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Figure 5 Examples of wide EGMs. Panel 1 depicts a wide rhythm, with EGM signals >158 ms (A). This is interpreted as VT by the device, and antitachycardia pacing is delivered (B), without an appreciable change in the arrhythmia. The wide EGM signals continue and become progressively more disorganized toward the end of the episode (C). The device detects a spontaneous termination of the tachyarrhythmia after delivery of antitachycardia pacing. Panel 2 depicts an extremely wide signal that is interpreted by the ICD as VF (A), and a shock is delivered (B). After the shock, the EGM signal remains extremely wide (C), although somewhat less fractionated. The postshock EGM is interpreted by the device as depicting successful termination of VF. Panel 3 depicts an extremely wide signal (A), as well as noncapturing pacing spikes from a permanent VVI pacemaker that had also been implanted (B). The wide EGM is sensed by the device as VF, and a shock is delivered (C), which terminates all spontaneous electrical activity. After the shock, ineffective bradycardic pacing continues (D).
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