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Figure 8 Proposed Schema of the Differential Effects of Adenosine for Atrial Tachycardia

Properties of triggered, automatic, and re-entrant arrhythmias are summarized, as developed in this study and other sources. Adenosine-sensitive atrial tachycardia is typically focal in origin and due to triggered activity or, far less commonly, automaticity. Adenosine-insensitive atrial tachycardia is either macro–re-entrant or micro–re-entrant, depending on circuit size and the resolution of the mapping system. Entrainment with post-pacing interval (PPI) nearly equal to the atrial tachycardia cycle length (ATCL) is typical for "macro" or "micro" re-entrant tachycardias but is not specific for these mechanisms (see text for discussion). Prolonged electrogram durations, >20% of the ATCL, may be recorded at early sites in micro–re-entrant tachycardias but are not typical at the origin of triggered and automatic rhythms. Electrogram durations at sites around a macro–re-entrant circuit might vary depending on local conduction characteristics. N/A = data not available; PES = programmed electrical stimulation.