Adenosine Asystole

Report:

Atrial flutter 300/min

High-grade (advanced) second degree AV block

Transient asystole

Ventricular escape beat

Comment:

The patient was admitted to CCU in flutter 310/min with 2:1 block (Fig 12a below). In all fairness, distinction from SVT cannot be made from this ECG. Carotid sinus massage had no effect. He was given amiodarone, 300 mg IV, which slowed the flutter rate minimally, to 300/min. Next, adenosine, 6 mg + 12 mg was administered, with transient ventricular standstill shown on the previous page. The flutter became obvious.

Adenosine, a relatively “pure” AV nodal blocker7, rarely causes this degree of block; pre-treatment with amiodarone probably helped. In atrial flutter, in fact, acceleration of the ventricular response has been reported8, 9. The patient remained, insofar as could be ascertained, asymptomatic and reverted spontaneously to sinus rhythm an hour later.

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