Seventy-three years old man implanted with a dual chamber ICD EnTrust DR in the context of a dilated cardiomyopathy with a low ejection fraction (LVEF<30%).
This episode is indeed a sinus tachycardia and was recorded while the patient was performing a stress test on a bicycle (Note in the text, that the activity sensor did not detect this particular form of exercise).
The PR Logic works for the initial detection of the tachycardia but not for its redetection. This algorithm is based on the permanent analysis of 6 simultaneous criteria :
1) Atrial and Ventricular rate analysis (median PP and RR intervals calculation)
2) Pattern of atrial and ventricular events (analysis of the P-wave position between 2 consecutive RR intervals)
3) AF counter (Counter of RR intervals with ≥2 of atrial signals by RR interval)
4) Far-field R wave sensing (Explore the consistency of the AA pattern. Search for consecutive « short-long-short » sequence of PP intervals)
5) Ventricular rate regularity (frequency of the two most common intervals)
6) Atrio-ventricular dissociation (Atrial and ventricular rate comparison)
For this patient, the ICD diagnosed an episode of sinus tachycardia :
1) No R-wave far field was detected
2) The P to R-wave relationship corresponded to a sinus tachycardia pattern : indeed, there were as many P-waves as R-waves and the P-waves were located into the second part of the RR cycle (zone of anterograde conduction).
3) The median RR and PR interval were within the expected range for this diagnosis.
Three detection zones are programmed. Discrimination in the VT zone is based only on the PR Logic algorithm. The sudden onset and the stability are turned off. With the PR Logic, the AF/Afl search, the sinus tachycardia, the SVT 1 :1 are activated. The present episode is labeled SVT because the PR logic algorithm had recognized a sinus tachycardia.
