Cardiac HealthStream Telemetry Practice Exam

The key idea is how these second‑degree AV blocks look on telemetry, specifically the behavior of the PR interval and when a beat is dropped. In Mobitz I (Wenckebach), you observe a progressive prolongation of the PR interval with each beat until a P wave is not followed by a QRS—the dropped beat after a lengthened PR. In Mobitz II, you see dropped beats without any preceding PR prolongation—the PR interval before the drop stays the same, and the block is typically below the AV node. Sometimes Mobitz II can have a wide QRS if the block is infranodal, whereas Mobitz I usually has a narrow QRS. This makes the pattern described in the correct choice the best match: progressive PR prolongation with eventual dropped beats for Mobitz I, and dropped beats without PR prolongation with a fixed PR interval for Mobitz II. The other options mix up these features or rely on symptoms, which aren’t reliable on telemetry.