Complete AV Block

Report:

Third degree AV block

Sinus bradycardia 42/min

Junctional beats (top strip)

Atrial fibrillation

Junctional escape rhythm 36/min

Pacemaker rhythm 82/min

Short QT interval ? digoxin toxicity

Comment:

The varied atrial activity has no effect on the junctional escape pacemaker, protected by the AV block.

Inverted junctional waves in the top strip may be designated as escape beats because of the general setting of bradycardia; they are not, strictly speaking, escape beats with respect to sinus P waves, which occur at approximately the same rate. The sinus cycle following the first junctional P wave is prolonged due to post-ectopic sino-atrial depression.

The QT interval of 0.40” is short for the rate (in this lead, at least), raising the possibility of digitalis toxicity. Sinus bradycardia is equally consistent with that diagnosis, while third degree AV block is one of its cardinal manifestations. Unfortunately, the patient’s records are no longer available.

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