Treatment
There are essentially 3 treatment options:
 | pain killers if the patient is not fit enough for any type of surgery |
| amputation |
| bypass surgery to get more blood to the lower leg |
The majority of patients fit into the last category and I will deal with this here. without bypass surgery around 70% of these patients will need an amputation. In addition to surgery we have to address the risk factors that led to this situation.
MEDICAL MANAGEMENT
The aim of medical management is to increase the survival of the patient and to prevent failure of the bypass graft. The section on lifestyle measures to tackle atherosclerosis outlines some of the ways used. Various drugs may also be started if the patient is not already on them:
| antiplatelet drugs - act on certain cells in the blood to make them less sticky. Aspirin and clopidogrel are the most commonly used. Aspirin is cheaper but has higher risk of causing bleeding from the stomach. Clopidogrel is slightly more effective and causes less bleeding but is more expensive. Overall these drugs reduce the risk of a cardiovascular event (heart attack or stroke) from 6% per year to 4.5% per year. Furthermore, they reduce the risk of requiring an operation by 85%. |
| anticholesterol drugs - the statins (pravastatin or simvastatin). These reduce the risk even further from 4.5% per year to 3% per year. |
| antihypertensive drugs - to control the blood pressure. |
ANGIOPLASTY
There may be some parts of the arterial tree which are suitable to stretching open with a balloon before the bypass operation. More recently a technique called 'subintimal angioplasty' has been employed to open long segments of blocked arteries - including the small arteries of the calf. This technique may be more suitable for patients who would tolerate a general anaesthetic for the bypass operation. For more details, see angiogram and angioplasty.
SURGICAL MANAGEMENT
This means bypassing the blocked segments of the arterial tree. The section on intermittent claudication (treatment) shows some of the bypass methods used. The figure below outlines these operations:
For the majority of cases of critical ischaemia the bypass graft has to be taken below the knee onto the small arteries of the calf (the anterior tibial, posterior tibial and peroneal arteries - see anatomy). For this purpose I use the patients own vein (either long saphenous vein or an arm vein) as these have been shown to be far superior to using synthetic ('plastic') grafts. The picture below shows an arm from which a vein has been removed:
Sometimes there is not enough good quality vein available. In this situation I try to either clear out the superficial femoral artery and take the graft form the lower extent of this to the calf arteries or use a synthetic graft from groin to just above the knee (femoro-popliteal graft in the figure above) and then vein from here down. This is called a composite-sequential graft.
The following sequence of pictures shows the long saphenous vein being used to take blood from the thigh to the artery along the shin (the anterior tibial artery). To use the vein, its side branches have to be tied off and the valves in it have to be destroyed to allow blood to flow down the vein. The first picture shows the cuts made in the leg to tie off the vein side branches. A number of small cuts are made, instead of one long cut, to enable better healing. You will see the surgeon wearing special glasses to magnify the field of view:
The vein is joined onto the artery in the thigh, above the blocked diseased segment, using permanent stitches:
The valves in the vein are then destroyed using a 'valvulotome' which is passed up the vein and withdrawn. As it is withdrawn, it catches the valves and tears them (the are very flimsy structures). This allows blood to flow down the vein. The vein is then 'tunneled' to the appropriate artery using a plastic tube. The appropriate artery is that artery which is open beyond the diseased blocked segments as determined by the angiogram (see investigations). The picture below shows the plastic 'tunneler' and the clip used to drag the vein graft to the correct position. The tunneler is then removed.
At the lower end, the arteries are very small and special magnifying glasses have to be used to carry out the stitching. The vein graft is stitched to the artery with permanent thread. The pictures below show the join in progress and the completed result.
Once the wounds are closed the patient is sent to the high dependency unit for 24 hours before transfer back to the ward.
Surgery is successful in about 80% of cases selected for surgery. Further interventions may be needed to keep the graft going. I have vein grafts duplex scanned every 3 months for the first year to pick up treatable problems. 70% - 80% of grafts have been reported to be functioning at 3 - 5 years after surgery.
Bypass surgery is not without problems. Around 10% of patients die as the result of surgery. This is a reflection of the general arterial disease in these patients as most die from heart problems. Wound problems including infection affect around 1 in 3 patients and are probably the commonest reason for patients having to stay longer in hospital. Infection of synthetic grafts can result in serious problems needing the graft to be removed and possibly the limb amputated.