Conversion of supraventricular tachycardia with adenosine administration

Electrocardiogram during conversion of supraventricular tachycardia to sinus rhythm with administration of adenosine. During tachycardia at a rate of 230 beats/min, there is a normal-appearing QRS complex without a delta wave (no ventricular preexcitation), and there is no distinct P wave. After conversion to sinus rhythm, there is a short PR interval (80 milliseconds) and wide up-sloping QRS complex (90 milliseconds) representing ventricular preexcitation, indicative of the Wolff-Parkinson-White syndrome.