Physician Communication - October 2007
Kinetra and Soletra Implantable Neurostimulators Lifted Wirebonds Device Recall

Device Recall/Important Patient Management Information

Models Affected:

• Model 7428 Kinetra
• Model 7426 Soletra
  

Separation of internal connections (lifted wirebonds) between the electronic circuit and battery may lead to sudden cessation of the intervention.

Serial Number Look-up for Kinetra and Soletra This Web-based tool can be used to identify whether a specific Kinetra or Soletra neurostimulator serial number is included in the lifted wirebonds device recall dated October 2007. Search for a Serial Number

Model 7428 Kinetra and Model 7426 Soletra Lifted Wirebonds - October 2007

Urgent: Device Recall
IMPORTANT PATIENT MANAGEMENT INFORMATION
Model 7428 Kinetra® and Model 7426 Soletra® Implantable Neurostimulators

Dear Healthcare Professional,

The purpose of this letter is to advise you of a problem with a subset of Model 7428 Kinetra® and Model 7426 Soletra® implantable neurostimulators where separation of internal connections (lifted wirebonds) between the electronic circuit and battery may lead to sudden cessation of therapy.

We are aware of 2 failures which led to adverse events where hospitalization was required because return of symptoms was severe. Modification in drug therapy was also required to control symptoms until a replacement device could be implanted. No permanent injury occurred. This letter also provides patient management recommendations for this issue.

In March 2006, Medtronic identified 24 implanted Kinetra devices in the United States and Europe believed to be at risk for this problem, which prompted distribution of customer letters to affected physicians. At that time, Medtronic estimated that up to two of those 24 implanted Kinetra devices may fail due to this problem.

Since that time, 8 additional returned devices were confirmed to have failed due to this problem (s6 of which were outside the identified population of 24 implanted devices).

As a result of our on-going monitoring and analysis of this problem, Medtronic is expanding the March 2006 customer communication to include all Kinetra and Soletra devices with electronic circuits that were cleaned with a particular cleaning solvent during manufacturing in several specific time periods.

Sudden cessation of therapy due to any cause (for example, normal or premature battery depletion, component failure) can result in the immediate return of symptoms. Symptoms may be worse due to rebound effect or the possible progression of the disease since initiating Deep Brain Stimulation (DBS) therapy.

• Symptoms specific to dystonia patients may include severe and painful muscle spasms; and for generalized dystonia patients, dystonic crisis.
• Symptoms specific to Parkinson's disease (PD) patients may include severe tremor, rigidity, bradykinesia, and akinetic crisis eventually resulting in decreased mobility.
• Symptoms specific to Essential Tremor patients may include a sudden return of tremor.

These symptoms may not be immediately responsive to pharmacotherapy.
This anomaly will leave the device in a non-functional (no telemetry, no output) or Power-On-Reset (POR) state. These states can be intermittent or permanent. The patient cannot rely on the patient programmer to identify this anomaly.

A device can be confirmed to be in the POR state through interrogation of the device with the physician programmer. A device in the POR state will have its parameters reset to the factory default settings with no stimulation output and its serial number will be unavailable.

While it may be possible to successfully reprogram an affected device that is in the POR state, the device may return to the POR state due to the intermittency of this anomaly. Therefore, this anomaly cannot be corrected permanently by reprogramming the device.

Affected Devices

The specific model and serial numbers of affected devices you are following or have implanted are attached to this letter. A serial number look-up application is also available on our website at KinetraSoletra.medtronic.com to confirm affected device serial numbers.

• For Kinetra, there are approximately 1200 devices worldwide that are affected by this communication, with approximately 120 active implants in the United States. To date, a total of approximately 22,000 Kinetra devices have been implanted worldwide.
• For Soletra, there are approximately 1860 devices worldwide that are affected by this communication, with approximately 1240 active implants in the United States. To date, a total of approximately 50,000 Soletra devices have been implanted worldwide.

Root Cause

In the affected devices, separation of internal connections has been observed between the electronic circuit and battery. Electronic circuits used in this subset of affected devices were cleaned with a particular cleaning solvent during manufacturing in several specific time periods that could reduce the strength of the internal connections over time.

A small number of devices manufactured outside these time periods have exhibited this same failure mechanism, and we attribute these failures to a base level of random failures not associated with any identifiable root cause.

Probability of Occurrence

As part of our ongoing returned product analysis, Medtronic has calculated the following data with regard to this failure mechanism.

There is no proactive testing that can predict which devices may fail in the future. The probability of device failure increases with implant duration. For devices from the affected populations that are still implanted and active, we estimate the probability of failure to be between 1.38% (confirmed Kinetra experience) and 2.52% (Weibull prediction model) after 5 years of implant duration.

The total number of additional device failures is estimated to be as many as 31 Kinetra devices and 47 Soletra devices. These estimates include a diverse patient population and variability in implant locations.

Recommendations

We realize that each of your patients is unique, and we support your clinical judgment in caring for them. To assist physicians in their patient care, Medtronic convened a medical advisory board composed of leading United States and European neurologists and neurosurgeons that provided support in developing the following recommendations:

• Consider the potential for this anomaly if your patient presents with a device in a nonfunctional (no telemetry, no output) or POR state
• Consider informing your patients of this risk and advise them to seek attention immediately if they experience a return of pre-implant or more advanced symptoms
• Determine whether prophylactic device replacement is warranted based upon
• consultation with your patient, including review of the patient's medical history

The following considerations may be helpful for your decision making:

• The length of time the device has been implanted
• The patient's current lifestyle (for example, participating in extreme sports, extensive traveling, operating machinery)
• For PD patients, the potential utility of rescue pharmacological treatment
• The risk of recurrent or worsening symptoms, particularly for generalized dystonia patients
• The relative risks of abrupt cessation of stimulation versus the risk of a device replacement surgical procedure (for example, risk of infection and consequent delay of reinitiating DBS therapy)

Report any malfunction, removal and replacement to Medtronic and FDA using the medical device reporting system. Return explanted devices to Medtronic for analysis.

Medtronic is communicating this information to the appropriate regulatory agencies.

For Assistance

In the United States, contact Medtronic Neuromodulation Technical Services at (800) 707-0933 or your local Medtronic representative. Outside of the United States, contact your Medtronic representative.

We appreciate your assistance with this matter and regret any inconvenience this may have caused you or your patient.

Sincerely,

George Aram
Vice President Quality
Medtronic Neuromodulation