Medtronic Defibrillators Safety Concerns

In October 2007, Medtronic issued a recall of their defibrillators that had Sprint Fidelis lead wires because the leads were fracturing at an alarming rate, causing 5 deaths and more than 1,000 injuries between 2004 and 2007, with more deaths occurring through 2009.

This recall affected Sprint Fidelis model numbers 6930, 6931, 6948, and 6949. Lead wires on ICDs pass information from the ICD to the heart, and vice-versa, allowing the defibrillator to send a life-saving electrical shock to the heart should it lapse into an arrhythmia. Without a reliable lead wire, many dire consequences may occur.

Medtronic began producing and distributing implantable cardioverter-defibrillators—ICDs—with new Sprint Fidelis lead wires in 2004. These leads were a modification of their existing Sprint Quattro model, a very successful and popular lead wire placed in their previous defibrillators. The Sprint Fidelis line sought to increase comfort by utilizing a new, ultra-thin wire, but did not test the new in patients before putting it on the market.

 
The FDA saw the new leads as a modification of an existing model and did not require testing before public distribution. Medtronic states that approximately 4,000 to 5,000 people with a Sprint Fidelis lead will have a fracture within 30 months of having their defibrillator implanted.
 
The consequences of a broken lead wire can be deadly. If a break does take place, three instances may result: the implanted defibrillator will beep, alerting the patient to seek immediate medical care, the fracture will create a massive electric shock that causes the patient extreme and sudden chest pain, or the fracture will drain the ICD’s battery, causing it to fail to deliver the necessary shock. Any of these situations, without prompt medical attention, can lead to death if the patient’s heart goes out of a normal rhythm.
 
The fractures occurred in two specific areas, the distal portion of the lead, affecting the anode (ring electrode) and the anchoring sleeve tie-down, mainly affecting the cathode (helix tip electrode), and sometimes the high voltage conductor. Breaks occurring near the high voltage conductor caused the ICD to be unable to deliver the necessary defibrillating shocks while anode or cathode conductor fractures (at either location) caused increased impedance, over sensing, increased interval counts, multiple inappropriate shocks, and/or loss of pacing output.

There is evidence that Medtronic knew about the problems with the new lead wires but did not act quickly enough to remedy the situation. By 2007, five patients died as a direct cause of broken leads and the problems associated with them while more than 1,000 other patients filed injury reports with other grievances related to fractured Sprint Fidelis lead.

 
These injury reports included 204 instances of unnecessary shocks before January 10, 2007 and 563 after that date relating to delayed or absent shocks when needed, associated chest pain, fainting, irregular heartbeats, and a myriad of other complaints. By January 10, 2007, there were 1,629 complaints, 767 of those due to inappropriate electrical shocks from the ICD.
 
While Medtronic is not discussing the reason these lead wires broke at such alarming rates, it is most likely that the super-thin design of the wire is not strong enough to sustain the stresses encountered during placement and the recovery period. Many questions arouse regarding why Medtronic did not issue their recall earlier, saving ICD patients the worry about their particular device and saving those with broken leads the pain of unnecessary shocks and other associated events
A Recall is Issued
 
In October 2007, Medtronic issued a recall, sending patients letters telling them that they were likely to suffer more from the replacement of the wires than if they left the device as is, and another letter to physicians stating that the leads could fracture at a “higher than expected” rate. The letter continued on to recommend that doctors watch over their ICD patients very closely for signs of fracture.
 
The only way to fix a broken lead wire is to replace it, a very dangerous and invasive surgery that involves removing the faulty wire and replacing it with a more reliable one. The problems with the surgery likely include extensive tissue damage, especially in patients who have had their devices implanted for some time, as the body eventually grows new tissues around the lead wire, totally encompassing the wire.
 
Recovery from the procedure is demanding, and medical professionals recommend only having it done if there is evidence that there is damage to the lead wire. In 2009, the death toll associated with the Sprint Fidelis leads rose to 13, including four associated with extracting the leads. It is impossible to tell whether a patient has a Sprint Fidelis wire without proper examination, so physicians and the FDA recommend that patients with an ICD consult their doctor as soon as possible for an exam. Medtronic is still stating that the best treatment is to leave the faulty leads in place unless fractured, and then, should extraction become necessary, an experienced surgeon should perform the surgery.
 
Sources:
 
  1. Groves, Reggie. Urgent Medical Device Information Sprint Fidelis® Lead Patient Management Recommendations. October 15, 2007. Retrieved from http://www.medtronic.com/product-advisories/physician/sprint-fidelis/PRO...
  2. Wolfe Sidney M. MD. Letter to the FDA urging an investigation of Medtronic defibrillator recall (HRG Publication #1826). October 16, 2007. Retrieved December 24, 2009 from http://www.citizen.org/publications/release.cfm?ID=7547
  3. Medtronic Defibrillator Leads Linked to Additional Deaths. Retrieved December 24, 2009 from http://firstwatch.jwatch.org/cgi/content/full/2009/316/3