BALTIMORE (WJZ)—A doctor accused of performing hundreds of unnecessary heart operations fights to keep his medical license.

Mike Hellgren explains what happened Wednesday in the case involving Dr. Mark Midei.

Midei faces very serious allegations, including providing substandard care. He says he simply followed his medical training.

Stents can be life-savers, popping open blocked arteries. Midei implanted thousands of them until a whistleblower’s complaint led to a review finding more than 500 of his patients may have gotten the device unnecessarily.

On Wednesday, the former star cardiologist appeared before the Maryland Board of Physicians, the regulatory body that could take away his license, fighting to keep it. He let his lawyer do the talking to WJZ.

“It’s quite difficult for Dr. Midei,” said his attorney Stephen Snyder. “It’s quite difficult for all of us. There’s a great deal at stake here, and we hope that the board will come up with the appropriate decision.”

The operations are lucrative, $12,000 each. A U.S. Senate report called the scandal a clear example of potential fraud and abuse.

WJZ investigations found some of the Midei’s former patients disagree.

“Dr. Midei said I had a 90 percent blockage and whoever did the subsequent reading said that I was less than 50 percent blocked. So I just said to him, ‘Well, how do you know who is right?’” said one former patient.

Others are angry over going through a potentially unneeded surgery.

“It just doesn’t seem right,” said another patient.

Midei has defended his record publicly in the past. Now he must wait to learn if this very public scandal costs him his career.

“I’m confident in everything I have done, every decision I’ve made,” Midei once said.

A federal investigation suggested that Midei had too cozy of a relationship with the stent manufacturer. Starting next year, any gifts more than $10 between physicians and manufacturers must be publicly recorded.

The doctor is no longer affiliated with St. Joseph Medical Center.