November 2005

Dear Doctor,

In accordance with Medtronic's commitment to keeping you informed about the performance of our products, we write to advise you about an issue with a specific subset of Sigma^® series pacemakers that may fail due to separation of interconnect wires from the hybrid circuit. This failure mechanism may present clinically as loss of rate response, premature battery depletion, intermittent or total loss of telemetry, or no output. There have been no reported patient injuries or deaths due to this issue.

Medtronic is communicating this information to the appropriate regulatory agencies.

Affected Devices
There are approximately 28,000 active implants, with approximately 6,650 in the US, out of an initial implant population of 40,000 worldwide. The specific model and serial numbers of affected devices you are following or have implanted are attached to this letter. Affected serial numbers are available online at http://SigmaSNList.medtronic.com.

Root Cause
Separation of redundant interconnect wires has been observed on hybrid terminal blocks. Device failure occurs only where both interconnect wires separate from a hybrid terminal block. In October 2005, we completed testing and analysis identifying the root cause of these failures and the affected population. Hybrid circuits used in this subset of devices were cleaned during manufacturing with a particular cleaning solvent that could potentially reduce the strength of the interconnect wire bond over time.

Low Probability of Occurrence
As part of the ongoing returned product analysis, Medtronic has observed 19 devices from the above population, approximately .05%, that have exhibited this failure mechanism. There is no provocative testing that can predict which devices may fail. Implant duration for the 19 failures ranged from 17-38 months. Our modeling predicts a failure rate from .17% to .30% over the remaining lifetime of these pacemakers.

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 and after discussion with our physician consultants, Medtronic offers the following recommendations:

• Medtronic does not recommend replacement of these devices prior to normal elective replacement (ERI), based on the low probability of occurrence of a serious event in this population.
• Continue routine follow up in accordance with standard practice.
• Advise patients to seek attention immediately if they experience return of symptoms (e.g., syncope or light headedness).
• Determine whether device replacement is warranted on a case-by-case basis based upon consultation with patients, review of the individual patient's medical history and consideration of the relative risks of an invasive procedure.

Physician and Patient Support
We regret the difficulties this may cause you and your patients. We will provide you with regular updates on the ongoing actual performance in our Product Performance Report, available at www.medtronic.com/crm/performance.

Should you elect to replace a device for a specific patient, Medtronic will provide a replacement device at no cost. Medtronic's Patient Services group at 1-800-551-5544 is always available to assist patients with this or other issues.

The information in this letter will be posted on Medtronic.com on December 5, 2005.

If you have any questions, or if we can be of assistance, please contact your local Medtronic Representative.

Sincerely,

MEDTRONIC, INC.

Stan Myrum

Vice President, Cardiac Rhythm Management Operations and Quality