Renal artery revascularization procedures could damage kidneys

Wake Forest University researchers have confirmed that fragments of atherosclerotic plaque released during angioplasty and stenting of renal arteries could impair kidney function. Findings suggest physicians might need to rethink how to perform these procedures safely.

More than three million people aged 65 or older suffer from renal artery stenosis in the U.S. Tens of thousands undergo percutaneous catheter angioplasty and stenting every year. Researchers have long suspected the procedure releases tiny particles of plaque into the bloodstream. An investigative group led by Dr. Matthew Edwards, an assistant professor of surgery at Wake's Baptist Medical Center, set out to measure these particles and establish their association with impaired kidney function.

Edwards and colleagues assessed 28 patients who underwent renal artery angioplasty and stenting between July 2005 and December 2006. The investigators used a balloon-based occlusive system as a protective device to keep plaque fragments from passing through the vessel. They took blood samples trapped by this device before aspirating the artery at the end of the intervention. Lab results revealed an average of more than 2000 embolic particles per procedure, some of them large enough to disrupt renal blood supply (J Vasc Surg 2007;46[1]:55-61).

Researchers found a statistically significant association between stent size and the release of particles larger than 60 micrometers (p = 0.009). Preoperative aspirin use appears to have helped reduce debris counts, suggesting that patients should not stop taking aspirin before the procedure. African Americans had the highest rate of potentially dangerous particles per sample compared to other ethnic groups (p = 0.002).

"These are the first data in humans to show that debris released during angioplasty and stenting of the kidney arteries can be harmful to kidney function," Edwards said.

In previous studies, Edward's group established the link between poor kidney function after renal artery stenting and a higher risk of heart attack, stroke, or death. The new findings could have several implications. A better understanding of endovascular therapy's potential complications, for instance, can lead to improved management of these patients. The use of protective devices to block or filter out emboli may also bolster results, Edwards said.

Some questions remain regarding such devices. Researchers observed that patients with high particle counts also had poorer postprocedural kidney function. They theorize that some protective devices are more effective than others or perhaps plaque breaks off just by putting the device in place. They are also weighing the possibility of predicting which plaques are more prone to release debris.

"We are currently conducting a clinical trial to try and answer these questions," Edwards said.

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