| Peripheral Problems |
| Most peripheral vascular disease affects the lower limbs although problems specific to the upper limbs do occur. The arteries to the upper limbs are thankfully relatively spared of atheromatous disease but can become blocked from an embolus. Larger emboli usually come from one of the heart chambers but smaller ones arise from the subclavian artery as it crosses over the top of the first rib. |
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This is a place where the artery can be damaged by rubbing on the rib as it leaves the chest to enter the base of the neck. Over time atheroma can build up in this localised segment and the damaged lining becomes a source of embolic particles similar the situation with the carotid arteries only on this occasion the particles end up in the small vessels supplying the fingers. |
| Raynaud's phenomenon affects the fingers and toes and can on occasions be serious enough to cause tissue loss. It is rare for it to be a primary disease and is more commonly seen as a secondary phenomenon following cold injuries or in vasculitic conditions such as Rheumatoid arthritis, polyarteritis nodosa, scleroderma and systemic lupus erythematosis
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| Atheroma is very common in the legs and is a frequent cause of symptoms. However, some people never notice that they have arterial disease in this area because the changes happen over time and in a gradual fashion. It is possible for smaller arteries to take up the blood flow as the main channel becomes narrowed.
These vessels are known as collaterals and were first described by the great surgical pioneer John Hunter in his work looking at the blood supply to the deer antlers. |
| He carried out an experiment where he tied off the carotid artery in a deer in the expectation that the antler on that side would fall off. When it failed to do so he assumed not that there was an alternative supply of blood to the germinal root of the antler but that his ligature must have slipped! He re-explored his original ligature to discover that his ligature was sound and only then came to the former conclusion. |
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| Atherosclerosis is the commonest cause of blockage of the femoral arteries in the lower limb and can lead to symptoms in one of two ways. Firstly the affected person gets cramp in the muscles during an activity such as walking. The cramp usually occurs in the calves but can affect the thighs and even the buttocks depending upon the site of the occlusion. This cramping is called Intermittent Claudication since it comes on during active use of the muscles, goes away on stopping only to return on resumption of the exercise. |
In most people this doesn't affect quality of life all that much. For example, an elderly lady in her eighties may not worry that she cannot walk more than a couple of hundred yards as long as she can get around her house and garden albeit slowly.
However, the 54 year old man who enjoys his golf is less likely to tolerate such restriction. Secondly there is the more serious limb threatening situation.
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| The arterial disease can become so bad that there is simply not enough blood getting to the peripheral tissues such as the toes to provide enough oxygen and nutrients to keep the tissues healthy. This leads to ischaemia and the nerves become sensitive since they are living tissue too and tell the brain that all is not well. This is interpreted as pain and if the problem is not resolved it becomes constant. This situation is
known as rest pain. |
| The sufferer has only two choices; to relieve the pain with drugs or to get more blood down to the toes. The drugs usually don't work so the unfortunate victim helps the blood on its way by using gravity.
The average person doesn't think this through for themselves but happens across the solution by accident. When the foot is held downwards the blood falls downhill and the tissues get more blood. Eureka! |
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| Sadly, there is a catch. It's all very well the blood getting down to the parts that other methods cannot reach but how does it get back again? The simple answer is that it doesn't; well not easily since there is very little umph from behind and the muscle pump from the side which usually empties the veins is inactive because exercise and the increased energy requirements only makes matters worse than they already are.
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The blood therefore pools in the foot and fluid collects in the tissues leading to swelling and further pain. If something is not done limb loss is almost inevitable. The slightest trauma leads to a cut which cannot heal since there is not enough blood supply for basic needs let alone repair and ulceration occurs as shown in
the picture here where the skin has broken down and the exposed tendons and surrounding tissues have died. |
| In this situation urgent restoration of blood flow and removal of the dead tissue is required and this is made possible by the use of a spare vein such as the long saphenous vein which is joined to a patent artery above (usually the femoral artery in the groin) and a patent artery below (such as the popliteal artery behind the knee). This is called a bypass and can be thought of as a road that is built to relieve traffic around a bottleneck. The only other alternative is an amputation, a procedure of last resort but which nevertheless can be the only and best approach to relieve pain and provide a reasonable quality of life:
"Amputation is one of the meanest yet one of the greatest operations in surgery"
Sir William Fergusson
1808 - 1877 |
This quick fly past over peripheral vascular disease barely scratches the surface but it would nevertheless be incomplete if Diabetes mellitus was not mentioned.
Diabetics get a double whammy when it comes to problems with their periphery. They get a peculiar type of arterial disease which tends to affect the smaller distal vessels in the calf, feet and toes. The atherosclerosis calcifies and sometimes the outline of even the small vessels in the foot can be seen easily on a plain X-ray. This makes the arteries stiff and inelastic contributing to the slow flow through the already narrowed pipe. |
| Things are made worse by the fact that the nerves in diabetics stop working
over time due to a combination of metabolic damage to the nerve sheaths and disease in the tiny blood vessels supplying them. Diabetics therefore cannot feel their toes and heels as well as normal people and blisters due to an ill-fitting shoe occur easily where the rest of us would feel discomfort which would invite preventative adjustment. The skin breaks, infection gets in (and as everyone knows diabetics get infected more easily that other people) leading to rapid spread, gross tissue damage and sometimes devastating tissue loss. Urgent measures such as intravenous antibiotics, thorough drainage of abscesses and removal of frankly dead tissue are essential if major amputation is to be prevented.
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