Introduction: Accessory pathways with atypical behavior may be interpreted as benign, according to studies conducted so far. However, there are exceptions to be taken into account to avoid unwanted evolution.
Methods: Between 1998 and 2018, 7 patients with aty-pical accessory pathways were evaluated in the Cardiac Electrophysiology departament of IBCV Timișoara. Patients were referred from other centers to perform electrophysiological testing and radiofrequency catheter ablation.
Results: Patients with accessory pathways with atypi-cal manifestation presented: • Wolff-Parkinson-White (WPW) syndrome with sudden death risk • Accessory pathways with exclusively retrograde conduction but demonstrating retrograde conduction only at increa-sed ventricular electrostimulation frequencies -2p The rigorous electrophysiological study has diagnosed the sudden death risk in WPW syndrome and the recipro-cal atrioventricular orthodromic tachycardia in the case of exclusively retrograde conduction pathways. One of the most representative cases of atypical behavior of the accessory pathway was WPW syndrome diagnosed as initially benign, but under certain circumstances chan-ged to risk of sudden death. Conditions associated with modification of the anterograde conduction through the accessory pathway by changing its electrophysio-logical properties in the WPW syndrome were: • fever illness • virosis with cardiac tropism • radiofrequen-cy catheter ablations with local thermal irritation, the modified properties of the accessory pathways being discovered after re-evaluation by electrophysiological study in the context of recidive.
Conclusions: Patients with unusual accessory pathways are at risk of developing associated complications, of which the most dreaded is sudden death by arrhythmic mechanism in the case of intermittent WPW syndrome with increased vital risk. Patients with exclusively re-trograde conduction pathways demonstrated at increa-sed frequencies of ventricular stimulation may remain undiagnosed in the absence of a thorough electrophy-siological study. Radiofrequency ablation can eliminate the risk of atypical behavioral complications in the WPW syndrome.