A challenging case of renovascular hypertension

Moderate arterial hypertension was incidentally diagnosed in an asymptomatic 14-year-old girl with an otherwise unremarkable medical history and physical examination. Serum creatinine, acute phase reactants and echocardiography were normal, whilst ocular fundus examination revealed mild retinal vascular tortuosity. High plasma renin and aldosterone levels suggested renovascular hypertension.

Three-dimensional volume-rendering computed tomographic (CT) angiography (Panel A) and catheter-based digital subtraction angiography (DSA) (Panel B) showed an absence of flow in both ostial and proximal segments of the left renal artery with a normal appearance of the aortic wall (arrow). A complex collateral arterial network, originating from a hypertrophic left lumbar artery (chevron), bypassed these segments and merged with a normal-sized middle tract of the left renal artery, causing a delayed parenchimography of the ipsilateral kidney in comparison with the contralateral (Panel B). All other aortic branches including right renal artery, as well as aorta and supra-aortic arteries, appeared normal on DSA. Left and right kidney size were comparable on CT. Surgical exploration could not find any vascular structure or remnant connecting the aortic wall to the residual segment of the left renal artery. Histological examination of a sample of aortic wall and periaortic tissue was unremarkable: the former showed a normal arterial wall, the latter revealed the presence of adipose tissue. Normalization of blood pressure was achieved after surgical reconstruction with aortorenal bypass.

Panel A Panel B

Among the recognized causes of renovascular hypertension in children are several congenital and acquired disorders. ¹ Congenital rubella syndrome was ruled out in our patient through her medical history. Physical examination did not reveal any stigmata of rare conditions such as neurofibromatosis and Marfan’s syndrome. Fibromuscular dysplasia, notably the focal or tubular type, seemed implausible due to the absence of any recognizable vascular structure in the obstructed segment together with any remarkable histological findings. Takayasu arteritis was unlikely because of the absence of clinical, laboratory and histological findings suggesting an inflammatory disorder. Furthermore, the left renal artery was the only involved vessel.

In conclusion, this challenging case revealed an unusual anatomic finding, apparently suggesting agenesis of the proximal segment of the left renal artery. Nevertheless, considering the normal appearance of the left kidney and downstream artery segments, together with the absence of vascular remnants, it seems reasonable to hypothesize an isolated disruption of proximal renal artery development during fetal or even early postnatal life, the etiology of which remains unclear. Whatever the cause, we speculate that this process could have induced the development of a compensatory collateral circle providing sufficient low-flow perfusion to sustain kidney trophism.

‘Images in vascular medicine’ is a regular feature of Vascular Medicine. Readers may submit original, unpublished images related to clinical vascular medicine. Submissions may be sent to: Mark A Creager, Editor in Chief, Vascular Medicine, via the web-based submission system at http://mc.manuscriptcentral.com/vascular-medicine