PMC5412663_01
Initial right ventricular lead noise discrimination algorithm (RVLND) inhibiting therapy due to detection of noise (N). The far-field electrogram reveals a stable intrinsic rate.
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The device transiently suppressed VF detection by recognizing the high rates as being noise (Figure 1) and due to the default time-out in the RVLND algorithm, VF would have been detected after 45 seconds of persistent noise.
The third high-voltage therapy (red box) caused the patient's intrinsic rate to accelerate to a high-frequency (ventricular fibrillation [VF]) rate, which is clearly visible in the far-field can to right ventricular coil electrogram.
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The ICD proceeded to deliver a sequence of maximum output 35-J shocks, the third of which induced true VF (Figure 2). Three subsequent shocks failed to terminate the VF (Figure 3), and therapy was automatically discontinued, leaving the patient in VF from which he was not resuscitated.
The fourth high-voltage therapy failed to terminate ventricular fibrillation.
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The ICD proceeded to deliver a sequence of maximum output 35-J shocks, the third of which induced true VF (Figure 2). Three subsequent shocks failed to terminate the VF (Figure 3), and therapy was automatically discontinued, leaving the patient in VF from which he was not resuscitated.