Ephedrine's effect on myocardial oxygen consumption (MVO2)?

• A. Decreases MVO2
• B. No change in MVO2
• C. Increases MVO2
• D. MVO2 fluctuates

Answer: (C)

The main concept is that myocardial oxygen consumption rises with the heart’s workload. Ephedrine increases sympathetic activity by both directly stimulating beta-1 receptors in the heart (raising heart rate and contractility) and indirectly increasing norepinephrine release (raising vascular tone and blood pressure). This combination heightens cardiac work and oxygen demand, so MVO2 goes up. It’s not a reduction or no change because the drug actively makes the heart work harder and faster, and the higher afterload from increased blood pressure also contributes to the increased oxygen consumption. In patients with limited coronary supply, this rise in MVO2 can raise the risk of ischemia.