Long-term effects of baroreflex activation therapy on glucose metabolism

Effect of baroreflex activation therapy on dipping pattern in patients with resistant hypertension

A relevant number of patients with resistant hypertension do not achieve blood pressure (BP) dipping during nighttime. This inadequate nocturnal BP reduction is associated with elevated cardiovascular risks. The aim of this study was to evaluate whether a nighttime intensification of BAT might improve nocturnal BP dipping. In this prospective observational study, non-dippers treated with BAT for at least 6 months were included. BAT programming was modified in a two-step intensification of nighttime stimulation at baseline and week 6. Twenty-four hours ambulatory BP (ABP) was measured at inclusion and after 3 months. A number of 24 patients with non- or inverted dipping pattern, treated with BAT for a median of 44 months (IQR 25-52) were included. At baseline of the study, patients were 66 ± 9 years old, had a BMI of 33 ± 6 kg/m² , showed an office BP of 135 ± 22/72 ± 10 mmHg, and took a median number of antihypertensives of 6 (IQR 4-9). Nighttime stimulation of BAT was adapted by an intensification of pulse width from 237 ± 161 to 267 ± 170 μs (p = .003) while frequency (p = .10) and amplitude (p = .95) remained unchanged. Uptitration of BAT programming resulted in an increase of systolic dipping from 2 ± 6 to 6 ± 8% (p = .03) accompanied with a significant improvement of dipping pattern (p = .02). Twenty four hours ABP, day- and nighttime ABP remained unchanged. Programming of an intensified nighttime BAT interval improved dipping profile in patients treated with BAT, while the overall 24 h ABP did not change. Whether the improved dipping response contributes to a reduction of cardiovascular risk beyond the BP-lowering effects of BAT, however, remains to be shown.

Metabolic associated fatty liver disease is a disease related to sympathetic nervous system activation

Strong evidence from animal and human studies shows that sympathetic nervous system (SNS) activation is a key factor in the development of metabolic associated fatty liver disease (MAFLD). Activation of the sympathetic nervous system plays an important role in the pathogenesis of obesity, metabolic syndrome, diabetes, hypertension, and MAFLD. When genetically susceptible subjects are exposed to a variety of epigenetic changes, their liver damage may develop into MAFLD. Thus, the pathogenesis of MAFLD is complex, involving the complex interaction of insulin resistance, abnormal hormone secretion, obesity, diet, genetic factors, immune activation, gut microbiota, and other factors. In these processes, the role of sympathetic nerves cannot be underestimated. Notably, SNS has been proposed as a therapeutic target for MAFLD by inhibiting sympathetic nerves. It is worthy of further discussion and research.

Metabolic Dysfunction-Associated Fatty Liver Disease (MAFLD)-A Condition Associated with Heightened Sympathetic Activation

Metabolic dysfunction-associated fatty liver disease (MAFLD) is the most common liver disease affecting a quarter of the global population and is often associated with adverse health outcomes. The increasing prevalence of MAFLD occurs in parallel to that of metabolic syndrome (MetS), which in fact plays a major role in driving the perturbations of cardiometabolic homeostasis. However, the mechanisms underpinning the pathogenesis of MAFLD are incompletely understood. Compelling evidence from animal and human studies suggest that heightened activation of the sympathetic nervous system is a key contributor to the development of MAFLD. Indeed, common treatment strategies for metabolic diseases such as diet and exercise to induce weight loss have been shown to exert their beneficial effects at least in part through the associated sympathetic inhibition. Furthermore, pharmacological and device-based approaches to reduce sympathetic activation have been demonstrated to improve the metabolic alterations frequently present in patients with obesity, MetSand diabetes. Currently available evidence, while still limited, suggests that sympathetic activation is of specific relevance in the pathogenesis of MAFLD and consequentially may offer an attractive therapeutic target to attenuate the adverse outcomes associated with MAFLD.

