On April 16, 2004 Medtronic announced that it was recalling two heart defibrillators because they have been linked to at least four deaths and one injury. These devices are used to shock the heart into normal rhythm after patients suffer irregular heartbeat or fibrillation, which are rapid, life-threatening arrhythmias, originating in the lower chambers of the heart.

The defibrillators are implanted surgically in the chest. When a cardiac arrhythmia occurs, the capacitor is charged and the device delivers the appropriate shock. Medtronic said that, with the suspect defibrillators, the capacitors may take longer than normal to charge near the end of the battery service life and could cause a delay in delivery or nondelivery of shock therapy. A delay or nondelivery of shock therapy can be life threatening.

The charging problem involves the Medtronic Micro Jewel II Model 7223Cx and the Medtronic GEM DR Model 7271 implanted cardioverter-defibrillators. Medtronic said that most of these devices were implanted in 1997 and 1998.