Family Medicine is losing ground to Emergency Medicine with the most missed questions this week.
The reasons why questions most often get missed fall into two categories, one is question structure, what we’ll call exam tricks, and the other is clinical knowledge. Test questions are designed to identify the difference between being familiar with a subject, and being an expert in the subject.
Exam tricks, sometimes referred to as stupid exam tricks, are on the exam for a reason. Most of the times you see a bit of extraneous information on one of your exam questions, it is relevant to a diagnosis. But occasionally, you will have certification questions where it distracts from the correct answer, giving you something familiar to fall back on if you don’t know the material well. Tricky.
The question is about diagnosing an atrial septal defect (ASD), and in this case, the most common type - ostium secundum.
The left-to-right shunt in an ASD leads to increased flow through the right heart, causing volume overload and subsequent dilation. This dilation contributes to conduction delays, manifesting as the incomplete RBBB pattern on the ECG. The correct answer is (b).
The most often incorrect answer was (d) left-axis deviation and first-degree atrioventricular block. Both Chagas disease and rheumatic heart disease lead to conduction disturbances, and Chagas presents with a classic RBBB with left anterior fascicular block. But the physical exam strongly points to atrial septal defect. The test-takers eyeballs hit the left-axis deviation and first-degree AV block and stop. 😀
The stupid exam trick here is the red herring of recent immigration from Central America, which is supposed to prompt you to consider Chagas disease or rheumatic heart disease. This type of distractor is not common across exam questions, but there will be some.
The clinical question is integration of physical findings with the ECG. Recognizing an incomplete RBBB and subtle right-axis deviation can be tricky. You need a thorough knowledge of the pathophysiology.
The distractor here serves the purpose of ensuring the test-taker has that knowledge. Asymptomatic congenital diseases may not be encountered frequently, because…asymptomatic. That lack of exposure can lead to gaps in recalling the associated ECG features.
This question appears in Med-Challenger Family Medicine Exam Review with CME
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