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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 ¼ 0.09), HR (P ¼ 0.08), but not MSNA (P ¼ 0.20) responses to mental stress. Long-term SLOWB decreased office SBP (P < 0.001), DBP (P < 0.01), HR (P ¼ 0.004), but not 24-h BP. Resting MSNA was unchanged after long-term SLOWB (P ¼ 0.68). Long-term SLOWB did not influence BP, HR or MSNA responses to handgrip and cold pressor, but reduced SBP (P ¼ 0.03), HR (P ¼ 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.
Background Slow breathing (SLOWB) alleviates symptoms of chronic heart failure (HF) but its long-term effects are unknown. We examined the acute and long-term impact of device-guided breathing on hemodynamics and prognostic parameters in HF patients with reduced ejection fraction (HFrEF).Methods and results Twenty-one patients with HFrEF (23.9 ± 5.8%, SD ± mean) on optimal medical therapy underwent blood pressure (BP), heart rate (HR), HR variability, 6-min walk test (6MWT), cardiopulmonary exercise testing (CPET), and echocardiography measurements before and 3 months after SLOWB home training (30 min daily). After 3 months, all patients were assigned to continue SLOWB (Group 1) or no-SLOWB (Group 2). All tests were repeated after 6 months. Acute SLOWB (18 ± 5 vs 8 ± 2 breaths/min, P < 0.001) had no influence on BP and HR but improved saturation (97 ± 2 vs 98 ± 2%, P = 0.01). Long-term SLOWB reduced office systolic BP (P < 0.001) but not central or ambulatory systolic BP. SLOWB reduced SDNN/RMSSD ratio (P < 0.05) after 3 months. One-way repeated measures of ANOVA revealed a significant increase in 6MWT and peak RER (respiratory exchange ratio) from baseline to 6-month follow-up in group 1 (P < 0.05) but not group 2 (P = 0.85 for 6MWT, P = 0.69 for RER). No significant changes in echocardiography were noted at follow-up. No HF worsening, rehospitalisation or death occurred in group 1 out to 6-month follow-up. Two hospitalizations for HF decompensation and two deaths ensued in group 2 between 3- and 6-month follow-up.
Conclusions SLOWB training improves cardiorespiratory capacity and appears to slow the progression of HFrEF. Further long-term outcome studies are required to confirm the benefits of paced breathing in HFrEF.