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Groenland EH, Spiering W. Baroreflex Amplification and Carotid Body Modulation for the Treatment of Resistant Hypertension. Curr Hypertens Rep 2020; 22:27. [PMID: 32166464 PMCID: PMC7067736 DOI: 10.1007/s11906-020-1024-x] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Abstract
PURPOSE OF REVIEW Patients with true resistant hypertension (RH) are characterized by having high sympathetic activity and therefore potentially benefit from treatments such as baroreflex amplification (baroreflex activation therapy (BAT) or endovascular baroreflex amplification therapy (EVBA)) or carotid body (CB) modulation. This review aims at providing an up-to-date overview of the available evidence regarding these two therapies. RECENT FINDINGS In recent years, increasing evidence has confirmed the potential of baroreflex amplification, either electrically (Barostim neo) or mechanically (MobiusHD), to improve blood pressure control on short- and long-term with only few side effects, in patients with RH. Two studies regarding unilateral CB resection did not show a significant change in blood pressure. Only limited studies regarding CB modulation showed promising results for transvenous CB ablation, but not for unilateral CB resection. Despite promising results from mostly uncontrolled studies, more evidence regarding the safety and efficacy from ongoing large randomized sham-controlled trials is needed before baroreflex amplification and CB modulation can be implemented in routine clinical practice.
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Affiliation(s)
- Eline H Groenland
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3508, GA, Utrecht, The Netherlands
| | - Wilko Spiering
- Department of Vascular Medicine, University Medical Center Utrecht, Utrecht University, 3508, GA, Utrecht, The Netherlands.
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Halbach M, Grothaus D, Hoffmann F, Madershahian N, Kuhr K, Reuter H. Baroreflex activation therapy reduces frequency and duration of hypertension-related hospitalizations in patients with resistant hypertension. Clin Auton Res 2020; 30:541-548. [PMID: 32052254 PMCID: PMC8302539 DOI: 10.1007/s10286-020-00670-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2019] [Accepted: 01/30/2020] [Indexed: 12/01/2022]
Abstract
Purpose Baroreflex activation therapy (BAT) has been shown to lower blood pressure in patients with resistant hypertension. The purpose of this study was to analyze whether this translates into a reduction of more relevant clinical endpoints. Methods Patients with resistant hypertension were treated with the second-generation BAT system. Records on hospitalization (dates of admission and discharge, main diagnosis) were obtained from medical insurance companies. Results Records on hospitalization were available for a period of 1 year before BAT in two patients and 2 years in 22 patients. The total number of hospitalizations per patient was 3.3 ± 3.5/year before BAT and 2.2 ± 2.7/year after BAT (p = 0.03). Hospitalizations related to hypertension were significantly decreased from 1.5 ± 1.6/year before BAT to 0.5 ± 0.9/year after BAT (p < 0.01). The cumulative duration of hypertension-related hospital stays was significantly reduced from 8.0 ± 8.7 days/year before BAT to 1.8 ± 4.8 days/year after BAT (p < 0.01). Office cuff blood pressure was 183 ± 27 mmHg over 102 ± 17 mmHg under 6.6 ± 2.0 antihypertensive drugs before BAT and 157 ± 32 mmHg over 91 ± 20 mmHg (both p < 0.01) under 5.9 ± 1.9 antihypertensive drugs (p = 0.09 for number of drugs) at latest follow-up. Daytime ambulatory blood pressure was 164 ± 21 mmHg over 91 ± 14 mmHg before BAT and 153 ± 21 mmHg (p = 0.03) over 89 ± 15 mmHg (p = 0.56) at latest follow-up. Heart rate was 75 ± 16 bpm before BAT and 72 ± 12 bpm at latest follow-up (p = 0.35). Conclusions Rate and duration of hypertension-related hospitalizations in patients with severe resistant hypertension were lowered after BAT. Whether the response is mediated through improvements in blood pressure control requires further studies. Electronic supplementary material The online version of this article (10.1007/s10286-020-00670-9) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Marcel Halbach
- Department of Internal Medicine III, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.
