Aortoiliac atherosclerosis is the buildup of fatty plaque in the two major blood vessels that supply your lower body: the lower portion of your aorta (the body’s largest artery) and the iliac arteries that branch off it into each leg. As plaque accumulates and hardens in these vessels, blood flow to your legs, pelvis, and abdominal organs gradually decreases. When the narrowing becomes severe enough to cause symptoms or restrict circulation, it’s often called aortoiliac occlusive disease.
Where It Happens in the Body
Your aorta runs from your heart down through your chest and abdomen. Just below the kidneys, it’s called the infrarenal aorta, and this is where aortoiliac atherosclerosis typically begins. A few inches lower, the aorta splits into two iliac arteries, one feeding each leg. The disease can affect the infrarenal aorta, the common iliac arteries, the internal iliac arteries (which supply the pelvis and reproductive organs), and the external iliac arteries (which continue into the legs).
What makes this location particularly consequential is that these are high-traffic vessels. They carry nearly all the blood destined for your lower half. Narrowing here creates a bottleneck that affects everything downstream, from your buttocks and hips to your feet.
How Plaque Builds Up
The process starts with damage to the inner lining of the artery wall. Once that lining is compromised, cholesterol-carrying particles (LDL, or “bad” cholesterol) slip beneath it and become trapped. Without the protective antioxidants found in the bloodstream, these particles oxidize and trigger an immune response.
White blood cells rush in and try to absorb the oxidized cholesterol, but they become overloaded and transform into “foam cells,” bloated with fat. Muscle cells from deeper layers of the artery wall also migrate inward and absorb cholesterol, adding to the growing mass. This creates a fatty streak, the earliest visible sign of atherosclerosis.
Over time, foam cells die and release their contents, forming a soft, lipid-rich core inside the artery wall called a necrotic core. To contain this unstable material, the muscle cells produce a layer of collagen and other structural fibers, creating a fibrous cap over the plaque. This cap is what separates the plaque’s toxic interior from flowing blood. If the cap stays thick and intact, the plaque remains stable. If it thins or ruptures, pieces can break off and travel downstream, blocking smaller arteries in the legs or feet.
As plaque matures, calcium deposits accumulate within it, making the artery stiff and further narrowing the channel available for blood flow.
What It Feels Like
In the early stages, you may feel nothing at all. Your body compensates by rerouting blood through smaller collateral vessels. This workaround can keep you symptom-free for years. But as the narrowing worsens and collateral routes can’t keep up, symptoms emerge.
The hallmark symptom is intermittent claudication: cramping, aching, or fatigue in your buttocks, hips, or thighs that starts when you walk and stops when you rest. Because the blockage sits high up in the arterial tree, the pain tends to hit in the buttocks and hips rather than the calves (which is more common with blockages further down the leg). Doctors categorize severity by how far you can walk before pain forces you to stop. Mild claudication means you can walk more than about 200 meters (roughly two city blocks) before symptoms appear; moderate means less than 200 meters.
When blockage becomes severe, pain can occur even at rest, particularly in the feet or toes while lying down. This represents a dangerous stage called critical limb ischemia, where tissues aren’t getting enough blood to survive without intervention.
Leriche Syndrome
A specific pattern called Leriche syndrome occurs when the aorta is completely or nearly completely blocked at its branching point. It produces a classic triad: claudication in both legs, erectile dysfunction (because the internal iliac arteries feeding the pelvis are starved of blood), and weak or absent pulses in the groin. This combination is a strong clinical signal pointing directly to aortoiliac disease.
Risk Factors
The same factors that drive atherosclerosis elsewhere in the body are responsible here. Smoking is the single strongest risk factor for peripheral artery disease and accelerates plaque growth in the aortoiliac segment. High blood pressure damages artery linings, giving cholesterol an entry point. Diabetes promotes inflammation and makes arteries more susceptible to plaque formation. High LDL cholesterol provides the raw material for plaque, and a sedentary lifestyle allows all of these factors to compound.
