Editorial note: The following quiz is related to the article Loss of Right Ventricular Capture: When It Is Not the Lead’s Fault Albert Y. Liu and colleagues in the January 2025 issue of Heart Rhythm Case Reports.

1. This 12-lead ECG was obtained at presentation from the patient in this case. Based on the QRS morphology, where is the patient most likely being paced?

2. Which of the following causes of pacemaker failure to capture would not be detectable on chest radiograph?

3. Which of the following causes of pacemaker failure to capture would most likely be accompanied by significant changes in bipolar lead impedance?

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