UMEM Cases, Part 2: When the ECG Conceals and When It Reveals

UMEM Potpourri ECG Cases with Dr. Amal Mattu


HPI

An 81-year-old woman presents with lightheadedness and marked bradycardia. Her ECG shows more P waves than QRS complexes, but the mechanism is not immediately clear. The key question is whether the PR intervals follow a pattern or whether the atria and ventricles are dissociated.

Before watching this week’s workout, review the arrival ECG carefully and consider:

    1. When there are more P waves than QRS complexes, what PR pattern would support complete heart block rather than second-degree AV block?
    2. Why does even slight PR variability make Mobitz II the wrong diagnosis?
    3. What additional clue does a slow but very regular narrow-complex escape rhythm provide?