Successful burst for repetitive episodes of VT

N° 7
Manufacturer Boston Scientific Device ICD Field Therapy

This 39-year-old woman presenting with ischemic cardiomyopathy and old myocardial infarction received a Boston Science Teligen dual chamber defibrillator for secondary prevention of VT at rates between 130 and 140 bpm. She suffered an electrical storm with multiples episodes of VT treated with ≥1 sequence(s) of ATP. 

Graph and trace

Summary 1

Episode of VT (discrimination V>A) at 140 bpm, treated with a single sequence of ATP.

Tracing 1

  1. sinus rhythm (AS-VS);
  2. tachycardia detected in the VT zone, starting suddenly, stable, though with a clear change in the morphology compared with sinus rhythm, particularly visible on the high-voltage channel. Atrioventricular dissociation (V>A) confirming the ventricular origin of the tachycardia;
  3. 8 out of 10 criterion fulfilled for the VT zone (V-Epsd);
  4. 10-sec Duration, throughout which the 6 out of 10 criterion remained fulfilled despite occasional VS classified cycles (sustained VT: V-Detect);
  5. burst of 10 complexes of ATP at fixed rate; RV pacing;
  6. successful burst and termination of the arrhythmia.

Summary 2

Second episode on the same day, requiring 2 bursts of ATP. 

Tracing 2

  1. VT already on going (AV dissociation), though the ventricular rate was below the lower limit of the VT zone. The ventricular events were, therefore, labeled VS;
  2. slight acceleration of the tachyarrhythmia, entering the VT zone (VT). The tachycardia remained at the limit of the VT zone. Alternating VS and VT cycles;
  3. 8 out of 10 criterion fulfilled for the VT zone;
  4. 6 out of 10 criterion no longer fulfilled;
  5. 8 out of 10 criterion again fulfilled;
  6. the 6 out of 10 criterion remained fulfilled for the entire Duration;
  7. first burst of 10 complexes;
  8. after the burst, beginning of the redetection phase;
  9. 8 out of 10 criterion fulfilled;
  10. end of the Duration of redetection for the VT zone (programmed at 1 sec); no therapy delivered since the cycle was classified VS (V-Dur marker, since the 6 out of 10 criterion remained fulfilled);
  11. V-Detect marker on the next short cycle;
  12. second burst of 12 cycles at the same rate than previously;
  13. successful burst and end of arrhythmia.

Summary 3

Further similar episode, on the same day, requiring 6 then 3 bursts of ATP.

Tracing 3

  1. same VT as during earlier episodes;
  2. first burst of 10 cycles of ATP;
  3. unsuccessful burst;
  4. second burst of 12 ATP cycles; no change in the rate stimulation compared with the previous burst, though 2 stimuli were added;
  5. unsuccessful burst;
  6. third burst of 14 ATP cycles; 2 pacing stimuli were added compared with the previous burst;
  7. unsuccessful burst;
  8. fourth burst of 14 ATP cycles;
  9. unsuccessful burst;
  10. fifth burst of 14 ATP cycles;
  11. unsuccessful burst;
  12. sixth and last burst of 14 ATP cycles;
  13. unsuccessful burst;
  14. first ramp of 10 ATP cycles with a 10-ms decrement; the coupling between the first paced cycle and the last sensed ventricular event is the same as the coupling between the first 2 stimuli; thereafter, the coupling between the stimuli decreases by 10 ms;
  15. unsuccessful ramp;
  16. second ramp of 12 ATP cycles with 10-ms decrement; the shortest cycle (245 ms) is, therefore, 20 ms shorter than that of the previous ramp;
  17. unsuccessful ramp;
  18. third ramp of 14 complexes with 10-ms decrement; the shortest coupling interval (220 ms) is the shortest programmed paced cycle;
  19. successful ramp and end of the episode.

This tracing shows, once again, the value of ATP as a means of sparing the batteries of the device and preserving the patient’s quality of life. This patient had developed multiples episodes of VT that were successfully treated with a single or several pacing sequences. A first series of 6 bursts was programmed, followed by a series of ramps. The latter is not a systematic choice in this range of rates, given the risk of acceleration to a rapid polymorphic tachycardia by the more aggressive ATP. In this patient, approximately 70% of the bursts of ATP were successful, while the ramps terminated the remaining 30% of attempts, avoiding thereby the delivery of electrical shocks. 

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