Adenosine-Induced Autogain102

Report:

Atrial flutter 320/min with 2:1 block

Ventricular standstill (third strip)

Continued atrial flutter

Escape complexes of unknown origin

Resumed 2:1 conduction of flutter (last two strips)

Comment:

At first the recording looks like the rare but well-recognised acceleration of ventricular response to flutter by adenosine103. In the third strip, the 12 mg dose of adenosine appears to have replaced 2:1 conduction with a brief (1.12") period of advanced block and then 1:1 conduction, with rate-dependent bundle branch block. The large complexes obviously have the same rate as the F waves.

The problem with that interpretation is that there are QRS complexes superimposed on the putative flutter with 1:1 conduction. This, and the knowledge that the patient remained asymptomatic (while coughing as instructed, but protesting and wondering why he had to cough), point out to a different interpretation: the monitor's AUTOGAIN function has augmented the F waves to make them look like QRS complexes.

The autogain device fooled me, amongst others. We should be wary as well as aware of new technologies.

146. 29 year old lady with congenital pulmonary stenosis. She had corrective surgery several years previously.