A 20-year-old patient complains of pain in the left lumbar region, arterial pressure rise up to 160/110 mm Hg. USI revealed that the structure and size of the right kidney were within age norms, there were signs of 3 degree hydronephrotic transformation of the left kidney. Doppler examination revealed an additional artery running to the lower pole of the kidney. Excretory urogram shows a narrowing in the region of ureteropelvic junction. Specify the therapeutic tactics: