Which statement correctly describes the intraoperative hemodynamic effects of nitrates, beta-blockers, and calcium channel blockers?

• A. Nitrates reduce preload and afterload; beta-blockers decrease heart rate and contractility; CCBs lower blood pressure
• B. Nitrates decrease preload and afterload; beta-blockers increase heart rate; CCBs lower blood pressure
• C. Nitrates decrease preload and afterload; beta-blockers increase heart rate; CCBs raise blood pressure
• D. Nitrates raise afterload; beta-blockers increase contractility; CCBs decrease heart rate

Answer: (A)

Intraoperative hemodynamics revolve around preload, afterload, heart rate, and contractility. Nitrates primarily cause venodilation, which lowers preload by reducing venous return to the heart; they can also reduce afterload at higher doses, but the dominant effect is preload reduction. Beta-blockers block beta-1 receptors on the heart, leading to a slower heart rate (negative chronotropy) and weaker contractions (negative inotropy). Calcium channel blockers decrease calcium entry into vascular smooth muscle and cardiac muscle; many lower blood pressure mainly by vasodilation and reduced afterload, while certain non-dihydropyridine CCBs also slow heart rate and reduce contractility.

The statement that nitrates reduce preload and afterload; beta-blockers decrease heart rate and contractility; calcium channel blockers lower blood pressure captures these general effects accurately, making it the best choice.