| | - David Grothaus
- Department of Internal Medicine III, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
| | - Fabian Hoffmann
- Department of Internal Medicine III, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany
| | | | - Kathrin Kuhr
- Institute of Medical Statistics and Computational Biology, University of Cologne, Cologne, Germany
| | - Hannes Reuter
- Department of Internal Medicine III, University of Cologne, Kerpener Str. 62, 50937, Cologne, Germany.,Evangelisches Klinikum Köln-Weyertal, Weyertal 76, 50931, Cologne, Germany
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Dyrvig Kristensen AM, Pareek M, Olsen MH, Bhatt DL. Baroreflex Activation Therapy for Resistant Hypertension and Heart Failure. US CARDIOLOGY REVIEW 2020. [DOI: 10.15420/usc.2019.13.2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
Hypertension and heart failure are important contributors to global morbidity and mortality. Despite therapeutic lifestyle and pharmacological measures, a significant proportion of people with hypertension do not reach treatment targets. Patients with resistant or poorly controlled hypertension are at significantly increased risk of cardiovascular events, including heart failure. Since dysfunction of the sympathetic nervous system appears to play a key role in the development and progression of both hypertension and heart failure, these patients may benefit from treatment modalities aimed at reducing sympathetic function. The purpose of this paper is to provide an overview of baroreflex activation therapy as a potential treatment strategy in patients with resistant hypertension or heart failure.
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Affiliation(s)
| | - Manan Pareek
- Department of Cardiology, North Zealand Hospital, Hilleroed, Denmark; Brigham and Women’s Hospital Heart and Vascular Center, Harvard Medical School, Boston, MA
| | - Michael Hecht Olsen
- Cardiology Section, Department of Internal Medicine, Holbaek Hospital, Holbaek, Denmark
| | - Deepak L Bhatt
- Brigham and Women’s Hospital Heart and Vascular Center, Harvard Medical School, Boston, MA
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Abstract
PURPOSE OF REVIEW To give an overview on recent developments in permanent implant-based therapy of resistant hypertension. RECENT FINDINGS The American Heart Association (AHA) recently updated their guidelines to treat high blood pressure (BP). As elevated BP now is defined as a systolic BP above 120 mmHg, the prevalence of hypertension in the USA has increased from 32% (old definition of hypertension) to 46%. In the past years, device- and implant-mediated therapies have evolved and extensively studied in various patient populations. Despite an initial drawback in a randomized controlled trial (RCT) of bilateral carotid sinus stimulation (CSS), new and less invasive and unilateral systems for baroreflex activation therapy (BAT) with the BAROSTIM NEO® have been developed which show promising results in small non-randomized controlled (RCT) studies. Selective vagal nerve stimulation (VNS) has been successfully evaluated in rodents, but has not yet been tested in humans. A new endovascular approach to reshape the carotid sinus to lower BP (MobiusHD™) has been introduced (baroreflex amplification therapy) with favorable results in non-RCT trials. However, long-term results are not yet available for this treatment option. A specific subgroup of patients, those with indication for a 2-chamber cardiac pacemaker, may benefit from a new stimulation paradigm which reduces the AV latency and therefore limits the filling time of the left ventricle. The most invasive approach for resistant hypertension still is the neuromodulation by deep brain stimulation (DBS), which has been shown to significantly lower BP in single cases. Implant-mediated therapy remains a promising approach for the treatment of resistant hypertension. Due to their invasiveness, such treatment options must prove superiority over conventional therapies with regard to safety and efficacy before they can be generally offered to a wider patient population. Overall, BAROSTIM NEO® and MobiusHD™, for which large RCTs will soon be available, are likely to meet those criteria and may represent the first implant-mediated therapeutical options for hypertension, while the use of DBS probably will be reserved for individual cases. The utility of VNS awaits appropriate assessment.
