Why should nitrates be avoided in suspected right ventricular infarction?

• A. They cause tachycardia
• B. They decrease preload, risking severe hypotension
• C. They decrease afterload
• D. They improve contractility

Answer: (B)

The main idea is that the right ventricle relies heavily on adequate venous return (preload) to pump effectively. In suspected right ventricular infarction, maintaining preload is essential to keep RV output and systemic blood pressure. Nitrates cause venodilation, which lowers venous return and reduces RV filling. That drop in preload can sharply decrease RV stroke volume and overall cardiac output, leading to severe hypotension or shock. Nitrates don’t improve contractility, and their modest afterload-reducing effect doesn’t help here; the big risk is the loss of preload. Clinically, if RV infarction is possible, preload should be supported (for example, with IV fluids) and nitrates avoided until RV function is clarified.