A narrowing of the kidney blood vessels will lead to the kidney being starved of a good enough blood supply. This leads to the kidney becoming smaller. Often it presents with high blood pressure. If this problem exists in both kidneys, it can lead to kidney failure and pulmonary edema (fluid in the lungs causing breathlessness).

The problem may be suggested by a kidney ultrasonogram which shows one kidney is smaller than the other, but can only be diagnosed with certainty by an angiogram of the kidney blood vessels.

Sometimes it may be felt that the narrowing should be stretched open using a fine, narrow balloon (angioplasty) and then kept open with a tube inserted into the blood vessel (a stent). All of this can be done from the "inside," during a procedure similar to an angiogram. In everybody with this problem, the blood pressure will be controlled, the cholesterol level checked and normalized, and aspirin may be given.

Links

http://www.webmd.com/hypertension-high-blood-pressure/guide/renal-artery-stenosis-symptoms-treatments
http://kidney.niddk.nih.gov/kudiseases/pubs/RenalArteryStenosis/
https://my.clevelandclinic.org/health/diseases/17422-renal-artery-disease