Valvular heart disease

Valvular heart disease refers to dysfunction of the aortic, mitral, pulmonic, or tricuspid valve. Disease takes two basic forms: stenosis, where a stiffened valve fails to open fully and obstructs forward flow, and regurgitation (insufficiency), where a valve fails to close completely and allows blood to leak backward. Either abnormality forces a heart chamber to work against extra pressure or volume, and over time drives hypertrophy, dilation, and eventually heart failure.

Each lesion has a signature murmur, and matching lesion to murmur is a classic exam skill. Aortic stenosis produces a crescendo-decrescendo systolic murmur radiating to the carotids, often with syncope, angina, and dyspnea on exertion. Mitral regurgitation causes a holosystolic murmur radiating to the axilla. Aortic regurgitation gives an early diastolic decrescendo murmur, and mitral stenosis an opening snap followed by a diastolic rumble.

Common causes include age-related calcific degeneration (aortic stenosis), myxomatous degeneration causing mitral valve prolapse, rheumatic fever — historically the leading cause of mitral stenosis — and infective endocarditis, which can destroy valve leaflets acutely. Congenital bicuspid aortic valve predisposes to early aortic stenosis. Untreated severe disease progresses to heart failure, arrhythmias such as atrial fibrillation, and elevated mortality, so severe symptomatic lesions are treated with valve repair or replacement.

USMLE Step 1 tests valvular heart disease heavily within cardiovascular pathology: expect questions pairing murmurs with lesions, linking rheumatic fever to mitral stenosis, and tracing how each lesion remodels the heart and progresses to heart failure.