In silico trial of baroreflex activation therapy for the treatment of obesity-induced hypertension

Clinical trials evaluating the efficacy of chronic electrical stimulation of the carotid baroreflex for the treatment of hypertension (HTN) are ongoing. However, the mechanisms by which this device lowers blood pressure (BP) are unclear, and it is uncertain which patients are most likely to receive clinical benefit. Mathematical modeling provides the ability to analyze complicated interrelated effects across multiple physiological systems. Our current model HumMod is a large physiological simulator that has been used previously to investigate mechanisms responsible for BP lowering during baroreflex activation therapy (BAT). First, we used HumMod to create a virtual population in which model parameters (n = 335) were randomly varied, resulting in unique models (n = 6092) that we define as a virtual population. This population was calibrated using data from hypertensive obese dogs (n = 6) subjected to BAT. The resultant calibrated virtual population (n = 60) was based on tuning model parameters to match the experimental population in 3 key variables: BP, glomerular filtration rate, and plasma renin activity, both before and after BAT. In the calibrated population, responses of these 3 key variables to chronic BAT were statistically similar to experimental findings. Moreover, blocking suppression of renal sympathetic nerve activity (RSNA) and/or increased secretion of atrial natriuretic peptide (ANP) during BAT markedly blunted the antihypertensive response in the virtual population. These data suggest that in obesity-mediated HTN, RSNA and ANP responses are key factors that contribute to BP lowering during BAT. This modeling approach may be of value in predicting BAT responses in future clinical studies.

Novel Non-Pharmaceutical Advancements in Heart Failure Management: The Emerging Role of Technology

Purpose of Review: To summarise and discuss the implications of recent technological advances in heart failure care. Recent Findings: Heart failure remains a significant source of morbidity and mortality in the US population despite multiple classes of approved pharmacological treatments. Novel cardiac devices and technologies may offer an opportunity to improve outcomes. Baroreflex Activation Therapy and Cardiac Contractility Remodelling may improve myocardial contractility by altering neurohormonal stimulation of the heart. Implantable Pulmonary Artery Monitors and Biatrial Shunts may prevent heart failure admissions by altering the trajectory of progressive congestion. Phrenic Nerve Stimulation offers potentially effective treatment for comorbid conditions. Smartphone applications offer an intriguing strategy for improving medication adherence. Summary: Novel heart failure technologies offer promise for reducing this public health burden. Randomized controlled studies are indicated for assessing the future role of these novel therapies.

Baroreflex Activation Therapy (BAT) Effectiveness Among Heart Failure Patients: A Systematic Review and Meta-Analysis

Heart failure is promoted by the imbalance of sympathovagal, which increased sympathetic and decreased parasympathetic activity. BAT, an electrical stimulation technology, cause the baroreflex to be activated and balances the sympathovagal. Systematic review and meta-analysis were conducted, including published reports about the effectiveness of BAT in heart failure patients from PubMed, Embase, Cochrane, and Google Scholar to calculate the pooled standard mean difference and 95% confidence interval (95% CI) using either random or fixed effect model. Our search strategy identified 161 possible studies. Thirteen studies have been included as a full-text review. We excluded seven of these papers due to review, and our analysis has included six papers. Our combined analysis has shown that BAT is associated with an improvement in NYHA class compared to control (0.19[95%CI: 0.11-0.31], p = 0.000). Our pooled analysis also found that BAT, compared to control, was associated with 6-MHWD improvement, (-136.25[95%CI: -181.34 - -91.17], p = 0.000). Our pooled analysis also found that BAT, compared to control, was associated with HF hospitalization (-6.38[95%CI: -8.46 - -4.30], p = 0.000). BAT has a significant effect on improving NYHA Class, 6-minute hall walk distance, and decreasing HF patient's hospitalization days. Meanwhile, there is an insignificancy on LVEF and QoL improvement in HF patients. Future studies are still needed.

