Aortic stenosis is due to an obstructive lesion that interferes with the blood flow out of the left ventricle. Depending upon the site of obstruction to the outflow of blood, the aortic stenosis may be divided into two categories.
Due to resistance to blood outflow from the left ventricle to the aorta, left ventricular hypertrophy occurs. There is back flow of blood to the left atrium, causing increased pressure in left atrium which in turn results in the increased pressure in the pulmonary veins and pulmonary vascular congestion. In case of severe obstruction the pulse pressure in the aorta is narrowed.