A 58-year-old man with a history of long-standing hypertension presents to the emergency department with sudden-onset, severe “tearing” chest pain radiating to his back. He is diaphoretic and anxious. Blood pressure is 198/110 mm Hg in the right arm and 162/96 mm Hg in the left arm. Pulse is 110/min. Cardiac auscultation reveals a new, high-pitched decrescendo diastolic murmur along the left sternal border. A portable chest radiograph shows a widened mediastinum. CT angiography demonstrates an intimal flap involving the ascending aorta with extension toward the aortic root.

Which of the following is the most appropriate definitive management?