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Abstract
Despite availability of effective drugs for hypertension therapy, significant numbers of hypertensive patients fail to achieve recommended blood pressure levels on ≥3 antihypertensive drugs of different classes. These individuals have a high prevalence of adverse cardiovascular events and are defined as having resistant hypertension (RHT) although nonadherence to prescribed antihypertensive medications is common in patients with apparent RHT. Furthermore, apparent and true RHT often display increased sympathetic activity. Based on these findings, technology was developed to treat RHT by suppressing sympathetic activity with electrical stimulation of the carotid baroreflex and catheter-based renal denervation (RDN). Over the last 15 years, experimental and clinical studies have provided better understanding of the physiological mechanisms that account for blood pressure lowering with baroreflex activation and RDN and, in so doing, have provided insight into which patients in this heterogeneous hypertensive population are most likely to respond favorably to these device-based therapies. Experimental studies have also played a role in modifying device technology after early clinical trials failed to meet key endpoints for safety and efficacy. At the same time, these studies have exposed potential differences between baroreflex activation and RDN and common challenges that will likely impact antihypertensive treatment and clinical outcomes in patients with RHT. In this review, we emphasize physiological studies that provide mechanistic insights into blood pressure lowering with baroreflex activation and RDN in the context of progression of clinical studies, which are now at a critical point in determining their fate in RHT management.
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Affiliation(s)
- Thomas E Lohmeier
- From the Department of Physiology and Biophysics (T.E.L., J.E.H.), University of Mississippi Medical Center, Jackson
| | - John E Hall
- From the Department of Physiology and Biophysics (T.E.L., J.E.H.), University of Mississippi Medical Center, Jackson.,Mississippi Center for Obesity Research (J.E.H.), University of Mississippi Medical Center, Jackson
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Wallbach M, Koziolek MJ. Baroreceptors in the carotid and hypertension-systematic review and meta-analysis of the effects of baroreflex activation therapy on blood pressure. Nephrol Dial Transplant 2019; 33:1485-1493. [PMID: 29136223 DOI: 10.1093/ndt/gfx279] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2017] [Accepted: 08/08/2017] [Indexed: 02/06/2023] Open
Abstract
Activation of baroreceptors in the carotid modulates the autonomic nervous system. Baroreflex activation therapy (BAT), which activates baroreceptors in the carotid, has become available in the treatment of resistant hypertension. Besides this, a carotid implant modulating baroreceptors as well as pharmacological modulation of carotid bodies were quite recently presented. This review will underscore currently available and promising approaches that activate baroreceptors in the carotid, and thereby contribute to beneficial effects in patients with arterial hypertension, and discusses potential organoprotective BAT effects beyond blood pressure (BP) reduction. A systematic review and meta-analysis was conducted including observational studies or randomized controlled trials that investigated the effect of BAT on BP in resistant hypertension. Nine studies, seven observational and two randomized, with a total of 444 patients, were included in the evaluation. Analysing the longest follow-up visit from the different studies, there was a significant reduction of systolic BP after BAT of -36 mmHg [95% confidence interval (CI) -42 to -30 mmHg]. Separate meta-analysis of the short-term (1-6 months) and long-term effects (≥12 months) revealed a reduction of -21 mmHg (95% CI -26 to -17 mmHg) and -38 mmHg (95% CI -46 to -30 mmHg), respectively. There are promising data both in the experimental and the clinical application for BAT. Though the present meta-analysis suggests beneficial effects of BAT on BP, the results must be interpreted extremely carefully. Considering that evidence from controlled trials is very limited, it is evident that there is a strong need for further investigation.
