What is Aortoiliac Occlusive Disease?

Aortoiliac occlusive disease (AIOD) is a type of peripheral artery disease that impacts the area of the aorta beneath the kidneys and the iliac arteries. Like other artery diseases, AIOD blocks blood flow to organs further down the body through narrowed passages or by the movement of plaque. AIOD can result in anything from no symptoms at all to severe conditions threatening a limb.

It’s common to find obstructions in the section of the aorta beneath the kidneys, the main iliac artery, internal iliac artery (near your tummy), external iliac artery, or any combination of these blood vessels. There are numerous risk factors for AIOD, and acknowledging these allows healthcare professionals to offer treatments to alleviate symptoms and potentially extend life. Since the introduction of artificial graft materials for replacing parts of the aorta in the 1960s, surgical treatment for AIOD has become accessible for patients.

What Causes Aortoiliac Occlusive Disease?

Aortoiliac occlusive disease (AIOD) is a type of peripheral artery disease that specifically affects the lower part of the aorta, the main vessel that supplies blood to the body. Much like other forms of peripheral artery disease, AIOD is usually caused by atherosclerosis, which is the buildup of fatty deposits on artery walls.

Several factors can lead to atherosclerosis and AIOD, including diabetes, high homocysteine levels (a type of amino acid in your blood), high blood pressure, high levels of fats in the blood, and tobacco use. Risk factors also include age, family history, race, and sex.

There’s also a rare but important cause of AIOD known as large vessel vasculitis, specifically a form called Takayasu arteritis. This is when the large arteries in your body, such as the aorta, become inflamed.

Risk Factors and Frequency for Aortoiliac Occlusive Disease

Determining the exact rate of people afflicted with aortoiliac occlusive disease (AIOD) and other forms of peripheral artery disease can be tricky, this is because many patients do not show any symptoms. However, research estimates suggest this disease impacts anywhere from 3.56% to over 14% of the general population. The condition tends to be more common in older age groups, with about 14% to 20% of people over 70 and 23% of those over 80 being affected. The disease is also found more often in men, non-Hispanic black populations, and those with certain risk factors.

The exact rate of aortoiliac occlusive disease is hard to calculate as many patients show no symptoms.
The disease is estimated to affect 3.56% to over 14% of the general population.
Older individuals are more susceptible, with 14%-20% of those over 70 and 23% over 80 estimated to be affected.
The condition is more common in men, non-Hispanic black populations, and those with specific risk factors.

Signs and Symptoms of Aortoiliac Occlusive Disease

People regularly experience a type of cramping pain that comes during and after exercise and is relieved by resting. This condition is called claudication. Physicians need to take a thorough history and conduct a complete physical exam to measure the severity of the condition and differentiate it from other potential diagnoses. The cramping often affects the muscles closer to the body’s center which might signal a higher degree of stenosis or narrowing of the arteries.

There’s also a specific group of symptoms that, when combined, is known as Leriche syndrome. These symptoms are buttock claudication, erectile dysfunction, and no detectable pulses in the femoral artery which is in the groin area. This syndrome was named after its discoverer, a famous French surgeon named Dr. René Leriche.

In some instances, patients may require emergency care because of severe stenosis or a sudden blockage of an artery by a blood clot, resulting in what’s known as chronic limb-threatening ischemia. Indicators of chronic limb-threatening ischemia include pain at rest, gangrene or tissue death from lack of blood flow, or an ulcer on the lower limb that has persisted for more than two weeks, all happening in the context of peripheral artery disease, a condition where the arteries serving the limbs are narrowed or blocked.

Testing for Aortoiliac Occlusive Disease

The Ankle-Brachial Index (ABI) is often the first test carried out when checking for arterial diseases because it is affordable, reliable, and non-invasive. This exam, together with pulse volume recordings, is recommended by key health organizations like the American Heart Association (AHA) and the US preventive services task force. A result less than 0.9 on this index could mean a person has arterial disease.

Other types of examinations like Duplex ultrasonography and CT angiograms offer more detailed information, such as the precise location and extent of any narrowing of the arteries. However, Magnetic resonance arteriography, while useful, can sometimes overestimate how narrow the arteries have become and can unnecessarily expose the patient to contrast agents.

Blood tests are also important for identifying potential risk factors. Testing for things like blood lipids, long-term blood sugar levels (hemoglobin A1c), lipoprotein A, and serum homocysteine levels can help pinpoint the cause. If there’s a history of blood clotting, additional tests for clotting time (PT, aPTT) and platelet count might be called for. If these regular tests do not provide clear clues, further testing for certain antibodies and proteins might be helpful. An electrocardiogram is also typically performed due to the connection between arterial disease and heart disease.

Treatment Options for Aortoiliac Occlusive Disease

The treatment for aortoiliac occlusive disease (AIOD) depends on when it’s diagnosed and how severe it is. If it’s found to cause chronic limb-threatening ischemia (CLTI), where blood flow to the limbs is severely limited, urgent medical care is needed to prevent tissue death or gangrene. The health of the patient, the condition of the limb, and the particular features of the disease help to determine how serious it is.

