Clinical meaning
Valvular heart disease involves stenosis (failure to open fully, creating a pressure gradient across the valve) or regurgitation (failure to close completely, allowing retrograde blood flow). Aortic stenosis (AS) creates a fixed obstruction to left ventricular (LV) outflow; the LV compensates through concentric hypertrophy to generate higher systolic pressures, but this increases myocardial oxygen demand while decreasing coronary perfusion pressure, producing the classic triad of angina, syncope, and heart failure. The murmur of AS is a crescendo-decrescendo (diamond-shaped) systolic murmur best heard at the right upper sternal border (aortic area) radiating to the carotids, with a late-peaking murmur indicating severe stenosis. Aortic regurgitation (AR) causes volume overload as blood regurgitates from the aorta back into the LV during diastole; the LV compensates with eccentric hypertrophy (dilation), and chronic AR produces a widened pulse pressure with bounding (water-hammer) pulses. The murmur is a high-pitched, blowing, decrescendo diastolic murmur best heard at the left sternal border with the patient sitting up and leaning forward. Mitral stenosis (MS), most commonly caused by rheumatic heart disease, creates obstruction to LV filling, increasing left atrial (LA) pressure, leading to LA dilation, pulmonary congestion, and pulmonary hypertension. The murmur is a low-pitched diastolic rumble heard at the apex with the bell in the left lateral decubitus position, often preceded by an opening snap. LA dilation predisposes to atrial fibrillation (AF) and thrombus formation. Mitral regurgitation (MR) allows systolic retrograde flow from LV to LA, causing LA and LV volume overload; chronic MR produces a holosystolic (pansystolic) blowing murmur at the apex radiating to the axilla. The NP differentiates acute from chronic presentations: acute severe valvular lesions (acute MR from chordae rupture, acute AR from endocarditis) present with cardiogenic shock because compensatory remodeling has not occurred, requiring emergent surgical intervention.