Successful burst for repetitive episodes of VT

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

14. same VT as during earlier episodes;
15. first burst of 10 cycles of ATP;
16. unsuccessful burst;
17. second burst of 12 ATP cycles; no change in the rate stimulation compared with the previous burst, though 2 stimuli were added;
18. unsuccessful burst;
19. third burst of 14 ATP cycles; 2 pacing stimuli were added compared with the previous burst;
20. unsuccessful burst;
21. fourth burst of 14 ATP cycles;
22. unsuccessful burst;
23. fifth burst of 14 ATP cycles;
24. unsuccessful burst;
25. sixth and last burst of 14 ATP cycles;
26. unsuccessful burst;
27. 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;
28. unsuccessful ramp;
29. 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;
30. unsuccessful ramp;
31. third ramp of 14 complexes with 10-ms decrement; the shortest coupling interval (220 ms) is the shortest programmed paced cycle;
32. successful ramp and end of the episode.