Incidence and management of prolonged charge times in the medtronic model 7219 implantable cardioverter defibrillator

The Medtronic Jewel PCD model 7219, introduced in 1994, was the first downsized, pectoral implantable cardioverter defibrillator (ICD), and many of these units are approaching or have reached the elective replacement indicator (ERI). Unlike later Medtronic ICDs and most other ICDs, in which ERI is defined by battery voltage, the ERI in the model 7219 series is defined when either the capacitor charge time to full output is repeatedly ≥ 14.5s or when battery voltage is ≤ 4.91 V. In this study we examined which of the two ERI criteria was met first in patients with this device model. We also assessed the effects of manual dumping and recharging and of increasing the automatic capacitor reformation frequency on prolonged charge times. In 16 patients with follow-up > 2 years, 15 reached the charge time ERI before battery voltage ERI. Manual dumping and recharging led to spuriously low charge times due to residual charge at the start of recharging, and increasing the automatic capacitor reformation frequency to once a month did not decrease prolonged charge times. Because of persistently prolonged charge times, 15 patients had generator changes. None of these patients had reached battery voltage ERI (battery voltage at time of explantation 5.06 ± 0.06 V). Thus in this early pectoral device, prolonged charge times occur commonly before battery voltage ERI is reached. Whether prolonged charge times will have an impact on device longevity in later model ICDs is unknown.