Dual chamber discrimination: V<A
Tracing
Manufacturer Abbott
Device ICD
Field Discrimination
N° 53
Patient
This 69-year-old man suffering from ischemic cardiomyopathy received a St Jude medical Fortify dual chamber ICD for primary prevention and was seen for a routine follow-up.
Main programmed parameters
- VF zone at 240 bpm, VT-2 zone at 200 bpm and VT-1 zone at 162 bpm
- 12 cycles in each the VF, VT-2 and VT-1 zones were needed for the diagnosis
- Effective discrimination in the VT-1 and 2 zones
- V<A: if all criteria are fulfilled; morphology (60%, 5 out of 8), stability (80 ms), with 60-ms AV association delta, 12 intervals
- V=A: if all criteria are fulfilled; morphology (60%, 5 out of 8), sudden onset (100 ms)
Graph and trace
Narrative
Episode of SVT diagnosed in the V<A arm. This patient needed the programming of 2 out of 2 criteria for the diagnosis of VT; the morphology criterion indicated SVT, whereas the stability criterion indicated VT. However, the AV association criterion (which was passive and not included in the diagnosis) favored SVT. No therapy was delivered.
Tracing
- AF-flutter with rapid ventricular rate, initially irregular, then more regular. Morphology in favor of SVT;
- from this complex onward, 12 cycles elapsed before the diagnosis, during which stability was analyzed;
- from this complex onward, 8 cycles elapsed before the diagnosis, during which morphology was analyzed;
- diagnosis of SVT in the V<A arm (SVT<); the morphology of the 8 analyzed complexes is in favor of SVT (similar morphology). The rhythm was interpreted as stable: out of the 12 analyzed cycles, the second shortest and second longest measured, respectively 344 and 375 ms, representing a 31-ms delta. While this criterion was in favor of VT the AV association (which was present) was in favor of SVT;
- slowing of the ventricular rate and diagnosis of return to sinus rhythm.
Other articles that may be of interest to you
The pertinent discriminators of AF or flutter with preserved AV conduction are stability, AV association and morphology. The programming of “All” is more specific than the programming of “One of”. In order to distinguish flutter from VT, the AV association criterion can be programmed. In this patient, this programming prevented the development of inappropriate therapies. The stability criterion is often misleading during episodes of AF with a rapid ventricular response or during flutter. This tracing probably shows flutter with 3:1 conduction.