Open operations for aortic aneurysms
The traditional way of treating an abdominal aortic aneurysm is by an ‘open operation’ – a traditional surgical operation through a long incision in the abdomen. These operations were first used in the 1950s and provide a reliable, long-term way of repairing the aorta, using a prosthetic (synthetic) graft. However, this is major surgery with the risk of complications or death, and the pros and cons need to be considered carefully for each individual patient.
Any aortic aneurysm can be treated by an open operation, whatever its shape, size or extent. Most abdominal aortic aneurysms have their upper end below the arteries to the kidneys (‘infrarenal aneurysms’) and the operation can be done through an abdominal incision. Occasionally aneurysms extend above the arteries to the kidneys (‘suprarenal aneurysms’) and these may require a longer incision extending up into the chest (see section ‘Special kinds of aortic aneurysms and aneurysms of other arteries’).
These operations are done by specialists in vascular surgery. Vascular surgeons deal with all kinds of arteries and veins but do not operate on the heart.
The anaesthetic
The anaesthetic and all the supportive care that accompanies it are of great importance for safe abdominal aortic surgery, and a great deal of preparation is required before the operation starts.
Wires are attached to the skin surface of the chest to monitor the heart and a probe is attached to a finger to measure the amount of oxygen in the blood (‘oxygen saturation’).
A number of ‘lines’ (tubes) are inserted into blood vessels – these usually include:
• ‘intravenous drip’ into an arm vein
• ‘central venous line’ into a major neck vein
• ‘arterial line’ into an artery at the wrist.
These allow fluid and drugs to be given into the circulation and also enable measurement of the central venous and arterial pressure, which help to guide fluid replacement and administration of drugs for the heart and the circulation.
A tube is passed into the windpipe (endotracheal tube) to allow oxygen and anaesthetic gases to be delivered to your lungs safely and securely. A catheter in passed into the bladder to drain urine and to measure the amount produced. A nasogastric tube is commonly inserted through the nose into the stomach, to keep the stomach empty during and after the operation. Commonly, an epidural is inserted into the lower back to help with pain relief after the operation.
A few of lines and tubes are inserted before a general anaesthetic is given (such as the intravenous drip) but most are put in after you are anaesthetised (such as the endotracheal tube, the nasogastric tube and the bladder catheter).
The operation
The incision
Operations for aneurysms are usually done through a ‘midline’ (vertical) incision or a transverse (horizontal) incision. The length of the incision depends on the build of the patient, the extent of the aneurysm and the preference of the surgeon, but a long incision is normal (traditionally from the bottom of the sternum [breastbone] to the pubic bone).
Another type of incision is an oblique one on the side of the abdomen: this allows a ‘retroperitoneal approach’ (behind the gut cavity) to the aorta. This may be particularly useful when the abdomen is difficult to reach as a result of previous surgery or there are special risks of infection (for example, in a patient with a colostomy).
Laparoscopic techniques
Some surgeons have reported using very small incisions and doing aortic aneurysm operations laparoscopically (using telescopes). This approach has not become popular, probably because it is rather difficult to learn, takes a long time to do and has possible risks – particularly if bleeding starts during the operation.
Repairing the aorta
The gut and other tissues are separated and moved aside to expose the aorta, which lies at the very back of the abdomen. The area of the aneurysm ‘neck’ is then carefully explored. This lies high up at the back of the abdomen and can be challenging to deal with, particularly in patients who are obese or stocky.
The neck of an aortic aneurysm usually lies just below the main arteries to the kidneys, in the area where the main vein from the left kidney (the left renal vein) crosses the aorta. A clamp is applied across the neck of the aneurysm to stop blood flow into it while the graft is stitched into place. A clamp is also placed across the right and the left iliac arteries to stop blood flowing back up into the aneurysm from the pelvis and the legs while the operation is done (some blood reaches the pelvis and legs through smaller arteries, even when the aorta is clamped above the aneurysm).
The shape of the bypass graft needed to replace an aortic aneurysm depends on whether the aneurysm affects only the aorta, or whether the iliac arteries are affected below the point at which the aorta divides (see the diagram). If the lowermost part of the aorta (where it divides into the two common iliac arteries) is of reasonably normal size then a tube-shaped graft can be used. If it is the area where the aorta or iliac arteries are affected by the aneurysm, a trouser-shaped (bifurcated) graft is used: one ‘limb’ is stitched to each iliac artery.
After applying clamps above the aneurysm to prevent bleeding the aneurysm sac is opened and the bypass graft is stitched in place. The usual kind of graft is made a fabric called Dacron; a number of types are available with slightly different properties, but their basic shape and strength are similar. Dacron is an inert substance that the body does not react to or try to reject. The stitches used to attach the graft are made of an inert kind of durable plastic, such as polypropylene.
The sac of the aneurysm is not removed, as removing it has no advantage and could result in damage to nearby structures. Despite this some publications still wrongly use the word ‘resection’ (removal) to describe the way aneurysms are repaired. The aneurysm sac is stitched over the graft at the end of the operation, which helps to separate it from the gut. The lining of the gut cavity (the peritoneum) is also stitched over the sac and the graft, which further helps to prevent any part of the gut sticking to the graft.
The gut is replaced in its correct position and the abdominal incision is closed using two or more layers of stitches.
Precautions and safety checks during aortic grafting
The surgeon, anaesthetist and all the others in the operating theatre team use many precautions and safety checks during this major and complex surgery, which include the following.
Protecting the heart from undue strain
The surgeon and anaesthetist work together to minimise the stress on the heart of clamping and unclamping the aorta (by giving drugs to control the blood pressure and by being sure that there is sufficient fluid in the circulation when the clamps are removed. This is particularly important for patients whose hearts have previous damage (for example from heart attacks), reduced blood flow or diseased valves.
Attention to blood flow down the legs
Aortic aneurysms commonly contain clotted blood (thrombus) and care is taken not to dislodge any of this down the arteries to the legs. The blood flow down both legs is checked at the end of the operation, by feeling the pulses at the feet and if necessary by using an ultrasound machine to listen to blood flow.
If the blood flow is compromised, then further surgery may need to be done before the operation is completed. This may mean:
• removing blood clots
• dealing with diseased arteries that have become damaged by clamping
• refashioning anastomoses (joins) of the graft to diseased (atherosclerotic) arteries.
Blood transfusion
If a blood transfusion is required, then special techniques are commonly used to give the patient back his or her own blood, rather than blood donated by other people. This can be done by removing some blood from the patient before the operation, or using a technique called ‘blood cell salvage’, which involves returning red blood cells lost by bleeding during the operation, through a special machine, to the patient.
Avoiding infection
The operating theatre is a sterile environment. Many precautions are taken, including avoidance of contact between the graft and the patient’s skin surface (even though the skin is thoroughly cleaned) and avoiding any contamination from the interior of the gut. It is routine to give an antibiotic as a precaution against bacterial graft infection.
Care after the operation
Normally patients go from the operating theatre to an intensive care or high dependency unit after aortic aneurysm repair and stay there for some time (often 24 to 48 hours) before returning to a surgical ward.
Pain relief and moving about
Good modern methods of pain relief mean that pain after this kind of major surgery can be controlled quite well, but movement is usually uncomfortable because the abdominal muscles have been incised and repaired.
Moving about will not cause any damage to the graft or to the stitched abdominal wound. It is important for patients to move about in bed, and to breathe and to cough to keep their lungs healthy.
Plenty of pain relief and encouraging movement are important, rather than restricting painkillers and allowing patients to lie still. It is usual for patients to be helped out of bed within 36 hours of surgery and to be starting to walk after 48 to 72 hours.
Drinking and eating
Usually after major abdominal surgery the gut ‘goes on strike’, usually for two or three days. Drinking any amount or eating can therefore cause distension, vomiting and a risk of vomit entering the lungs.
If a nasogastric tube has been inserted, this helps to keep the stomach empty for the first day or two after the operation (the tube is then removed). During this time intake by mouth is normally restricted to small amounts of water. Thereafter, increasing amounts of fluid are allowed, followed by gradual introduction of food. Most patients are drinking and eating after three or four days.
The lines and tubes
These are removed one by one, when they are no longer needed. The last ones to go are usually the epidural, the intravenous drip (or neck line) and the urinary catheter (in that order).
The epidural is left in place for up to five days to provide really good pain relief. While the epidural remains it is usual to keep the urinary catheter and an intravenous line in place as well. It is common for patients to be free of all their tubes after about five days.
Coming out of hospital
Before you leave hospital the surgical team will want to be sure that you have recovered sufficiently to leave their care. There are a number of considerations:
Infection and complications
No evidence of infection or other complications in the wound or elsewhere that need further hospital treatment.
Mobility
The pace with which patients become mobile varies from person to person: many fit people are walking about fairly well after four or five days and get home within a week. Those who are frail or less fit may take longer, but most people whose home circumstances allow are home within about ten days.
Home circumstances
People who have a fit spouse or other carer at home will usually leave hospital earlier than those who live alone or who need to care for others. Sometimes, transfer is arranged to a community hospital or other ‘halfway house’ for a short spell before patients go home to care for themselves.
Medication
On going home after an operation for an aortic aneurysm, most people will continue with all the regular medicines that they were on before the operation. These normally include a low dose of aspirin and often a statin (which lowers blood cholesterol). Painkillers will be prescribed if you still need them (a mild painkiller such as paracetamol is often enough).
When you get home
An open operation for an aortic aneurysm is very major surgery, and full recovery takes several weeks, although this can vary from person to person. You should try doing anything that you feel able to do, but in the early days after going home it is normal to tire quickly.
People are usually doing all the activities that they want within a month of the operation, but it takes longer than this (up to six months) to regain full strength and vitality, particularly for people who are older. None of this should discourage people from getting fully active as quickly as they can. Some people become active and regain their vitality quickly: the speed of recovery varies a lot.
In the first week or two after going home it is not unusual for people to experience days when they feel depressed, and even tearful – as after any major illness or surgery. Sometimes the operation can disturb appetite, the taste of food, the ability to concentrate for any length of time and the sleep pattern. All these gradually return to normal.
Following an operation involving a long abdominal incision, aches, pains and twinges are common with increasing activity, but no damage is likely to be done to the wound by getting fully active quickly.
Long-term outlook
Once an aortic aneurysm has been repaired by grafting at an open operation further trouble is very unlikely and no special checks need to be made on the graft. Patients have had grafts of this kind in place for 20 or 30 years (and longer) without them deteriorating or causing problems.
