Treatment for abdominal aortic aneurysms

Aortic aneurysms are a bulging weakness in the wall of a large blood vessel which takes blood from the heart and distributes it to the rest of the body. This bulge in the weak section of the aorta can start to grow very slowly from the age of 50 or 60, growing on average by 2  mm to 5 mm per year. The condition is completely asymptomatic and in many people goes unnoticed.

The tendency to dilate the aorta can be inherited and it is worthwhile to screen the siblings or children of a patient with an aortic aneurysm after they reach 55 or 60 years of age (ultrasound is the simplest and the best screening method while CT is best for planning repair).

Once an aneurysm exceeds 5.5 cm in diameter there is a significant risk of rupture of the aneurysm which will cause intense pain, cardiovascular collapse and even death if the patient isn't taken to hospital urgently and taken to theatre for repair. Less than 50% of those who suffer ruptured aneurysms survive.

Mater vascular surgeon Dr Tim McGahan has provided the following case study to Generally Speaking about a patient who had an infrarenal aortic aneurysm that was repaired in the new CardioVascular Unit at Mater Private Hospital.

Case scenario

A 72 year old man with a steadily enlarging infrarenal aortic aneurysm which had been followed with ultrasound since 2004 until it approached 5.5cm.

Problem

Although open aortic aneurysm repair is the gold standard for the treatment of aneurysms this man had inducible cardiac ischaemia on his exercise stress echo cardiogram which placed him at high risk of a cardiac event during open surgery.

Assessment

A cardiology review was performed. CT angiogram using a 64 slice CT scanner. Routine pre-op, chest X-ray and routine blood tests.

Operation

Endovascular repair of infrarenal aortic aneurysm using a Cook “Zenith” endovascular graft. This device is inserted via bilateral groin incisions. It is a three piece modular dacron vascular graft supported by multiple stents. The three “stent grafts” are inserted through large calibre tubes introduced into the aorta and iliac arteries via the femoral arteries in the groin. A large abdominal incision and the need for aortic cross clamping are therefore avoided.

The procedure usually requires a general anaesthetic and is performed under image intensifier control, in this case in the new cardiovascular laboratories at Mater Private Hospital. Operating theatre staff and Cath lab staff worked together as the femoral artery exposure requires surgical incisions in the groins.

Angiography is used to ensure accurate placement of the stent graft below the renal arteries so that there is no obstruction to flow to the kidneys and to check the final result. The common femoral arteries are repaired with sutures and the groin wounds are closed in layers.

Post-op. course

There is usually no need for the patient to be nursed in intensive care after an endovascular aortic aneurysm repair. The patient recommenced a normal diet on the evening of surgery and was mobilised fully the next day although the groin wounds were moderately painful.

Discharge

Discharge in this case occurred on the second post-operative day. Open repair would have required a one to two day ICU stay and five to seven days in hospital.

To conclude, elective planned repairs are far more successful with less than five percent mortality but a long recovery. Endovascular repair has enabled us to offer safer surgery for those with co-morbidities which make the open surgical repair an unacceptable risk, such as severe heart or lung disease.

However, the endovascular technique is only readily available to those with suitably shaped aneurysms with a good length of normal aorta below the renal arteries into which to lodge the graft with the stents. This creates a seal to cut off the blood flow to the aneurysm sac and thus stop its enlargement and possible rupture. Also a more intense follow-up is required after the endovascular repair. Yearly X-ray plus CT or ultrasound must be done to check on the position of the graft as 1 in 20 can slip and further intervention may be required over the next ten years.

To refer a patient to Dr Tim McGahan please contact his rooms on +61 7 3163 7700.