Vascular Surgery JC002: Toe Gangrene And Leg Ulcer: Peripheral Vascular Ischaemia, Acute Vascular Emergencies Flashcards
Anatomy of Lower limb arteries
Common Iliac
—> External Iliac
(—> passes under Inguinal ligament)
—> Common Femoral
—> Superficial Femoral (main supply to lower limb) / Deep Femoral
(—> passes through Ductus hiatus / Adductor canal to back of knee)
—> Popliteal
—> Anterior Tibial (first branch coming off, lateral) + Posterior Tibial (longest, medial) + Peroneal (middle, in interosseous membrane)
—> Dorsalis Pedis
***Superficial Femoral:
- most frequently diseased artery in lower limb
Arterial Occlusive Diseases
2 classes (**Distinct entities —> Different presentations, implications, prognosis, treatment):
1. Acute occlusion
- **Embolism (from heart e.g. AF)
- ***Thrombosis
- Trauma
- Chronic occlusion
- ***Atherosclerosis
- Vasculitis
- Entrapment
2 Peripheral Arterial Disease problems occurring in Exam:
1. Leg pain
2. Ulcer / Gangrene in foot
Chronic Arterial Occlusive Disease: Atherosclerotic Occlusive Disease
A systemic disease! —> Other parts are affected as well! E.g. Heart
Risk factors:
- Smoking
- DM
- HT
- Hyperlipidaemia
- Family Hx
Symptoms 皮肉痹痛 (Chronic lower limb ischaemia):
1. Intermittent claudication
- **calf / thigh
- muscle ischaemia (∵ ↑ demand for oxygen due to exercise)
- **subsides with rest
- ***reproducible claudication distance —> pain force patient to stop walking
- Rest pain (X severe form of claudication)
- toes / forefoot (NOT in calf)
- ischaemia of **skin + SC tissue (X muscle pain, ∵ usually muscles are well-supplied)
- severe obstruction —> basal metabolic conditions is not met —> occurs at parts furthest from blood supply (i.e. skin, SC tissue)
- pain at rest
- **improves on dependency (hanging legs down)
- ***critical ischaemia
—> severe skin changes in leg
—> atrophy of toes
—> resting pain
—> viability of leg threatened - Tissue loss / Gangrene
- **painful ulcers (vs painless in venous ulcer) (∵ resting pain)
- **gangrene (dry: non-infected, well-demarcated / wet: infected)
- **pressure areas (∵ pressure impair bloodflow) —> Tip of toe, Heel, Metatarsal head
- **clean cut, no pigmentation, ***no swelling (no bloodflow)
- infected: poor margin, swelling, fluid, gas, redness, inflammation, cellulitis - Skin changes
***NOT Leg swelling: never a sign of PAD
Clinical evaluation for Arterial Occlusive Disease
- Does patient have arterial disease?
- vs O/T problem? - Acute / Chronic?
- How severe?
- claudication: not severe
- other than claudication: ***critical ischaemia - Where is obstruction?
- Why?
Major levels of arterial occlusion
- Aortoiliac (Major vessel occlusion)
- absent Femoral pulse
- absent Popliteal pulse
- absent Distal pulse
—> Seldom tissue loss
—> **Claudication of buttocks, thighs, calf instead
—> **Impotence (∵ internal iliac obstructed) - Femoro-popliteal (at Superficial femoral artery: Medium size artery disease)
- present Femoral pulse
- absent Popliteal pulse
- absent Distal pulse
—> **Claudication of calfs
—> **Tissue loss - Distal (Small artery disease e.g. DM, Renal failure)
- present Femoral pulse
- present Popliteal pulse
- absent Distal pulse
—> **Worst prognosis —> End arteries —> **Tissue loss / Gangrene
—> Not much claudication
NB: Hx / PE cannot disclose status of ***Tibial vessels
Management flow of Lower Limb Ischaemia / Peripheral Arterial Disease
- Patient
Address risk factors:
- Age
- Cardiac
- Pulmonary
- Strokes - Limb
- Limb not threatened (Claudication) —> **Relative indication for intervention (Conservative treatment first)
- Limb at risk (i.e. Critical ischaemia) (Rest pain, Tissue loss) —> **Absolute indication for intervention
(Presence of gangrene: 5 year mortality rate up to 50% (SpC Revision))
Investigations for Peripheral Arterial Disease
- P/E of pulses
- **Ankle-Brachial index (ABI): **Ankle systolic pressure / Arm systolic pressure
(Ankle systolic pressure: use doppler to measure posterior tibial pulse, compress ankle with cuff, pressure when doppler show flow again after slowly releasing cuff)
—> Normal: 1
—> Asymptomatic: 0.8
—> **Claudication: 0.5-0.6
—> **Tissue loss: 0.3-0.4 (30-40 mmHg)
Use:
—> Assess severity
—> Monitor treatment effect by measuring ABI before + after surgery
—> Follow-up use - ***USG Duplex
- Confirm obstruction
- Bloodflow (whether turbulence presence)
- Waveform
—> Good: Triphasic
—> Bad: Monophasic
- Velocity - Treadmill exercise
- Do ABI again —> ↓ ABI confirms peripheral arterial insufficiency - Arteriography
- Conventional type: seldom done, indicated only when ***surgery is planned
- NOT for diagnosis
- CT angiogram
- MRI angiogram (no radiation, no interference from calcification)
(Pitfalls of ABI: (from web)
- Severely calcified non-compressible artery may give falsely elevated reading
- ABI may be normal in patients with moderate stenosis of aorta-iliac artery
- ABI may be normal if sufficient collateral circulation present)