Twiddler’s syndrome after implantation of baroreflex activation therapy: a case report

Background Twiddler’s syndrome is a rare complication after implantation of cardiac pacemakers or cardioverter-defibrillators that usually occurs within the first year after the procedure. However, it has not yet been described following implantation of baroreflex activation therapy (BAT). Case summary A 61-year-old female patient was referred to the cardiology outpatient clinic due to uncontrolled arterial hypertension despite maximal doses of several established drugs. Therefore, right-sided BAT implantation was successfully performed in February 2017 with good clinical response. Because of sustained neck pain at the site of stimulator, surgical revision was performed in November 2019 including a switch of the lead to the contralateral position. Approximately 1 month later, Twiddler’s syndrome was identified on the basis of recurrent pain at the generator site necessitating pocket-revision, however, the lead was only untwisted but not replaced. A few weeks afterwards, unfortunately, lead revision was indispensable due to lead fracture. Discussion This case presents the uncommon phenomenon of Twiddler’s syndrome after BAT implantation. In addition, the commonly twisted lead should always be replaced as well during surgical pocket-revision in order to ensure proper long-term function.

Device Therapy of Hypertension

In the past decade, efforts to improve blood pressure control have looked beyond conventional approaches of lifestyle modification and drug therapy to embrace interventional therapies. Based upon animal and human studies clearly demonstrating a key role for the sympathetic nervous system in the etiology of hypertension, the newer technologies that have emerged are predominantly aimed at neuromodulation of peripheral nervous system targets. These include renal denervation, baroreflex activation therapy, endovascular baroreflex amplification therapy, carotid body ablation, and pacemaker-mediated programmable hypertension control. Of these, renal denervation is the most mature, and with a recent series of proof-of-concept trials demonstrating the safety and efficacy of radiofrequency and more recently ultrasound-based renal denervation, this technology is poised to become available as a viable treatment option for hypertension in the foreseeable future. With regard to baroreflex activation therapy, endovascular baroreflex amplification, carotid body ablation, and programmable hypertension control, these are developing technologies for which more human data are required. Importantly, central nervous system control of the circulation remains a poorly understood yet vital component of the hypertension pathway and mandates further investigation. Technology to improve blood pressure control through deep brain stimulation of key cardiovascular control territories is, therefore, of interest. Furthermore, alternative nonsympathomodulatory intervention targeting the hemodynamics of the circulation may also be worth exploring for patients in whom sympathetic drive is less relevant to hypertension perpetuation. Herein, we review the aforementioned technologies with an emphasis on the preclinical data that underpin their rationale and the human evidence that supports their use.

Cost-impact analysis of baroreflex activation therapy in chronic heart failure patients in the United States

Background The study evaluated the cost of baroreflex activation therapy plus guideline directed therapy (BAT + GDT) compared to GDT alone for HF patients with reduced ejection fraction and New York Heart Association Class III or II (with a recent history of III). Baroreflex activation therapy (BAT) is delivered by an implantable device that stimulates the baroreceptors through an electrode attached to the outside of the carotid artery, which rebalances the autonomic nervous system to regain cardiovascular (CV) homeostasis. The BeAT-HF trial evaluated the safety and effectiveness of BAT. Methods A cost impact model was developed from a U.S. health care payer or integrated delivery network perspective over a 3-year period for BAT + GDT versus GDT alone. Expected costs were calculated by utilizing 6-month data from the BeAT-HF trial and existing literature. HF hospitalization rates were extrapolated based on improvement in NT-proBNP. Results At baseline the expected cost of BAT + GDT were $29,526 per patient more than GDT alone due to BAT device and implantation costs. After 3 years, the predicted cost per patient was $9521 less expensive for BAT + GDT versus GDT alone due to lower rates of significant HF hospitalizations, CV non-HF hospitalizations, and resource intensive late-stage procedures (LVADs and heart transplants) among the BAT + GDT group. Conclusions BAT + GDT treatment becomes less costly than GDT alone beginning between years 1 and 2 and becomes less costly cumulatively between years 2 and 3, potentially providing significant savings over time. As additional BeAT-HF trial data become available, the model can be updated to show longer term effects.