By Dr. Thomas Burnell and Dr. Bethany Turner
Next Lesson - Acute Coronary Syndrome
Core
Venous diseases become more common as people age. Varicose veins are a common vein pathology (disease), thought to affect at least a third of the population.
A varicose vein is a vein that is tortuous (winding), twisted or dilated (widened). The superficial veins of the legs are commonly affected, meaning varicose veins are commonly seen under the skin. Risk factors for varicose veins include older age, a family history of varicose veins, female sex, pregnancy, obesity, and prolonged standing or sitting. An example is an occupation that involves a lot of standing.
Image - A leg with varicose veins. The veins can be seen bulging from the skin
Creative commons source by Nini00 [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
Normally, venous blood from the legs flows upwards through superficial veins which eventually flow into deeper veins. The flow of blood is assisted by valves in veins which allow blood to move up towards the heart and prevent blood from flowing back down. This ensures that venous blood only flows in one direction.
If the veins become dilated due to the weakening of the wall of the vein, the leaflets (flaps) of the valves are pulled apart. This lets blood leak back through the valve by the downward pull of gravity (retrograde flow). Blood builds up below the faulty valve. This increases the pressure on the valves closer to the feet, so more blood flows backwards through these overwhelmed valves. The cycle continues and spreads further down the superficial venous network. Blood pools in the lower legs, forming varicose veins.
Patients often complain of their legs feeling heavy, tense and itchy. As the veins become more damaged, twisted and tortuous, they will push against the skin and cause the skin to appear bumpy.
Diagram - The difference between a normal vein and a varicose vein. In the varicose vein, the veins are contorted, dilated and bulge underneath the skin. Also illustrated is the concept of retrograde flow: venous blood is flowing in both directions through the faulty valve
Creative commons source by Jmarchn, modified from Varicose veins.jpg of National Heart Lung and Blood Institute (NIH) [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
Varicose veins have several associated complications:
- Haemorrhage
- The walls of the varicose veins are thin and bulge from the skin, making them more susceptible to damage through trauma.
- For emergency first aid, raise the leg to a level higher than the heart (to help venous blood drain from the leg). Also apply direct pressure to the bleed. Bleeding from varicose veins can be severe, so urgent medical assessment is required, followed by admission to a vascular service (a hospital team that treats blood vessel disease).
- Thrombophlebitis
- This is inflammation of a vein caused by the formation of a small clot (also called superficial vein thrombosis). The clot forms due to stasis (slow, stagnant flow) of blood within the varicose vein. It is often self-limiting (settles on its own), but in some cases can extend or be associated with deeper venous thrombosis, so clinical assessment is important.
- Patients can experience swelling and pain over the affected vein.
- Venous hypertension
The incompetence (failure to close properly) of the valves in varicose veins means that venous blood leaks backwards instead of flowing up towards the heart. This results in blood pooling at the bottom of the vein, building up the pressure in the vein which causes venous hypertension.
As well as varicose veins, another cause of venous hypertension is calf-muscle-pump failure. The calf muscles play an important part in forcing blood up the deep veins in the calf. These muscles can fail to contract, for example because of immobility or a shuffling gait (walking with small, dragging steps). Blood then builds up in the veins under higher pressure.
Venous hypertension is associated with complications such as:
- Oedema - the blood in the varicose veins is under high pressure and so fluid leaks into the interstitium (the tissue space between cells) causing oedema.
- Varicose eczema (also called venous eczema) - the sustained high pressure in the veins causes eczema (itchy, red, scaly skin) of the overlying skin. These patients are susceptible to developing ulcers.
- Brown skin staining - red blood cells leak from the veins under the high pressure into the surrounding tissue. Macrophages (immune cells that clear away debris) then break down the cells, and the iron in their haemoglobin is oxidised from iron(II), Fe2+, to iron(III), Fe3+. The Fe3+ formed is deposited in the skin as haemosiderin (a brown, iron-containing pigment) and stains the skin brown.
- Lipodermatosclerosis - long-term inflammation and hardening (fibrosis) of the skin and the subcutaneous fat, caused by sustained venous hypertension.
- Venous ulceration - the skin and the subcutaneous fat become increasingly damaged by the sustained high pressure, eventually resulting in an ulcer. This is a break in the skin below the knee that has not healed within 2 weeks. Venous ulcers typically occur between the ankle and mid-calf.
- Deep vein thrombosis (DVT) - venous stasis (slow blood flow) and hypercoagulability (blood that clots too easily) can predispose to clot formation in the deep veins of the leg. Varicose veins are a recognised risk factor for DVT, but the clot forms in the deep venous system, not in the superficial varicose veins themselves. The link also works the other way: a DVT can damage the valves of the deep veins, which raises venous pressure again (post-thrombotic syndrome, long-term leg pain, swelling and skin changes after a DVT).
