In patients with coronary artery disease, epinephrine can contribute to myocardial ischemia by doing what?

In patients with coronary artery disease, epinephrine can contribute to myocardial ischemia by doing what?

• A. Increasing myocardial oxygen demand
• B. Improving oxygen supply
• C. Reducing heart rate
• D. Decreasing contractility

Answer: (A)

In this scenario the key idea is the balance between oxygen supply and demand in the heart. Epinephrine raises how hard and how fast the heart beats, which increases the heart’s oxygen consumption. It also tends to raise blood pressure and afterload, all of which make the heart work harder and use more oxygen. In coronary artery disease, the arteries can’t deliver additional oxygen quickly enough when demand climbs, so this mismatch can trigger myocardial ischemia. That’s why the best choice is increasing myocardial oxygen demand. The other options would either improve oxygen supply or reduce the heart’s work, which would lessen ischemia, not provoke it.

In this scenario the key idea is the balance between oxygen supply and demand in the heart. Epinephrine raises how hard and how fast the heart beats, which increases the heart’s oxygen consumption. It also tends to raise blood pressure and afterload, all of which make the heart work harder and use more oxygen. In coronary artery disease, the arteries can’t deliver additional oxygen quickly enough when demand climbs, so this mismatch can trigger myocardial ischemia.

That’s why the best choice is increasing myocardial oxygen demand. The other options would either improve oxygen supply or reduce the heart’s work, which would lessen ischemia, not provoke it.