How aortic stenosis could cause left ventricular hypertrophy?

Left ventricular hypertrophy usually develops in response to excessive blood pressure (pressure overload) or excessive blood volume filling the left ventricle (volume overload).

When the aortic valve is narrowed, blood flow from the heart into the aorta and on to your body is obstructed. Aortic stenosis causes blood pressure to build in the left ventricle.

Severe AS produces a nearly fixed cardiac output. When the patient exercises, their peripheral vascular resistance will decrease as the blood vessels of the skeletal muscles dilate to allow the muscles to receive more blood to allow them to do more work. This decrease in peripheral vascular resistance is normally compensated for by an increase in the cardiac output. Since patients with severe AS cannot increase their cardiac output, the blood pressure falls and the patient will syncopize due to decreased blood perfusion to the brain.