ATP before charging

Tracing
N° 15
Manufacturer Medtronic Device ICD Field Therapy
Patient

Same patient as the previous tracing.

Graph and trace

The graph appears identical to the previous tracing.

  1. the EGM shows a regular tachycardia with intervals detected in the VF zone; detection of a VF episode;
  2. the first programmed therapy is now a burst before the charging of the capacitors; the device delivers an ATP sequence but does not begin charging the capacitors;
  3. the burst is successful; absence of capacitor charge.
Comments

ATP during charging enables painless treatment of ventricular tachycardia without the risk of delaying shock treatment when necessary. Once the diagnosis of VF is established, the charge begins and ATP is delivered simultaneously. If thereafter, VF is reconfirmed, the shock is delivered. If the patient has returned to sinus rhythm, the shock is withheld. This hence allows treating tachycardia painlessly if the ATP is successful, without delaying the onset of shock if the ATP is unsuccessful. However, even if it is successful, ATP saves little energy.

ATP before charging reduces energy consumption. Once the diagnosis of VF is established, ATP is delivered. If VF is reconfirmed after ATP, the capacitor begins charging. If the arrhythmia has been terminated, the charge is not initiated. This allows withholding charging of the capacitors if the ATP is successful. On the other hand, if ATP is unsuccessful, it delays shock delivery by a few seconds.  

The device delivers the ATP before or during the charge only if the last 8 detected ventricular intervals are equal to or longer than the programmed value ("Deliver the ATP if last 8 RR ≥"). If one programs the charge saver, the device automatically switches from an ATP delivered during charging to an ATP before charging if the former has been successful on a programmable number of consecutive episodes.

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