Accessory Renal Arteries — Mostly , But Not Always , Innocuous Renin-Dependent Hypertension Caused by Nonfocal Stenotic Aberrant Renal Arteries — Proof of a New Syndrome . Hypertension

S ince the classical observation of Harry Goldblatt (1), hyperreninism resulting from renal ischemia has become an established paradigm to explain several forms of hypertension. The closest human counterparts to the experimental model of Goldblatt are the various forms of renal artery stenosis, fibromuscular or atherosclerotic. The clinical diagnosis is based on the combination of an activated renin-angiotensin system and morphologic evidence of a hemodynamically relevant arterial stenosis, ideally supplemented by evidence of deficient renal perfusion (2– 4). Accessory renal arteries have been known since the early days of human autopsy. It has been reported that they occur in 26% of individuals (5) and originate mostly directly from the aorta (6). Their frequency reflects the complexity of the organogenesis of the kidney:They represent vestiges of the ascent of the kidneys during the 6th to 9th weeks of gestation from the pelvis to the final lumbar location. This movement is accompanied by sequential sprouting of branches from the aorta while the preceding lower branches disappear. Nevertheless, it remains puzzling why this is infrequent in rats (I haven’t seen a single case in a great number of rats on which I operated). After the report of Marshall (7), there have been numerous claims in the literature that accessory renal arteries increase the risk of hypertension (7–13). The death knell to this hypothesis seemed to be the study of Gupta and Tello (6), who studied 185 hypertensive patients using magnetic resonance angiography. They found that the risk to find a renal artery stenosis in an individual with an accessory artery as compared with an individual with a single renal artery was not significantly different. This observation is undoubtedly correct, but the beauty of medicine is that there is no rule without an occasional exception. In this context several authors referred to the successful surgical treatment of renal hypertension in children, but this concerned partial nephrectomy when lesions of intrarenal vessels associated with segmental hypoplasia (Ask-Upmark), reflux nephropathy, or arteriovenous malformations (14)—quite unrelated to the topic under discussion here. In the distant past, Györi (15) had postulated that supernumerary renal arteries were more prone to develop stenosing lesions and, more importantly, he also speculated that they are longer and their calibre is smaller than the main arterial trunk, thus raising resistance and potentially predisposing to underperfusion according to the law of Hagen-Poiseuille. This hypothesis had prompted Glodny et al. (16) to study 62 consecutive patients who had undergone angiography for various reasons. The kidneys were supplied by 2 single arteries in 29 patients and by multiple renal arteries in 33 patients. Before stimulation, the plasma renin was significantly higher (P 0.0127) in the latter group (1.73 0.38 ng angiotensin I/ml per min versus 0.79 013 ng angiotensin I/ml per min); 60 min after stimulation the respective values were 3.7 0.50 versus 2.59 0.4. The authors concluded that an activated renin system contributed to the BP elevation in these patients, but these observational data failed to prove a causal relationship. The paper of Kem et al. (17) is remarkable because it went beyond these reports and provided proof for an activated renin system by documenting an activated renin system before and normalization of BP after resection of the nonstenosed but narrow accessory artery with partial nephrectomy. A 5-yr-old boy with severe hypertension had no stenosis of renal vessels but also had an elongated, nonstenosed, aberrant artery arising from the common iliac artery near the aortic bifurcation feeding the lower pole of the right kidney. The renal vein renin ratio (right/left) was 2:1 in the recumbent position (to exclude ptosis of the kidney). By ultrasonography there was a difference in kidney size (right kidney, 9.4 3.5 cm; left kidney, 8.8 3.8 cm). The basal ratio of plasma aldosterone/plasma renin