S11) The Peripheral Arterial and Venous Systems Flashcards
Describe the role of the calf muscles in blood circulation in the limbs
- The veins in the lower limb have valves which permit unidirectional blood flow
- When the calf muscles contract, the deep veins are compressed and blood flows upwards
Briefly describe the role of perforating veins in the lower limb
- When the muscles relax, blood is “sucked” into the deep veins via the perforating veins from the superficial veins
- The valves in the perforating veins only allow unidirectional blood flow
Describe the pathology of the perforating veins of the lower limb
Varicosities result when the valves in the perforating veins become incompetent or diseased
What are varicose veins?
Varicose veins are tortuous, twisted, or lengthened veins
Describe the pathophysiology of varicose veins
The vein wall is inherently weak in varicose veins, which leads to dilatation and separation of valve cusps so that they become incompetent
What are the symptoms of varicose veins?
Occur along the vein itself (trunk varices):
- Heaviness
- Tension
- Aching
- Itching
What are the 5 complications of varicose veins resulting from venous hypertension due to calf muscle pump failure?
- Oedema
- Skin pigmentation
- Varicose eczema
- Lipodermatosclerosis
- Venous ulceration
What are the complications of varicose veins resulting from the vein itself?
- Haemorrhage
- Thrombophlebitis
What is thrombophlebitis?
Thrombophlebitis is an inflammatory process that causes a venous thrombosis to form, commonly in the legs:
- Superficial thrombophlebitis
- Deep vein thrombosis
What are the causes of calf muscle pump failure?
- Failure of calf muscle contraction – immobility, obesity, reduced movement
- Deep vein incompetence
- Superficial vein incompetence (volume overload)
What is the pathophysiology of thrombosis?
Virchow’s triad:
- Changes in the lining of the vessel wall
- Changes in the flow of blood
- Changes in the constituents of blood
In terms of Virchow’s triad, what is the most important factor in the pathophysiology of arterial thrombosis?
Changes in the lining of the vessel wall
In terms of Virchow’s triad, what is the most important factor in the pathophysiology of venous thrombosis?
Changes in the flow of blood
Does stasis lead to thrombosis?
Stasis + another provocateur (trauma, oral contraceptive pill, dehydration, cancer)
Distinguish between arterial and venous thrombosis in response to bleeding
- Arterial thrombosis in response to bleeding involves vasoconstriction, platelets, extrinsic and then intrinsic pathways, hence arterial thrombi are platelet rich
- Venous thrombosis in response to bleeding involves venoconstriction, intrinsic then extrinsic pathways, hence, venous thrombi are fibrin rich
Where can you feel the femoral pulse?
The femoral pulse can be palpated at the mid-inguinal point
Where can you feel the popliteal pulse?
Popliteal pulse is palpated deep in the popliteal fossa (difficult to feel)
Where can you feel the dorsalis pedis pulse?
Dorsalis pedis pulse can be palpated just lateral to extensor hallucis longus tendon
Where can you feel the posterior tibial pulse?
The posterior tibial pulse can be palpated posterior to the medial malleolus
Describe normal lower limb circulation
- No symptoms
- Full set of lower limb pulses
Describe aortoiliac occlusion
- Bilateral buttock, thigh and calf claudication
- Absent lower limb pulses
- Rare
Describe common iliac occlusion (unilateral)
- Right buttock, thigh and calf claudication
- Absent right lower limb pulses
- Not so common
Describe common femoral occlusion (unilateral)
- Right thigh and calf claudication
- Absent right lower limb pulses
- Not so common
Describe superficial femoral artery occlusion (unilateral)
- Right calf claudication
- Femoral pulse present, absent popliteal and pedal pulses
- Commonest finding in patients with claudication
