Which of the following is NOT listed as a cause of low cardiac output?

• A. MI
• B. Hypovolemia
• C. Tamponade
• D. Hyperkalemia

Answer: (D)

The main idea here is understanding the direct ways that cardiac output can be reduced: by the heart’s pumping ability, by the amount of blood returning to the heart, or by a physical obstruction that prevents filling or outflow. A myocardial infarction directly damages contractility, so the heart can’t pump effectively. Hypovolemia lowers preload, meaning there’s less blood available to be ejected each beat. Tamponade physically compresses the heart, limiting its filling and reducing stroke volume. Hyperkalemia, while it can cause dangerous rhythm problems that may drop cardiac output, is an electrolyte disturbance rather than a direct mechanism that reduces output in the same direct ways as the others. In this context, it isn’t listed as a primary cause of low cardiac output, so it’s the correct choice.