[Ischemic renal disease and renal artery stenosis]

Effects of Norepinephrine on Renal Cortical and Medullary Blood Flow in Atherosclerotic Rabbits

OBJECTIVE

The aim of this study was to explore the effect of norepinephrine (NE) on renal cortical and medullary blood flow in atherosclerotic rabbits without renal artery stenosis.

METHODS

Atherosclerosis was induced in 21 New Zealand white rabbits by feeding them a cholesterol-rich diet for 16 weeks. Thirteen healthy New Zealand white rabbits were randomly selected as controls. After atherosclerosis induction, standard ultrasonography was performed to confirm that there was no plaque or accelerated flow at the origin of the renal artery. Contrast-enhanced ultrasound (CEUS) was performed at baseline and during intravenous injection of NE. The degree of contrast enhancement of renal cortex and medulla after the injection of contrast agents was quantified by calculating the enhanced intensity.

RESULTS

The serum nitric oxide (NO) level in atherosclerotic rabbits was higher than that in healthy rabbits (299.6±152 vs. 136.5±49.5, P<0.001). The infusion of NE induced a significant increase in the systolic blood pressure (112±14 mmHg vs. 84±9 mmHg, P=0.016) and a significant decrease in the enhanced intensity in renal cortex (17.78±2.07 dB vs. 21.19±2.03 dB, P<0.001) and renal medulla (14.87±1.82 dB vs. 17.14±1.89 dB, P<0.001) during CEUS. However, the enhanced intensity in the cortex and medulla of healthy rabbits after NE infusion showed no significant difference from that at baseline.

CONCLUSION

NE may reduce renal cortical and medullary blood flow in atherosclerotic rabbits without renal artery stenosis, partly by reducing the serum NO level.

Open and endovascular treatment by covered and multilayer stents in the therapy of renal artery aneurysms: mid and long term outcomes in a single center experience

AIM

The purpose of this paper is to evaluate the mid and long terms outcomes of open and endovascular surgical treatment, as well as multilayer stent, in patients affected by Renal Artery Aneurysm (RAA).

PATIENTS AND METHODS

Twenty five patients with RAA (24 monolateral and 1 bilateral aneurysm, 26 aneurysms) were observed between 2000 and 2015: 4 were not treated due to the small size of the aneurysm (< 2.5 cm); out of the remaining, 16 underwent endovascular treatment, 2 were treated by open surgery consisting in aneurysmectomy and graft reconstruction and 5 (in 1 patient bilateral) were treated by ex vivo repair and autotransplantation.

RESULTS

Out of the 22 patients treated for RAA, one patient operated upon open surgery presented an early thrombosis of a PTFE graft, followed by nephrectomy (4.7%); one patient underwent autotransplantation showed an ureteral kinking without functional consequences. In a follow-up ranging from 1 and 11 years (mean 5 years), no deaths were observed; all the renal arteries repaired were patents and 16 out of 21 patients had a significative reduction of systemic blood pressure.

DISCUSSION

The choice of the best treatment is based on aneurysm's morphology according to Rundback's classification. The type I, involving the main renal artery, is always treated by endovascular approach; type II, involving renal artery bifurcations may be treated by open surgery or multilayer stents; type III (hilar or intraparenchymal aneurysms) needs only an open surgical treatment as autotransplantation.

CONCLUSION

Based on our experience it seems that most of RAAs may be treated by endovascular technique. The ex vivo autotransplantation represents the first-line treatment in hilar and intraparenchymal aneurysms. Multilayer stents seem to have good outcome in the treatment of aneurysms involving arterial bifurcations. Mid and long term results, related to kidney preservation and to normalization of blood pressure, seems satisfying.