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This study is to investigate the effect of slow breathing on heart rate, blood pressure, heart rate variability (HRV) and blood pressure variability (BPV) in essential hypertension.
Sixty essential hypertensive patients underwent controlled breathing at 8 and 16 breaths per minute. ECG, respiratory and blood pressure signal were recorded simultaneously. The effect of slow breathing on heart rate, blood pressure and respiratory peak were analysed, and high-frequency (HF), low-frequency (LF) power and LF/HF ratio of HRV and BPV were studied by traditional and corrected spectral analysis.
Slow breathing (8 breaths per minute) compared with 16 breaths per minute, reduced heart rate (P<0.001), decreased the blood pressure (P<0.001), and shifted respiratory peak towards left (P<0.001). Compared to 16 breaths/min, traditional spectral analysis showed increased LF power and LF/HF ratio, decreased HF power of HRV and BPV at 8 breaths per minute (P<0.001 except HF power of BPV). As breathing rate decreased, corrected spectral analysis showed increased HF power, decreased LF power, LF/HF ratio of HRV and BPV (P<0.001).
Slow breathing can reduce heart rate and blood pressure, and it’s mechanism could be indeed capable of shifting sympatho-vagal balance towards vagal activities.