Intravascular Ultrasound Can Be Used to Locate Nerves, but not Confirm Ablation, During Renal Sympathetic Denervation.

BACKGROUND: No methods exist for confirming nerve ablation in catheter-based renal sympathetic denervation (RDN). METHODS: We investigated the feasibility of using intravascular ultrasound (IVUS) to locate nerves and observe nerve integrity changes during RDN in a pig. To confirm our observations, we used post-RDN histological sections matched anatomically to the IVUS images. RESULTS: IVUS revealed multiple hypoechoic structures along the renal artery, whose locations matched those of nerves in the histological sections. Nerves clustered near the junction between the renal artery and vein. Histology confirmed necrosis of nerve bundles at RDN ablation sites, but no changes in echogenicity were observed using IVUS. CONCLUSIONS: Although IVUS cannot currently be used to confirm ablation during RDN, it clearly reveals some clusters of renal sympathetic nerves. It remains to be demonstrated how IVUS can guide RDN devices and potentially improve ablation success.

Reduction of Blood Pressure Following After Renal Artery Adventitia Stripping During Total Nephroureterectomy: Potential Effect of Renal Sympathetic Denervation.

BACKGROUND Catheter-based renal sympathetic denervation has been reported to be effective for treatment resistance hypertension in Australia and Europe. However, in the blinded SYMPLICITY HTN-3 trial, renal denervation did not achieve a significant decrease in blood pressure (BP) in comparison to sham controls. There have been various discussions on the factors that influenced this result. CASE REPORT Two men on antihypertensive therapy underwent unilateral radical nephroureterectomy for cancer of the renal pelvis. When the renal artery adventitia was stripped and cauterized just before renal artery ligation, the measured BP of the 2 men increased after stripping adventitia and decreased gradually after cauterization of the renal artery. This was presumably due to removal of renal artery sympathetic nerves, similar to the mechanism of catheter-based renal sympathetic denervation, although anesthesia, fluid infusion, and/or mesenteric traction may have had an influence. CONCLUSIONS A similar strategy involving thoracolumbar sympathectomy was reported about 50 years ago. The clinically significant blood pressure reduction in these patients suggests renal denervation is effective.