If you’re preparing for the United States Medical Licensing Examination® (USMLE®) Step 1 exam, you might want to know which questions are most often missed by test-prep takers. Check out this example from Kaplan Medical, and read an expert explanation of the answer. Also check out all posts in this series.

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Two sets of cardiovascular function curves

The graph shows two sets of cardiovascular function curves. The solid lines describe the cardiovascular performance of a 60-year-old man, with point "N" indicating normal resting conditions. The two broken lines describe cardiovascular performance in the same man six months after he suffered a myocardial infarction. Auscultation of his chest reveals moderate rales bilaterally.

He takes daily walks as recommended by his cardiologist, but he tires easily and coughs excessively whenever he attempts to walk rapidly. His resting cardiac output is now 4.5 L per minute.

Which of the following is most likely his right atrial pressure at rest?

A. 0 mm Hg.

B. 1 mm Hg.

C. 4 mm Hg.

D. 7 mm Hg.

E. 9 mm Hg.

F. 11 mm Hg.

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The correct answer is D.

The patient's cardiovascular performance at rest is indicated by the two broken lines that intersect at a cardiac output of 4.5 L per minute and a right atrial pressure (RAP) of 7 mm Hg. 

Did you answer the test-prep question correctly? Login to learn more from Kaplan Medical about the test-taking strategy behind getting the right answer. That includes:

  • Evaluating the clinical vignette.
  • Why other answer choices can be eliminated.
  • Tips to remember.
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