Nerve Ablation Safely Lowers BP in CKD - MedPage Today PDF Print
By Chris Kaiser, Cardiology Editor, MedPage Today

Published: May 18, 2012

Reviewed by Dori F. Zaleznik, MD; Associate Clinical Professor of Medicine, Harvard Medical School, Boston.

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Catheter-based renal nerve ablation helps lower resistant hypertension, but now researchers have found that it works as well in those with chronic kidney disease (CKD), a pilot study showed.

In 15 patients with resistant hypertension and stage 3 and 4 CKD, bilateral renal denervation lowered blood pressure by a mean of 34/14 mmHg at 1 month and 32/15 mmHg at 6 months, reported Markus Schlaich, MD, of the Baker IDI Heart & Diabetes Institute in Melbourne, Australia, and colleagues.

The mean estimated glomerular filtration rate (eGFR) did not change after the procedure, even though patients received contrast media for renal catheterization or CO2 angiography, according to the study published online in the Journal of the American Society of Nephrology.

Ablating renal nerves via the renal arteries by scarring the tissue with radiofrequency energy reduces sympathetic nerve activity, which then reduces blood pressure.

However, sympathetic nerve activation is also associated with the progression of chronic kidney disease and adverse cardiovascular outcomes, Schlaich and colleagues said.

Consequently, renal denervation performed to lower blood pressure might also have beneficial effects for kidney disease, they suggested.

Previous studies of renal denervation to reduce resistant hypertension included patients with an eGFR greater than 45 mL/min per 1.73 m2. In the current study, the mean eGFR was 31 mL/min per 1.73 m2.

The mean age of patients was 61 and three-quarters had diabetes. Patients were on a mean of 5.6 antihypertensive drugs, and the average systolic office blood pressure was 174 mmHg. The cohort of 15 patients comprised six women and the mean body mass index was 33 kg/m2.

For the procedure, patients received an average of 9.9 ablations. In six patients, CO2angiography was used along with a decreased volume of contrast media. The average volume of contrast in these patients was 46.7 mL compared with 82.5 mL in patients who did not receive CO2 angiography.

After the renal denervation procedure, Schlaich and colleagues found no significant differences in kidney function compared with baseline.

There were no differences according to serum creatinine or cystatin C levels and according to plasma creatinine, cystatin C, or urea levels, they reported.

At 3 months post procedure, the average night-time systolic blood pressure declined significantly from 154 mmHg to 140 mmHg (P=0.03). At 6 months, it remained controlled at 144 mmHg.

Diastolic pressure at 3 months also declined significantly from an average of 78 mmHg to 70 mmHg (P=0.018), and the pattern continued at 6 months as well (78 mmHg versus 75 mmHg, P=0.02).

They concluded that bilateral renal denervation in patients with moderate to severe CKD is safe and effective.

Although the study was small, researchers said that it also showed the potential for the procedure to have beneficial effects other than lowering blood pressure, including increasing hemoglobin and decreasing proteinuria, brain natriuretic peptide levels, and peripheral arterial stiffness index.

They advised against generalizing their findings to the larger population of patients with various forms of CKD. Rather, these findings can provide "guidance for further studies," they said.

This study was funded in part by grants from the National Health and Research Council of Australia and the Victoria government's Operational Infrastructure Support Program.

Schlaich reported relationships with Medtronic, Abbott Pharmaceuticals, Novartis Pharmaceuticals, Servier, and Boehringer Ingelheim. His co-authors reported relationships with Medtronic, Pfizer, and Wyeth Pharmaceuticals. One co-author is an employee of Medtronic.

From the American Heart Association:

Primary source:Journal of the American Society of Nephrology
Source reference:
Hering D, et al "Renal denervation in moderate to severe CKD" J Am Soc Nephrol 2012; DOI: 10.1681/ASN.2011111062.

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Chris Kaiser

Cardiology Editor

Chris has written and edited for medical publications for more than 15 years. As the news editor for a United Business Media journal, he was awarded Best News Section. He has a B.A. from La Salle University and an M.A. from Villanova University. Chris is based outside of Philadelphia and is also involved with the theater as a writer, director, and occasional actor.

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