Indeed, in aortic stenosis, because of the fixed obstruction to blood flow out from the heart, it may be impossible for the heart to increase its output to offset peripheral vasodilation.A third mechanism may sometimes be operative. Due to the hypertrophy of the left ventricle in aortic stenosis, including the consequent inability of the coronary arteries to adequately supply blood to the myocardium (see "Angina" below), abnormal heart rhythms may develop. These can lead to syncope.Finally, in calcific aortic stenosis at least, the calcification in and around the aortic valve can progress and extend to involve the electrical conduction system of the heart. If that occurs, the result may be heart block, a potentially lethal condition of which syncope may be a symptom. Congestive heart failure
Congestive heart failure (CHF) carries a grave prognosis in people with AS. People with CHF attributable to AS have a 2-year mortality rate of 50% if the aortic valve is not replaced. CHF in the setting of AS is due to a combination of left ventricular hypertrophy with fibrosis, systolic dysfunction (a decrease in the ejection fraction) and diastolic dysfunction (elevated filling pressure of the LV). Associated symptoms
In Heydes syndrome, aortic stenosis is associated with gastrointestinal bleeding due to angiodysplasia of the colon. Recent research has shown that the stenosis causes a form of von Willebrand disease by breaking down its associated coagulation factor (factor VIII-associated antigen, also called von Willebrand factor), due to increased turbulence around the stenotic valve.
While those with congenital bicuspid aortic valve make up 30-40% of those presenting during adulthood and typically presenting earlier (ages 40+ to 50+) than those with tricuspid aortic valves (65+).Acute rheumatic fever post-inflammatory is the cause of less than 10% of cases. Rare causes of aortic stenosis include Fabry disease, systemic lupus erythematosus, Paget disease, high blood uric acid levels, and infection. Pathophysiology
The human aortic valve normally consists of three cusps or leaflets and has an opening of 3.0-4.0 square centimeters. When the left ventricle contracts, it forces blood through the valve into the aorta and subsequently to the rest of the body. When the left ventricle expands again, the aortic valve closes and prevents the blood in the aorta from flowing backward (regurgitation) into the left ventricle. In aortic stenosis, the opening of the aortic valve becomes narrowed or constricted (stenotic) (e.g., due to calcification). Degenerative (the most common variety), and bicuspid aortic stenosis both begin with damage to endothelial cells from increased mechanical stress. Inflammation is thought to be involved in the earlier stages of the pathogenesis of AS and its associated risk factors are known to promote the deposition of LDL cholesterol and lipoprotein(a), a highly damaging substance, into the aortic valve, causing significant damage and stenosis over time. Infiltration of inflammatory cells (macrophages, T lymphocytes), followed by the release of inflammatory mediators such as interleukin-1-beta and transforming growth factor beta-1 occurs.