Closed-loop control of the heart rate by electrical stimulation of the vagus nerve

Abstract

Stimulation of the vagus nerve potentially decreases the risk of sudden cardiac death. An improvement of the technique would be its regulation using the heart rate (HR) as a feedback variable. We address the possibility of closed-loop control of the HR, focusing on the stimulation parameters, nerve fibre populations and the reproducibility of the cardiovascular response. The response to electrical stimulation of the vagus nerve was studied in seven acute experiments on pigs. Feedback regulation of the HR over periods of 5 min was carried out. Three main populations of myelinated fibres were found. The performance of the controller was significantly better at amplitudes higher than those needed for stimulation of the myelinated components only. A 18% change in the duration of the RR interval could be controlled in all experiments. The possibility of closed-loop control of the HR seems to be promising.

On-off closed-loop control of vagus nerve stimulation for the adaptation of heart rate

“…Although VNS is commonly delivered in an open-loop approach, it is now recognized that adaptive, closed-loop approaches may be necessary to optimize the therapy and minimize side effects of neuro-stimulation devices [8]- [11]. A variety of physiological data may be employed as control variables in a closed-loop approach, depending on the target function of VNS control.…”

“…Other closed-loop systems for VNS control, based on the adaptation of the VNS frequency are proposed in [12] and [11]. In [12], a control system, based on the classical cumulative sum control chart technique, adjusts stimulation frequency in order to regulate the average ventricular rate during atrial fibrillation in dogs.…”

Average reference recording from the vagal nerve reveals an evoked indirect response

“…The vagal nerve is a possible source of information about these organs. The response of fibers in the vagal nerve to electrical stimulation has been studied in both animals and humans [1][2][3][4]. Compound action potentials (CAPs) with components coming from thick, myelinated fibers to thin, unmyelinated fibers are identified.…”

“…Compound action potentials (CAPs) with components coming from thick, myelinated fibers to thin, unmyelinated fibers are identified. The thickest fibers have the highest conduction velocity, up to 70m/s [3]. The thinnest fibers have the lowest conduction velocity, as low as 1.2m/s [1].…”

“…This distance needs to be large enough to ensure that the stimulus artifact does not obscure the components of the compound action potentials in the recordings, and that the various components do not overlap. In previous studies [1][2][3][4] the distance between stimulation and recording site was divided by the time between the stimulus and the recorded components of the CAP to determine the conduction velocities. It was assumed that each component of the CAP was a direct effect of the stimulus applied to the nerve.…”