Introduction
In general, abdominal aortic aneurysms (AAA) should be treated at 5.5cm in men and 5.0cm in women.
Open surgical repair involves exposing the aorta through the abdomen and then replacing it with an artificial graft by suturing it into position. Open aneurysm surgery is a major procedure with an inpatient stay of 7-10 days.
Indications
Once a AAA reaches threshold size it should be considered for repair. The choice of open surgical repair vs endovascular stenting depends on a number of factors:
- Age.
- General health – particularly cardiac, respiratory or kidney issues.
- Aneurysm configuration – some are not suited to stenting because of their position and shape.
- Ability to undergo surveillance – aneurysm stents require regular follow-up surveillance scans, not required following open surgical repair.
The best option for each patient requires individual evaluation and discussion to decide on the most appropriate treatment option.
To aid decision making a number of investigations will be performed. These assess the above factors to assist with decision making.
- CT angiogram – this scan will confirm the size of the AAA, it’s shape and suitability for repair.
- Cardiac stress test – routine investigation to assess fitness for surgery from cardiac viewpoint. Open AAA surgery does place the heart under stress.
- Respiratory function tests – routine assessment of lung function.
- Blood tests – routine check of blood count, electrolytes, kidney and liver function, coagulation profile and a cross match of blood should a transfusion be required.
Preoperative Instructions
Generally, admission will be required the day prior to surgery to allow repeat pathology tests to be performed.
You will be advised on any medications that need to be stopped or modified for your surgery. Blood thinners and diabetic medications will require a management plan.
Once admitted to the ward, the blood tests and an ECG will be performed. The abdomen will be shaved if required and medications reviewed.
You will require to fast for the procedure. This will depend on your procedure time and will be confirmed on admission. For most patients this will entail fasting from 12 midnight the night before your surgery.
Procedure
The procedure will be performed under a general anaesthetic in the operating theatre complex. The anaesthetist will insert a central venous catheter into a neck vein, an arterial line into the wrist and a peripheral line into one of the forearm veins. These lines are to allow monitoring of vital signs and administration of medications and fluids.
A catheter will be placed into the bladder to allow monitoring of kidney function and fluid balance and a warming blanket will be used to maintain body temperature.
The surgery will take 2-3 hours. To allow repair of the aneurysm an incision will be made on the abdomen. This is usually up and down the middle of the abdomen but may also be across from side to side depending on the configuration of the aneurysm. This will be discussed prior to the surgery.
Once the abdominal cavity is opened the aneurysm is exposed. Blood thinners are given to prevent any clot formation and then the Aorta is clamped. This stops the blood flow through the aneurysm to allow repair. The aneurysm is opened and then an artificial graft is sutured in to replace the weakened aneurysm wall. The graft is usually made form Dacron, a very strong material. The aneurysm itself is not removed but is then wrapped around the graft to separate it from the bowel. The abdomen is then sutured closed and the patient is then transferred to the intensive care unit for monitoring.
Postoperative Instructions
The initial recovery is performed in the intensive care unit. This would normally be for 24 hours but that time may be extended if there are any concerns. Careful monitoring of blood pressure, respiratory function and urine output are performed. Pain relief is provided and this is usually via a Patient Controlled Analgesia (PCA) infusion. With a PCA, the patient can press a button that delivers a dose of pain relief as needed.
Physiotherapy is very important in the early post-operative period to encourage deep breathing and to assist with mobilisation as soon as possible. Regular deep breathing exercises are important as it is quite common to develop some collapse in the lungs from major abdominal surgery.
After aneurysm surgery the bowel will tend to be paralysed for several days, so clear fluids are consumed initially and this is slowly increased to a normal diet as the bowel recovers. Too much food too soon can cause nausea and vomiting.
It does take some time to get back to normal mobility. Most patients are suitable for discharge 7 days after the surgical procedure. Once home, it is important to gradually return to all of usual activities. Regular daily walking is important aiming for 30 minutes per day. To allow the abdominal wound to heal, avoidance of heavy lifting (over 5 kilograms) should be avoided for at least 6 weeks. Aneurysm surgery is a major procedure and it is best to avoid driving a motor vehicle or heavy machinery until fully recovered and at least 4 weeks is recommended.
Risks
Open Aortic Aneurysm surgery is a major intervention. Every organ in the body can be affected by the surgery. Some of the potential complications, whilst rare, can be severe and life threatening. Obviously, aneurysm surgery is performed to protect against the risk of aneurysm rupture which has a very high risk of death.
The most common complications include:
- Heart attack – the stress of surgery can strain the heart.
- Pneumonia – shallow breathing post-operatively increases the risk of chest infection.
- Kidney failure.
- Constipation.
- Deep vein thrombosis.
- Circulation issues to the legs.
- Wound infection.
- Urinary tract infection.
- Graft infection.
Treatment Alternatives
Aneurysm surgery is only performed for large aneurysms that pose a risk of rupture and subsequent death.
Endovascular stenting is an alternative procedure that should be considered for patients at risk of increased complications from open AAA surgery. Unfortunately, not all patients are suitable for endovascular stenting due to the configuration of their aneurysms.
If the risk of surgery is too high, then not operating is an option. Clearly this leaves the patient at risk of aneurysm rupture and the risk vs benefits of surgery vs no surgery need to be carefully considered.
Related Information
Abdominal Aortic Aneurysms
Thoracic Aortic Aneurysms
Aortic Aneurysm Stenting