Chapter 2 · Therapies · Case 5

Double anti-tachycardia pacing sequence

Patient and episode

Patient

  • Same patient as above. Male implanted with a triple chamber defibrillator (Viva Quad CRT-D) for ischaemic cardiomyopathy.

The recording

Tap a number on the trace, or an entry in the list below

Rate / interval plot

Medtronic ICD electrogram, segment 1 of 1 — Double anti-tachycardia pacing sequence

EGM

Medtronic ICD electrogram, segment 1 of 2 — Double anti-tachycardia pacing sequence
Medtronic ICD electrogram, segment 2 of 2 — Double anti-tachycardia pacing sequence
  1. What diagnosis is suggested by the interval plot? Probable episode of monomorphic VT detected in the VF zone and treated by a first burst which appeared ineffective and then by a second burst which appeared effective.
  2. What is the first therapy delivered by the device? The episode is detected in the VF zone; when the initial VF counter is full, a burst before charging is delivered.
  3. Has the device charged its capacitors? No, this is a burst before charging; when the burst is effective, the device does not charge its capacitors.
  4. What is the second therapy delivered by the device? The first burst was ineffective; the redetection criterion is verified (12 / 16 cycles classified as VF); the second therapy is a burst during charging (ATP + start of capacitor charging).
  5. What does ‘abandon’ mean? The burst was effective in terminating the arrhythmia; after 4 consecutive ventricular paced cycles, the criterion for confirming the persistence of the arrhythmia is not met (criterion of 2/5 rapid cycles) and the charge is interrupted (therapy discontinued).

Points to remember

  • This tracing shows a specific aspect of Medtronic defibrillators: the possibility of programming 2 bursts of ATP in the VF zone for the same episode.
  • When ATP before charging is programmed, a first burst is delivered; if this burst proves ineffective, a burst during charging is delivered where the second burst and charging occur simultaneously; this helps increase the proportion of arrhythmias detected in the VF zone that are terminated by pacing rather than a shock.

Practice out loud

Just describe the tracing. What do you think is going on? Describing the numbers can help.

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From Medtronic ICD — clinical cases by P. Bordachar, A. Thiyagarajah, L. Fontagne, M. Strik, S. Ploux. Published by Cardiocases. Every numbered marker on a recording is explained in the list beneath it; tap a marker on the trace or an entry in the list.

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