reported new malfunctions in three models of implanted defibrillators manufactured by recent acquiree Guidant.
The malfunctions involve the Renewal 3, Renewal 4 and Vitality HE heart device models, which are usually implanted directly under the skin. The latest occurred in devices that were implanted deeper, below the pectoral muscle, and were placed in a "reversed" position, said the Natick, Mass.-based device maker.
"Testing has confirmed that repetitive mechanical stress applied to a specific area of the titanium case can induce component damage and device malfunction, if the device is implanted in this rarely utilized, uncommon manner," according to a company press release Monday.
Although implant positioning is not reported to the company, Boston Scientific says that according to its information, the number of devices susceptible to this problem is less than 1%. Both patients affected by the problem underwent successful replacement procedures, Boston says.
The company issued an advisory to physicians review implant positioning to determine whether their patients are susceptible to the problem.
Boston also reported a risk of early battery depletion in 996 defibrillators and cardiac resynchronization devices implanted worldwide, which came from a single lot from a single supplier.
As of May 8, premature battery depletion has been confirmed in 30 devices returned to the company, and there are additional reports of possible premature battery depletion in 46 devices. No deaths or injuries have been reported under this advisory.
Guidant, which was acquired by Boston Scientific last month, recalled a number of devices last year because of premature battery depletion and short circuiting. Two patients died as a result of previous device failures.
The implanted heart devices are designed to provide a shock to the hearts of patients with potentially deadly arrhythmias.
Boston Scientific's shares fell 35 cents, or 1.7%, to $20.35.