Mobitz I vs Mobitz II

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Both Mobitz I and Mobitz II are forms of second-degree AV block, with very different degrees of importance.

 

Mobitz I (Wenckebach)

• progressive lengthening of the PR interval

• then a dropped beat

• then the pattern repeats

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Mobitz II

• a fixed PR interval

• then a sudden dropped beat

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Mobitz I is often less dangerous. Mobitz II is more concerning because it may reflect more serious conduction system disease.

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Key pearl: If the PR interval stays the same and then a beat drops, think Mobitz II.

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Mobitz I vs Mobitz Video

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