Friday, December 04, 2009

Boston Scientific Issues 'Soft' Defibrillator Advisory

Boston Scientific recently issued a new device advisory for their current line of Teligen ICD and Cognis CRT-D automatic defibrillator devices. The advisory affects only those devices that are implanted beneath the breast muscle (subpectorally) on the chest wall. It seems two (2) devices implanted (of 77,000 total devices implanted worldwide) in this location experienced weakening of a header bond caused by significant forces applied to the header by the pectoralis muscle to the rib. This resulted in altered lead impedances and the introduction of noise to the defibrillator sensing lead that might inhibit pacing or result in inappropriate tachycardia therapies (shocks).

The submuscular implantation location is an uncommon location to implant the devices. It is estimated that only 5% (3850) of the 77,000 devices implanted, were implanted in the subpectoral location.

From Boston Scientific's "Dear Doctor" letter:
Boston Scientific has determined that the bond between the header and case could be weakened by significant forces associated with a subpectoral implant procedure or when a device in a subpectoral position is pushed against a rib during contraction of the pectoralis muscle. A weakened header bond may alter lead impedance and introduce noise that may inhibit pacing therapy or initiate inappropriate tachy therapy. Additional mechanical stress applied to a weakened bond may eventually cause header connection wires to fracture, resulting in loss of therapy.

. . .

Rate of Occurrence
The implant orientation of devices is not reported to Boston Scientific, making it difficult to provide rate of occurrence and prediction information. We have received two (2) reports worldwide of subpectoral implants with weakened header bonds. We estimate that 5% of approximately 77,000 COGNIS and TELIGEN devices worldwide have been implanted in a subpectoral location.

The following factors may also impact the risk of failure if implanted in a subpectoral location:

• Exact location of the patient’s ribs relative to the device
• Body size and/or muscle mass of the patient (risk may increase for larger/muscular patients)
• Activity level and/or occupation of the patient (risk may increase for more active patients)


For future implants:
• Boston Scientific recommends that subpectoral implantation of affected COGNIS CRT-Ds or TELIGEN ICDs (Table 1) be avoided until improvements to header bond strength are available for devices in your geography.

For affected devices (Table 1) implanted in a subpectoral location:
• Follow patient at least once every three months as recommended in device instructions for use.
• Consider advising patients to contact their physician or clinic if they receive shocks, in order to ensure timely review of associated electrograms and other device data via in-clinic or remote interrogation.
In summary, the devices need to be followed as usual (every three months), but are not recommended for removal unless they begin to develop erratic behavior. The warranty and unreimbursed medical expenses "may" be honored in "certain geographies."


Reference: Boston Scientific's webpage with more information as well as links to the Dear Doctor and Dear Patient letters


Anonymous said...

Hello Dr. Wes,
I just received a Boston Scientific Telegen for a change out from a Guidant defibrillator. I received the replacement around 10/21/09. This new device checks lead impedance via wireless network. Now, it is normally at 1000 and just recently it has been detecting 2000 for just a split second when it checks the device for lead impedances. The strange thing is, it is not detecting it every day. Once every 12 to 15 days and it is during my sleep. What do you think it is doing during the day? Where I am really struggling with this is I have had a device that has malfunctioned and shocked me 22 times while I was awake and suffer some side effects from that day even 8 years later. Now I am re-living the same thing. Doctors cannot reproduce the interference when I go in and it is starting to really get to me emotionally.
Any advice on what I should ask my doctor or where I should go from here.

Anonymous said...

Hello Dr. Wes,
Please help, I am frustrated and at wits end.
I had an ICD BSX Teligen implanted 06/15/2009 for ARVD. This is my 5th ICD in 6 years. Same EP doctor through all procedures. My OP reports states the position of my ICD Teligen E110 is in a submuscular fashion below the right infraclavicular area. My EP physican states this location does not comply with the BSX Teligen advisory. I called the customer service line for BSX, talked with a pleasant gentleman whom states, if the ICD is not in a subcutaneous location and it is a submuscular location, this does fall within the BSX advisory guidelines for the E110 Teligen ICD. I also checked my model and serial number on the BSX advisory website and my Teligen ICD is on of the list of affected models. Please help me as to what I should do? I am so confused.
Is there a difference between a submuscular ICD implant vs a subpectoral implant?
Thank you for all your help.