Which drug is used to manage a patient with a dissecting aneurysm to rapidly reduce heart rate and shear force?

• A. Esmolol
• B. Labetalol
• C. Nifedipine
• D. Hydralazine

Answer: (A)

In a dissecting aneurysm, the priority is to rapidly lower heart rate and the force of blood against the aortic wall to limit propagation of the tear. Esmolol fits best because it is an ultra-short-acting IV beta-1 blocker that quickly reduces heart rate and myocardial contractility, thereby lowering the dP/dt and wall shear stress on the aorta. Its effects wear off quickly, allowing precise titration and rapid withdrawal if blood pressure becomes too low. Labetalol can reduce BP and heart rate too, but it has a slower onset and is less easily titrated in the exact moment the patient needs rapid HR control. Nifedipine lowers blood pressure but can trigger reflex tachycardia, increasing shear on the aorta. Hydralazine similarly can cause reflex tachycardia and unpredictable BP changes, making it less ideal in this scenario. Thus esmolol is the best choice for rapidly achieving the desired reduction in heart rate and shear force.