On November 12, 2007, the Wall Street Journal reported concerns over St. Jude Medical Inc.’s Riata line of defibrillator leads. The Riata line of defibrillator leads are wires used to connect an implantable defibrillator to cardiac patients’ hearts. The wires are under scrutiny for possible flaws, as in rare instances the leads may lead to punctures.

There have been four recent cases involving patients in Nebraska, New York City, and the Czech Republic. These cases have been reported to St. Jude and the U.S. Food and Drug Administration (FDA), and will be printed in the online medical journal Pace.

Defibrillator leads are affixed to the wall of the heart and are designed to sense a heart’s rhythm. When an unstable rhythm is detected, the implanted defibrillator is supposed to dispatch an electrical shock.

In four reported cases, St. Jude Medical’s Riata defibrillator leads became detached from the heart. Detached defibrillator leads could cause very serious injuries. Riata leads might poke holes through the heart. In one reported case, Riata leads nearly poked through a patient’s skin. A punctured heart could bleed into the pericardial sac, causing a lethal condition in which pressure builds around the heart, rendering it unable to beat effectively.

In addition, if a Riata lead is detached from the heart it may not sense aberrant heart rhythms and a patient might suffer serious consequences, including death, from an underlying medical condition.

“There is a legitimate concern that the problem may be more than physician misadventure and that there may be an inherent design flaw, at least in some models of the Riata leads,” wrote Dr. Steven C. Vlay, a cardiologist and heart-rhythm specialist at Stony Brook University in Stony Brook, NY, in a Pace editorial.

The president of St. Jude’s cardiac-rhythm management division, Eric Fain, said perforation rates with the 121,000 Riata leads implanted so far are at or lower than those reported for other defibrillator leads. In a registry created by St. Jude Medical to track patients implanted with Riata leads, a perforation rate of 0.33% has been seen in 1,207 patients implanted with all Riata leads.

However, reports published earlier this year by the journal Heart Rhythm showed higher perforation rates. In April, Massachusetts General Hospital reported a 3.8% rate of perforation in certain models of Riata leads. The New York Hospital Queens reported that they saw five perforations out of the 59 Riata leads implanted in their hospital – a failure rate of 8.5%.

The number of perforations caused by Riata leads could be higher than reported since these experiences are not always reported by doctors.

The Riata lead is the second defibrillator lead under scrutiny this year. In October 2007, Medtronic’s Sprint Fidelis defibrillator lead was removed from the market after the company reported it may fracture at a higher rate than another Medtronic lead, the Sprint Quattro.

Source: Thomas M. Burton and Anna Wilde Matthews, “St. Jude Defibrillator Wire Gets Scrutiny,” Wall Street Journal, November 12, 2007.