This 63-year-old man presenting with severe dilated cardiomyopathy underwent implantation of a Boston Science Cognis triple chamber defibrillator for primary prevention. Multiple arrhythmic episodes diagnosed in the VF zone were treated by ATP.
Summary
An arrhythmic episode at 201 bpm was initially detected in the VT zone, programmed as a monitor only (tachy therapy de-activated), explaining the absence of treatment delivery. However, the arrhythmia, which subsequently accelerated to 240 bpm, was then detected in the VF zone, and a sequence of ATP was delivered.
Tracing
This tracing illustrates the power of the Quick Convert algorithm to pace-terminate organized ventricular arrhythmias detected in the VF zone. This ATP sequence can only be delivered after an initial detection in the VF zone, as long as the rate of the tachycardia is ≤250 bpm. The characteristics of this ATP sequence are not programmable, consisting of a burst of 8 stimuli at a cycle length equivalent to 88% of the tachycardia cycle length and a shortest stimulation cycle length of 220 ms. Thereafter, the device examined the efficacy of the therapy. If ≥2 out of 3 cycles were diagnosed as long, the charge was cancelled. Conversely, if ≥ 2 out of 3 cycles were diagnosed as short, the charge of the capacitors began. In this patient, termination of the VT without delivering a shock was an obvious advantage, and a major improvement from the perspective of his quality of life. Furthermore, the cancellation of the capacitors’ charge spared the batteries. On the hand, had ATP been unsuccessful, the onset of the charge would have been delayed by 2 to 3 seconds.
