Second-Degree Type II (Mobitz II) — ECG Academy Lesson

Learn to identify second-degree Type II AV block by its constant PR interval with sudden dropped QRS complexes, understand the infranodal level of block, and recognize why this rhythm carries a high risk of progression to complete heart block.

Learning Objectives

• Describe the hallmark pattern: constant PR intervals with intermittently non-conducted P waves
• Explain why the PR interval does NOT change before a dropped beat — the key distinction from Type I
• Identify the anatomic level of block as below the AV node (Bundle of His or bundle branches)
• Recognize that a wide QRS in Type II suggests the block is low in the conduction system
• List common conduction ratios (2:1, 3:1, 4:1) and explain what they mean
• Explain why Type II carries a high risk of progression to complete heart block
• Describe the urgent monitor tech response required for this rhythm