Dataset Information

The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model.

ABSTRACT:

Rationale

Recently, the efficacy of renal denervation (RDN) has been debated. It is discussed whether RDN is able to adequately target 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 by 29±67% (P = 0.01). In contrast, renal resistance reserve increased from 1.74 (1.28) to 1.88 (1.17) (P = 0.02) during follow-up. Vascular histopathology showed that most nerves around the treated arteries were located outside the lesion areas (8±7 out of 55±25 (14%) 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 (?: -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.

SUBMITTER: Verloop WL

PROVIDER: S-EPMC4654519 | biostudies-literature | 2015

REPOSITORIES: biostudies-literature

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Publications

The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model.

Verloop Willemien L WL Hubens Lisette E G LE Spiering Wilko W Doevendans Pieter A PA Goldschmeding Roel R Bleys Ronald L A W RL Voskuil Michiel M

PloS one 20151120 11

<h4>Rationale</h4>Recently, the efficacy of renal denervation (RDN) has been debated. It is discussed whether RDN is able to adequately target the renal nerves.<h4>Objective</h4>We aimed to investigate how effective RDN was by means of functional hemodynamic measurements and nerve damage on histology.<h4>Methods and results</h4>We performed hemodynamic measurements in both renal arteries of healthy pigs using a Doppler flow and pressure wire. Subsequently unilateral denervation was performed, fo ...[more]

PMID: 26587981

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Project description:BackgroundInitial catheter-based renal sympathetic denervation (RSD) studies demonstrated promising results in showing a significant reduction of blood pressure, while recent data were less successful. As an alternative approach, the objective of this study was to evaluate the feasibility of using magnetic resonance-guided high-intensity focused ultrasound (MRgHIFU) to perform RSD in a porcine model.MethodsAn intravascular fiber optic temperature probe was used to confirm energy delivery during MRgHIFU. This technique was evaluated both in a vascular phantom and in a normotensive pig model. Five animals underwent unilateral RSD using MRgHIFU, and both safety and efficacy were assessed. MRI was used to evaluate the acoustic window, target sonications, monitor the near-field treatment region using MR thermometry imaging, and assess the status of tissues post-procedure. An intravascular fiber optic temperature probe verified energy delivery. Animals were sacrificed 6 to 9 days post-treatment, and pathological analysis was performed. The norepinephrine present in the kidney medulla was assessed post-mortem.ResultsAll animals tolerated the procedure well with no observed complications. The fiber optic temperature probe placed in the target renal artery confirmed energy delivery during MRgHIFU, measuring larger temperature rises when the MRgHIFU beam location was focused closer to the tip of the probe. Following ablation, a significant reduction (p = 0.04) of cross-sectional area of nerve bundles between the treated and untreated renal arteries was observed in all of the animals with treated nerves presenting increased cellular infiltrate and fibrosis. A reduction of norepinephrine (p = 0.14) in the kidney medulla tissue was also observed. There was no indication of tissue damage in arterial walls.ConclusionsPerforming renal denervation non-invasively with MRgHIFU was shown to be both safe and effective as determined by norepinephrine levels in a porcine model. This approach may be a promising alternative to catheter-based strategies.

Project description:BackgroundRenal denervation (RDN) lowers blood pressure (BP), but BP response is variable in individual patients. We investigated whether measures of pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, predict BP drop following RDN.MethodsFrom the randomized, sham-controlled SPYRAL HTN-OFF MED Pivotal trial, we performed a post hoc analysis of BP waveforms from 111 RDN patients and 111 sham controls, obtained with a brachial cuff-based sphygmomanometer. Waveforms were acquired during ambulatory BP monitoring at diastolic BP level and processed with validated ARCSolver algorithms to derive hemodynamic parameters (augmentation index; augmentation pressure; backward and forward wave amplitude; estimated aortic pulse wave velocity). We investigated the relationship between averaged 24-hour values at baseline and the change in 24-hour BP at 3 months in RDN patients, corrected for observed trends in the sham group.ResultsThere was a consistent inverse relationship between baseline augmentation index/augmentation pressure/backward wave amplitude/forward wave amplitude/estimated aortic pulse wave velocity and BP response to RDN: the decrease in 24-hour systolic BP/diastolic BP was 7.8/5.9 (augmentation index), 8.0/6.3 (augmentation pressure), 6.7/5.4 (backward wave amplitude), 5.7/4.7 (forward wave amplitude), and 7.8/5.2 (estimated aortic pulse wave velocity) mm Hg greater for patients below versus above the respective median value (P<0.001 for all comparisons, respectively). Taking augmentation index/augmentation pressure/backward wave amplitude/forward wave amplitude/estimated aortic pulse wave velocity into account, a favorable BP response following RDN, defined as a drop in 24-hour systolic blood pressure of ≥5 mm Hg, could be predicted with an area under the curve of 0.70/0.74/0.70/0.65/0.62 (P<0.001 for all, respectively).ConclusionsThese results suggest that pulsatile hemodynamics, obtained during 24-hour ambulatory BP monitoring, may predict BP response to RDN.

Dataset Information

The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model.

Rationale

Objective

Methods and results

Conclusion

Publications

The Effects of Renal Denervation on Renal Hemodynamics and Renal Vasculature in a Porcine Model.

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