- Symptoms and signs are usually in one leg only. They include pain, tenderness and swelling (often noticeable in the calf), with warmth, redness and pitting oedema (swelling that leaves a dent when pressed). Whole-body (systemic) features such as fever are less common.
- A DVT can embolise. If part of the thrombus breaks off and travels in the circulation as an embolus, it can travel up to the pulmonary circulation and lodge to cause a pulmonary embolism.
Image - A patient with a deep vein thrombosis in their right leg. The leg is swollen and erythematous (red) compared to the left leg
Creative commons source by James Heilman, MD [CC BY-SA 3.0 (https://creativecommons.org/licenses/by-sa/3.0)]
Arteries can become stenosed (narrowed) as a result of atherosclerosis. Stenosis of arteries can reduce the flow of blood through the artery. Stenosis can occur in some of the arteries of the legs.
Due to the stenosis, patients can experience intermittent claudication. This is pain and cramping in the muscles of the leg when walking or exercising. It is relieved by rest (within 10 minutes). It is caused by reduced oxygen delivery to the muscles. If the stenosis is more severe, then patients can experience pain in the leg or foot at rest. This rest pain is a feature of chronic limb-threatening ischaemia (previously called critical limb ischaemia). Typically, patients describe a severe burning pain in the foot and leg that continues even at rest. Patients may get some relief at night by hanging the leg off the bed or sleeping in a chair, as gravity then increases blood flow to the foot. If left untreated, arterial stenosis may lead to ulceration (open sores) and gangrene (death of tissue due to loss of blood supply), usually in the foot and toes.
Locating the stenosis is carried out by checking for pulses in that limb. The main leg pulses from proximal to distal are:
- Femoral - mid-inguinal point: halfway between the anterior superior iliac spine (the bony point at the front of the pelvis) and the pubic symphysis (where the two pubic bones meet).
- Popliteal - deep in the popliteal fossa (the hollow behind the knee).
- Dorsalis pedis - on the top of the foot, lateral to the extensor hallucis longus tendon (the tendon that lifts the big toe).
- Posterior tibial - behind the medial malleolus (the bony bump on the inner side of the ankle).
The patient’s symptoms and pulses will be different depending on where the stenosis is:
- Aortoiliac stenosis (narrowing of the lower aorta and the iliac arteries, the large arteries of the pelvis):
- Bilateral buttock, thigh and calf claudication
- All lower limb pulses are absent
- Common iliac artery stenosis:
- Unilateral buttock, thigh and calf claudication
- Unilateral absent lower limb pulses
- Common femoral artery stenosis:
- Unilateral thigh and calf claudication
- Unilateral absent lower limb pulses
- Superficial femoral artery stenosis:
- Unilateral calf claudication
- Femoral pulse present, but popliteal and pedal (foot) pulses absent
- This is the most common site of artery stenosis in the leg
Sudden occlusion (blockage) of an artery has two main causes. The first is thrombosis: a clot forms within an artery that is already narrowed by atherosclerosis, often when a plaque ruptures. The second is an embolus: a clot or other material that breaks off elsewhere, travels in the blood and lodges in the artery. Emboli can come from the heart, where a clot can form in atrial fibrillation (an irregular heart rhythm). They can also come from an abdominal aortic aneurysm (AAA), which is a bulge in the wall of the aorta in the abdomen.
Sudden occlusion of an artery is very serious. It is a medical emergency (acute limb ischaemia), and anyone with a suspected case needs emergency assessment by a vascular specialist (a doctor who treats diseases of the blood vessels). Skeletal muscle tolerates a lack of blood supply for only 4 to 6 hours. The longer the symptoms last, the less likely it is that the limb can be saved.
The signs and symptoms of occlusion of an artery are typically the six P’s. They result from the lack of blood reaching the tissues. Not all six need to be present:
- Pain
- Paralysis
- Paraesthesia (pins and needles, or numbness)
- Pallor (paleness)
- Perishingly cold to touch
- Pulseless
Initially the affected limb will be white as the perfusion to the tissues is severely reduced. After a few hours, the deoxygenated blood in the limb causes it to become cyanotic (there is a blue tinge to the skin). At this stage the skin blanches (turns pale) when pressure is applied. As the ischaemia progresses, the skin becomes mottled (patchy and marbled in colour) and no longer blanches, indicating severe tissue ischaemia. Urgent specialist management is needed as soon as acute limb ischaemia is suspected, before these skin changes develop. By the time the skin is mottled and no longer blanches, limb salvage (saving the limb) may no longer be possible.
Edited by: Dr. Ben Appleby
Reviewed by: Dr. Marcus Judge
- 10037
