Accurate discrimination of atrial fibrillation
Patient
This 61-year-old man received a Lumax 340 HF-T triple chamber defibrillator for primary prevention indication in the context of a dilated cardiomyopathy with left bundle branch block. An event report (yellow color) was issued in the context of a classified SVT.
Main programmed settings
- VF zone (260 ms limit), VT2 zone (330 ms limit), VT1 zone (370 ms limit)
- 12/16 cycles in the VF zone, 16 cycles in the VT2 zone and 26 cycles in the VT1 zone were needed for the diagnosis
- Maximum sensitivity programmed at 0.8 mV
- VF zone: ATP one shot, followed by 8 shocks of maximum strength (40 J); VT2 zone: 3 bursts of ATP, followed by a single 20-J shock, followed by 7 shocks of maximum strength; VT1 zone: 4 bursts of ATP, followed by 3 ramps, followed by a single 7-J shock, followed by a single 12-J shock, followed by 6 shocks of maximum strength;
- Effective discrimination in the VT2 and VT1 zones (SMART discrimination)
- Pacing mode: biventricular DDD at 50 bpm
Trace
Telecardiology tracing
The 4 channels available are 1) the markers with the time intervals, 2) the atrial (A) sensing channel, 3) the right ventricular (RV) sensing channel, and 4) the left ventricular (LV) sensing channel;
- mode switch for atrial arrhythmia (MSw DDI);
- fast and irregular atrial rhythm with rapid and irregular atrioventricular conduction, consistent with atrial fibrillation. On the atrial channel, the cycles are classified As or Ars; on the ventricular channel, Vs markers indicate the cycles outside the VT1 zone (370 ms limit) and markers FibA indicate the shorter cycles;
- classification of SVT episode in the PP<RR arm. On several occasions, the ventricular cycles are irregular and the RR cycles are unstable. Consequently, the device classified the episode as atrial fibrillation and no therapy was delivered.
