Second-Degree Type I (Wenckebach) — ECG Academy Lesson

Master the progressive PR prolongation pattern of Wenckebach block, recognize the grouped beating pattern, and understand why this AV-nodal level block is generally more benign than Type II.

Learning Objectives

• Describe the hallmark pattern: progressive PR prolongation followed by a dropped QRS
• Explain why the PR interval resets to its shortest value after the dropped beat
• Recognize the grouped beating pattern on a rhythm strip
• Identify that the block occurs at the level of the AV node
• List common causes including inferior MI, increased vagal tone, and AV-nodal blocking medications
• Differentiate Type I from Type II second-degree block by PR interval behavior