Visceral artery aneurysms
A visceral artery aneurysm is a ballooning of a portion of the splenic, renal, hepatic or mesenteric arteries. These arteries supply blood to the spleen, kidney, liver and intestines, respectively.
Aneurysms are the result of weakening and thinning of the artery wall. When a portion of the arterial wall stretches and swells to more than 50 percent of the original diameter, this is called an aneurysm. Aneurysms in the abdominal portion of the aorta — below the diaphragm — are the most common (see abdominal aortic aneurysms.)
The biggest threat posed by an aneurysm is rupture. A ruptured aneurysm, which requires emergency treatment, can lead to severe pain, internal bleeding, a sudden drop in blood pressure and, if not treated quickly, death.
Aneurysms that have been discovered prior to rupture need to be measured, closely monitored and evaluated for treatment. Small visceral artery aneurysms, those less than two centimeters in diameter, can often be left untreated, yet observed periodically to check for growth.
The symptoms associated with a visceral artery aneurysm are variable and depend on which artery is affected. Aneurysms associated with the renal artery, for example, may disrupt kidney function, leading to high blood pressure (see renovascular hypertension.) Some aneurysms are only discovered upon rupture. Prior to rupture, aneurysms may be found during diagnostic tests, like ultrasound, X-rays or MRIs, which have been ordered to evaluate some other health problem.
The exact causes of visceral artery aneurysms are unknown.
Most visceral artery aneurysms are diagnosed with an ultrasound scan or with a CT scan. The scans are simple, non-invasive exams conducted on an outpatient basis. These exams measure the diameter of the aneurysm — a key element in determining the best treatment. Many times, aneurysms are discovered during imaging tests, such as X-rays or MRIs, that are being performed for other reasons.
The risk of rupture is greatest if a visceral artery aneurysm is greater than two centimeters or if the aneurysm is rapidly increasing in size. Small aneurysms should be monitored. Medication to control blood pressure may help to slow the rate of enlargement of an intact aneurysm. Elective surgical repair of the artery is the only definitive cure. However, risk of rupture must be weighed against the risks associated with surgery and the patient’s pre-existing conditions.
Open surgical repair
During a traditional surgical repair, the surgeon makes an incision in the abdominal wall, removes the distended portion of the artery and replaces it with a segment of a vein from the patient or a synthetic tube called a graft. A hospital stay of between five and 10 days is usually required. Recovery and return to a normal routine takes one to two months.
Endovascular repair (EVAR)
Some visceral artery aneurysms can be embolized, or filled with particulate material that causes the diseased segment of the artery to fill with clot (thrombus). Other visceral artery aneurysms can be treated with a stent graft. This is a metallic mesh tube with a fabric covering; the dilated segment of the artery is lined with the stent graft, effectively fixing the artery from the inside. Both of these procedures are performed via catheters inserted, under local anesthesia, through small punctures into the artery in the groin. The catheter is then advanced, under X-ray guidance, into the diseased visceral artery.
The hospital stay is usually one to two days and most patients return to their normal activities within about a week. However, endovascular repair is not an option for all aneurysms of the visceral arteries. Patients must have arterial anatomy that is compatible with the endovascular therapy. The Vascular Center’s surgeons and imaging experts have experience with endovascular treatment of visceral artery aneurysms, receiving referrals from area physicians faced with the most challenging cases.