Aortic aneurysms strike an estimated 1.5 to 2 million Americans and cause 15,000 deaths each year. They occur when a localized portion of the aorta becomes dilated, with all layers of the aortic wall involved. The aneurysm tends to expand, growing at least 50% larger in diameter, until eventually rupturing—all too often causing death.
The larger the aneurysm, the more likely it is to rupture. Rupture severely compromises blood flow to internal organs, causing a cascade of ominous complications. The most common aneurysm site is the abdominal aorta between the renal and the inferior mesenteric arteries.
Causes and risk factors
Atherosclerosis may lead to an aneurysm by damaging the lining of the aorta. In many cases, though, the underlying cause of an aneurysm is unknown.
Aortic aneurysms are five times more common in men than women. Smoking and hypertension are major risk factors; they both damage the endothelial lining of the aorta and other arteries. Smoking also promotes aneurysm growth.
An aortic aneurysm may cause no symptoms or only vague ones, such as chest, abdominal, or back pain. As it enlarges and presses on nearby organs or tissues, pain or discomfort may worsen. In about 75% of cases, an aortic aneurysm is detected incidentally during a routine medical examination or from a chest X-ray or an imaging scan done for another reason.
Signs and symptoms may vary with aneurysm location.
- An abdominal aortic aneurysm is the most likely type to be asymptomatic. However, it may cause indigestion, nausea, vomiting, and back or flank pain.
- An aneurysm in the ascending aorta typically causes chest, neck, or back pain and may lead to an aortic valve murmur. If not detected promptly, it may cause aortic regurgitation and possibly heart failure.
- An aneurysm in the aortic arch may decrease blood flow to the carotid arteries and cause strokelike neurologic symptoms.
- A thoracic aortic aneurysm may lead to respiratory symptoms, such as coughing or wheezing, along with numbness in the extremities, which might signal decreased circulation to the spinal cord.
Treatment options for an aortic aneurysm depend on the diameter of the aneurysm. They may include continued observation, pharmacologic therapy, risk-factor reduction (including smoking cessation and control of hypertension and hypercholesterolemia), and surgical repair. If the aneurysm is at relatively low risk for rupture (indicated by a diameter less than 4 cm) and doesn’t require urgent surgical or endovascular intervention, continued observation may be adequate to detect aneurysm enlargement. (See Aneurysm sites and rupture risks.) Typically, ultrasound and computed tomography (CT) scans are done at least annually to track aneurysm growth. Aneurysms with diameters less than 4 cm warrant annual ultrasound and CT scans; those with diameters of 4.5 to 5 cm warrant semiannual ultrasound and CT scans.
Pharmacologic therapy should be optimized for all patients, even those who will undergo surgical repair. Typically, patients receive medications similar to those prescribed for treating coronary artery disease. Antiplatelet drugs, statins, and beta blockers may be prescribed to prevent complications.
Open surgical repair
If a relatively small aneurysm grows larger or symptoms develop, aneurysm repair must be considered. When aneurysm diameter exceeds 5 cm, the risk of rupture exceeds the risk of surgery, necessitating surgical intervention.
Conventional open surgical repair is the most common procedure. The surgeon makes an incision, crossclamps and opens the aorta, and sews a graft into place. This allows blood to flow through the newly placed graft rather than through the diseased aortic portion.
However, open repair is a major abdominal or thoracic surgical procedure and may require a long, difficult recovery. Recovery varies with repair location and the patient’s age and general health. The surgery typically is recommended for younger and relatively healthy patients because of good long-term outcomes; grafts may last for 20 to 30 years. However, the surgery has a 30-day mortality of 4% to 12%. Associated complications include wound infection, perioperative bleeding, colonic ischemia, myocardial infarction, pneumonia, renal failure, and paraplegia.
For more fragile or elderly patients who aren’t candidates for open repair, endovascular aneurysm repair (EVAR) may be a better option as it’s less invasive and reduces recovery time. Since it was first successfully performed in 1991, many hospitals around the world have offered this procedure. Less invasive than open repair, it causes fewer complications (including less blood loss) and reduces hospital days.
EVAR has a better 30-day mortality rate (1.6% to 2%) than conventional surgery (4% to 12%), but requires extended follow-up research on its long-term success; data currently are being collected to determine whether it’s a reasonable long-term option. More research also is needed to further understand medical management of patients after EVAR. Yet even if EVAR doesn’t replace conventional open surgical repair, it may serve as a complementary treatment option. (See Inside an EVAR procedure.)
With EVAR, endograft durability is uncertain. Also, the endograft may move inside the aorta because graft placement is less secure than with open surgery. In addition, surrounding blood vessels or organs may be damaged during the procedure.
Another potential complication is an endoleak—persistent flow of blood outside the graft lumen. Endoleaks occur in four types:
- Type I: blood flow occurs between the stent graft and aneurysm wall due to an ineffective or incomplete seal at the end of the graft
- Type II: retrograde blood flows from collateral branches
- Type III: blood flows into the aneurysm sac because of tears in the graft fabric or graft disconnection
- Type IV: blood flows through the graft due to permeability of the graft fabric.
EVAR can cause some of the same postoperative complications as open repair, such as those associated with decreased circulation from the aorta. Renal complications, limb ischemia, and groin hematoma or infection may arise.
Postoperatively, blood pressure control is crucial. Blood pressure must remain within a certain range—not too high or too low. Hypertension may damage the area of repair, whereas hypotension may cause decreased spinal perfusion, possibly leading to paraplegia.
When caring for a patient recovering from EVAR, stay alert for arrhythmias. Closely monitor the circulation, temperature, and color of extremities and watch for edema. Document the patient’s vital signs, respiratory status, and fluid balance regularly. Note complaints of fatigue or acute pain of abrupt onset.
Assess the patient’s and family’s emotional status. Discovery of an aneurysm and the stress of choosing a treatment plan can be overwhelming. Listen closely and watch for nonverbal signs of anxiety, such as nervousness, agitation, irritability, and restlessness.
Be aware that patients may be concerned about loss of control. They may be used to managing their home and professional lives; to suddenly find out they have a serious condition may be devastating. Also, they may sense something bad is going to happen. Stay alert for trembling and shaking—or, conversely, denial of obvious tension or anxiety. When you combine your nursing knowledge and skills with compassion, you can help ensure optimal recovery for patients who have had aortic aneurysms.
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Marian Soat is a clinical nurse specialist in the cardiovascular and vascular surgical intensive care units at the Cleveland Clinic in Cleveland, Ohio.