Cardiovagal and sympathetic baroreflex regulation in heart failure

Introduction: Arterial baroreflex sensitivity (BRS) is characterized by the magnitude of physiological responses to arterial pressure changes. Rapid RR interval responses are quantified by cardiovagal BRS parameters, sympathetic responses could be assessed by changes in muscle sympathetic nerve activity (MSNA). Abnormal indices in heart failure are associated with poor outcome. Patients and methods: 52, heart failure patients (age 59 ± 10 years, EF 37 ± 11%), and 11, age-matched healthy volunteers were studied. From ECG and arterial pressure recordings up-BRS and down-BRS values were determined using the method of spontaneous sequences. The low frequency cross-spectral gain, the LF alpha was also determined. Percutaneous puncture of the peroneal nerves allowed determination of MSNA burst incidence (burst/100 cycles), which was correlated to corresponding diastolic pressure bins of 3 mmHg, yielding a sympathetic BRS, the BRSSY-incidence. Results: Up- and down-BRS could be calculated in 19% of the patients, LF alpha was determined in 69%. Those with missing cardiovagal BRS values showed diminished RR interval variation, and higher levels of NT-proBNP. The measurable cardiovagal BRS indices did not separate patients and healthy volunteers. BRSSY-incidence could be determined in 58% of the patients. The sympathetic gain as well as the burst incidence differed significantly between patients and healthy volunteers. Missing BRSSY-incidence was associated with higher burst incidence. Conclusion: Cardiovagal BRS indices have limited value in differentiating healthy and heart failure subjects. Incalculable values among patients indicate more severe disease state. BRSSY-incidence does separate healthy and diseased population, the missing BRSSY-incidence values are related to increased sympathetic activity. Orv Hetil. 2021; 162(3): 91–98.