OAS system enables cardiologists to break through intensely calcified arteries

A small, electric medical device designed to break through severely calcified coronary arteries is drawing praise at Methodist University Hospital.

Methodist is the first in West Tennessee to use the device – called the Diamondback 360 Coronary Orbital Atherectomy System (OAS) – according to the hospital and the OAS manufacturer.

In November, Rami Khouzam, MD, director of the cardiac cath lab at Methodist, performed the first of about a half-dozen local procedures with the OAS, which is made by Cardiovascular Systems Inc. (CSI) of St. Paul, Minn.

“Until now, interventional cardiologists have only been able to successfully treat patients with minor plaque buildup,” said Khouzam, who is also associate professor of medicine and program director of the Interventional Cardiology Fellowship at the University of Tennessee Health Science Center.

“The (OAS) enables cardiologists to break through intensely calcified arteries which represent up to 40 percent of coronary lesions," he said. "Without this technology, patients with heavily calcified arteries would need to be treated with open-heart surgery, leading to longer recovery times, lengthier hospital stays and significantly higher costs.”

There would seem to be a ready market for the procedure.

According to the American Heart Association, 16.3 million men and women in the United States have coronary artery disease, a life-threatening condition that occurs when fatty material called plaque builds up on the walls of arteries, causing them to harden, narrow and reduce blood flow to the heart.

Some 600,000 people die every year -- one of every four deaths -- from heart disease.

CSI received clearance in 2007 from the U.S. Food and Drug Administration to use the OAS system for peripheral arteries, and in October 2013 the approval was extended for use in coronary arteries, said CSI spokesman Jack Nielsen.

The company says the Diamondback OAS is the first coronary system for calcium removal, known as atherectomy, in more than 20 years.

Some 2,600 of the devices have been sold to leading institutions across the United States, and the company plans to move into the international market in the next few years, Nielsen said.

He added that other hospitals in Tennessee using the device include Vanderbilt University Medical Center in Nashville, Turkey Creek Medical Center in Knoxville and Johnson City Medical Center.

The Diamondback utilizes an electrically driven 1.25mm diamond-coated crown to sand away calcified plaque in coronary arteries, clearing the way for placement of a stent and the resumption of normal blood flow.

As the crown rotates and orbit increases, centrifugal force presses the crown against the lesion, reducing arterial calcium without injury to healthy tissue.

“The patient has a regular cardiac catheterization, through the femoral or radial approach, under conscious sedation and local anesthesia,” Khouzam said. “Guide wires are passed through the guiding catheter to cross the stenotic/calcified lesion inside the coronary artery. Then the CSI orbital atheterectomy is used over the wire with multiple rotations at 80,000 to 120,000 rpm. This facilitates the path of the stent, which otherwise would not be able to cross some of these lesions.”

He said the procedure involves only a few minutes of treatment time.

Khouzam added that the risk for coronary artery disease increases if a person has high blood pressure, abnormal cholesterol, diabetes or a family history of heart disease.

He said the OAS is easier, less cumbersome and more user friendly to physicians and lab staff compared to the old Rotablator system, which, he said, uses an older, less efficient technology.

“Rare potential risks of using either technology is dissection, perforation of the coronary arteries, which are potential complications anyway when performing high-risk percutaneous coronary interventions in such heavily calcified and diseased arteries,” Khouzam said.

Methodist University Hospital, a core teaching hospital for UTHSC, is part of Methodist Le Bonheur Healthcare, an integrated health delivery system.