gms | German Medical Science

AV reentrant tachycardia is the most common arrhythmia in childhood. Radiofrequency catheter ablation becomes a main method of treatment and noninvasive determination of the underlying mechanism is important before the procedure.In order to discriminate AV node reentrant tachycardia (AVNRT) and AV reciprocating tachycardia (AVRT) several ECG criteria are used.

Objectives: We evaluated the predictive value of several ECG markers narrow QRS complex tachycardia.

Methods: 27 children (mean age 12.5 years) after complete electrophysiological study and successful radiofrequency ablation of AVNRT or AVRT were studied. The 12-lead ECG were recorded during spontaneous narrow QRS complex (<0,11s)tachycardia. AV reciprocating tachycardia utilizing an accessory pathway was presented in 19 cases and atriventricular node reentrant tachycardia has been found in 8 cases. For detecting AVRNT and AVRT we studied: ST segment changes, RP duration, pseudo r'/S waves. Results: ST segment depression more than 2 mm was presented in 12 cases of AVRT (specificity and sensitivity 63%) and in 3 children with AVNRT. Neither pseudo r'waves in V1 nor pseudo S waves in inferior leads were shown during both tachycardia. The retrograde P waves were visible in 8 children with AVRT (specificity 75%, sensitivity 42%) and only in 2 children with AVNRT (specificity 58%, sensitivity 25%). RP' exceeded 110 ms in 7 of the 19 cases of AVRT (specificity 100%, sensitivity 37%). The combination of discernible P wave and ST segment depression more than 2 mm was found in 3 cases of AVRT (specificity 100%, sensitivity 15,8%).

Conclusion: The most valuable markers in our study were discernible P wave and ST segment depression more than 2 mm, their combination increased the predicative value. If even one of these features are not presented on the ECG during tachycardia a differentiation between two electrophysiological mechanisms of tachycardia by standard ECG was complicated.