Non-invasive Cardiac Imaging, Nuclear Cardiology & Echocardiography

Biography

Biography: Pieter A. Doevendans

Abstract

Rationale: Recently, the efficacy of renal denervation (RDN) has been questioned. It is discussed whether RDN is able to adequately reach the renal nerves.

Objective: We aimed to investigate how effective RDN was by means of functional hemodynamic measurements and nerve damage on histology.

Methods and results: We performed hemodynamic measurements in both renal arteries of healthy pigs using a Doppler flow and pressure wire. Subsequently unilateral denervation was performed, followed by repeated bilateral hemodynamic measurements. Pigs were terminated directly after RDN or were followed for 3 weeks or 3 months after the procedure. After termination, both treated and control arteries were prepared for histology to evaluate vascular damage and nerve damage. Directly after RDN, resting renal blood flow tended to increase. In contrast, renal resistance reserve increased significantly during follow-up. Vascular histopathology showed that most nerves around the treated arteries were located outside the lesion areas, whereas only14% of the nerves per pig were observed within a lesion area. Subsequently, a correlation was noted between a more impaired adventitia and a reduction in renal resistance reserve (β: -0.33; P=0.05) at three weeks of follow-up

Conclusion: Only a small minority of renal nerves was targeted after RDN. Furthermore, more severe adventitial damage was related to a reduction in renal resistance in the treated arteries at follow-up. These hemodynamic and histological observations may indicate that RDN did not sufficiently target the renal nerves. Potentially, this may explain the significant spread in the response after RDN.

Figure 6: Title: Nerve damage outside the lesion area Legend: 3 weeks histology results showing a treated vessel with nerve damage outside the lesion area. A 20 x magnification (a-e) zooms in on the affected nerve that is indicated with an arrow in picture 1- 6. Serial sections were stained with HE, MST, α-SMA, S100, PGP9.5 and TH. The perineurial tissue and nerves located at the opposite site of the lesion were affected by an extensive inflammatory 21 response (1,a and 2,b), increased proliferation of myofibroblasts (3,c), a reduction in neural tissue (4,d;5,e) and loss of neurotransmitter production of the affected nerves. (adapted from publication in PlosOne 2015).