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ECG Findings

  • PR interval greater than 200 ms (normal 120-200 ms) with no significant variation in PR intervals between beats.

  • Each P wave is followed by a QRS complex.


  1. This type of heart block usually does not affect heart function and can be considered nonpathologic (especially in athletes or patients with higher vagal tone).

  2. First-degree block may also occur due to heart disease (myocarditis, rheumatic fever), drugs (digoxin, amiodarone, β-blockers, calcium channel blockers), or as a normal part of aging.


First-Degree AV Block. (ECG contributor: James V. Ritchie, MD.)


The PR interval is fixed (double arrows) and is longer than 0.2 seconds, or five small blocks.

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