Spike rate of multi-unit muscle sympathetic nerve fibers after catheter-based renal nerve ablation.
Patients with treatment-resistant arterial hypertension exhibited profound reductions in single sympathetic vasoconstrictor fiber firing rates after renal nerve ablation. In contrast, integrated multi-unit muscle sympathetic nerve activity (MSNA) changed little or not at all. We hypothesized that conventional MSNA analysis may have missed single fiber discharges, thus, obscuring sympathetic inhibition after renal denervation. We studied patients with difficult-to-control arterial hypertension (age 45-74 years) before, 6 (n = 11), and 12 months (n = 8) after renal nerve ablation. Electrocardiogram, respiration, brachial, and finger arterial blood pressure (BP), as well as the MSNA and raw MSNA signals were analyzed. We detected MSNA action-potential spikes using 2 stage kurtosis wavelet denoising techniques to assess mean, median, and maximum spike rates for each beat-to-beat interval. Supine heart rate and systolic BP did not change at 6 (ΔHR: -2 ± 3 bpm; ΔSBP: 2 ± 9 mm Hg) or at 12 months (ΔHR: -1 ± 3 mm Hg, ΔSBP: -1 ± 9 mm Hg) after renal nerve ablation. Mean burst frequency and mean spike frequency at baseline were 34 ± 3 bursts per minute and 8 ± 1 spikes per second. Both measurements did not change at 6 months (-1.4 ± 3.6 bursts/minute; -0.6 ± 1.4 spikes/second) or at 12 months (-2.5 ± 4.0 bursts/minute; -2.0 ± 1.6 spikes/second) after renal nerve ablation. After renal nerve ablation, BP decreased in 3 of 11 patients. BP and MSNA spike frequency changes were not correlated (slope = -0.06; P = .369). Spike rate analysis of multi-unit MSNA neurograms further suggests that profound sympathetic inhibition is not a consistent finding after renal nerve ablation.
Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany.
Jens
J
Tank
Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany.
Karsten
K
Heusser
Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany.
Julia
J
Brinkmann
Department of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany.
Bernhard M
BM
Schmidt
Department of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany.
Jan
J
Menne
Department of Cardiology and Angiology, Hannover Medical School, Hannover, Germany.
Johann
J
Bauersachs
Department of Nephrology and Hypertension, Hannover Medical School, Hannover, Germany.
Hermann
H
Haller
Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University, Nashville, TN, USA.
André
A
Diedrich
Institute of Clinical Pharmacology, Hannover Medical School, Hannover, Germany. Electronic address: jordan.jens@mh-hannover.de.
Jens
J
Jordan
D000200:Action Potentials / Q000502:physiology*; D000368:Aged; D001794:Blood Pressure / Q000502:physiology; D017115:Catheter Ablation / Q000379:methods*; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006973:Hypertension / Q000601:surgery*; D007668:Kidney / Q000294:innervation* / Q000601:surgery*; D008297:Male; D008875:Middle Aged; D018482:Muscle, Skeletal / Q000294:innervation; D009412:Nerve Fibers / Q000502:physiology; D009476:Neurons, Efferent / Q000502:physiology; D013562:Sympathectomy; D013564:Sympathetic Nervous System / Q000503:physiopathology / Q000601:surgery*
Arterial hypertension; blood pressure; microneurography; renal denervation