13th International Congress
THE "NEW FRONTIERS"
OF ARRHYTHMIAS 1998

January 24-31, 1998
Marilleva, Trento, Italy

S-166

Dual chamber pacemaker defibrillator:
clinical results

Ali Oto.
Hacettepe University School of Medicine, Ankara, Turkey

Detection of supraventricular tachyarrhythmias by a new algorithm using atrioventricular association

Currently to overcome the problem of inappropriate shocks for supraventricular arrhythmias the ICD devices have been loaded with several features including onset, stability, electrogram configuration and hemodynamic sensing criteria. Recently it has been suggested that incorporation of atrial electrogram monitoring and analysis of AV association allow sensitive and specific differentiation between ventricular and supraventricular tachycardia^9,10. In a study performed by Nair et al¹¹, a new algorithm including such a feature with dual chamber sensing ICD device (Defender 9001, Ela Medical) has been tested. The algorithm uses atrial and ventricular signals and performs a tiered analysis of arrhythmia in three steps: 1. cycle length sorting, 2. majority rhythm identification and 3. VT/SVT/ST sorting. Importantly four criteria have been used for detection and classification of tachy-arrhythmias in this algorithm namely ventricular rate, stability of RR intervals, type of AV association, acceleration magnitude and origin. The type of AV association has been used to differentiate VT and SVT in such a way that a stable ventricular rhythm without AV association is identified as VT and a stable ventricular rhythm with N: 1 association is defined as SVT. This algorithm was evaluated in 156 episodes of induced sustained tachycardias including SVT, atrial flutter, atrial fibrillation, ventricular tachycardia, flutter and fibrillation. The algorithm correctly diagnosed 96% of ventricular tachycardia episodes, 100% of ventricular fibrillation episodes and 92% of double tachycardia episodes (VT/VF associated with atrial flutter or fibrillation). The positive predictive value for the diagnosis of atrial fibrillation and flutter were 92% and 86%, respectively. In another study the same algorithm was used to evaluate the performance in discriminating the sinus rhythm. Twenty-four episodes of sinus tachycardia have been documented and in all cases the diagnosis was correct and no therapy was delivered.