Valvular Heart Disease USMLE Step 1 Practice Question

A 55-year-old man with a 20-year history of poorly controlled hypertension presents to the emergency department with progressive dyspnea on exertion and orthopnea for the past 3 days. He denies chest pain or syncope. Vital signs: BP 162/58 mmHg, HR 92/min, RR 20/min, SpO2 96% on room air. On cardiac auscultation, a high-pitched, blowing diastolic murmur is heard best at the left sternal border at the 4th intercostal space and increases in intensity when the patient leans forward and holds his breath in expiration. The apical impulse is hyperdynamic and displaced laterally. Peripheral pulses are brisk and bounding bilaterally. Chest X-ray demonstrates mild pulmonary edema without cardiomegaly. Which of the following valvular lesions best explains this clinical presentation?