Electrophysiological effect of adenosine triphosphate and adenosine on atrial and ventricular action potential duration in humans

Bolus injection of adenosine triphosphate (ATP) or adenosine is widely used clinically for terminating supraventricular tachycardia. However, bolus in jection of these drugs has been reported to provoke atrial fibrillation (Af ib). The effects of ATP and adenosine on the monophasic action potential du ration (MAPD) of atrial and ventricular muscle was investigated, as well as the changes in the spatial distribution of atrial functional refractorines s caused by adenosine. Bolus injection of ATP and adenosine shortened atria l MAPD; no change was observed in the ventricle. Because local f-f interval s during atrial fibrillation correlate with the atrial refractory period, c hanges in mean f-f intervals in the right atrial appendage, His bundle regi on, coronary sinus ostium and distal coronary sinus were compared before an d after injection of adenosine during induced Afib. Maximal shortening of f -f intervals was observed in the right atrial appendage. Inhomogeneous shor tening of atrial refractoriness may account for the Afib following bolus in jection of ATP or adenosine.