July 13, 2018Journal of HypertensionOpen Access

Procedural and anatomical predictors of renal denervation efficacy using two radiofrequency renal denervation catheters in a porcine model

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Why the study?

Does radiofrequency renal denervation using Symplicity Spyral or IberisBloom catheters reduce renal norepinephrine tissue concentrations in a porcine model?

Structured PICO

Does radiofrequency renal denervation using Symplicity Spyral or IberisBloom catheters reduce renal norepinephrine tissue concentrations in a porcine model?

Population

Domestic swine (n=23)

Intervention

Bilateral renal denervation in main and branch segments of renal arteries using Symplicity Spyral (SPY) or IberisBloom (IBB) multielectrode catheter systems

Comparator

Sham procedure

Outcome

Renal norepinephrine (NEPI) tissue concentrations and histological lesion depth and area at 7 dayssurrogate

Both Symplicity Spyral and IberisBloom radiofrequency renal denervation catheters demonstrated similar histopathological lesion characteristics and significant reduction of renal norepinephrine levels in a porcine model, with efficacy correlating with the number of ablations per millimeter.

Implication

Supports preclinical RDN validation with both catheters; leaves open translation to human hypertension outcomes.

Abstract

INTRODUCTION: Several renal denervation (RDN) systems are currently under investigation for treatment of hypertension by ablation of renal sympathetic nerves. The procedural efficacy of devices, however, is variable and incompletely understood. This study aimed at investigating procedural and anatomical predictors of RDN efficacy by comparing two radiofrequency catheter systems in a porcine model. METHODS: Domestic swine were assigned into two treatment groups (n = 10) and one sham group (n = 3). Bilateral RDN in main and in branch segments of renal arteries was performed using two different multielectrode catheter systems [Symplicity Spyral (SPY) and IberisBloom (IBB)]. After 7 days, measurement of norepinephrine (NEPI) tissue concentrations and histological analyses have been performed. RESULTS: Renal NEPI tissue concentration following RDN was significantly reduced when compared with Sham (SPY: -95 ± 3% vs. Sham, P < 0.001; IBB: -88 ± 11% vs. Sham, P < 0.001). Histological evaluation showed comparable lesion depth and lesion area (lesion depth: SPY-main 6.26 ± 1.62 mm vs. SPY-branch 3.49 ± 1.11 mm; IBB-main 5.93 ± 1.88 mm vs. IBB-branch: 3.26 ± 1.26 mm, P < 0.001; lesion area: SPY-main 43.5 ± 29.5 mm vs. SYP-branch 45.0 ± 38.0 mm; IBB-main 52.3 ± 34.8 mm vs. IBB-branch 44.0 ± 42.6 mm, P = 0.77; intergroup SPY vs. IBB, P = 0.73). Histological investigations documented a significant correlation between number of ablations per millimeter length of renal artery and reduction in NEPI tissue concentration. CONCLUSION: The two devices under investigation demonstrated similar histopathological lesion characteristics and similar reduction of renal NEPI levels. An increase in number of ablations per millmeter length of renal artery resulted in improved efficacy and reduced variability in treatment effects.