Management of non-sustained VT and Duration

Tracing
N° 10
Manufacturer Boston Scientific Device ICD Field Therapy
Patient

This 80-year-old man suffering from severe ischemic cardiomyopathy and episodes of non-sustained VT underwent implantation of a Boston Science Cognis triple chamber defibrillator. He presented with a complaint of frequent palpitation and electrical shock.

Graph and trace

Summary 1

Episode of non-sustained VT.

Tracing 1

  1. atrial sensed biventricular stimulated rhythm;
     
  2. VT (AV dissociation);
     
  3. 8 out of 10 criterion fulfilled (V-Epsd); from this diagnosis onward the initial Duration of the VT zone began;
     
  4. spontaneous termination of the arrhythmia before the end of Duration;
     
  5. end of initial Duration (programmed at 3 sec); no treatment was possible on a cycle outside the zone of tachycardia; the 6/10 criterion remained fulfilled;
     
  6. the 6 out of 10 criterion was no longer fulfilled; no therapy was delivered; switch to permanent DDD pacing;
     
  7. second episode of non-sustained VT ending during the post-redetection Duration programmed at 3 sec. No therapy delivered;
     
  8. third episode of non-sustained VT during the Duration. No therapy delivered;
     
  9. fourth episode of non-sustained VT during the Duration. No therapy delivered;

Summary 2

Episode of VT requiring 2 salvos of ATP.

Tracing 2

  1. non-sustained VT identical to the previous tracing;
     
  2. recurrent non-sustained VT;
     
  3. third episode of non-sustained VT;
     
  4. further episode of VT identical to the previous;
     
  5. at the end of the post-redetection Duration, VT did not end spontaneously; detection of an episode of sustained VT (V-Detect);
     
  6. no additional delay takes place between the detection of an episode of sustained VT and ATP (unlike a shock, when the treatment is delivered after an additional delay corresponding to the charge of the capacitors and the reconfirmation at the end of the charge); burst of 8 ATP cycles;
     
  7. successful burst or spontaneous termination;
     
  8. further episode of non-sustained VT;
     
  9. identical sequence with VT lasting longer, burst of ATP and termination.

Summary

VT with 3 sequences of ATP, followed by VT accelerated by ATP and delivery of maximum 41-J electrical shock.

Graph and tracing

  1. non-sustained VT;
     
  2. VT of longer duration, burst of ATP and termination;
     
  3. VT of longer duration, burst of ATP and termination;
     
  4. VT of longer duration, burst of ATP and termination;
     
  5. VT of longer duration, burst of ATP;
     
  6. no termination; VT was and accelerated into the VF zone (very rapid VT);
     
  7. diagnosis of VF and charge of the capacitors;
     
  8. end of charge and reconfirmation of arrhythmia;
     
  9. 41-J shock;
     
  10. termination of the arrhythmia and return to sinus rhythm.
Comments

This clinical case underscores the importance of programming Duration. Before the delivery of ATP, no additional delay takes place between the end of Duration and therapy. Conversely, the charge time and the confirmation following the charge are added before the delivery of an electrical shock. Therefore, it is critical to optimize the programming of Duration in order to facilitate the spontaneous termination of non-sustained VT, while not compromising the safety of the patient. This patient presented with multiple episodes of non-sustained VT. The initial Duration was set at 3 sec. While it allowed the spontaneous termination of some episodes, it was probably too short for a large proportion of episodes, enabling the delivery of appropriate, though probably unnecessary therapies. Furthermore, a salvo of ATP accelerated the initial tachycardia to a rapid tachyarrhythmia that compromised the patient’s safety and required the delivery of an electrical shock. In this patient, it seemed key, therefore, to lengthen the initial and post-redetection Durations, in order to facilitate the spontaneous termination of non-sustained VT, especially since it is asymptomatic.