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Rhythm Filters
Zoom: 100%
Measurement: --
PR / Heart Block Measurement Guide
Paper speed: 25 mm/s → 1 small box = 0.04 s (40 ms), 1 large box = 0.20 s.
PR interval: Normal is 0.12–0.20 s (3–5 small boxes).
- 1° AV block: PR > 0.20 s and constant.
- 2° Type I (Wenckebach): PR progressively lengthens, then dropped QRS.
- 2° Type II: PR constant on conducted beats with intermittent dropped QRS.
- 3° (complete) block: AV dissociation — P waves and QRS march independently.
Tip: Use RR box count to estimate rate and compare atrial vs ventricular regularity in blocks.
What is this rhythm?
Generated: 0
Correct: 0
Accuracy: --%
Pro tip: Use the measurement tool to compare atrial vs ventricular rates when practicing AV blocks.