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Affiliation(s)
- Manuel Wallbach
- Department of Nephrology and Rheumatology, University Medical Center Göttingen, Göttingen, Germany
| | - Michael J Koziolek
- Department of Nephrology and Rheumatology, University Medical Center Göttingen, Göttingen, Germany
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Zhang L, Lai H, Li L, Song X, Wang G, Fan X, Liu J, Yang S, Wang S. Effects of acupuncture with needle manipulation at different frequencies for patients with hypertension: Result of a 24- week clinical observation. Complement Ther Med 2019; 45:142-148. [DOI: 10.1016/j.ctim.2019.05.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2019] [Revised: 03/28/2019] [Accepted: 05/07/2019] [Indexed: 10/26/2022] Open
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9
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Safety profile of baroreflex activation therapy (NEO) in patients with resistant hypertension. J Hypertens 2018; 36:1762-1769. [DOI: 10.1097/hjh.0000000000001753] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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10
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Chunbin W, Fu S, Jing H. Efficacy and safety of baroreflex activation therapy for treatment of resistant hypertension: a systematic review and meta-analysis. Clin Exp Hypertens 2018; 40:501-508. [PMID: 29624472 DOI: 10.1080/10641963.2016.1273943] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
To provide definite evidence for the anti-hypertensive benefit of Baroreflex Activation Therapy (BAT) for resistant hypertension, we performed a systematic review and meta-analysis to evaluate the efficacy and safety of BAT. Electronic searches were conducted in PubMed, EMBASE, The Cochrane Library and Web of Science. Two reviewers independently determined the eligibility of studies and extracted the data. The quality of all included studies was evaluated by the use of the Newcastle Ottawa Scale (NOS). Disagreements were settled through discussion. Twelve studies, included one randomized clinical trials (RCTs) and eleven prospective studies were eligible for qualitative analysis and five prospective studies were selected for meta-analysis. The data of analysis showed office systolic blood pressure (SBP)(WMD = -24.01, 95% CI = -28.65 to -19.36, P= 0.753I2 = 0.0%) and diastolic blood pressure (DBP)(WMD = -12.53, 95% CI = -15.82 to -9.24,P = 0.893,I2 = 0.893) decreased by BAT treatment.The effect on SBP was both significant in the Barostim neo TM device (WMD = -22.49, 95% CI = -29.13 to 15.84, P= 0.443; I2 = 0.0%) and Rheos System (WMD = 25.46, 95% CI = -31.96 to -18.96, P= 0.703; I2 = 0.0%). Our study found office BP were significantly decreased by BAT treatment, but available evidence is limited by risk of bias, small sample size, and few RCTs. Thus, there is presently insufficient evidence to fully evaluate the efficacy and safety of BAT for Patients with Resistant Hypertension. Additional high-quality RCT research with long-term follow-up is required.
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Affiliation(s)
- Wang Chunbin
- a Department of Cardiology , The Second Affiliated Hospital of Chongqing Medical University, The Third People's Hospital of Chengdu , Chongqing , Sichuan , China
| | - Shiquan Fu
- b Department of Cardiology , Jiangjin Central Hospital , Chongqing , China
| | - Huang Jing
- a Department of Cardiology , The Second Affiliated Hospital of Chongqing Medical University, The Third People's Hospital of Chengdu , Chongqing , Sichuan , China
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Brognara F, Castania JA, Dias DPM, Lopes AH, Fazan R, Kanashiro A, Ulloa L, Salgado HC. Baroreflex stimulation attenuates central but not peripheral inflammation in conscious endotoxemic rats. Brain Res 2018; 1682:54-60. [PMID: 29317289 DOI: 10.1016/j.brainres.2018.01.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2017] [Revised: 12/16/2017] [Accepted: 01/02/2018] [Indexed: 01/11/2023]
Abstract
We previously reported that activation of the baroreflex, a critical physiological mechanism controlling cardiovascular homeostasis, through electrical stimulation of the aortic depressor nerve attenuates joint inflammation in experimental arthritis. However, it is unknown whether baroreflex activation can control systemic inflammation. Here, we investigate whether baroreflex activation controls systemic inflammation in conscious endotoxemic rats. Animals underwent sham or electrical aortic depressor nerve stimulation initiated 10 min prior to a lipopolysaccharide (LPS) challenge, while inflammatory cytokine levels were measured in the blood, spleen, heart and hypothalamus 90 min after LPS treatment. Baroreflex activation did not affect LPS-induced levels of pro-inflammatory (tumor necrosis factor, interleukin 1β and interleukin 6) or anti-inflammatory (interleukin 10) cytokines in the periphery (heart, spleen and blood). However, baroreflex stimulation attenuated LPS-induced levels of all these cytokines in the hypothalamus. Notably, these results indicate that the central anti-inflammatory mechanism induced by baroreflex stimulation is independent of cardiovascular alterations, since aortic depressor nerve stimulation that failed to induce hemodynamic changes was also efficient at inhibiting inflammatory cytokines in the hypothalamus. Thus, aortic depressor nerve stimulation might represent a novel therapeutic strategy for neuroprotection, modulating inflammation in the central nervous system.
