Valvular Heart Disease Mechanisms

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...