Age plays a role too. Aortoiliac disease becomes increasingly common after age 50, and men are affected more often than women in earlier decades, though the gap narrows after menopause.
How It’s Diagnosed
The first test is usually the ankle-brachial index, or ABI. It compares blood pressure at your ankle with blood pressure in your arm. A healthy ratio is 1.0 to 1.4. An ABI between 0.7 and 0.9 suggests mild disease. A reading of 0.41 to 0.69 indicates moderate blockage. Anything at or below 0.4 signals severe disease with critical ischemia.
When the ABI confirms a problem, imaging pinpoints the exact location and extent of the blockage. CT angiography and contrast-enhanced MR angiography are both highly accurate, with sensitivity and specificity rates around 96% to 98% for detecting significant narrowing. CT angiography uses X-rays and contrast dye to produce detailed 3D images of the arteries. MR angiography uses magnetic fields and a gadolinium-based contrast agent. Duplex ultrasound is another option, though it’s somewhat less precise for the aortoiliac segment compared to CT or MR imaging.
Treatment Without Surgery
Medical management focuses on slowing or stopping plaque progression, reducing the risk of heart attack and stroke (which share the same underlying disease process), and improving walking ability. The 2024 guidelines from the American College of Cardiology recommend high-intensity statin therapy with the goal of cutting LDL cholesterol by at least 50%. For patients already on the maximum tolerated statin dose whose LDL remains at 70 mg/dL or above, adding a second cholesterol-lowering medication is a reasonable next step.
Antiplatelet therapy helps prevent blood clots from forming on plaque surfaces. Blood pressure control and blood sugar management (for those with diabetes) are equally important. Smoking cessation is non-negotiable; continued smoking dramatically accelerates disease progression and worsens outcomes from any procedure.
Supervised exercise programs are one of the most effective nonsurgical treatments for claudication. Structured walking programs, typically three sessions per week for three months, gradually extend the distance you can walk before pain sets in.
Procedures and Surgery
When medical management and exercise aren’t enough, two main approaches can restore blood flow. The choice depends on the location, length, and severity of the blockage.
For shorter, less complex blockages (classified as type A or B lesions under an international grading system), endovascular treatment is preferred. This involves threading a catheter through a blood vessel, inflating a small balloon to widen the narrowed area, and often placing a stent to keep it open. Recovery is faster than open surgery, and most people go home within a day or two. Five-year patency rates (the percentage of treated arteries that remain open) are around 70%.
For longer or more complex blockages (type C or D lesions), open surgery is generally recommended. The most common procedure is aortobifemoral bypass, where a synthetic graft is sewn from the aorta to both femoral arteries in the groin, creating a new pathway that bypasses the blocked segment entirely. This is a major operation requiring general anesthesia and a hospital stay of several days to a week. Recovery takes weeks to months. However, long-term results are superior: five-year patency rates range from 85% to 94%, and even at ten years, about 82% of grafts remain open.
The trend in recent years has been toward using endovascular techniques for increasingly complex blockages, especially in patients who are poor candidates for open surgery due to age or other health conditions. Results in these more challenging cases are improving but still don’t match the durability of surgical bypass for the most severe disease.
What Happens Without Treatment
Untreated aortoiliac atherosclerosis doesn’t just limit your walking. As disease progresses, rest pain develops, wounds on the feet stop healing, and tissue death (gangrene) can occur, potentially requiring amputation. Plaque fragments can also break loose and travel to smaller arteries in the legs and feet, causing sudden pain, blue or purple discoloration of the toes, and acute limb-threatening ischemia.
Because atherosclerosis is a systemic disease, blockages in the aortoiliac segment strongly predict the presence of plaque in the coronary arteries and the arteries supplying the brain. People with peripheral artery disease have a significantly elevated risk of heart attack and stroke, which is why aggressive cholesterol and blood pressure management matters even when leg symptoms seem mild.