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Affiliation(s)
- Fernanda Brognara
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Jaci A Castania
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Daniel P M Dias
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Alexandre H Lopes
- Department of Pharmacology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Rubens Fazan
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil
| | - Alexandre Kanashiro
- Department of Physiological Sciences, Federal University of São Carlos, São Carlos, SP, Brazil
| | - Luis Ulloa
- Department of Surgery, Center for Immunology and Inflammation, Rutgers University - New Jersey Medical School, Newark, NJ 07103, USA.
| | - Helio C Salgado
- Department of Physiology, Ribeirão Preto Medical School, University of São Paulo, Ribeirão Preto, SP, Brazil.
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Grisk O. Caudal medullary and cervical spinal cord neurons in cardiovascular regulation. J Hypertens 2017; 35:1950-1951. [PMID: 28858195 DOI: 10.1097/hjh.0000000000001441] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Olaf Grisk
- Department of Physiology, University of Greifswald, Greifswald-Karlsburg, Karlsburg, Germany
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13
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Barorezeptorakivierungstherapie bei therapierefraktärer Hypertonie: Indikation und Patientenselektion. Internist (Berl) 2017; 58:1114-1123. [DOI: 10.1007/s00108-017-0308-y] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
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Le Jemtel TH, Richardson W, Samson R, Jaiswal A, Oparil S. Pathophysiology and Potential Non-Pharmacologic Treatments of Obesity or Kidney Disease Associated Refractory Hypertension. Curr Hypertens Rep 2017; 19:18. [PMID: 28243928 DOI: 10.1007/s11906-017-0713-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
PURPOSE OF REVIEW The review assesses the role of non-pharmacologic therapy for obesity and chronic kidney disease (CKD) associated refractory hypertension (rf HTN). RECENT FINDINGS Hypertensive patients with markedly heightened sympathetic nervous system (SNS) activity are prone to develop refractory hypertension (rfHTN). Patients with obesity and chronic kidney disease (CKD)-associated HTN have particularly heightened SNS activity and are at high risk of rfHTN. The role of bariatric surgery is increasingly recognized in treatment of obesity. Current evidence advocates for a greater role of bariatric surgery in the management of obesity-associated HTN. In contrast, renal denervation does not appear have a role in the management of obesity or CKD-associated HTN. The role of baroreflex activation as adjunctive anti-hypertensive therapy remains to be defined.
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Affiliation(s)
- Thierry H Le Jemtel
- Division of Cardiology, Tulane University Medical Center, New Orleans, Louisiana, USA. .,Division of Cardiology, Tulane University School of Medicine, 1430 Tulane Ave SL-42, New Orleans, LA, 70112, USA.
| | - William Richardson
- Department of Surgery, Ochsner Health System, New Orleans, Louisiana, USA
| | - Rohan Samson
- Division of Cardiology, Tulane University Medical Center, New Orleans, Louisiana, USA
| | - Abhishek Jaiswal
- Division of Cardiology, Tulane University Medical Center, New Orleans, Louisiana, USA
| | - Suzanne Oparil
- Division of Cardiovascular Disease, University of Alabama, Birmingham, AL, USA
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Blood pressure after blinded, randomized withdrawal, and resumption of baroreceptor-activating therapy. J Hypertens 2017; 35:1496-1501. [DOI: 10.1097/hjh.0000000000001339] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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Hildebrandt DA, Irwin ED, Lohmeier TE. Prolonged Baroreflex Activation Abolishes Salt-Induced Hypertension After Reductions in Kidney Mass. Hypertension 2016; 68:1400-1406. [PMID: 27777356 DOI: 10.1161/hypertensionaha.116.08293] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2016] [Revised: 09/04/2016] [Accepted: 09/28/2016] [Indexed: 12/20/2022]
Abstract
Chronic electric activation of the carotid baroreflex produces sustained reductions in sympathetic activity and arterial pressure and is currently being evaluated for therapy in patients with resistant hypertension. However, patients with significant impairment of renal function have been largely excluded from clinical trials. Thus, there is little information on blood pressure and renal responses to baroreflex activation in subjects with advanced chronic kidney disease, which is common in resistant hypertension. Changes in arterial pressure and glomerular filtration rate were determined in 5 dogs after combined unilateral nephrectomy and surgical excision of the poles of the remaining kidney to produce ≈70% reduction in renal mass. After control measurements, sodium intake was increased from ≈45 to 450 mol/d. While maintained on high salt, animals experienced increases in mean arterial pressure from 102±4 to 121±6 mm Hg and glomerular filtration rate from 40±2 to 45±2 mL/min. During 7 days of baroreflex activation, the hypertension induced by high salt was abolished (103±6 mm Hg) along with striking suppression of plasma norepinephrine concentration from 139±21 to 81±9 pg/mL, but despite pronounced blood pressure lowering, there were no significant changes in glomerular filtration rate (43±2 mL/min). All variables returned to prestimulation values during a recovery period. These findings indicate that after appreciable nephron loss, chronic suppression of central sympathetic outflow by baroreflex activation abolishes hypertension induced by high salt intake. The sustained antihypertensive effects of baroreflex activation occur without significantly compromising glomerular filtration rate in remnant nephrons.
