How do the kidney and vascular diseases connect to hypertension?

Renovascular HTN.: A condition called renovascular hypertension arises when blood flow to the kidney is constricted--either by physical problems with the blood vessel wall or by narrowing in the case of hardening of the arteries (atherosclerosis). Decreased blood flow to the kidney results in hormonal signals from the kidney that increase salt and water retention, leading to high blood pressure states.