Descending Aneurysm/Dissection

Most aneurysms of the aorta involve the abdominal aorta and usually begin at or below the level of the renal arteries.  A sack-like bulge forms in the weakened area.  When blood leaks through the weakened wall a rupture has occurred.  It is important to repair aneurysms before they rupture.  Survival is more than four times more likely when an aneurysm is repaired prior to rupture of the aneurysm.  Aneurysms less than five centimeters in diameter rarely rupture.

Aneurysms of the descending thoracic aorta are less common than abdominal aortic aneurysms but are equally dangerous.  Some descending thoracic aortic aneurysms are due to a weakened aortic wall like the abdominal aortic aneurysm.  Others are caused by a tear in the inner layer of the aorta allowing blood to burrow up and down the aortic wall weakening the wall of the aorta.  This is called an aortic dissection.  If blood leaks through the entire aortic wall into surrounding tissues a rupture has occurred.

Most aneurysms are not symptomatic.  Most are discovered incidentally on a physician’s examination or an ultrasound or CT scan ordered for other reasons.  Medicare now will pay for a one time screening ultrasound of the abdominal aorta in men 65 and older.  Non-ruptured aneurysms may cause back or abdominal pain.  A dissecting descending thoracic aneurysm classically causes severe tearing pain between the shoulder blades and back pain.

Surgery

Most abdominal aortic aneurysms are now treated using the Endovascular Abdominal Aortic Aneurysm Reconstruction technique or EVAR.  This involves threading a large stent covered with a cloth like material through the arteries in the groin.  The stent graft is opened on the inside of the aneurysm relining the aorta and relieving the pressure on the weakened and bulging aortic wall.  Most patients who undergo EVAR are ready for discharge from the hospital in one to two days.  Some aneurysms cannot be safely repaired using this technique and will require a conventional repair through an incision on the abdominal wall.

Many descending thoracic aortic aneurysms are now reconstructed using these same stent graft techniques.  Others require incisions through the chest and abdominal cavities.

Medical Management

Abdominal aortic aneurysms are usually managed medically when they are less than five centimeters in diameter.  Their diameter is checked every six to twelve months with ultrasound or CT scan.  Surgical repair of aneurysms in most patients is recommended when they are five centimeters or larger.  Cessation of smoking and good control of blood pressure may decrease the rate of growth of the aneurysm.  People with aneurysm disease also have increased risk of having undetected coronary artery disease and may benefit from cardiology evaluation.

For most descending thoracic aortic dissections medical management is preferred.  Surgical therapy is reserved for continued growth of the aneurysm or obstruction of blood flow to the legs or vital organs such as the kidneys or intestines.