For less severe cases, particularly in patients who may not be well enough for surgery, treatment can often be managed with medical care. This often involves managing health conditions that might worsen AIOD, such as diabetes, high cholesterol, high blood pressure, conditions that make blood more likely to clot, and tobacco use, as an outpatient. Following a healthy diet and getting regular exercise are also beneficial, with supervised exercise programs being especially helpful, potentially increasing the distance a patient can walk by up to 340%.

Medication can also help with symptoms like claudication – pain in the legs or arms when exercising – with drugs like cilostazol and pentoxifylline often being effective. Cilostazol can also help to keep any grafts from surgeries open and prevent them from becoming too narrow, while pentoxifylline provides relief but is less effective.

During the CAPRIE trial, it was found that clopidogrel was better than aspirin at preventing death from stroke, heart attacks, or other issues caused by blocked blood flow. Although other similar drugs haven’t been studied in the same way, it’s usually not recommended to use two in combination for initial treatment. The exception to this is vorapaxar, which has been shown to improve conditions that cause severe lack of blood flow in the limbs, particularly when used with other drugs like clopidogrel. Similar improvements haven’t been seen from using Vitamin K blockers alone or alongside aspirin, but one study found that a combination of rivaroxaban and aspirin did reduce serious issues caused by disease in the arteries supplying the limbs.

In terms of surgical treatment, there are a few different options. An aortoiliac bypass, where a graft is used to reroute blood around the clogged area in the major arteries that supply the lower body and legs, is effective, with over 90% still working well after 5 years. However, it’s a major surgery requiring the aorta (the main artery in the body) to be clamped, which isn’t always suitable. The alternative is an axillary-bifemoral bypass. It’s less invasive, as the graft is tunneled under the skin from an artery in the chest to those in the thighs. It’s a common choice for surgical treatment and has good longevity, with most still working well after 5 and 10 years.

Finally, there’s percutaneous transluminal angioplasty (PTA), which can be used instead of more invasive surgery. An inflatable balloon is guided through the artery to the blockage, where it’s expanded to squash the plaque against the artery wall, allowing better blood flow. This has a similar success rate to the surgical options, with most still working well after a year, and studies show even better results when a stent is placed to keep the artery open. These treatments have also been beneficial for complex, calcified blockages.

When someone has symptoms that seem like aortoiliac occlusive disease (AIOD) – a condition where the main artery that supplies blood to the lower body is blocked – there are other potential causes that physicians should consider. These other possibilities fall into two categories: vascular and non-vascular.

For vascular possibilities, these might include:

Arterial aneurysm: a bulging, weak area in an artery wall
Arterial dissection: a tear in the artery wall
Embolism: a blocked artery caused by a blood clot or other substance
Giant cell arteritis (GCA) and Takayasu arteritis: inflammation of the arteries
Venous claudication: pain in leg muscles due to insufficient blood flow

Non-vascular causes to consider could be:

Musculoskeletal pain: pain coming from your muscles or skeleton
Neurogenic claudication: nerve damage causing discomfort or pain in your lower body

It’s necessary for doctors to consider all these possibilities to ensure the correct diagnosis and treatment.

What to expect with Aortoiliac Occlusive Disease

Without any medical intervention, the outlook for a condition is generally poor. However, if the body develops alternative blood flow pathways on its own (self-compensating collateral circulation), the overall clinical outcomes could get better. In addition, patients with more distal (far from the center of the body) conditions typically experience worse outcomes. Medication can be beneficial, potentially delaying or even eliminating the need for surgery.

The outlook after surgery is generally positive. The mortality rate within 30 days of the procedure is around 2-3%. Two significant success rates are observed 5 and 10 years after the AFB surgery, being 86.2% and 77.6% respectively. Furthermore, the 10-year rates reveal a 97.7% survival rate for limbs affected and an overall survival rate of 91.7%.

Endovascular intervention, a special nonsurgical treatment, demonstrates even better results with a lower mortality rate of 0.6% during hospital stays. The success rate remains high at 96% and 94% during the first and second year, respectively. A comparative analysis between open bypass surgery and endovascular intervention has been presented in Table 1.

Possible Complications When Diagnosed with Aortoiliac Occlusive Disease

If aortoiliac occlusive disease (AOID) is left untreated, it can lead to several complications. These include fatigue, weakness, impotence, and sexual dysfunction due to reduced blood flow. Other problems can occur too. Heart failure, heart attack, gangrene, and the need for amputation are more likely in people with untreated AOID. Surgical and endovascular treatments for AOID also carry their own risks.

Fatigue
Weakness
Impotence
Sexual dysfunction
Heart failure
Heart attack
Gangrene
Requirement for amputation
Risks of surgical/endovascular treatment:
- Clotting in the graft
- Wound infection
- Bleeding
- Complications from anesthesia

Preventing Aortoiliac Occlusive Disease

Patients are taught how to change their lifestyle and habits to help stop their disease from getting worse. This often involves stopping smoking, doing more physical exercise, and changing what they eat. Regular check-ups every 3-6 months are also recommended. If a man-made graft is used in a procedure, it’s important the patient knows there’s a lifelong risk of it getting infected. As a result, they’ll need to take antibiotics as a precaution before going through any dental, stomach, or urinary procedures.