A 79-year-old woman presents to the Emergency Department with sudden-onset severe chest and back pain...

This patient has a Stanford type B aortic dissection , involving the descending thoracic aorta distal to the left subclavian artery, with no evidence of branch vessel compromise or rupture. MCCQE objectives emphasize that uncomplicated type B dissections are managed medically , whereas type A dissections (ascending aorta) require urgent surgical repair.

The immediate priority is to reduce shear stress on the aortic wall by controlling heart rate and blood pressure . Intravenous beta-blockers such as labetalol or esmolol are first-line therapy. The goal is to reduce heart rate to approximately 60 bpm and lower systolic blood pressure to 100–120 mm Hg. This decreases the force of left ventricular contraction (dP/dt), limiting propagation of the dissection.

Endovascular or open repair is reserved for complicated cases (e.g., malperfusion, rupture, refractory pain, uncontrolled hypertension). Anticoagulation with heparin is contraindicated due to bleeding risk. Observation alone without blood pressure control is inappropriate.

Therefore, intravenous labetalol is the best next step.