L16: Peripheral arterial and venous disease Flashcards
What are the different classification of veins in the lower leg?
Superficial–> subcutaneous tissue
Deep–> underneath deep fascia (with major arteries)
What connects the superficial and deep veins?
Perforating veins
What are the superficial veins of the leg?
Long (great) saphenous vein–> formed from dorsal venous arch, up medial side of the leg, anterior to medial malleolous at ankle into the femoral vein under inguinal ligament –> external iliac
Short (small) saphenous vein–>formed form the dorsal venous arch of the foot, passes posteriorly to the lateral malleolous between two heads of gastrocnemius into the popliteal vein –> femoral vein–> external iliac
What are the deep veins of the leg?
Anterior tibial vein–> some branches from dorsal venous arch
Posterior tibial vein and peroneal (fibular) vein–> posterior tibial vein enters posterior to medial malleolous
Posterior surface of knee all 3 untie to form popliteal vein –> femoral vein –> external iliac
Profunda femoris vein–> drains muscles of thigh –> femoral vein –> external iliac
Describe what the calf muscle pump is?
The ‘Peripheral heart’
Gravity makes blood return difficult
Calf muscle contraction–> squeezes blood from superficial to deep via perforating veins
Valves open–> blood enters deep veins–> valves close prevent retrograde movement
Soleus and gastrocnemius important ones
Venous pressure in foot reduced during exercise
What are some common peripheral venous diseases?
Varicose veins
Venous eczema and ulceration
Venous hypertension
Thrombosis (DVT specifically)
What are varicose veins?
Valves ineffective and blood movement is slow or even reversed
Walls of veins weaken–> varicosities develop and valve cusps separate becoming incompetent
Veins tend to be tortuous, twisted
Form bumps under the skin
Usually asymptomatic
Usually saphenous veins
What pathologies can develop as a result of varicose veins?
- Pt describe heaviness and aching, muscle cramps, throbbing and itchy skin–> along affected vein
- Haemorrhage–> usually warm shower, blood pooling in legs, dilates BV–> bleeding along the leg
- Varicose eczema
- Superficial vein thrombophlebitis–> thrombus with inflammation–> painful erythematous and increased risk of DVT
- Chronic venous insufficiency–> reflux or obstruction–> venous hypertension
- Oedema
- Haemosiderin staining–> RBC released, oxidised by macrophages, Fe2+–> Fe3+, rusting appearance on skin
- Lipodermatosclerosis (inflammation and thickening of fat layer under the skin)
- Venous ulceration
What happens during venous eczema?
Chronic, itchy red and swollen tight skin
Lipodermatosclerosis can develop–> hard to touch (hardening of fatty tissue)
What happens during ulceration?
Chronic painful exposed skin
Often develop around hard nodular areas e.g. medial malleolous–> result of venous hypertension
Difficult to treat
Developement of chronic venous insufficiency occurs in 50% DVT patients
Why does the calf muscle pump fail? Who is at risk of calf muscle failure?
Plantar flexion of the foot required
Deep veins can be incompetent—> valve failure, blockages—> retrograde flow—> overwhelmed
Superficial vein incompetence—> blood from deep —> superficial —> calf muscle pump overflows
Immobility, obesity, elderly, people with Parkinson’s disease (shuffle- don’t walk properly) —> at risk
How is calf muscle failure treated?
Ligation (tie veins to stop them bulging) and vein stripping (removal of vein)
What are the difference between arterial and venous thrombosis?
Arterial—> platelet rich - activated endothelium- aggregate- plug hole —> most common cause atheroma
Venous —> fibrin rich, little platelet—> caused by stasis of blood- little flow coagulation of blood
- Stasis with an additional factor—> trauma, COCP, dehydration…
What is Virchow’s triad? How does it lead to thrombus formation?
- Blood flow
- Vessel wall
- Blood components
Change in one (usually two) of these leads to thrombus formation
What is a deep vein thrombosis (DVT)?
Clotting of blood in a deep vein
Usually calf
Due to impaired venous return and hypercoaguability
Can develop into pulmonary embolism—> (fatal) consequence
What are the signs of DVT?
Vary in severity and frequency
Usually asymmetric
Calf tendernesss, warmth, distended and visible superficial veins, oedema
Pyrexia (raised body temp) with no other cause
What are some other causes for DVT formation?
Soft tissue trauma
Cellulitis
Lymphatic obstruction
How is DVT diagnosed?
Wells’ score
Pre test probability —> how likely you are to develop DVT
Signs and symptoms
What are some of the risk factors for DVT?
Stasis—> before and after surgery, long haul flights etc
Trauma—> prothrombotic state
Malignant
Pregnancy —> hypercoaguable blood
How is DVT avoided?
Promote mobility soon after surgery
Prophylaxis —> anticoagulants —> given before surgery
How is physiology designed to limit actue ischaemia?
Collateral circulation
Alternative routes to the same destination
How does the body adapt to deal with stenosis of vessels over a period of time?
Build collateral vessels over period of time
What happens during acute limb ischaemia?
Occlusion of vessels occurs acutely–> minutes to days
No collateral circulation develops
Blood supply to area distal to occlusion cut off
6P’s of ischaemia
Refer to vascular surgical unit
Assess extent of threat of limb–> angioplasty, thrombectomy, intra-arterial thrombolysis or amputation
What are the 6P’s for the symptoms of ischaemia?
Pain --> initially Pallor Paraesthesia --> tingling or numbness Paralysis Pulseless Perishing with cold --> no perfusion
What is chronic peripheral arterial disease?
Intermittent claudication of the lower limb (cramping pain induced by exercise)
Partially occluded BV –> atherosclerosis –> muscle can’t get blood supply
How is chronic peripheral arterial disease managed?
Exercise--> develop collateral vessels Smoking cessation Antiplatelet drugs Angioplasty Bypass graft
What is critical ischameia? What happens if it is untreated?
Rest pain–> pain at rest
Eased by hanging foot out of bed etc… gravity last attempt at getting blood to limb
Leads to ulceration and gangrene–> viability of limb severely compromised
What is the pathology of claudication?
Atheroma–> atherosclerosis–> claudication
Untreated–> ischaemia when blood supply cut off
Collateral arteries develop to try and deal with it but eventually they become blocked too
What pulses can be palpated in a healthy lower limb?
Femoral pulse–> Midinguinal point (mid way between ASIS and pubic symphysis)
Popliteal pulse–> deep in popliteal fossa
Dorsalis pedis pulse–> lateral to extensor hallucis longus tendon
Posterior tibial pulse–> behind the medial mallelous
How is blood flow recorded?
Doppler ultrasound
Measures real time flow and velocity
How does doppler ultrasound work?
As blood flows sound is produced
If it is moving away from the machine it is lower frequency
If it is moving towards the machine it is higher frequency
Echos from stationary tissue remains the same
What index is commonly used to measure the flow in the lower limbs? Where is it measured? How is it calculated?
Ankle-brachial pressure index (ABPI)
Measured in brachial, dorsalis pedis and posterior tibia arteries
Calculated
- divide ankle systolic by brachial systolic
What is ABPI used to diagnose?
ABPI < 0.9 indicate peripheral artery disease
