What is an Aneurysm?
An aneurysm is an abnormal dilatation or swelling arising from an artery. It can affect a number of arteries, most commonly the aorta, the main artery of the chest and abdomen. The most likely location is for an aneurysm is just below the arteries to the kidneys. Aneurysms may involve the iliac arteries in the pelvis (see diagram)
How do you know if you have an aneurysm?
Most people with aneurysms are unaware they have one. It usually produces little, if no symptoms, and is most often discovered by chance, on a scan undertaken for other reasons. An aneurysm is sometimes detected on routine examination of your abdomen. Occasionally, an aneurysm may cause pain, in the back or side. When this occurs, it is recommended you see your doctor immediately.
What will happen if I ignore the aneurysm?
Untreated, the aneurysm will continue to expand and ultimately burst. The rate of expansion is variable, 1mm to 5mm per year. The risk of rupture is directly related to the size of the aneurysm. Aneurysms with diameters under 5cm have a very low risk of rupture, though this can vary depending on other factors, such as the configuration of the aneurysm.
When should the aneurysm be treated?
Intervention is usually but not always recommended when the aneurysm exceed 5 – 5.5cm diameter. The purpose of intervention is to prevent rupture or alleviate symptoms..
What happens if the aneurysm ruptures?
Sudden onset of severe back or side pain may be an indicator that the aneurysm is about to rupture. Immediate transfer to hospital is vital for survival. Rupture can cause severe shock (profound hypotension) through blood loss. A high mortality rate (greater than 50% of patients who reach hospital) is associated with rupture, which underlines the importance of early diagnosis and treatment.
How are aneurysms treated? (see operations performed)
Open Repair. This involves open surgery through a long incision in the abdomen. It has been performed for over 60 years, and still has an important role today with excellent outcomes, both short term and long term. It involves the replacement of the aneurysm with an artificial Dacron graft.
Endovascular Repair. This technique has now become the treatment of choice in most patients undergoing aneurysm repair. It can be performed without making any major incisions. It is performed in the catheter laboratory using a stent-graft, delivered into the aneurysm from the femoral (groin) arteries, thereby excluding the aneurysm from the circulation, and at the same time, maintaining normal blood flow to the lower limbs.
What determines which procedure is appropriate?
This decision is made by your surgeon. It depends on a number of anatomical factors outlined on the abdominal CT scan
What are the risks of the procedure?
This will depend on how the aneurysm is treated and is discussed in detail in operations performed.
What happens before, on the day and after the procedure?
This procedure still has an important role in the management of a minority of patients with aortic aneurysms (AAA).
In order to prepare for this procedure, it is vital that a full medical work-up be obtained to confirm fitness for anaesthesia.
This will involve a number of blood tests, an assessment of the heart with an ECG and thallium scan, and referral to a cardiologist if there are any concerns about your heart.
Day of procedure
You may be admitted on the morning of the procedure if your work-up has been completed. You will be required to bring ALL of your usual medications.
It is important to fast for at least 6 hours prior to the procedure. For a morning procedure, you will need to fast from midnight, whereas for an afternoon procedure, this will mean fasting from 7am.
Your anaesthetist will consult you prior to the operation, and explain the anaesthetic and its risks to you.
A full general anaesthetic is administered. A tube is inserted into your windpipe (trachea) to help with your breathing while you are asleep. A catheter is also inserted into your bladder to help in monitoring your fluid status. This will remain in-situ for the first 48 hours.
The operation is performed through a midline abdominal incision, passing from the chest to the pubic bone.
Heparin is administered to help keep the blood thin. The aorta is clamped above and below the aneurysm. In over 90% of cases, this occurs below the arteries to the kidneys, so there is no interruption in blood flow to the kidneys. Clot adherent to the wall of the aneurysm is removed, and back bleeding from arteries coming off the aneurysm controlled.
In order to restore vascular continuity, a synthetic graft (Dacron) either as a tube or “trouser” is sewn into position. Clamps are released to restore circulation to both legs, usually sequentially and slowly, to allow fluid replacement and maintenance of blood pressure. All vascular joins are checked and any leaks sealed.
All patients return to the intensive care unit for at least the first 24 hours for stabilisation, correction of any fluid imbalance and to ensure heart and lung function is optimised.
Patients are then transferred to the ward, where oral fluids and diet is slowly re-introduced, and mobilisation commenced. It is a gradual process, but most patients are fit for discharge at about 7 to 10 days following the procedure.