The risk of having an abdominal aortic aneurysm (AAA) is that it may leak or burst – this is known as rupture. If the rupture is a major one, then sudden death may be the result because so much blood escapes from the aorta into the gut cavity or into the area behind it. Rupture of an AAA is one cause of sudden death in old age and may be mistaken for a heart attack because there was no suspicion that the person had an AAA. In a person with heart problems, the sudden blood loss and pain from rupture of an aortic aneurysm may cause the heart to stop (even without escape of a very large volume of blood).
Some surgeons use the phrase ‘leaking aortic aneurysm’ to describe the situation when blood has escaped from an AAA but the patient has not developed a very low blood pressure, and ‘ruptured’ to refer to the situation when the patient has become pale and sweaty with a very low blood pressure because of major blood loss (‘shocked’). Others use the phrase ‘ruptured aortic aneurysm’ to refer to all aneurysms which have leaked (‘ruptured’ means ‘burst’).
What happens when blood leaks from an AAA?
The effects depend to a large extent on the size and position of the rupture. There are two main types of rupture.
Retroperitoneal leak or rupture
If blood leaks into the space around the aorta behind the gut cavity then the leak is ‘contained’ by the tissues and you are more likely to survive long enough to get to hospital.
Free intraperitoneal rupture
If the rupture is into the gut cavity (the peritoneal cavity) then there are no tissues to ‘contain’ the escape of blood from the aorta, and it is much less likely that patient will survive to be taken to hospital. Virtually all the blood in the circulation can escape into the peritoneal cavity.
What are the symptoms?
The typical symptoms and signs of leakage of blood from an AAA are:
• pain in the back and the abdomen
• together with the signs of ‘shock’, being cold, clammy and pale
• rapid heart rate
• low blood pressure
Is it a ruptured AAA?
Rupture of an AAA may easily be confused with other conditions. The combination of sudden severe pain in the upper abdomen, together with shock, can suggest a heart attack, perforation of a peptic ulcer causing peritonitis or pancreatitis (inflammation of the pancreas).
Symptoms suggestive of other conditions may persist for many hours, or even days, before the diagnosis of a leaking AAA becomes clear – either as a result of a scan or because the patient develops other obvious signs, such as shock and a pulsating mass that can be felt in the abdomen.
Pain in the abdomen and back can suggest passage of a stone down the tube from the kidney (ureteric colic). Pain and tenderness in the lower abdomen may lead to suspicion of colonic spasm or diverticulitis.
Pain concentrated in the back can be confused with acute lumbar back pain from arthritis of the spine or a disc problem – especially if leakage of blood around the nerves in the lumbar area lead to ‘sciatica’ – pain radiating down the leg.
At the other extreme, people may ‘drop dead’ very suddenly as a result of aneurysm rupture, without ever receiving any medical attention.
Overall, about half of those whose aortic aneurysms leak reach hospital for possible treatment and about half of those who have an operation survive.
How is the diagnosis made?
If the symptoms are typical – abdominal and back pain with shock – and if the leaking aneurysm can be felt by examining the abdomen, then no other tests may be needed.
Feeling a leaking AAA may be very easy in a slim person – simply placing a hand in the middle of the abdomen reveals a pulsating swelling that is tender. The situation is quite different in patients who are stocky or obese, when it may be difficult or impossible to feel pulsation or a definite swelling.
It may simply be clear that some kind of serious problem has occurred inside the abdomen and the decision may then be made to do a scan (CT or ultrasound) or sometimes to proceed directly to operation. A CT scan shows up an AAA clearly and also shows up any substantial leak (but it is not always possible to be certain from a scan that an aneurysm has not leaked).
Operation for ruptured aortic aneurysms
This is almost exclusively by open operation at the present time. In most cases, emergency treatment is required without any delay if the patient’s life is to be saved. EVAR is simply not practical on this basis, although it may be used increasingly in future, particularly in patients with contained leaks whose condition is stable (but they may deteriorate suddenly and disastrously at any time).
Specific complications and problems
An open operation for ruptured or leaking aneurysms is the same as described previously for aneurysms that have not leaked, but the surgery is technically more challenging and is attended by many potential problems, including the following:
• There is blood under tension all around the aorta and this can cause damage to the tissues, including small veins and arteries, so leading to further bleeding, which may be difficult to stop.
