More than 214 St. Jude Eon and Eon Mini implantable pulse generators (IPGs) have failed due to battery issues, causing potentially serious burns and other problems for patients, according to the manufacturer.
Late last month, St. Jude Medical issued an update to a recall of the Eon and Eon Mini IPGs (Product Code 65-3716 and 65-3788). The devices were removed from the market in 2011, due to defective internal battery components, which are sometimes unable to recharge properly, resulting in shorter charges or sudden loss of power.
The battery defect was a result of inner weld failures within the battery due to weld cracks. Initially, the weld cracks were attributed to moisture within the battery; but additional analysis has disproved this theory.
St. Jude put forth a new cause for the problems in the letter, dated July 26, indicating they were caused by “[a] need to more frequently maintain and replace certain tools during the internal battery welding process by a St. Jude Medical supplier in order to assure complete alignment between the welding apparatus and the battery.”
These failures resulted in loss of pain relief and led to subsequent explant surgeries in some situations. Adverse effects of explant surgery can cause pain, scarring, infection and complications with anesthesia.
In another follow-up letter, St. Jude reports that it has taken steps to correct the problem with the battery supplier, suggesting that un-implanted devices should be returned to the company for a free replacement. Implanted devices should not be immediately explanted, but closely monitored for malfunction.
A total of 325 battery issues have been reported due to overheating problems, resulting in 72 removals and reports of first degree and second degree burns in at least three patients. At least 127 of these reports pertained to the warmth and heating of the IPG, resulting in 29 explants, and 214 of Eon Mini IPG’s resulting in 43 explants.
These burns were a result of batteries overheating while recharging. The heat generation was a byproduct of energy dissipation that occurs when an electromagnetic field is used to inductively transfer energy between 2 objects, according to the letter.
St. Jude reported the company has taken steps to correct the problem with the battery supplier by “implementing design improvements to the charger to address possible increased energy dissipation when the IPG and charger are misaligned or the IPG is located too near the surface of the skin.” The firm also advises patients who feel discomfort or pain to stop charging until the discomfort subsides and to adjust the position of the antenna and attempt more frequent recharging for shorter periods to avoid problems.
In recent years, problems with manufacturing defects have also been cited as the cause of problems with St. Jude Riata and Riata ST ICD leads, which were recalled after it was discovered that the small wires used to connect an implantable defibrillator to the heart may poke through the insulation. According to allegations raised in several St. Jude Riata lawsuits filed following the recall, the company failed to manufacture the leads consistent with the FDA approved processes, exposing patients to a risk of problems with the lead wire.