title: Utility of a Novel Biofeedback Device for Within-Breath Modulation of Heart Rate in Rats: A Quantitative Comparison of Vagus Nerve vs. Right Atrial Pacing.
abstract: In an emerging bioelectronics era, there is a clinical need for physiological devices incorporating biofeedback that permits natural and demand-dependent control in real time. Here, we describe a novel device termed a central pattern generator (CPG) that uses cutting edge analog circuitry producing temporally controlled, electrical stimulus outputs based on the real time integration of physiological feedback. Motivated by the fact that respiratory sinus arrhythmia (RSA), which is the cyclical changes in heart rate every breath, is an essential component of heart rate variability (HRV) (an indicator of cardiac health), we have explored the versatility and efficiency of the CPG for producing respiratory modulation of heart rate in anesthetized, spontaneously breathing rats. Diaphragmatic electromyographic activity was used as the input to the device and its output connected to either the right cervical vagus nerve or the right atrium for pacing heart rate. We found that the CPG could induce respiratory related heart rate modulation that closely mimicked RSA. Whether connected to the vagus nerve or right atrium, the versatility of the device was demonstrated by permitting: (i) heart rate modulation in any phase of the respiratory cycle, (ii) control of the magnitude of heart rate modulation, and (iii) instant adaptation to changes in respiratory frequency. Vagal nerve pacing was only possible following transection of the nerve limiting its effective use chronically. Pacing via the right atrium permitted better flexibility and control of heart rate above its intrinsic level. This investigation now lays the foundation for future studies using this biofeedback technology permitting closer analysis of both the function and dysfunction of RSA.
authors: School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK.
authors: Erin L
authors: EL
authors: O'Callaghan
authors: Department of Physics, University of Bath Bath, UK.
authors: Ashok S
authors: AS
authors: Chauhan
authors: Department of Physics, University of Bath Bath, UK.
authors: Le
authors: L
authors: Zhao
authors: School of Physiology, Pharmacology and Neuroscience, University of BristolBristol, UK; Department of Physiology, School of Medicine of Ribeirão Preto, University of São PauloSão Paulo, Brazil.
authors: Renata M
authors: RM
authors: Lataro
authors: Department of Physiology, School of Medicine of Ribeirão Preto, University of São Paulo São Paulo, Brazil.
authors: Helio C
authors: HC
authors: Salgado
authors: Department of Physics, University of Bath Bath, UK.
authors: Alain
authors: A
authors: Nogaret
authors: School of Physiology, Pharmacology and Neuroscience, University of Bristol Bristol, UK.
authors: Julian F R
authors: JF
authors: Paton
keywords: cardiac pacing; heart rate variability; novel biofeedback device; respiratory sinus arrhythmia; vagal nerve stimulation