Which drug class reduces preload and afterload during anesthesia management?

• A. Nitrates
• B. Beta-blockers
• C. Calcium channel blockers
• D. Diuretics

Answer: (A)

The question emphasizes lowering wall stress by reducing the volume the heart must handle ( preload ) and the resistance it pumps against ( afterload ). Nitrates achieve this mainly through venodilation, which reduces venous return and thus preload. At higher doses they also cause arterial dilation, lowering systemic vascular resistance and afterload. This combination makes nitrates especially useful in anesthesia when you want to ease ventricular workload and control blood pressure.

Beta-blockers slow the heart and reduce contractility, decreasing myocardial oxygen demand, but they don’t target preload directly. Calcium channel blockers can lower afterload through vasodilation and may affect preload to some extent, yet their primary use isn’t immediate preload reduction and they can cause hypotension or conduction issues. Diuretics reduce preload by decreasing blood volume, but their effects are slower and they don’t address afterload acutely.