RESUMO
BACKGROUND: The differential diagnosis between orthodromic atrioventricular reentry tachycardia (AVRT) and atypical AV nodal reentrant tachycardia (aAVNRT) is sometimes challenging. We hypothesize that aAVNRTs have more variability in the retrograde conduction time at tachycardia onset than AVRTs. METHODS: We aimed to assess the variability in retrograde conduction time at tachycardia onset in AVRT and aAVNRT and to propose a new diagnostic tool to differentiate these two arrhythmia mechanisms. We measured the VA interval of the first beats after tachycardia induction until it stabilized. The difference between the maximum and minimum VA intervals (∆VA) and the number of beats needed for the VA interval to stabilize was analyzed. Atrial tachycardias were excluded. RESULTS: A total of 107 patients with aAVNRT (n = 37) or AVRT (n = 64) were included. Six additional patients with decremental accessory pathway-mediated tachycardia (DAPT) were analyzed separately. All aAVNRTs had VA interval variability. The median ∆VA was 0 (0 - 5) ms in AVRTs vs 40 (21 - 55) ms in aAVNRTs (p < 0.001). The VA interval stabilized significantly earlier in AVRTs (median 1.5 [1 - 3] beats) than in aAVNRTs (5 [4 - 7] beats; p < 0.001). A ∆VA < 10 ms accurately differentiated AVRT from aAVNRT with 100% of sensitivity, specificity, and positive and negative predictive values. The stabilization of the VA interval at < 3 beats of the tachycardia onset identified AVRT with sensitivity, specificity, and positive and negative predictive values of 64.1%, 94.6%, 95.3%, and 60.3%, respectively. A ∆VA < 20 ms yielded good diagnostic accuracy for DAPT. CONCLUSIONS: A ∆VA < 10 ms is a simple and useful criterion that accurately distinguished AVRT from atypical AVNRT. Central panel: Scatter plot showing individual values of ∆VA in atypical AVNRT and AVRT. Left panel: induction of atypical AVNRT. The VA interval stabilizes at the 5th beat and the ∆VA is 62 ms (maximum VA interval: 172 ms - minimum VA interval: 110 ms). Right panel: induction of AVRT. The tachycardia has a fixed VA interval from the first beat. ∆VA is 0 ms.
Assuntos
Feixe Acessório Atrioventricular , Taquicardia por Reentrada no Nó Atrioventricular , Taquicardia Reciprocante , Taquicardia Supraventricular , Humanos , Taquicardia por Reentrada no Nó Atrioventricular/diagnóstico , Sistema de Condução Cardíaco , Taquicardia Reciprocante/diagnóstico , Fascículo Atrioventricular , Diagnóstico Diferencial , EletrocardiografiaRESUMO
The recognition of the presence, location, and properties of unusual accessory pathways for atrioventricular conduction is an exciting, but frequently a difficult, challenge for the clinical cardiac arrhythmologist. In this third part of our series of reviews, we discuss the different steps required to come to the correct diagnosis and management decision in patients with nodofascicular, nodoventricular, and fasciculo-ventricular pathways. We also discuss the concealed accessory atrioventricular pathways with the properties of decremental retrograde conduction that are associated with the so-called permanent form of junctional reciprocating tachycardia. Careful analysis of the 12-lead electrocardiogram during sinus rhythm and tachycardias should always precede the investigation in the catheterization room. When using programmed electrical stimulation of the heart from different intracardiac locations, combined with activation mapping, it should be possible to localize both the proximal and distal ends of the accessory connections. This, in turn, should then permit the determination of their electrophysiologic properties, providing the answer to the question "are they incorporated in a tachycardia circuit?". It is this information that is essential for decision-making with regard to the need for catheter ablation, and if necessary, its appropriate site.