What is the primary goal of pharmacologic therapy in acute dissecting aneurysm?

• A. Decrease heart rate and blood pressure to reduce shear
• B. Increase heart rate to improve perfusion
• C. Increase afterload
• D. No pharmacologic therapy

Answer: (A)

In acute dissecting aneurysm, the priority of pharmacologic therapy is to minimize the forces that drive the dissection—the shear stress on the aortic wall. Reducing both heart rate and systolic blood pressure lowers the rate of pressure change (dP/dt) and the overall wall stress, which helps prevent propagation of the intimal flap and potential rupture. That's why the best approach is to lower heart rate and blood pressure.

Typically, IV beta-blockers (like esmolol or labetalol) are given first to depress heart rate and reduce BP. If BP remains high after heart rate control, a vasodilator such as nitroprusside may be added carefully to lower BP further, but only after HR is managed, because vasodilators alone can trigger reflex tachycardia that increases shear. Increasing heart rate or afterload would worsen the dissection, and doing nothing pharmacologically would fail to control the dangerous progression.