Has anyone had renal vascular hypertension not due to stenosis?

I have very high renal artery velocities in only one renal artery (several Dopplers months apart), sudden onset very high blood pressure that is hard to control with medication, but no stenosis shows up on CTA or MRA. My BP is very high all day when I'm upright and low when I'm still lying down after sleeping. No history of hypertension before this. What can cause renal vascular hypertension/very high velocity that isn't due to stenosis? All endocrine and fixed structural causes seem to have been ruled out. Has anyone experienced anything similar?