A 55-year-old woman had the following electrocardiogram recorded at her annual physical. She reported to her doctor that sometimes her pulse rate feels strong and at other times it feels weak. Standard limb lead II is shown. What is her likely diagnosis?

Question

A 55-year-old woman had the following electrocardiogram recorded at her annual physical. She reported to her doctor that sometimes her pulse rate feels strong and at other times it feels weak. Standard limb lead II is shown.  What is her likely diagnosis?

Quizplus · Accepted Answer

The ECG shows a regular rhythm with a narrow QRS complex, indicating sinus rhythm. However, there are occasional dropped beats, which is indicative of a second-degree AV block. The fact that the dropped beats are not preceded by a lengthening PR interval suggests that this is a Mobitz type II block rather than a Mobitz type I (Wenckebach) block. The patient's symptoms of alternating strong and weak pulse are consistent with intermittent AV block.

A 55-Year-Old Woman Had the Following Electrocardiogram Recorded at Her