A 68-year-old male with a 15-year history of poorly controlled hypertension presents to the emergency department with acute-onset, severe "tearing" chest pain radiating to the back. On examination, blood pressure is 165/95 mmHg in the right arm and 135/80 mmHg in the left arm. A new early diastolic decrescendo murmur is heard at the left sternal border. Chest X-ray shows widened mediastinum. CT angiography confirms acute aortic dissection involving the ascending aorta with an intimal flap. The structure marked **A** in the diagram represents the primary intimal tear. Which of the following pathophysiological mechanisms best explains the formation of this tear in the setting of chronic hypertension?