|Abdominal Aortic Aneurysm|
An aneurysm is enlargement of a blood vessel to more than 1.5 times its normal diameter. Any artery can become aneurysmal, with the most common being the abdominal or thoracic aorta. Aneurysmal disease is the 12th leading cause of death in the U.S. and remains an under recognized condition.
Similar to a balloon, the bigger the artery gets, the thinner its wall becomes, and the greater the likelihood of rupturing. The natural history of aneurysmal disease is that over time, most will increase in size until they rupture. Since expansion and rupture rates are extremely unpredictable, it is aneurysm size that is used as the most significant factor in assessing risk from rupture. The average growth rate of an aneurysm is between 2-4 mm per year. Annual rupture risk increases exponentially with arterial size and is less than 3% for aneurysms below 4 cm and approximately 8-10% for 5 cm aneurysms.
Most aneurysms are thought to result from inherited problems with collagen and elastin metabolism that cause weakening of these arterial wall components. Under the forces of blood pressure, the weakened artery dilates over time. Up to 5% of the male population has aneurysms and the overall incidence is increasing. Aneurysms are associated with other medical conditions such as hypertension, peripheral vascular and carotid artery disease, heart attack, COPD, and a family history of aneurysms.
|Thoracic Aortic Aneurysm
|Thoracic Aortic Aneurysm
treated with stent graft
Most aneurysms are silent and without symptoms. They are found by feeling a wide abdominal aortic pulse or on an imaging study for an unrelated condition. In 15-20% of patients, the first indication of an aneurysm is its actual rupture. Elective aneurysm repair is associated with only 2-5% mortality rate while only 10% of those with ruptured aneurysms survive to reach medical care. Emergency operations have only a 40-50% chance of survival. Early detection and timely repair is critically important.
Once an aneurysm is detected, blood pressure should be controlled to reduce the forces on the arterial wall, and ultrasound examinations performed every 6 months until the aneurysm produces symptoms, demonstrates rapid expansion, or reaches the appropriate size for repair. Patients with non-symptomatic aneurysms are offered surgical repair when the risk of rupture (or other complications) outweighs the risk of repair: which translates to an aneurysm size of 5.5 cm diameter for the thoracic aorta, 5cm for the abdominal aorta, 3cm for the iliac arteries, 2cm for the femoral arteries, and 1.2cm for the popliteal arteries.
The goal of repair is to prevent rupture or other complications by replacing the worn out portion of the artery. Currently, there are two treatment alternatives: open repair or an endovascular stent graft. Open repairs have been the mainstay of treatment since the 1950’s. The damaged section of artery is effectively “cut out”, and a graft (arterial replacement) spliced in. It is an excellent, durable repair but associated with several days of day hospital stay and a 4-6 week total recovery period.
With endovascular repair, a stent graft is inserted into the bloodstream through small groin incisions and the device anchored to normal portions of the artery above and below the aneurysm either by friction, hooks, or both depending upon the type of device used. This technique equals open repair in preventing death from rupture, but requires only a 24-36 hour hospital stay and 2-4 weeks for recovery. Stent grafts are currently available in a limited range of sizes, so not every aneurysm can be treated with this technology
Outcomes are best when these procedures are done by fellowship trained vascular surgeons who have the complete range of skills to perform either type of repair and handle any associated challenges or complications. At EvergreenHealth Heart & Vascular Care, we are nationally recognized leaders in the use of stent graft technology and help educate other physicians in the use of these devices.