JBL EMT Practice Exam

Which of the following would cause the greatest increase in cardiac output?

1. Decreased heart rate and increased stroke volume

2. Decreased stroke volume and decreased heart rate

3. Decreased stroke volume and increased heart rate

4. Increased heart rate and increased stroke volume

The correct answer is: Decreased heart rate and increased stroke volume

Decreasing heart rate and increasing stroke volume would lead to the greatest increase in cardiac output. When the heart rate decreases, the heart has more time to fill with blood, allowing it to increase the volume of blood ejected with each heartbeat (stroke volume). By having more blood pumped out with each contraction and maintaining a moderate heart rate, the heart can efficiently deliver a larger volume of blood to the body per minute, resulting in a higher cardiac output. In contrast, the other options would not result in a significant increase in cardiac output. Decreasing both stroke volume and heart rate (Option B) or decreasing stroke volume while increasing heart rate (Option C) would likely lead to a decrease in cardiac output. On the other hand, increasing both heart rate and stroke volume (Option D) may not necessarily yield as substantial an increase in cardiac output compared to the scenario described in Option A.