Effect of baroreflex activation therapy on renal sodium excretion in patients with resistant hypertension.
OBJECTIVE
Activation of the sympathetic nervous system increases sodium retention in resistant hypertension. Baroreflex activation therapy (BAT) is an interventional method to reduce sympathetic overactivity in patients with resistant hypertension. This study aimed to assess the effect of BAT on urinary sodium excretion.


METHODS
From 2012 to 2015, consecutive patients with resistant hypertension and blood pressure (BP) above target despite polypharmacy strategies were consecutively included in this observational study. BAT was provided with the individual adaption of programmed parameters over the first months. 24-h urinary sodium excretion (UNa) was estimated at baseline and after 6 months using the Kawasaki formula in patients undergoing BAT. Additionally, the fractional sodium excretion, plasma renin activity, and aldosterone levels were assessed.


RESULTS
Forty-two patients completed the 6-month follow-up period. Office systolic and ambulatory 24-h systolic BP at baseline were 169 ± 27 mmHg and 148 ± 16 mmHg despite a median intake of 7(3-9) antihypertensive drugs. After 6 months of BAT, systolic office BP decreased to 150 ± 29 mmHg (p < 0.01), 24-h systolic BP to 142 ± 22 mmHg (p = 0.04) and 24-h UNa increased by 37% compared to baseline (128 ± 66 vs. 155 ± 83 mmol/day, p < 0.01). These findings were accompanied by a significant increase in fractional sodium excretion (0.74% [0.43-1.47] to 0.92% [0.61-1.92]; p = 0.02). However, in contrast to the significant BP reduction, eGFR, plasma sodium, renin activity and aldosterone levels did not change during BAT. The increase in sodium excretion was correlated with the change in eGFR (r = 0.371; p = 0.015).


CONCLUSION
The present study revealed a significant increase of estimated 24-h UNa which may contribute to the long-term BP-lowering effects of this interventional method.
['Lipphardt|Mark|M|', 'Koziolek|Michael J|MJ|', 'Lehnig|Luca-Yves|LY|', 'Schäfer|Ann-Kathrin|AK|', 'Müller|Gerhard A|GA|', 'Lüders|Stephan|S|', 'Wallbach|Manuel|M|http://orcid.org/0000-0002-1162-4682']
D000328:Adult D000368:Aged D000959:Antihypertensive Agents D017704:Baroreflex D015331:Cohort Studies D005260:Female D005919:Glomerular Filtration Rate D006801:Humans D006973:Hypertension D007668:Kidney D008297:Male D008875:Middle Aged D012964:Sodium D016896:Treatment Outcome
Baroreflex activation therapy Resistant hypertension Sympathetic nervous system Urinary sodium excretion Kawasaki formula