Which drug is typically avoided in the medical management of a descending aortic dissection?

• A. Sodium nitroprusside
• B. Labetalol
• C. Esmolol
• D. Hydralazine

Answer: (A)

The main idea is to reduce the forces that push on the torn aortic wall by lowering heart rate and the rate of pressure rise in the aorta. Drugs that rapidly lower blood pressure without controlling heart rate can trigger a reflex increase in sympathetic activity, which raises heart rate and wall stress and can worsen the dissection. Sodium nitroprusside is a powerful arterial vasodilator that drops blood pressure quickly but causes a strong reflex tachycardia. That tachycardia increases shear on the dissection site, potentially promoting extension or rupture. Because of this, nitroprusside is typically avoided unless combined with a beta-blocker to blunt the heart rate response. In contrast, beta-blockers like labetalol or esmolol directly reduce heart rate and dP/dt, lowering both pressure and the speed of pressure change, which helps protect the aorta. Hydralazine lowers BP but can also provoke reflex tachycardia and is used with beta-blockade when needed, but it is not preferred first-line.