An internal defibrillator is a complex device that includes a battery, condensers, an electric circuit and various other components. It is also attached to 1, 2 or 3 electrodes placed within the heart. This material is extremely sophisticated and the devices are fabricated using the highest standards of quality control. The large companies making defibrillators are under strict regimentation enforced by American and Canadian organisations responsible for ensuring the quality of medical products. From time to time, while certain devices are functioning, defections can appear. There can be isolated problems with a device that affect some but not all patients who have the same implanted defibrillator model. There may also be a problem within a model series that is noted months or even years after the implantation and it is the team of electrophysiologists who must respond according to the recommendations laid out by the manufacturers.

Recently the company Medtronic sent out a warning stating that there could be a rapid depletion of the battery in certain defibrillators within their MARQUIS series. This risk is very low (evaluated at 1/10 000). In any case, during the second life of the battery this risk can increase to 1.5%. For this reason there was a discussion between the electrophysiologists and a certain number of patients who were seen were proposed to have their defibrillators changed. Every large company making defibrillators have had this type of recall and there is no guaranty that there will not be more recalls in the future. It is important to note that these problems, even when they are serious, should not worry people who have a defibrillator in place since we are able to react within a very short time frame. As stated previously, prior to placing a device on the market many studies are carried out to ensure a reduction in as many future risks and/or problems as is possible. Do not hesitate to contact your electrophysiologist if you have any questions or concerns with regards to your implanted defibrillator. 

Gilles O'Hara, MD, F.R.C.P., F.A.C.C.
Chef du secteur d'électrophysiologie