12. Effect of tachycardia rates on ATP profile
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Interpretation
- After a conducted sinus rhythm
- Onset of monomorphic VT detected in the VT zone.
- After 20 persistence cycles, an ATP is delivered, a ramp from the outset. The coupling interval of the first cycle is 85% of the tachycardia reference coupling interval (335 ms) calculated on the average of the last 4 persistence cycles (value obtained via the Ā« Analysis Ā» menu)
- Unsuccessful, and upon validation of the VT majority in redetection, a second burst is applied. The cycles of this ramp are identical to the previous ramp, since the tachycardia reference coupling interval is the same. There is no programmed decrement, but a cycle is added to this ramp which therefore includes 6+1 cycles
- Unsuccessful, a third ramp is applied. The tachycardia reference coupling interval is now a little shorter (289 ms), such that the coupling interval of the ramp cycles will be shorter, always 85% of the reference coupling interval of 289 ms.
- During the 3rd ramp, we can see that the last 5 cycles of the ramp are at the minimum programmed coupling interval of 220 ms, explaining the plateau of the 3rd ramp on the tachogram. This ramp is therefore particularly aggressive.
Comments
- This case illustrates once again the sequence of therapies according to an increasingly aggressive escalation. The ramps follow one another by adding a cycle to each ensuing ramp
- A ramp is a very brutal therapy which risks degrading a monomorphic tachycardia into ventricular fibrillation. Its coupling percentage must be higher than that of a burst. If the percentage of the coupling time of the first cycle of the ramp is low, this means a fast ATP onset rate followed by an acceleration which quickly reaches the programmed minimum coupling time.
- In this patient, it is ramps that are applied and not bursts as programmed in the VT zone. This results from the Ā« Autoswitch ATP Ā» function which will analyse the type of ATP that was effective during the previous VT episode (ATP 1 or ATP 2) that was successfully treated. The type of ATP that was effective will be the first applied on the next VT episode. It is therefore certain that a ramp was effective during the previous VT episode. Programming this function to Ā« No Ā» will cause the first ATP applied in the VT zone of each episode to be a burst.
- In point of fact, this function is interesting on paper, since we can assume that what has been effective once will also be effective the next time. However, the tachycardias may have a different emergence and therefore a different circuit, such that therapy that has entered the circuit of one tachycardia may not be able to penetrate the circuit of another. Even if the tachycardia is exactly the same, the conditions of onset may differ: exertion/rest, postprandial/fasting, night/day, time of day relative to the taking of medication, serum electrolytes, hemodynamic state, etc. In all of these cases, this appealing theory may not work.
- However, certain patients will respond favourably to this situation.
Message
- The Ā« Autoswitch ATP Ā» function allows to immediately use the ATP sequence that was effective on a VT from a previous episode.
- It should be understood that the first line of therapy may be a ramp.
- The ramp is an aggressive therapy with pacing cycles often reaching the minimum coupling value programmed at the end of the sequence.
- The programming decision should be on a case-by-case basis.
- Information on the number of Ā« Autoswitch ATP Ā» occurrences and the date of the last switch is displayed on the ATP programming screen.
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1. Question
Patient
A 58-year-old woman, implanted with a dual-chamber PARADYM DR, in secondary prevention for sustained monomorphic VT due to arrhythmogenic dysplasia of the right ventricle. She consulted after having received shocks.
Programming
Ā Three zones are programmed:
- A monitoring zone between 120 and 160/min, after 30 persistence cycles;
- A VT zone between 160 and 220/min with 3 Bursts + Scan, then 3 Ramps, then 16 J, then 42 Jx5, after 20 persistence cycles;
- A VF zone above 220/min, with a ramp between 220 and 240/min if stable VT, and 6X42J, after 10 persistence cycles.
Tachogram
EGM
What is your opinion?
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