Complications of Arteriography (SpC Revision)
- Access-related
- Bleeding
- Pseudoaneurysm
- AV fistula
- Nerve / Vein injury
- Dissection
- Embolisation - Contrast-related
- Renal impairment
- Allergy
***Treatment of Intermittent Claudication
Claudication (limb not threatened)
—> treatment not indicated unless QOL severely affected
—> 2 classes: Improve survival + Improve symptoms
Survival improvement:
1. ***Risk factor modification
- Smoking
- HT
- Lipid
- DM
- Drugs
- ***Antiplatelet (↓ risk of MI / stroke) (NOT treat claudication symptom but just to improve survival)
(- Statin)
Symptoms improvement:
1. **Exercise
- **Supervised exercise programme
—> improve muscle metabolism, train muscle to use oxygen better
—> stimulate collateral formation
- Drugs
- **Cilostazol (Pletaal) —> PDE3 inhibitor —> ↑ cAMP —> ↑ PKA —> **Inhibit platelet aggregation + ***Vasodilation
- Naftidrofuryl (Praxilene) —> selective antagonist of 5-HT2 receptors —> ↑ cellular oxidative capacity
- Pentoxyphylline (Trental) —> PDE inhibitor —> ↑ cAMP —> ↑ PKA —> Inhibit platelet aggregation + Vasodilation
***Above measures can cure 50% of patients
- ***Endovascular intervention (Balloon)
- Endarterectomy
- Balloon angioplasty + Stenting - ***Surgery bypass
Surgery for Chronic Arterial Obstruction
Indications:
- Disabling claudication
- ***Critical ischaemia —> Limb salvage
Principle:
- ***Never amputate digits (esp. dry gangrene) before revascularisation
—> ∵ amputation creates wet wound
—> poor healing in the first place (∵ no blood supply) + potential for infection
—> unless spreading infection / wet gangrene
Revascularisation
1. ***Endarterectomy (Local procedure: removal of plaque including intima + media of artery)
Indications:
- Larger vessels
- Short segments
- Stenosis (rather than long occlusion)
- e.g. Iliac, Carotid
- ***Arterial bypass
- take a conduit connecting inflow to outflow
Anatomical (the bypass takes normal route of blood flow):
- Aorto-iliac
- Aorto-femoral
- Femoro-popliteal
Extra-anatomical (strange routes):
- Femoro-femoral (take blood from one femoral artery to the obstructed one)
- Axillo-femoral
Conduit:
- **Reverse great saphenous vein
- **Bypass grafts (e.g. Dacron)
- ***Balloon angioplasty + Stenting
- For short segment stenosis
Advantages:
- Less invasive, low risk
- Repeatable
- Short recovery, better tolerated by old age patients
- Cost
- Low morbidity / mortality
Disadvantage:
- **Durability (esp. for small artery stenting, poor long term patency rate)
- Stents (expensive)
- Adjuncts procedures required
- Recurrence
- **In-stent restenosis
- Stent fractures
- Amputation
- After revascularisation —> have healthy wound —> then can amputate (enhanced recovery)
- Lots of complications
- Below knee (higher rehabilitation / ambulatory potential, ∵ knee preserved but heal poorly ∵ smaller vessels)
- Above knee (much better wound healing ∵ many collaterals but poorer rehabilitation / ambulatory potential)
Classification of Femoral-Popliteal lesions
TASC-II (TransAtlantic Inter-Society Consensus for the Management of Peripheral Arterial Disease)
A: Short segment, Single segment
B, C: Long segment, Multiple segment
D: Total occlusion, Small vessels
A, B, C: Endovascular
D: Open Surgery
Adjuncts to Endovascular approach
- Laser
- Cryoplasty
- Directional atherectomy
- Rotation atherectomy
- Absorbable stents
- Drug eluting balloons
- Drug eluting stents
Acute Arterial Occlusion
Surgical emergency —> need revascularisation within hours
- ***Embolism (from heart e.g. AF)
- usually at Bifurcation of common femoral artery / Aortic bifurcation - Thrombosis (on top of chronic occlusion)
- Trauma
Acute obstruction
—> not enough time to develop collaterals
Distinctive symptoms (***記: 6P):
1. Pain (sudden onset)
2. Paresthesia / Numbness
3. Pallor / Cyanotic
4. Pulseless
5. Paralysis (advanced stage)
6. Perishing cold
—> Rmb: NO gangrene / ulceration / atrophy / claudication (皮肉痹痛)
Treatment of Acute Arterial Occlusion
Surgical emergency (within ***6 hours)
Diagnosis: Clinical
1. **Embolectomy
- Fogarty Embolectomy Catheter
- done under local anaesthesia
2. **Thrombolysis (in selected cases)
3. ***Anticoagulant
Consequences of revascularisation:
- **Reperfusion syndrome
—> damaged muscles swell up after delayed revascularisation
—> **Compartment syndrome
—> Necrosis
Treatment of Reperfusion syndrome: ***Fasciotomy
Subsequent management after revascularisation:
1. Locate ***source of emboli
- Echocardiogram (see if AF / residual clots)
- Treat complications
- **Compartment syndrome —> Fasciotomy
- **Electrolyte: HyperK —> Arrhythmia
- Renal failure (Rhabdomyolysis) —> Foley catheter + Rehydrate patients
Common pitfalls of Arterial disease
- Mis-diagnosis of claudication
- Toe amputation before revascularisation
- Misuse of expensive imaging modality (CTA / MRA) to replace P/E
- Delay recognition of acute ischaemia
- Beware of “leg pain”
- Treating the angiogram —> Never intervene for asymptomatic disease!
