Abstract
ObjectiveFor 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.MethodsA 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.ResultsThe 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.ConclusionThe 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.
Highlights
High blood pressure (BP) is one of the leading causes of morbidity and mortality worldwide
For a substantial portion of patients with hypertension, their BP is uncontrolled by currently available antihypertensive drugs, which are designated as having resistant hypertension (Bisognano et al, 2011)
Tremendous evidences have proved that neuromodulation techniques such as functional electrical stimulation (FES) of the carotid baroreceptor (Scheffers et al, 2010; Bisognano et al, 2011; Lohmeier and Iliescu, 2011; Bakris et al, 2012; Hoppe et al, 2012)/vagus nerve (Plachta et al, 2014; Gierthmuehlen et al, 2016; Annoni et al, 2019) and renal sympathetic denervation (RSD) by different devices and techniques [including surgical sympathectomy (Smithwick, 1948), laparoscopic sympathectomy (Gao et al, 2019), catheterbased radiofrequency ablation (Krum et al, 2009), endovascular ultrasound (Fengler et al, 2019), injection of neurotoxic agents (Lohmeier and Hall, 2019), external stereotactic radiofrequency (Cai et al, 2019), external high-intensity focused ultrasound (Wang et al, 2013), etc.,] might reduce BP through sympathetic nerve activity inhibition
Summary
High blood pressure (BP) is one of the leading causes of morbidity and mortality worldwide. Tremendous evidences have proved that neuromodulation techniques such as functional electrical stimulation (FES) of the carotid baroreceptor (Scheffers et al, 2010; Bisognano et al, 2011; Lohmeier and Iliescu, 2011; Bakris et al, 2012; Hoppe et al, 2012)/vagus nerve (Plachta et al, 2014; Gierthmuehlen et al, 2016; Annoni et al, 2019) and renal sympathetic denervation (RSD) by different devices and techniques [including surgical sympathectomy (Smithwick, 1948), laparoscopic sympathectomy (Gao et al, 2019), catheterbased radiofrequency ablation (Krum et al, 2009), endovascular ultrasound (Fengler et al, 2019), injection of neurotoxic agents (Lohmeier and Hall, 2019), external stereotactic radiofrequency (Cai et al, 2019), external high-intensity focused ultrasound (Wang et al, 2013), etc.,] might reduce BP through sympathetic nerve activity inhibition These procedures of current neuromodulation methods are either invasive or associated with complete nerve damage. Despite that the catheter-based RSD procedures are minimally invasive and the procedures of performing external stereotactic radiofrequency or external high-intensity focused ultrasound for RSD are non-invasive, BP is reduced by completely destroying the renal sympathetic nerve by utilizing the high intensity of the radiofrequency/ultrasound energy
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