A cross-sectional imaging study to identify organs at risk of thermal injury during renal artery sympathetic denervation

Paradise™ Ultrasound Renal Denervation System for the treatment of hypertension

Catheter-based renal denervation is a novel treatment approach for patients with hypertension and initial unblinded trials have shown promising results. The Paradise™ Ultrasound Renal Denervation System (ReCor Medical, CA, USA) is an ultrasound-based catheter with a distal balloon that acts as a coolant to protect the renal arterial wall. This device received CE-mark in 2012. Randomized, sham-controlled trials and postmarket studies have shown promising efficacy and safety results. Currently, three additional ongoing randomized, sham-controlled trials are underway in the USA, Europe, Japan and Korea, and the results will be pivotal in device approval in some of these countries. These studies with larger numbers of patients and longer duration of follow-up are needed to further confirm the safety and efficacy of this device.

Effects of renal denervation on vascular remodelling in patients with heart failure and preserved ejection fraction: A randomised control trial

OBJECTIVE

To assess the effect of renal denervation (RDT) on micro- and macro-vascular function in patients with heart failure with preserved ejection fraction (HFpEF).

DESIGN

A prospective, randomised, open-controlled trial with blinded end-point analysis.

SETTING

A single-centre London teaching hospital.

PARTICIPANTS

Twenty-five patients with HFpEF who were recruited into the RDT-PEF trial.

MAIN OUTCOME MEASURES

Macro-vascular: 24-h ambulatory pulse pressure, aorta distensibilty (from cardiac magnetic resonance imaging (CMR), aorta pulse wave velocity (CMR), augmentation index (peripheral tonometry) and renal artery blood flow indices (renal MR). Micro-vascular: endothelial function (peripheral tonometry) and urine microalbuminuria.

RESULTS

At baseline, 15 patients were normotensive, 9 were hypertensive and 1 was hypotensive. RDT did not lower any of the blood pressure indices. Though there was evidence of abnormal vascular function at rest, RDT did not affect these at 3 or 12 months follow-up.

CONCLUSIONS

RDT did not improve markers of macro- and micro-vascular function.

Renal denervation in heart failure with preserved ejection fraction (RDT-PEF): a randomized controlled trial

AIM

Heart failure with preserved ejection fraction (HFpEF) is associated with increased sympathetic nervous system (SNS) tone. Attenuating the SNS with renal denervation (RDT) might be helpful and there are no data currently in humans with HFpEF.

METHODS AND RESULTS

In this single-centre, randomized, open-controlled study we included 25 patients with HFpEF [preserved left ventricular (LV) ejection fraction, left atrial (LA) dilatation or LV hypertrophy and raised B-type natriuretic peptide (BNP) or echocardiographic assessment of filling pressures]. Patients were randomized (2:1) to RDT with the Symplicity™ catheter or continuing medical therapy. The primary success criterion was not met in that there were no differences between groups at 12 months for Minnesota Living with Heart Failure Questionnaire score, peak oxygen uptake (VO2 ) on exercise, BNP, E/e', LA volume index or LV mass index. A greater proportion of patients improved at 3 months in the RDT group with respect to VO2 peak (56% vs. 13%, P = 0.025) and E/e' (31% vs. 13%, P = 0.04). Change in estimated glomerular filtration rate was comparable between groups. Two patients required plain balloon angioplasty during the RDT procedure to treat renal artery wall oedema.

CONCLUSION

This study was terminated early because of difficulties in recruitment and was underpowered to detect whether RD improved the endpoints of quality of life, exercise function, biomarkers, and left heart remodelling. The procedure was safe in patients with HFpEF, although two patients did require intraprocedure renal artery dilatation.

Renal denervation for the management of resistant hypertension

Renal sympathetic denervation (RSD) as a therapy for patients with resistant hypertension has attracted great interest. The majority of studies in this field have demonstrated impressive reductions in blood pressure (BP). However, these trials were not randomized or sham-controlled and hence, the findings may have been overinflated due to trial biases. SYMPLICITY HTN-3 was the first randomized controlled trial to use a blinded sham-control and ambulatory BP monitoring. A surprise to many was that this study was neutral. Possible reasons for this neutrality include the fact that RSD may not be effective at lowering BP in man, RSD was not performed adequately due to limited operator experience, patients’ adherence with their anti-hypertensive drugs may have changed during the trial period, and perhaps the intervention only works in certain subgroups that are yet to be identified. Future studies seeking to demonstrate efficacy of RSD should be designed as randomized blinded sham-controlled trials. The efficacy of RSD is in doubt, but many feel that its safety has been established through the thousands of patients in whom the procedure has been performed. Over 90% of these data, however, are for the Symplicity™ system and rarely extend beyond 12 months of follow-up. Long-term safety cannot be assumed with RSD and nor should it be assumed that if one catheter system is safe then all are. We hope that in the near future, with the benefit of well-designed clinical trials, the role of renal denervation in the management of hypertension will be established.