ATP during charging and acceleration of tachycardia

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Male patient implanted with a single-chamber Ellipse defibrillator for secondary prevention in the context of ischemic cardiomyopathy

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Episode 1

sinus rhythm
rapid, monomorphic tachycardia detected in the VF zone
diagnosis of VF; start of capacitor charging and simultaneous emission of a burst of 8 complexes at a fixed frequency
Acceleration of arrhythmia with identical morphology
at the end of charging, confirmation followed by a 36-joules electric shock
diagnosis of end of episode after 3 cycles classified as VS

Episode 2

Sinus rhythm with PVC
Rapid tachycardia, detected alternating between the VF zone and the VT2 zone
diagnosis of VF after 30 cycles classified as F; start of capacitor charging and simultaneous emission of a burst of 10 complexes at a fixed frequency
acceleration of arrhythmia with different morphology
at the end of charging, confirmation then 30 jouless electric shock
diagnosis of sinus return after 3 cycles classified as VS

Episode of VF treated with a burst and a 36-joules electric shock

Episode of VF treated with a burst and a 30-joules electric shock

Points to remember

Acceleration of VT and deterioration into VF are well-documented complications following a sequence of anti-tachycardia pacing, with an incidence of around 1 to 5%, justifying the absolute necessity of programming electrical shocks asbackup in the VF zone; the effectiveness and safety of anti-tachycardia pacing are inversely related; a greater number of tachycardias can be reduced with a more aggressive protocol (short pacing intervals, more cycles per sequence, more sequences) but with an increased risk of acceleration
•Anti-tachycardia pacing can 1) accelerate the tachycardia with a morphology identical to the previous one (first example), 2) accelerate the tachycardia with a different morphology (second example), or 3)cause organized tachycardia to degenerate into VF
To reduce the risk of accelerating the tachycardia, the maximum stimulation frequency is programmable; the characteristics of the sequence (coupling, number of stimuli) correspond to those of the sequence programmed in the VT2 zone
ATP before or during the load will not be delivered after treatment in another zone (e.g., accelerated VT2 in the VF zone).