Acceleration of FVT by a ramp and successful treatment by a shock

Patient

A 68-year-old recipient of an EnTrust VR single chamber ICD implanted for secondary prevention after a large anterior myocardial infarction, syncope and VT, presents with recurrent syncope and perception of ICD shock.

Trace

Sinus rhythm;
Sudden onset of a tachycardia detected in the VT and FVT via VF zone (TS and TF*);
FVT is detected (TF);
Ramp : 8 pulses in 10-ms decrements down to a lower limit of 200 ms (300 bpm);
Acceleration of the VT into a fast and organized tachycardia entering the VF zone;
Delivery of burst of ATP during charge of the capacitors;
The tachycardia is not terminated by a burst of ATP;
The capacitors charge up and an unsuccessful burst is delivered during the charge;
A 35.1 J DC shock is delivered without delay;
End of the episode.

Comments

This is another illustration of a burst of ATP delivered during charge of the capacitors. If unsuccessful, the shock delivery is not delayed. ATP 1) cannot be programmed before or during VT at rates >250 bpm, 2) has not been found effective for these very rapid tachycardias, and 3) would be unsafe. For example, in case of lead fracture, inter-artifacts intervals <150 ms might trigger ATP with a risk of induction of a life-threatening tachyarrhythmia.

Take home message

This episode is similar to the previous, but a shock was required to terminate the tachycardia.

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