Atrial flutter and atrioventricular block

Intraatrial reentry tachycardia in an 18-year-old man following Mustard operation for D-transposition of the great arteries. There is 2:1 atrioventricular conduction and low-amplitude "flutter" waves (f waves), making the diagnosis difficult to recognize. The administration of adenosine results in the obvious appearance of f waves. The sweep speed is 50 mm/sec.