Blood Pressure Modulation With Low-Intensity Focused Ultrasound Stimulation to the Vagus Nerve: A Pilot Animal Study

Abstract

Objective For hypertensive individuals, their blood pressure (BP) is often managed by taking medications. However, antihypertensive drugs might cause adverse effects such as congestive heart failure and are ineffective in significant numbers of the hypertensive population. As an alternative method for hypertension management, non-drug devices-based neuromodulation approaches such as functional electrical stimulation (FES) have been proposed. The FES approach requires the implantation of a stimulator into the body. One recently emerging technique, called low-intensity focused ultrasound stimulation (FUS), has been proposed to non-invasively modulate neural activities. In this pilot study, the feasibility of adopting low-intensity FUS neuromodulation for BP regulation was investigated using animal models. Methods A FUS system was developed for BP modulation in rabbits. For each rabbit, the low-intensity FUS with different acoustic intensities was used to stimulate its exposed left vagus nerve, and the BP waveform was synchronously recorded in its right common carotid artery. The effects of the different FUS intensities on systolic blood pressure (SBP), diastolic blood pressure (DBP), mean blood pressure (MAP), and heart rate (HR) were extensively examined from the BP recordings. Results The results demonstrated that the proposed FUS method could successfully induce changes in SBP, DBP, MAP, and HR values. When increasing acoustic intensities, the values of SBP, DBP, and MAP would tend to decrease more substantially. Conclusion The findings of this study suggested that BP could be modulated through the FUS, which might provide a new way for non-invasive and non-drug management of hypertension.

Afterload reduction after non-invasive vagus nerve stimulation in acute heart failure

“…This acute reduction in BP was previously demonstrated when selective and non-selective VNS therapy was performed to anesthetized rats ( Plachta et al, 2014 , 2016 ). Low-intensity focused ultrasound VNS technique also reduced BP and HR in rabbits ( Ji et al, 2020 ).…”

The sustainable antihypertensive and target organ damage protective effect of transcranial focused ultrasound stimulation in spontaneously hypertensive rats

“…Thus, targeting the core nucleus of the autonomic neural network and inhibiting SNS activity may have beneficial effects on hypertension. For example, baroreceptor stimulation by baroreflex activation therapy [44], rostral subcallosal neocortex stimulation by DBS [45], vagus nerve stimulation by LIFU [46], and kidney stimulation by LIFU [47] all reported antihypertensive effects. This VLPAG is involved in the integration of autonomic nerve function, with strong functional brain connections to the solitary tract nucleus and medulla oblongata regions [48].…”

Recent updates in autonomic research: a focus on new technologies with high-resolution procedures to study sympathetic nerve activity, plasma proteomic profiling in POTS, and non-invasive neuromodulation with focused ultrasound

“…Ji and colleagues demonstrated that low-intensity FUS of the vagus nerve was capable of lowering blood pressure in normotensive animals [11]. In a study published in the Journal of Neural Engineering [12], the same group investigated the effect of FUS of the left vagus nerve on blood pressure, heart rate, respiratory rate, heart rate variability (HRV), systolic blood pressure variability, and baroreflex sensitivity (BRS) in fifty 12-week-old spontaneously hypertensive rats.…”