Aortic Stenosis

Aortic stenosis is narrowing at the aortic valve that obstructs blood leaving the left ventricle. The ventricle must generate unusually high pressure to push blood through a restricted valve opening. This is a fixed obstruction: when activity increases and tissues need more cardiac output, the narrowed valve limits how much forward flow can rise. The pressure load causes concentric left-ventricular hypertrophy. At first, the thicker ventricle preserves ejection. Over time, however, the stiff muscle relaxes poorly and needs adequate filling pressure. Left-sided filling pressures rise, causing pulmonary congestion and exertional dyspnea. Later, myocardial dysfunction can reduce systolic function and cause heart failure. Angina can occur even without coronary artery disease because hypertrophied myocardium has a greater oxygen demand while high ventricular pressure can impair coronary perfusion. Exertional presyncope or syncope occurs when cardiac output cannot increase enough to maintain cerebral perfusion during activity, especially as peripheral vessels dilate with exertion. Aortic stenosis is not the same as aortic sclerosis. Sclerosis describes valve thickening or calcification without hemodynamically significant obstruction. A murmur may be present with sclerosis, but echocardiography distinguishes it...