Electrocardiogram in Potassium Depletion : Part II: Atrial and Nodal Tachycardia in Digitalis Intoxication

As a toxic manifestation of digitalis ten episodes of paroxysmal atrial tachycardia with block, five episodes of nonparoxysmal A-V nodal tachycardia with block, two episodes of paroxysmal A-V nodal tachycardia and one episode of atrial flutter with block were observed in fourteen cases. Excessive dosage of digitalis, long-standing heart disease and siginificant potassium depletion resulting from the use of diuretics appeared to have precipitated these arrhythmias. Possible mechanisms operating in the production of the arrhythmias were discussed with reference to potassium and the existence of nonparoxysmal type of atrial tachycardea was suggested.