What defines Mobitz type II second-degree AV block?

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Multiple Choice

What defines Mobitz type II second-degree AV block?

Mobitz type II second-degree AV block is defined by intermittent nonconducted atrial impulses without a preceding change in the PR interval. On the ECG you’ll see P waves marching through, and occasionally a P wave is not followed by a QRS complex, creating a dropped beat, while the PR interval on the beats that do conduct stays the same. This pattern reflects a block below the AV node, often in the His-Purkinje system, and it can be associated with a wide QRS if the block is distal. It differs from Mobitz I, where the PR interval progressively lengthens before a drop, and from complete heart block, where no atrial impulses conduct to the ventricles. Because the block can progress to complete heart block, it’s a presentation that usually prompts careful monitoring and consideration of pacing.

Mobitz type II second-degree AV block is defined by intermittent nonconducted atrial impulses without a preceding change in the PR interval. On the ECG you’ll see P waves marching through, and occasionally a P wave is not followed by a QRS complex, creating a dropped beat, while the PR interval on the beats that do conduct stays the same. This pattern reflects a block below the AV node, often in the His-Purkinje system, and it can be associated with a wide QRS if the block is distal. It differs from Mobitz I, where the PR interval progressively lengthens before a drop, and from complete heart block, where no atrial impulses conduct to the ventricles. Because the block can progress to complete heart block, it’s a presentation that usually prompts careful monitoring and consideration of pacing.

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