The most appropriate next step in treatment is to start an esmolol infusion. Acute medical therapy is indicated in aortic dissection to lower blood pressure and heart rate, both of which are elevated in this patient. β-Blockers are the drug of choice owing to their antihypertensive and negative chronotropic effects, which lead to reduced shear stress on the aortic wall. Options include propranolol, labetalol, and esmolol. Esmolol is a very short-acting intravenous agent that allows careful titration of blood pressure and heart rate and may be useful in patients with aortic dissection. Nondihydropyridine calcium channel blockers are preferred second-line agents in patients who are unable to tolerate β-blockade. In patients with aortic dissection, the target systolic blood pressure should be 100 to 120 mm Hg, and the target heart rate should be below 65/min.

Fenoldopam is a dopamine agonist that acts as an antihypertensive agent. Because it effectively lowers blood pressure without impairing kidney perfusion, it may be advantageous in patients with hypertensive emergencies accompanied by acute kidney injury. However, unlike β-blockers, it does not reliably lower the heart rate and would not be a preferred treatment for this patient with acute aortic dissection.

Direct vasodilators such as hydralazine increase aortic wall shear stress and are more difficult to use in predictably controlling blood pressure. They are therefore not used in treating acute aortic dissection.

Nitroglycerin produces relatively greater venodilation than arteriolar dilation and would not reliably reduce blood pressure into target range in this patient. A second agent would also be required to lower heart rate, as nitroglycerin does not have chronotropic effects.