Potential Separation of Interconnect Wires (2005)
Sigma Implantable Pulse Generators
Original Date of Advisory:
A specific subset of Sigma series pacemakers may fail due to separation of interconnect wires from the hybrid circuit. You may use the "Search for Information by Serial Number" tool on the home page to determine if a specific device is affected.
This subset of Sigma series pacemakers that may fail due to separation of interconnect wires from the hybrid circuit may present clinically as loss of rate response, premature battery depletion, intermittent or total loss of telemetry, or no output.
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, testing and analysis identified 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.
No provocative testing can predict which devices may fail.
Patient Management Recommendations
Recommendation for the management of patients who have pacemakers affected by this advisory were changed in May 2009. Current recommendations are:
We realize that each patient requires unique clinical consideration and we support your judgment in caring for your patients. After consultation with Medtronic’s Independent Physician Quality Panel, Medtronic offers the following recommendations for patients in the 2005 Sigma advisory:
- Physicians should advise their patients to seek medical attention immediately if they experience symptoms (e.g., fainting or lightheadedness).
- Physicians should consider device replacement for patients who are both pacemaker dependent and who have been implanted with a device in the affected subsets. Medtronic will offer a supplemental device warranty if the device is not already at elective replacement time.
- Physicians should continue routine follow-up in accordance with standard practice for those patients who are not pacemaker dependent.
Patient management recommendations remain unchanged. As of March 6, 2017, 850 devices out of approximately 40,000 devices worldwide have been confirmed as having experienced interconnect wire separation.
Four hundred eighty-four(484) of the Sigma devices (1.1%) were returned with information indicating a problem with the patient’s pacing system prior to explant. The remaining 366 Sigma devices (0.90%) were returned with no information indicating a potential malfunction while implanted or with insufficient information to determine the state of the device at explant. Lacking definite information indicating proper operation until explant, these remaining devices are conservatively categorized as having experienced interconnect wire separation while implanted.
Our original modeling predicted a failure rate from 0.17% to 0.30% over the remaining lifetime of these pacemakers. However, as of May 2009 updated modeling now predicts a failure rate of 3.9% over the remaining device life of those devices still in service at that time.
Out of the initial advisory population of 40,000 worldwide, less than 300 remain active worldwide.
|Initial Affected Population||Number of Confirmed Advisory Related Events||Estimated Remaining Active Population||Current Malfunction Rate (confirmed malfunctions over total population)||Predicted Malfunction Rate Over the Remaining Life of the Devices Still Implanted|
40,000 Implanted Worldwide (est.) (9,900 United States)
484 Worldwide (98 United States) with information indicating a clinical presentation. An additional 366 Worldwide (67 US) without information indicating a clinical presentation or with insufficient information to determine the state of the device at explant.
less than 300 worldwide
1.1% Worldwide (1.0% United States)