Permanent form of junctional tachycardia

12-lead ECG and lead II rhythm strip obtained from a patient with junctional tachycardia at a rate of 165 beats/min. The QRS complex is narrow and there are negative P waves with a long RP interval due to slow retrograde conduction via an accessory pathway. The tachycardia tends to terminate spontaneously and recur, as seen in the rhythm strip. Termination is due to retrograde block in the accessory pathway with absence of the retrograde P wave (arrow). An atrial premature beat (*) reinitiates the tachycardia.