ECG of atrial tachycardia with resultant paroxysmal complete AV block

The continous lead II electrocardiogram (ECG) tracing initially shows a regular tachycardia at a rate of 160; the QRS complex is wide with a terminal S wave compatible with a right bundle branch block. There is gradual slowing of the rate with the development of atrioventricular (AV) nodal block; ultimately a series of nonconducted P waves (arrows) are seen and there is one escape ventricular premature beat (*). After a second ventricular premature beat (+), sinus rhythm is restored.