Effects Of Slow Breathing Rate On Blood Pressure And Heart Rate Variabilities

ObjectiveTo investigate the effects of slow breathing rate on heart rate variability(HRV) and blood pressure variability (BPV) in healthy subjects.Methods53healthy volunteers underwent three periods of controlled breathing at8,12and16breaths/min. ECG, respiratory and blood pressure signal wererecorded continuously and simultaneously. In our study, the influence of therespiration on RR interval (RRI) and blood pressure were observed.Simultaneously, we studied the effects of slow breathing rate on RRI, amplitudeof blood pressure oscillation, respiration peak, heart rate, High-frequency (HF)power, low-frequency (LF) power and LF/HF ratio of HRV and BPV. Then wecorrected the effect of slow breathing rate on respiratory peak shift which in turninfluenced spectral analysis.Results1. We observed RRI and blood pressure cyclical changes coincided withthe respiratory cycle. Typically, heart rate accelerated and blood pressure fallenduring inspiration and heart rate slowed down and blood pressure raised duringexpiration.2. As breathing rate reduced, amplitude of RRI and blood pressureoscillation increased, heart rate slowed (all P <0.001), respiratory peak shiftedtowards left (all P <0.001). 3. Compared to16breaths/min, traditional spectral analysis showeddeceased HF power, increased LF power and LF/HF ratio of HRV and BPV at arate of8breaths/min (all P <0.01).4. As the breathing rates decreased gradually, corrected spectral analysisshowed increased HF power, deceased LF power and LF/HF ratio of HRV andBPV at a rate of8breaths/min (all P <0.01except statistically significantrespiratory rate effect was not found in LF power of BPV).Conclusion1. The variation of cardiac cycle interval was synchronous with respiration,known as respiratory sinus arrhythmia. The fluctuation of blood pressure wassynchronous with respiration, and defined these oscillations asrespiration-related BPV. Respiratory sinus arrhythmia and respiration-relatedBPV constituted the essential component of HRV and BPV, respectively. Powerspectrum of Respiratory sinus arrhythmia and respiration-related BPV mayeasily entrain respiration peak.2. Reductions of breathing rate shifted the respiratory peak into the junctionof HF and LF or even below LF range. In accordance with this shift, the effect ofslow breathing rate on respiratory peak shift should be corrected when weperformed HRV and BPV spectral analysis.3. Corrected spectral analysis demonstrated that slow respiration cancause increase in HF power and decease in LF power and LF/HF ratio. Thesedemonstrated that slow breathing was indeed capable of increasing vagalactivities and shifting sympatho-vagal balance towards vagal activities. ObjectiveTo investigate the changes of heart rate variability (HRV) and bloodpressure variability (BPV) and effects of slow breathing rate on HRV and BPV inessential hypertension (EH) patients.Methods27EH patients and53healthy volunteers underwent three periods ofcontrolled breathing at8,12and16breaths/min. ECG, respiratory and bloodpressure signal were recorded continuously and simultaneously. In our study,the changes of HRV and BPV were observed in EH patients. Simultaneously,we studied the effects of slow breathing rate on respiration peak, heart rate,High-frequency (HF) power, low-frequency (LF) power and LF/HF ratio of HRVand BPV. Then we corrected the effect of slow breathing rate on respiratorypeak shift which in turn influenced spectral analysis.Results1. We observed deceased HF power, increased LF power and LF/HF ratioof HRV and BPV in EH patients compared to the healthy volunteers (P <0.05inHF, LF and LF/HF ratio of HRV).2. As breathing rate reduced, amplitude of RRI and blood pressureoscillation increased, heart rate slowed (all P <0.05), respiratory peak shiftedtowards left (all P <0.001).3. Compared to16breaths/min, traditional spectral analysis showed deceased HF power, increased LF power and LF/HF ratio of HRV and BPV at arate of8breaths/min (P <0.05in LF and LF/HF ratio of HRV and BPV).4. As the breathing rates decreased gradually, corrected spectral analysisshowed increased HF power, deceased LF power and LF/HF ratio of HRV andBPV at a rate of8breaths/min (all P <0.05except statistically significantrespiratory rate effect was not found in LF power of BPV).Conclusion1. Decrease in HF power in EH patients suggested decreasing vagalactivities.2. Reductions of breathing rate shifted the respiratory peak into the junctionof HF and LF or even below LF range. In accordance with this shift, the effect ofslow breathing rate on respiratory peak shift should be corrected when weperformed HRV and BPV spectral analysis.3. Corrected spectral analysis demonstrated that slow respiration can causeincrease in HF power and decease in LF power and LF/HF ratio in EH patients.These demonstrated that slow breathing was indeed capable of decreasingblood pressure and adjusting blood pressure variability and decreasingcardiovascular risk. This opens a new area of future research in the bettermanagement of patients with essential hypertension...