Cause of temporarily reduced P-R interval?

[John Phillips]

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Hi there

What will cause a temporary reduction in a patient's P-R interval? I have noticed a fair bit of variation in the P-R intervals of certain patients, particularly athletes, and have heard a variety of explanations. These range from extertion immediately prior to the ECG to the ingestion of cold water to recent caffeine intake.

What do other people think?

John 😕

 

[ArkansasHogMD]

I would assume that anything that would suppress vagal tone or increased adrenergic release would shorten the PR interval. For example, exercise, caffeine intake, dobutamime, anticholinergics would all shorten PR interval. Keep in mind I'm a medical student so I'm not sure this correct but just my assumption.

 

[joeDO2]

another med student level response here but I have heard that the PR can shorten with hypokalemia. i could maybe see this as a reason for the athletes as they can be electrolyte depleted. other than that, there can be small changes in PR with changes in rate. as far as i know, the usual things you think of for short PR- wpw, lgl- keep pretty constant lengths.