Aortic stenosis (AS)
During aortic stenosis, the cusps of the aortic valve fail to open completely, decreasing blood flow capacity. The cusps are hardened, commissures are fused and the orifice is narrowed.
- AS initially leads to LVH (concentric hypertrophy as a compensatory mechanism) and later dilation (once it can no longer compensate).
- The dilated LV may lead to mitral regurgitation, reduced ejection fraction and cardiac output, and left heart failure.
- Once the output is low enough, it presents as syncope, angina, and dyspnea during exertion, and sometimes arrhythmias and heart failure.
Etiology
- Age-related calcification (aortic sclerosis). Fibrosis and calcification of the valves, similar to atherosclerosis.
- Most common cause of AS in older adults.
- HTN, elevated lipoprotein A levels, smoking, and psoriasis are risk factors.
- Congenital bicuspid valve calcification. The presence of two cusps instead of three. It is the most common congenital cardiovascular abnormality.
- Most common cause of AS in young adults (10-20 yo).
- Rheumatic fever (see below)