ICD problems--is the device to blame?

摘要

The tracings shown are taken from a patient with a single chamber, primary prevention Medtronic Virtuoso defibrillator (Medtronic Inc., Minneapolis, MN, USA). The device is set to recognize ventricular fibrillation (VF) at cycle length <320 ms (188 beats per minute [bpm]) with a fast ventricular tachycardia (FVT) zone up to 280 ms (214 bpm). The number of intervals to detect (NID) is set at 18/24 with a redetect NID of 12/16.The interval plot (Figure 1) initially shows the end of a previous tachycardia episode. Subsequent ventricular pacing is suggested by lack of sinus variation with interspersed premature complexes not producing expected postectopic pauses. Following two critically timed premature complexes, a rapid tachycardia ensues with ventricular cycle lengths initially within the VF/FVT zone. After 17 beats, the tachycardia appears to terminate spontaneously with six-sensed events out of the VF/FVT zone up to beat 23.