You should continue to focus on your blood pressure (target BP goal <130/80 mmHg) as advised by your Nephrologist. You have a well functioning left kidney and as long as your overall kidney function is stable(would also be obvious by checking serum creatinine level) and blood pressure is well controlled, there is no reason to pursue additional tests even to rule out renal artery blockage (which would seem unlikely in the above scenario). Additionally, one could check urine to quantify albumin/protein leakage which often is present in some one with hypertension.