• Getting ‘control’ of the aorta by placing a clamp at the neck (top end) of the aneurysm may be challenging, because of the amount of blood and clots all around the aorta. Trying to expose the neck of the aneurysm through the blood, clots and damaged tissues can lead to further damage to nearby veins.
• If the aneurysm has ruptured from its front surface into the peritoneal cavity there may be torrential bleeding as soon as the abdomen is opened. Getting control of the aorta may then be most difficult, and sometimes impossible.
• Stitching a graft in place can be particularly awkward if the abdomen is deep (in obese or stocky people), through damaged tissues filled with blood clots. The condition of the arteries above and below the aneurysm may be poor, especially in very elderly people with a lot of atherosclerosis.
• There is more chance of blood clots or thrombus entering the arteries to the legs, or forming within them during the operation, than during non-emergency surgery.
All the potential problems described in the section ‘Special kinds of aortic aneurysms and aneurysms of other arteries’ (for planned ‘elective’ surgery on non-ruptured aneurysms) are even more likely to occur after operation for ruptured aneurysms. Patients having operations for ruptured aneurysms have had no chance for the consideration and preparation done before elective operations, and little may be known about their medical condition.
They may have suffered variable periods of low blood pressure before getting to hospital and this makes heart attacks, heart failure and death all more likely, and also predisposes to kidney failure.
Any pre-existing medical problems, such as angina, heart failure, bronchitis or mildly impaired kidney function, make serious failure of the heart, lungs or kidneys more likely. The combination of all three – ‘multiple organ failure’ – is a frequent cause of death after operation for ruptured aneurysms.
The massive blood transfusion often needed during operation poses risks including poor blood clotting (leading to further bleeding that may be difficult to stop) and lung problems.
Deciding not to operate
Doing very major surgery on people who will not survive is neither good medicine nor kind patient care. For some patients this decision is clear. For example the bed-bound patient in a nursing home with severe mental and/or physical problems may be most considerately managed with really good pain relief and without transfer to hospital. The same applies to patients who are known to have advanced cancer or other conditions associated with very limited life expectancy.
The decision is more difficult in someone whose chances of survival seem poor but whose life might possibly be saved by surgery. Their own wishes (either expressed or conveyed through close relatives) are paramount but these may not be easy to divine when someone is in great pain, shocked or unconscious.
How might the surgeon decide whether to operate?
Many attempts have been made to define criteria which might be used to predict those patients who will not survive. Clinical criteria such as:
• previous cardiac arrest
• very low blood pressure
• blood tests such as low haemoglobin (red blood cells) and raised creatinine (poor kidney function)
can be a helpful guide, especially when a patient has two or three of these together.
There is usually no single or easy way of making the decision for kind palliative care, with pain relief and maximum comfort, rather than for operation. It involves consideration of the patient’s general condition and quality of life, the severity of their acute medical condition and the wishes that they have expressed.
Sensitive conversation with close family members is always of the greatest importance for the ‘best’ decisions to be reached. Remember, however, that it is the duty of doctors to do what they believe to be in the best interests of the patient. It is neither the right of any relatives to insist on particular treatment, nor should any relative ever be left to feel that they bear the burden of a decision not to operate. That is the responsibility of the surgeon (sometimes with advice from other specialists, such as anaesthetists).
What about the future after operation for a ruptured aortic aneurysm?
Having a ruptured aneurysm is a major ‘illness’ and the operation to treat it is also very major. Serious complications are common and substantial periods of time in an intensive care unit may be necessary.
All this can lead to a slow recovery, with fatigue and a reduced sense of wellbeing for weeks or months. Some people, who were fit to start with and who suffer no serious complications, may get back to normal quickly.
At the other extreme, an elderly and unfit person may never recover well from this kind of surgery (and this is a consideration in deciding on the wisdom of surgical treatment).
Following recovery from the operation, life expectancy is restored to ‘normal’. As described for non-emergency operations, the grafts used for repair of aneurysms are very durable and normally work well for the rest of a person’s life.