Heart-defibrillator wires made by St. Jude Medical Inc. are responsible for at least 20 deaths because of "high-voltage failures," according to a prominent cardiologist's analysis published online in a cardiac-medicine journal.

About 79,000 of the Riata and Riata ST defibrillator wires, called "leads," are still implanted in patients in the U.S., although St. Jude stopped selling the devices in December 2010. A year later, St. Jude said it was recalling them due to a tendency for the metal wires to wear through their silicone covering.

However, the article by Minneapolis cardiologist Robert G. Hauser of the Minneapolis Heart Institute and published in the journal Heart Rhythm, said that the "failures that have resulted in death...appeared to be caused" by short-circuiting unrelated to the protruding wires. He said the deaths occurred over about five years.

"The deaths are rare, but more frequent than you would expect," said Dr. Hauser in an interview. "It's another example of our flawed regulatory system."

The Food and Drug Administration, which is responsible for medical device safety, said it now requires more pre- and post-approval clinical data than it did when Riata leads were approved.