Peripheral Artery Restenosis

Peripheral artery restenosis is a complication that occurs when arteries that were previously treated with procedures like angioplasty or stenting become narrowed again, limiting blood flow to the legs or other parts of the body.

Table of contents

• What Is Peripheral Artery Restenosis
• How Restenosis Develops
• Risk Factors for Restenosis
• Restenosis Rates in Different Arteries
• Treatment Options
• Impact on Patient Care

What Is Peripheral Artery Restenosis

Peripheral artery restenosis happens when an artery that was opened up with treatment becomes narrow again^[1]. This is a common problem that can occur after doctors perform procedures to improve blood flow in arteries affected by peripheral artery disease (a condition where arteries become narrowed, usually due to buildup of fatty deposits called plaque).

When doctors treat blocked arteries, they typically use procedures called angioplasty (using a balloon to widen the artery) or place a stent (a small mesh tube that helps keep the artery open). These treatments work by creating small tears in the artery wall and compressing the plaque to make more room for blood to flow. Unfortunately, these same changes can trigger the body’s healing response, which sometimes leads to the artery becoming narrow again over time^[1].

How Restenosis Develops

Restenosis develops through three distinct phases. The first phase happens immediately after the procedure, when the artery may spring back to a narrower size. Stents are particularly effective at preventing this early narrowing^[1].

The second phase involves changes to the artery wall itself. After the procedure causes injury to the artery, special cells in the outer layer of the artery wall are activated. These cells produce a substance rich in collagen, which is a protein that provides structure to tissues. At the same time, the injury exposes materials inside the artery wall that cause blood cells called platelets (tiny disc-shaped cells that help blood clot) to become activated. These platelets release chemicals that promote inflammation^[1].

The third phase involves the movement and growth of smooth muscle cells and other cells into the injured area. Over time, the area that becomes narrowed again contains mainly smooth muscle cells, proteins, collagen, and other structural materials. Unlike the original blockage, which was caused by fatty plaque buildup, restenotic tissue has relatively few cells and is composed primarily of these structural materials^[1].

Risk Factors for Restenosis

Several factors can increase the likelihood that restenosis will occur. These can be grouped into factors related to the patient and factors related to the specific artery and blockage being treated^[1].

Patient-Specific Factors

People with diabetes (a condition where blood sugar levels are too high) face particularly high risk for restenosis. Diabetes causes increased dysfunction of the cells lining the arteries, more active platelets, and a more aggressive response to injury. Most research has also found that women are more likely to develop restenosis than men^[1].

Markers of inflammation in the body also correlate with worse outcomes. Tests that measure substances like C-reactive protein (a protein that indicates inflammation in the body), certain cholesterol particles, and blood clotting factors can help predict who might be at higher risk^[1].

Factors Related to the Artery

The type of artery matters significantly. Muscular arteries, which distribute blood to different parts of the body and have more smooth muscle cells in their walls, generally have higher restenosis rates than elastic arteries, which are larger vessels that conduct blood away from the heart^[1].

One of the strongest predictors of restenosis is the size of the artery. Smaller blood vessels and those that remain narrow even after treatment are at much greater risk of becoming blocked again. Other important factors include how long the blockage is, how much plaque is present, and the condition of the smaller blood vessels beyond the treated area. Blockages with more plaque and those in arteries that feed areas with poor blood vessel networks are more likely to develop significant restenosis^[1].

Restenosis Rates in Different Arteries

The rate at which restenosis occurs varies depending on which artery is treated. Carotid arteries in the neck, which are elastic arteries, have relatively low restenosis rates ranging from 5% to 8% after treatment with angioplasty and stenting^[1].

In the legs, restenosis is more common. For arteries in the thigh and knee area, studies have shown that 40% to 60% of patients develop restenosis within 12 months after balloon angioplasty alone. Even with the use of special metal stents called nitinol stents, which have better durability than balloon angioplasty alone, there remains a 20% to 50% chance of restenosis at one year^[12].

Treatment Options

When restenosis occurs, several treatment approaches may be considered. Doctors may perform another angioplasty procedure, place additional stents, or in some cases recommend surgery to bypass the narrowed area^[8].

Some medications may help reduce the risk of restenosis. Cilostazol is a medication that has several effects that may be beneficial. It helps prevent platelets from clumping together, relaxes blood vessels, reduces the growth of smooth muscle cells in artery walls, and improves the function of cells lining the arteries. Research suggests that taking cilostazol may reduce the need for additional procedures after treatment of arteries in the thigh and knee area^[12].

However, cilostazol can cause side effects including headache, diarrhea, and palpitations. More importantly, because it belongs to a class of drugs called phosphodiesterase 3 inhibitors, it should not be given to patients with any signs of congestive heart failure (a condition where the heart cannot pump blood effectively) due to concerns about increased mortality risk^[12].

Impact on Patient Care

Restenosis has a growing impact on how peripheral artery disease is treated. One study found that the proportion of leg bypass surgeries performed after a previous procedure in the same leg increased by 72% over an eight-year period, rising from 22% of all leg bypass surgeries in 2003 to 38% in 2011^[6].

While patients undergoing a second bypass surgery had similar rates of immediate complications like heart attack, death, and amputation compared to those having their first bypass, they faced different long-term challenges. Patients with a history of restenosis requiring repeat surgery had higher rates of later procedures and lower survival rates of the bypass itself^[6].

This growing need for repeat procedures highlights the importance of understanding and preventing restenosis. It also emphasizes the need for ongoing monitoring and care after any procedure to treat peripheral artery disease.