Why does renal or aortic stenosis usually cause hypotension?

Renal stenosis: Renal artery stenosis causes high blood pressure, hypertension, due to a hormone produced by the affected kidney. But aortic stenosis causes the opposite, hypotension, due to the low amount of blood released through the heart valves into the aorta.

They don't: Renal artery stenosis usually causes hypertension. In fact it can be difficult to control. Aortic stenosis doesn't cause hypotension until very late which can be dangerous if the heart has thickened. In my experience most of my patients with aortic stenosis have either normal or high blood pressure.