Objective: Acute slow breathing (SLOWB) affects sympathetic cardiovascular regulation, but its long-term effects are unknown. Using device-guided breathing we explored short-term and long-term SLOWB effects on blood pressure (BP), heart rate (HR) and muscle sympathetic nerve activity (MSNA) in essential hypertension.
Methods: We measured BP, HR and MSNA in 10 hypertensive individuals at rest, during laboratory stressors, before and after acute SLOWB, and 8 weeks after SLOWB exercise. Twelve matched hypertensive controls underwent a similar protocol excluding SLOWB intervention. Office and 24-h BP were obtained at baseline and at follow-up.
Results: Acute SLOWB had no influence on BP, HR, but decreased MSNA (P < 0.01). BP, HR, MSNA responses to handgrip were comparable before and after acute SLOWB. Acute SLOWB tended to reduce SBP (P = 0.09), HR (P = 0.08), but not MSNA (P = 0.20) responses to mental stress. Long-term SLOWB decreased office SBP (P < 0.001), DBP (P < 0.01), HR (P = 0.004), but not 24-h BP. Resting MSNA was unchanged after long-term SLOWB (P = 0.68). Long-term SLOWB did not influence BP, HR or MSNA responses to handgrip and cold pressor, but reduced SBP (P = 0.03), HR (P = 0.03) responses to mental stress without MSNA changes. In controls BP, HR, MSNA responses to laboratory stressors remained unchanged at baseline and at follow-up.
Conclusion: In essential hypertension, MSNA is reduced during acute SLOWB, but remains unaltered following long-term SLOWB. Long-term SLOWB reduces office, but not ambulatory BP and HR. SLOWB attenuates cardiovascular response to mental stress, but not physical stressors. These findings may be indicative of beneficial SLOWB effects on stress reduction in essential hypertension.
aDepartment of Hypertension and Diabetology, Medical University of Gdansk, Gdansk, Poland
bICRC, Department of Cardiovascular Diseases, St Anne's University Hospital Brno, Brno, Czech Republic
cDivision of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA
dDepartment of Clinical Medicine and Prevention, University of Milano-Bicocca
eDepartment of Cardiology, S. Luca Hospital, Istituto Auxologico Italiano, Milan, Italy
Correspondence to Dagmara Hering, MD, PhD, Department of Hypertension and Diabetology, Medical University of Gdansk, Debinki 7c, 80-952 Gdansk, Poland. Tel: +48 58 349 2065; fax: +48 58 349 2601; e-mail: email@example.com
Abbreviations: BP, blood pressure; bpm, beat per minute; HR, heart rate; MSNA, muscle sympathetic nerve activity; SLOWB, slow breathing
Received 9 June, 2012
Revised 4 October, 2012
Accepted 8 January, 2013