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Affiliation(s)
- Drew A Hildebrandt
- From the Department of Physiology and Biophysics (D.A.H., T.E.L.) and Department of Surgery (D.A.H.), University of Mississippi Medical Center, Jackson; and Trauma Services, North Memorial Medical Center, Robbinsdale, MN (E.D.I.)
| | - Eric D Irwin
- From the Department of Physiology and Biophysics (D.A.H., T.E.L.) and Department of Surgery (D.A.H.), University of Mississippi Medical Center, Jackson; and Trauma Services, North Memorial Medical Center, Robbinsdale, MN (E.D.I.)
| | - Thomas E Lohmeier
- From the Department of Physiology and Biophysics (D.A.H., T.E.L.) and Department of Surgery (D.A.H.), University of Mississippi Medical Center, Jackson; and Trauma Services, North Memorial Medical Center, Robbinsdale, MN (E.D.I.).
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Ng KA, Greenwald E, Xu YP, Thakor NV. Implantable neurotechnologies: a review of integrated circuit neural amplifiers. Med Biol Eng Comput 2016; 54:45-62. [PMID: 26798055 DOI: 10.1007/s11517-015-1431-3] [Citation(s) in RCA: 58] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2015] [Accepted: 12/11/2015] [Indexed: 11/24/2022]
Abstract
Neural signal recording is critical in modern day neuroscience research and emerging neural prosthesis programs. Neural recording requires the use of precise, low-noise amplifier systems to acquire and condition the weak neural signals that are transduced through electrode interfaces. Neural amplifiers and amplifier-based systems are available commercially or can be designed in-house and fabricated using integrated circuit (IC) technologies, resulting in very large-scale integration or application-specific integrated circuit solutions. IC-based neural amplifiers are now used to acquire untethered/portable neural recordings, as they meet the requirements of a miniaturized form factor, light weight and low power consumption. Furthermore, such miniaturized and low-power IC neural amplifiers are now being used in emerging implantable neural prosthesis technologies. This review focuses on neural amplifier-based devices and is presented in two interrelated parts. First, neural signal recording is reviewed, and practical challenges are highlighted. Current amplifier designs with increased functionality and performance and without penalties in chip size and power are featured. Second, applications of IC-based neural amplifiers in basic science experiments (e.g., cortical studies using animal models), neural prostheses (e.g., brain/nerve machine interfaces) and treatment of neuronal diseases (e.g., DBS for treatment of epilepsy) are highlighted. The review concludes with future outlooks of this technology and important challenges with regard to neural signal amplification.
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Affiliation(s)
- Kian Ann Ng
- Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, Singapore, 117456, Singapore. .,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore.
| | - Elliot Greenwald
- Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
| | - Yong Ping Xu
- Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore
| | - Nitish V Thakor
- Singapore Institute for Neurotechnology (SINAPSE), National University of Singapore, Singapore, 117456, Singapore.,Department of Electrical and Computer Engineering, National University of Singapore, Singapore, 117576, Singapore.,Department of Biomedical Engineering, Johns Hopkins University, Baltimore, MD, 21205, USA
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