Ventriculoatrial conduction metrics for classification of ventricular tachycardia with 1:1 retrograde conduction in dual-chamber sensing implantable cardioverter defibrillators.

The introduction of dual-chamber sensing in implantable cardioverter defibrillators (ICDs) has greatly reduced the incidence of false detection due to supraventricular tachycardias. The remaining arrhythmias which serve to confound classification are supraventricular tachycardias (SVTs) with 1:1 anterograde conduction and ventricular tachycardias (VT) with 1:1 retrograde conduction. An algorithm has been designed and tested (28 patients) which employs ventriculoatrial (VA) conduction measurements to separate 1:1 VTs from 1:1 SVTs. A study was conducted to assess realistic VA interval boundaries for classification of arrhythmias with 1:1 retrograde atrial conduction. Intracardiac atrial and ventricular recordings of 7 passages of VT with retrograde conduction, 12 passages of atrioventricular nodal reentrant tachycardia (AVNRT), 3 passages of atrial tachycardia (AT), 8 passages of sinus tachycardia (ST), and 2 passages of orthodromic reentrant tachycardia (ORT) were analyzed. Automated real-time atrial and ventricular waveform recognition was performed on each passage and VA intervals were measured. Separation of VT with retrograde conduction from other 1:1 supraventricular tachycardias was effected by imposing discrete VA interval boundaries. VA boundaries of 80 ms to 234 ms classified 1:1 VT with 100% sensitivity (SENS) and 80% specificity (SPEC). In addition, the lower boundary completely classified AVNRT with 100% SENS and 100% SPEC, and all passages of ST were contained above the upper boundary. These findings could be of importance in algorithms for next-generation implantable cardioverter defibrillators which include two-chamber (atrial and ventricular) sensing and two-chamber interval measurements.