Presentation
Stage III CKD, HTN, and A-fib admitted for hypertensive emergency and AKI, now undergoing secondary hypertension workup. Renal US and MRA abdomen revealed >60% stenosis of the right and left main renal arteries.
Patient Data
Delay in time to peak of the right kidney from 4 minutes (baseline) to 12 minutes (ACE-I challenge).
Spit function:
Baseline: Left (49.6%), Right (50.4%)
ACE-I challenge: Left (54.2%), Right (45.8%)
Delay in time to peak activity in the affected kidney of more than 2 minutes when compared to the baseline study is considered highly probable for renovascular hypertension.
Case Discussion
Not all cases of renal artery stenosis will cause renovascular hypertension. Some patients will show no response to angioplasty or stenting. ACE inhibition renography can be used to determine which patients with renal artery stenosis could benefit from intervention.
High probability criteria for renovascular hypertension:
- 10% decrease in differential (split) function (i.e. 50/50 to 60/40)
- retained cortical activity at 20 minutes differing from the contralateral kidney by more than 20%
- delay in time to peak activity in the affected kidney of more than 2 minutes when compared to the baseline study or unaffected kidney