Charge Timetsec): Waveform: Pathway:
Delivered Energy (J): Impedance(ohms):
Figure 10.18. Prolonged charge time causing a delay in therapy and syncope in a patient with a Medtronic 7221 ICD. Examination of the therapy sequence report from this patient reveals a charge time of 20.6 seconds to deliver a 20-J shock for ventricular fibrillation. This could result from capacitor or component failure, or from battery voltage near the end of the battery's life.
The ICD patient who presents with a sustained ventricular tachyarrhyth-mia should be promptly treated using accepted advanced cardiac life support protocols. The ICD should be inactivated until possible causes of malfunction have been explored (see Box 10.2).
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