First-in-man report of a novel dedicated radiofrequency catheter for renal denervation via the transulnar approach

Renal denervation in resistant hypertension: a review of clinical trials and future perspectives

A previous report using the National Health and Nutrition Examination Survey demonstrated an increase in the prevalence of resistant hypertension, which does not respond to traditional therapy and medication. Studies using various animal hypertensive models have demonstrated significant blood pressure (BP) reduction following renal artery denervation (RDN). Catheter-based RDN became available in clinical trials as a possible treatment option for resistant hypertension. Although first clinical trials of RDN have demonstrated the efficacy and safety of this treatment mortality for lowering BP in patients with resistant hypertension, the role of RDN has been questioned since the results of the Symplicity HTN-3 trial. Considering the ethnic differences demonstrated in the Symplicity HTN-Japan and Global Symplicity registry, by contrast, RDN might be an effective for resistant hypertension in Asian population. Here, we discuss RDN applications and technology, the old and new clinical evidence of RDN, patients' selection of RDN responder, and optimization of RDN procedure in this review. The available evidence demonstrates that RDN could be effective in carefully selected patients with resistant hypertension, paving the way for future research in this area.

Renal denervation in a patient with a highly tortuous renal artery using a guide extension catheter: a case report

Background

Catheter-based renal denervation (RDN) has been introduced to treat resistant hypertension. Although the technology of RDN has been largely improved, denervation of tortuous renal arteries remains challenging.

Case presentation

This is a case report of a 49-year-old man with drug resistant hypertension. The patient was selected for RDN after ruling out possible causes of secondary hypertension. Computed tomography angiography showed a highly tortuous left renal artery. An Iberis multielectrode ablation catheter failed to reach the target vessel with a regular guiding catheter. A 5-French extension catheter was introduced into the proximal segment of the main left renal artery to provide extra support force, which enabled successful ablation of the highly tortuous left renal artery. His ambulatory blood pressure was significantly decreased at 1 month follow-up.

Conclusions

It is feasible and effective to use a guide extension catheter for denervation of highly tortuous renal arteries. The present study provides a useful method to ablate tortuous and angled renal arteries and branches.

Renal Sympathetic Denervation in Patients with Resistant Hypertension: A Feasibility Study

Background/Aims

We assessed the feasibility of renal sympathetic denervation (RDN) treatment in patients with resistant hypertension using the Iberis® RDN system. This study was a prospective, multicenter, single-arm feasibility registry.

Methods

We collected data from patients who underwent RDN treatment using the Iberis system. From November 2014 to February 2016, 16 patients from 6 centers in Europe were enrolled in this registry.

Results

Consistent reductions in the 24-h systolic blood pressure (SBP) and diastolic blood pressure were obtained. At any follow-up point, more than 70% of the patients were responders. The change in the 24-h SBP at 1 month was strongly correlated with that at 12 months.

Conclusion

The Iberis system is safe and effective in patients for the treatment of resistant hypertension. Furthermore, our results suggest that we can estimate the effect of RDN in the long term at the 1-month follow-up point using the 24-h SBP.

Acute changes in histopathology and intravascular imaging after catheter-based renal denervation in a porcine model

OBJECTIVES

We first aimed to identify the histopathological changes occurring immediately after renal denervation (RDN) with radiofrequency energy, and then to assess the feasibility of determining procedural success using currently available clinical intravascular imaging techniques.

BACKGROUND

Catheter-based RDN has been used as an alternative therapy for hypertension. However, no practical endpoint to determine procedural success during treatment has been established.

METHODS

A total of 39 ablation lesions were induced in vivo in eight porcine renal arteries and a total of 15 ablation lesions were induced ex vivo in five excised porcine renal arteries with a radiofrequency delivery device. Acute histological changes and appearance on intravascular imaging of the lesions were investigated with light microscopy, transmission electron microscopy, intravascular ultrasound (IVUS), and optical frequency domain imaging (OFDI).

RESULTS

Marked changes were noted in media, adventitia, and perirenal-arterial nerves immediately after in vivo ablation. Changes visualized on IVUS were characterized by focal adventitial thickening comprising a relatively echogenic layer around a heterogeneously hypoechoic interior region, and on OFDI as disappearance of the external elastic membrane signals with high scattering of signals in the surface layer. The changes after ex vivo ablation were histopathologically identical to those from in vivo ablation. There were statistically significant positive correlations in measured dimensions (area, depth, width, and diameter) of ablation lesions between histopathology and IVUS/OFDI findings (Pearson correlation coefficients = 0.69-0.77).

CONCLUSIONS

These findings suggest that observation of treated renal arteries by IVUS or OFDI immediately after RDN improves the success rate of RDN.

First report of transradial renal denervation with the dedicated radiofrequency Iberis™ catheter

We describe the first use of transradial access renal denervation in a patient with resistant hypertension using a dedicated radiofrequency catheter (Iberis™; Terumo Medical Corporation, Tokyo, Japan). The system includes a generator and a 4 Fr single-use radiofrequency (RF) device which has to be introduced via a 6 Fr guiding catheter. Radiofrequency energy is delivered at the tip of the catheter. The system was CE approved in March 2013.

Where and when device therapy may be useful in the management of drug-resistant hypertension

Device therapy for the treatment of uncontrolled and resistant hypertension has evolved significantly over the past several decades. Both renal artery disease and sympathetic hyperactivity have been linked to resistant hypertension. This manuscript will review the current evidence base supporting device therapy (e.g., renal artery revascularization, sympathetic nervous system modulation) for resistant hypertension.