Describe the aortic valve sclerosis as one cause.
Aortic valve sclerosis: calcification and fibrosis of aortic valve leaflets
Most common cause of aortic stenosis
Occurs at an increasing rate as patients age (prevalence is 35% in those aged 75–85 years)
Similar pathophysiology to atherosclerosis (see risk factors for atherosclerosis)
Describe the biscupid aortic valve (BAV) as one cause.
fusion of two of the three aortic-valve leaflets in utero
Most common congenital heart valve malformation , predominantly affects males (3:1)
Predisposes the valve to dystrophic calcification and degeneration
Patients present with symptoms of aortic stenosis earlier than in regular aortic valve calcification.
Congenital aortic stenosis is rare and usually features a unicuspid or bicuspid valve.
Describe rheumatic fever as one cause.
Rare cause of AS in high-income countries due to consistent use of antibiotics for the treatment of streptococcal pharyngitis
Still remains a significant cause of AS in lower-income countries, where antibiotics may be less readily available
Stenosis is caused by commissural fusion.
Describe the pathophyisology.
Narrowed opening area of the aortic valve during systole → obstruction of blood flow from left ventricle (LV) → increased LV pressure → left ventricular concentric hypertrophy, which leads to:
Increased LV oxygen demand
Impaired ventricular filling during diastole → left heart failure
Reduced coronary flow reserve
Initially, cardiac output (CO) can be maintained
Later, the decreased distensibility of the left ventricle reduces cardiac output and may then cause backflow into the pulmonary veins and capillaries → higher afterload (pulmonic pressure) on the right heart → right heart failure
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