The Race Is Not to the Swift…

Report:

Sinus rhythm & arrhythmia 58 - 74/min.

Left anterior hemiblock (LAHB).

Right bundle branch block (RBBB).

Second degree AV block, 2:1, rate-dependent.

Comment:

The patient has, in addition to obvious conduction problems, an abnormally marked sinus arrhythmia: impulse formation may not be much better than their conduction.

At the time of transition to 1:1 conduction, the sinus slowing is almost imperceptible, but it becomes quite marked further down the rhythm strip. The resolution of the block with slowing of the sinus rate indicates its rate-dependency; it would have been interesting (but unethical) to see its response to atropine. A block at the ventricular level would be expected to get worse. Festina lente!

Most centres would advise prophylactic pacing for this ECG. I would prefer to offer it at the slightest provocation.

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