Cesium-induced atrial tachycardia degenerating into atrial fibrillation in dogs: Atrial torsades de pointes?

Introduction: In this study, we investigated whether the potassium channel blocker, cesium chloride (CsCl), which is capable of producing early afterdepolarizations (EADs) and polymorphic ventricular tachyarrhythmias resembling torsades die pointes, might exert similar effects in the atria. Methods and Results: In nine anesthetized open chest dogs, 5 mL of CsCl in incremental doses (0.05, 0.1, 0.15, 0.2, 0.25 mM/mL) was injected irate the sinus node artery to induce atrial arrhythmias. A polymorphic atrial tachycardia (P-AT) apparently triggered by an EAD and degenerating into atrial fibrillation resulted after CsCl administration in six dogs, but not in the remaining three dogs at any dose of CsCl, The P-AT developed during a normal atrial rate (110 +/- 13.5 beats/min) on six occasions and during atrial bradycardia (58.6 +/- 17.9 beat/min) five times. P-AT that occurred during a normal atrial rate had the last normal P wave temporally closely related to ventricular activation, with a VA interval of almost zero (1.3 +/- 3.3 msec), whereas P-AT induced from are atrial bradycardia had Pro relation to ventricular activation. The % EAD in the atrial bradycardia group (13.9 +/- 2.5) exceeded that in the normal atrial rate group (10.9 +/- 1.8) (P < 0.05). Conclusion: CsCl induces atrial EADs that provoke P-AT that degenerates into atrial fibrillation, P-AT has some characteristics similar to ventricular torsades de pointes.