Calcific Aortic Stenosis (Tricuspid)

A 78-year-old man presents with exertional dyspnea and syncope on stair climbing. On examination, he has a harsh crescendo-decrescendo systolic ejection murmur at the right second intercostal space radiating to the carotids, pulsus parvus et tardus, and soft A2. Echocardiography shows severe aortic stenosis (AVA 0.7 cm², mean gradient 48 mmHg, peak velocity 4.5 m/s) with preserved LV ejection fraction and concentric LV hypertrophy. The surgical specimen reveals a tricuspid aortic valve. The structure marked **A** in the diagram—nodular calcific masses on the cusps—is characteristic of which pathophysiologic process?