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Figure 3 Stored intracardiac electrograms from a patient presenting with sustained monomorphic ventricular tachycardia (rate, 200 beats/min) associated with lightheadedness and dizziness. The patient received an appropriate shock for ventricular tachycardia, which terminated this arrhythmia, then received a total of five additional inappropriate shocks due to oversensing during sinus rhythm immediately after appropriate therapy was delivered.