CHAPEL HILL, N.C. — In the United States each year, about 21,000 people learn they have a potentially fatal condition even though they feel fine.

Without any warning, an aortic aneurysm killed comic actor John Ritter last year. A new procedure currently in clinical trials treats the condition without open surgery.

In January, Addie Hoskins learned an aortic aneurysm near her heart would keep her from doing many of the things she loved. Too much activity or stress could cause it to burst, killing her instantly.

Aside from the fear, she felt fine physically. Three out of four people with the condition never feel any symptoms.

"I guess that's why they call it the silent killer," Hoskins said.

The traditional treatment is open surgery. Doctors offered Hoskins the option of taking part in a clinical study for a new procedure. She liked what she heard.

"First of all, they would not have to cut my chest open, and next, I wouldn't be in the hospital a long time," she said.

Open surgery would keep her in the hospital from one to two weeks with months of recovery.

"Now, with this procedure, they're in and out of the hospital within 24 to 36 hours," said Dr. Mark Farber of University of North Carolina Hospitals.

All because of a device called a thoracic stent graft.

The much shorter procedures starts with an incision near the groin. Next, a catheter threads a thoracic stent graf up to the thoracic aorta. When released, it expands and stays in place.

"Then the fabric actually covers the defect or weakening section of the artery so that blood can then flow through the device," Farber said.

Hoskins got the stent in late March and by May she was back in her garden.

"Now, Dr. Farber told me I can do anything that I feel like doing," she said.

Hoskins goes in for occasional checkups to see if the stent is still in place. Doctors do not know how long the stent will keep doing its job.

Aortic aneurysms are caused by genetic defects, hardening of the arteries or high blood pressure. They are usually detected while doctors look for other problems.