Peripheral arterial disease (PAD)

Question 1

3 Types of PAD

Answer 1

1. Chronic lower limb ischemia
2. Acute lower limb ischemia
3. Upper limb ischemia

Question 2

Anatomy of lower limb

Answer 2

Aorta will divide into 2 common iliac artery
Common iliac artery will divide into external & internal iliac artery

external iliac artery-below inguinal ligament-common femoral artery
Common femoral artery will give profunda femoris/deep femoral artery & continue as superficial femoral artery

superficial femoral artery in popliteal fossa-popliteal artery-enter leg & divide into
1. anterior tibial artery
2. common tibio-peroneal trunk (posterior)- posterior tibial artery & peroneal artery

Question 3

What happens in PAD? (Pathology)

Answer 3

In atherosclerotic artery, there is a fatty plaque-atherosclerosis

In cross section of the artery, half or almost half of the luminal artery is blocked by the atherosclerotic plaque (pathology)

Question 4

Onset & progression of PAD

Answer 4

1. acute ischemia
   - A sudden onset of severe pain, paresthesia, & paralysis in a previously asymptomatic patient suggest an acute embolic event-> symptomatic from few hours to <15 days
2. chronic ischemia
   - A long history of reduced walking distance with claudication pain suggestive of atherosclerotic disease-> symptomatic for >15 days
3. acute on chronic ischemia
   - A sudden worsening of symptoms in a patient who has a long history of claudication may suggest thrombosis of a clinically stenosed vessel

Question 5

Pathophysiology of PAD (chronic lower limb ischemia)

Answer 5

Mainly due to atherosclerosis & TAO

Slow progressive occlusion, enough time for collateral vessels formation
symptoms are few days to >15 days

Disparity between demand & supply of O2-> tissue or muscle undergo ‘Anaerobic metabolism’- release lactic acid & p substances- stimulate peripheral nerve ending- stimulate pain/intermittent claudication

progressively develop intermittent claudication-> rest pain-> ischemic ulcers-> gangrene (dry gangrene)

Question 6

Pathophysiology of PAD (acute lower limb ischemia)

Answer 6

Mainly due to embolus from heart/thrombosis from an artery

Sudden occlusion-> no time for collaterals

Symptoms: few hours to <15 few days

Presentation:
1. Mottling of skin
2. sensory motor loss
3. sudden gangrene

Question 7

History/symptoms of PAD (chronic lower limb ischemia)

Answer 7

Presents with intermittent claudication
- the development of pain in the muscles of the thigh/calf that is induced by exercise
- the site of pain depends on the level of occlusion of the artery (thigh, leg, foot)

The pain invariably starts after walking a particular distance & relieved by rest-> “Claudication distance”

If the disease progresses, “rest pain” develops. often relieved by ‘hanging the leg out of the bed’/’cry of the dying nerve’

Question 8

History/symptoms of PAD (acute lower limb ischemia)

Answer 8

Acute arterial occlusion causes a sudden onset of limb pain, often associated with loss of function & altered sensation

6 P’s
1. Pain- unrelenting & severe
2. Pallor
3. Paresthesia
4. Paralysis
5. Pulselessness
6. Poikilothermia (extreme of cold)

Question 9

Physical exams/signs of PAD (chronic lower limb ischemia)

Answer 9

1. pale & cool limb
2. loss of hair & brittle nails- lack of nutrition
3. weak/absent peripheral pulses
4. guttering of veins (veins not filled up)
5. blistering of skin & ulceration (critical limb ischemia)
6. Frank dry gangrene (critical limb ischemia)
7. burger’s angle of vascular insufficiency
   - the normal limb can be raised upto 90 degrees without loss of colour, but an ischemic limb will blanch on raising the limb above the horizontal
   - the angle at which this occurs is called “Buerger’s angle”
   - if <20 degrees-> severe ischemia
8. dependant rubor (after elevation, place leg down-> not normal colour but red colour temporarily)

Question 10

Physical exams/signs of PAD (acute lower limb ischemia)

Answer 10

6 P’s
1. Pain- unrelenting & severe
2. Pallor
3. Paresthesia
4. Paralysis
5. Pulselessness
6. Poikilothermia (extreme of cold)

Note: Mottling of skin (dusky purple colour)- is characteristic of acute lower limb ischemia

Question 11

Investigations in PAD

Answer 11

1. Ankle-brachial pressure index (ABPI)
2. Arterial duplex scan- Gold standard for arterial & venous disease
3. Digital subtraction angiogram (DSA)
4. CT Angiogram/MR Angiogram

Question 12

Diagnostic Algorithm of PAD

Answer 12

From history & examination: acute, chronic, acute on chronic

Accordingly to table, do perform investigations & identify & treat accordingly

Note: Atherosclerosis affects a larger vessel while TAO affects medium & smaller-sized vessels