet
• Critical ischaemia:

  • Rest pain (not just when walking)
  • +/- gangrene or ulcers
  • Doppler pressures in foot <50mmHg
• Vascular rest pain:

  • Felt in toes/foot
  • Often severe
  • Worse at night
  • Hang foot out of bed or sleeps in chair (gravity)
• Critical ischaemia:

  • >70% will need amputation if nothing is done
  • Priority is revascularisation to unblock or bypass diseased vessels
  • Key investiations are:
  • Duplex scan (non-invasive)
  • Angiogram
  • CT or MRA

  
• Acute ischaemia of the leg - causes:

  • Thrombosis
  • Embolus
  • Trauma
  • Extrinsic comression
  • Severe venous obstruction
  • Low flow states/vasospasm
  • Vasoconstrictor drugs
• Sources of emboli:

  • Heart
  • Atrial fibrillation
  • Myocardial infarction
  • Valve disease
  • Arteries
  • Aneurysms (aorta/popliteal/thoracic)
  • Stenoses
  • Veins - paradoxical embolus
  • Tumours
  • Foreign bodies
• Pathophysiology of acute ischaemia:

  • Nerves/muscle more sensitive to ischaemia
  • Skin/subcutaneous tissue less sensitive
  • Time critical factor
  • Level and collaterals
  • Propagation of thrombus
  • Irreversible changes after 4-6 hours
• Clinical signs of acute ischaemia:

  • Pain in leg
  • Pale/cold leg
  • Pulseless
  • Paralysis - can't stand/walk
  • Paraesthesia/numbness - can't feel leg
• Management of acute ischaemia:

  • Heparin/analgesia
  • Resuscitate - ABC
  • Catheter/CVP line etc
  • Surgery as emergency
  • Embolectomy
  • Bypass
  • If too late - amputation
• Aortic aneurysms:

  • Most common in men over 65 - increased risk if smoke and are hypertensive
  • Uncommon in women
  • Grow slowly and most eventually rupture
  • Rupture often fatal
  • Are treated when above 5.5cm in diameter
  • Can be treated by open surgery or stenting

  
• Abdominal Aortic Aneurysm (AAA) Ultrasound Screening:

  • Simple and safe
  • No radiation exposure
  • Sensitivity and specificity are nearly 100%
  • Cost-effective
  • Has reduced ruptured AAAs
• 1 in 6 strokes are due to carotid disease
• Internal carotid artery stenosis:

  • Causes TIA and strokes by:
  • Embolisation usually
  • Or restriction of flow occassionally
  • If symptomatic usually intervene if stenosis >70%
  • TIA = a 'mini stroke' - resolves within 24 hours - can affect vision, speech or limbs commonly
• Atherosclerosis is a single systemic disorder with different clinical presentations (heart, brain, legs etc). Priority = treat modifiable risk factors:

  • Lifestyle (smoking, exercise, diet, weight)
  • Pharmacological - statins and clopidogrel, BP, insulin etc
• Claudication is a risk factor for cardiovascular death (MI and stroke) as well as amputation
• Critical ischaemia leads to amputation unless treated
• Acute ischaemia of leg - surgical emergency
• Aortic aneurysms - main risk = rupture
• Carotid endarterectomy prevents strokes