Scenario: This is a dual-lead (II and V1) monitoring strip from a 72-year-old man admitted to the emergency department for nonspecific chest pain. The patient’s initial chest pain quickly resolved with nitroglycerin, and he remains asymptomatic. In fact, the patient and his wife are ready to go home because it is getting late and they do not want to drive home in the dark.

Interpretation: Normal sinus rhythm with first degree atrioventricular (AV) block at 60 beats per minute (bmp), with a brief episode of nonsustained ventricular tachycardia (NSVT).

The underlying rhythm is normal until the burst of NSVT occurs. However, when the PR interval is carefully measured, it exceeds 0.20 seconds, thereby meeting the criteria of first-degree AV block, a rhythm in which every sinus impulse is transmitted to the ventricles yet there is a delay in the conduction of the impulse. First-degree AV block is generally...

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