At its worst, it can cause dangerous complications -- severe pain, gangrene, even loss of limbs.
Treatment options range from lifestyle changes, exercise and medications to angioplasty or even surgery.
Now, for patients with the most serious blockages, researchers are studying a new, experimental option: adult stem cells.
Watching Rodney Schoenhardt work on his house, you'd never know that just a few months ago he couldn't even stand up.
"I couldn't even think about walking. I couldn't even put my foot on the ground. I was in a wheelchair," he said.
He had critical limb ischemia -- arterial blockages that cut off blood flow to his legs.
"Gangrene, ulcers, they can't walk, and they're facing amputation," Interventional Cardiologist Gabriel Lasala, MD, said.
"He didn't think he was going to save all my toes. He said I might even lose my foot," Schoenhardt said.
For Rodney, a clinical trial at T-C-A Cellular Therapy changed everything. Two different kinds of stem cells were removed from his bone marrow, then processed in these incubation chambers.
"You need two types of cells. One cell that can give rise to the endothelial, that is the inner part of the blood vessel, and the other cell to take care of the outer part," Scientific Director Jose Minguell, PhD said.
Once the stem cells expanded and multiplied into the millions, they were injected back into his leg.
"What we try to do with stem cells is what nature does, create new blood vessels by injecting stem cells in the area that is suffering from lack of blood flow," Lasala said.
Months, or even just weeks after the procedure, doctors say all 26 patients in the trial had less pain, and increased activity -- including Rodney.
"It not only saved my leg, it saved my life," he said.
This adult stem cell trial was designed for critical limb ischemia (is-kee-me-ah) patients who are not candidates for surgery and have run out of conventional options. The amount of improvement from the stem cells may depend on how far advanced the patient's disease is. The therapy is still investigational, and studies are continuing.