Adenosine-Sensitive Bundle Branch Reentry, Introduction: Bundle branch
reentry is an uncommon mechanism for ventricular tachycardia. More in
frequently, both fascicles of the left bundle may provide the substrat
e for such macroreentrant bundle branch circuits, so-called interfasci
cular reentry, The effect of adenosine on bundle branch reentrant mech
anisms of tachycardia is unknown. Methods and Results: A 59-year-old m
an with no apparent structural heart disease and history of frequent s
ymptomatic wide complex tachycardias was referred to our center for fu
rther electrophysiologic evaluation, During electrophysiologic study,
a similar tachycardia was reproducibly initiated only during isoproter
enol infusion, which had the characteristics of bundle branch reentry,
possibly using a left interfascicular mechanism, Intravenous adenosin
e reproducibly terminated the tachycardia, Application of radiofrequen
cy energy to the breakout site from the left posterior fascicle preven
ted subsequent tachycardia induction and rendered the patient free of
spontaneous tachycardia during long-term follow-up, Conclusions: Patie
nts with ventricular tachycardia involving a bundle branch reentrant c
ircuit may be sensitive to adenosine, These results suggest that adeno
sine may not only inhibit catecholamine-mediated triggered activity bu
t also some catecholamine-mediated reentrant ventricular arrhythmias.