Congenital Renal Arteriovenous Malformation: A Rare but Treatable Cause of Hypertension.

BACKGROUND Congenital renal vascular anomalies have been classified into 3 categories: cirsoid, angiomatous, and aneurysmal. These classifications are based on the size, location, and number of vessels involved. Aneurysmal malformations, such as the one reported here, have a single (and dilated) feeding and draining vessel. The prevalence of renal AVMs is estimated at less than 0.04%, making them rare causes of secondary hypertension. CASE REPORT A 29-year-old white woman was seen in the hypertension clinic as a referral from high-risk obstetric clinic for management of hypertension (HTN). A secondary hypertension workup with Doppler waveforms of the renal arteries revealed prominent diastolic flow in the left compared to the right. For confirmation, an MRA was done, which showed a large left renal upper-pole arteriovenous malformation (AVM) with associated vascular shunting and early opacification of the left renal vein. This congenital AVM was identified as the cause of her hypertension. Angiography and coil embolization were performed. The patient's BP normalized within a few days and she was taken off her antihypertensive medications. CONCLUSIONS This case illustrates that a careful review of duplex waveforms beyond just peak velocity and ratios is important to identify uncommon pathologies. This is important, as renal AVMs respond well to embolization, with resolution of hypertension in 59% of patients treated.