A defibrillator that was recalled by its manufacturer could deliver random shocks to the heart, a class-action lawsuit alleges.

In 2007, Minneapolis-based Medtronic Inc. issued a global recall of special wires that link a patient’s heart with a defibrillator implanted in the body.Sherry Robinson and her husband Greg Horning say the bouts of violent shocks she had before the leads in her defibrillator were removed changed her life. (Mike Hornbrook/CBC)

Defibrillators monitor the heart for deadly irregular heartbeats and use electrical impulses to jolt it back to normal. More than 6,000 Canadians were fitted with the products before the wires or leads were recalled.

At least five people with the devices died before the company recalled the leads. Since then, as many as 20 more deaths have occurred. Studies suggest the failure rate of the leads increases over time.

Dr. Jamil Bashir, a cardiac surgeon at St. Paul’s Hospital in Vancouver who implanted the defibrillators in patients, said doctors at the hospital have removed more than 100 of the leads.

"We had seen ourselves at St. Paul's some failures of the lead," Bashir recalled. "We had been concerned about that and we mentioned it to the company. It wasn't too far after that the recall actually happened."

When the leads broke, the malfunctioning device shocked patients repeatedly within minutes.

Sherry Robinson of Sechelt, B.C., said she experienced a series of violent shocks before her leads were removed.

Robinson said she's lost faith in Medtronic. She's joined a class action lawsuit against the company, which covers more than 6,300 Canadians and their families who were implanted with the defective leads, whether or not they're having problems with the devices. There should have been a clinical trial before patients got modified defibrillator leads, says Dr. Jamil Bashir. (Mike Hornbrook/CBC)

Victoria Paris, a lawyer with Kim Orr in Toronto, the law firm that launched the class action, claims claims Medtronic was more than negligent. The suit alleges the company failed to disclose the defects in a timely fashion.

"As soon as they discovered that there were problems, they should have let doctors know right away," Paris said. "They should have let patients know."

Medtronic Canada declined several requests for an interview. In a written statement to CBC News, it denied the allegations and said they have not been proven in court, adding it will defend itself vigorously.

Call for clinical trial

Lawyers want to know whether Canadian health officials rubber-stamped approval of the defibrillator from the U.S. Food and Drug Administration, which itself relied heavily on data supplied by Medtronic.

The lawyers claim the FDA approval was based on earlier, more reliable leads, which Medtronic re-engineered to be thinner without going through the U.S. regulator's lengthy approval process.

There should have been a clinical trial before patients got the modified device, Bashir said.

"Why do we have to rush to bring them on the market if the main advantage is really just making them smaller?" the cardiac surgeon said.

An Ontario judge approved the case as a class action in 2009. It could take a year or more before lawyers argue it in court.

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With files from CBC's Mike Hornbrook