Immunity and the carotid body: implications for metabolic diseases

Neuro-immune communication has gained enormous interest in recent years due to increasing knowledge of the way in which the brain coordinates functional alterations in inflammatory and autoimmune responses, and the mechanisms of neuron-immune cell interactions in the context of metabolic diseases such as obesity and type 2 diabetes. In this review, we will explain how this relationship between the nervous and immune system impacts the pro- and anti-inflammatory pathways with specific reference to the hypothalamus-pituitary-adrenal gland axis and the vagal reflex and will explore the possible involvement of the carotid body (CB) in the neural control of inflammation. We will also highlight the mechanisms of vagal anti-inflammatory reflex control of immunity and metabolism, and the consequences of functional disarrangement of this reflex in settlement and development of metabolic diseases, with special attention to obesity and type 2 diabetes. Additionally, the role of CB in the interplay between metabolism and immune responses will be discussed, with specific reference to the different stimuli that promote CB activation and the balance between sympathetic and parasympathetic in this context. In doing so, we clarify the multivarious neuronal reflexes that coordinate tissue-specific responses (gut, pancreas, adipose tissue and liver) critical to metabolic control, and metabolic disease settlement and development. In the final section, we will summarize how electrical modulation of the carotid sinus nerve may be utilized to adjust these reflex responses and thus control inflammation and metabolic diseases, envisioning new therapeutics horizons.

Syndecan-4 as a Marker of Endothelial Dysfunction in Patients with Resistant Hypertension

(1) Background: Arterial hypertension (HTN) is one of the most relevant cardiovascular risk factors. Nowadays multiple pharmaceutical treatment options exist with novel interventional methods (e.g., baroreflex activation therapy (BAT)) as a last resort to treat patients with resistant HTN. Although pathophysiology behind resistant HTN is still not fully understood. There is evidence that selected biomarkers may be involved in the pathophysiology of HTN. (2) Methods: We investigated serum SDC4-levels in patients suffering from resistant HTN before and 6 months after BAT implantation. We collected 19 blood samples from patients with resistant HTN and blood pressure above target and measured serum SDC4-levels. (3) Results: Our results showed high serum SDC4-levels in patients with resistant HTN as compared to a healthy population. Patients with both, resistant HTN and diabetes mellitus type II, demonstrated higher serum SDC4-levels. β-blockers had lowering effects on serum SDC4-levels, whereas calcium channel blockers were associated with higher levels of serum SDC4. BAT implantation did not lead to a significant difference in serum SDC4-levels after 6 months of therapy. (4) Conclusion: Based on our results we propose SDC4 is elevated in patients suffering from resistant HTN. Thus, SDC4 might be a potential marker for endothelial dysfunction in patients with resistant hypertension.

Effects of Baroreflex Activation Therapy on Ambulatory Blood Pressure in Patients With Resistant Hypertension

Baroreflex activation therapy (BAT) has been demonstrated to decrease office blood pressure (BP) in the randomized, double-blind Rheos trial. There are limited data on 24-hour BP changes measured by ambulatory BP measurements (ABPMs) using the first generation rheos BAT system suggesting a significant reduction but there are no information about the effect of the currently used, unilateral BAT neo device on ABPM. Patients treated with the BAT neo device for uncontrolled resistant hypertension were prospectively included into this study. ABPM was performed before BAT implantation and 6 months after initiation of BAT. A total of 51 patients were included into this study, 7 dropped out from analysis because of missing or insufficient follow-up. After 6 months, 24-hour ambulatory systolic (from 148±17 mm Hg to 140±23 mm Hg, P <0.01), diastolic (from 82±13 mm Hg to 77±15 mm Hg, P <0.01), day- and night-time systolic and diastolic BP (all P ≤0.01) significantly decreased while the number of prescribed antihypertensive classes could be reduced from 6.5±1.5 to 6.0±1.8 ( P =0.03). Heart rate and pulse pressure remained unchanged. BAT was equally effective in reducing ambulatory BP in all subgroups of patients. This is the first study demonstrating a significant BP reduction in ABPM in patients undergoing chronically stimulation of the carotid sinus using the BAT neo device. About that BAT-reduced office BP and improved relevant aspects of ABPM, BAT might be considered as a new therapeutic option to reduce cardiovascular risk in patients with resistant hypertension. Randomized controlled trials are needed to evaluate BAT effects on ABPM in patients with resistant hypertension accurately.