March 22, 2019BMC Cardiovascular DisordersOpen Access

Acute changes in morphology and renal vascular relaxation function after renal denervation using temperature-controlled radiofrequency catheter

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Why the study?

Catheter-based RDN is a strategy for resistant hypertension, but acute changes in vascular morphology and relaxation function remain unevaluated.

Does radiofrequency catheter-based renal denervation cause acute changes in vascular morphology and relaxation function in a mini-pig model?

Structured PICO

Does radiofrequency catheter-based renal denervation cause acute changes in vascular morphology and relaxation function in a mini-pig model?

Population

6 mini-pigs

Intervention

Unilateral renal denervation (RDN) using conventional temperature-controlled cardiac radiofrequency catheter

Comparator

Sham-RDN (same procedure except for the ablation)

Outcome

Acute changes in vascular morphology (histological and molecular biology analyses) and relaxation function (in vitro vascular tension testing)surrogate

In a porcine model, acute renal denervation using a temperature-controlled radiofrequency catheter caused vascular wall injury and endothelial dysfunction, potentially negatively impacting vascular relaxation.

Implication

Acute RDN injury in mini-pigs raises safety concerns; leaves open translation to human outcomes.

Abstract

BACKGROUND: Resistant hypertension and renal sympathetic hyperactivity are closely linked, and catheter-based renal denervation (RDN) is regarded as a new treatment strategy. However, the acute changes in vascular morphology and relaxation function have yet to be evaluated, and these may be important for the efficacy and safety of the procedure. In this study, we explored these questions by conventional temperature-controlled cardiac radiofrequency catheter-based RDN in a pig model. METHODS: Six mini-pigs were randomly divided into the renal denervation (RDN) group (n = 3) and the Sham-RDN group (n = 3). Animals in the RDN group underwent unilateral radiofrequency ablation, and those in the Sham-RDN group underwent the same procedure except for the ablation. The pigs were examined by angiography pre- and post-RDN and were euthanized immediately thereafter. Renal arteries were processed for histological and molecular biology analyses as well as for in vitro vascular tension testing. RESULTS: Compared with the Sham-RDN group, the RDN caused vascular intima and media injury, renal nerve vacuolization, mild collagen fiber hyperplasia and elastic fiber cleavage (all p < 0.05). The RDN group also significantly exhibited nitric oxide synthase pathway inhibition and decreased endothelium-independent vascular relaxation function Compared to the Sham-RDN group (all p < 0.05). CONCLUSIONS: In this porcine model, renal artery denervation led to vascular wall injury and endothelial dysfunction in the acute phase, which negatively affected vascular relaxation function. Thus, this process may be detrimental to the prognosis and progress of hypertension patients.