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Xu B, Gao Y, Zhang Q, Li X, Liu X, Du J, Jin H. Establishment and validation of a multivariate predictive model for the efficacy of oral rehydration salts in children with postural tachycardia syndrome. EBioMedicine 2024; 100:104951. [PMID: 38171114 PMCID: PMC10796963 DOI: 10.1016/j.ebiom.2023.104951] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2023] [Revised: 12/08/2023] [Accepted: 12/19/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGROUND The therapeutic effectiveness of the empirical and unselected use of oral rehydration salts (ORS) on postural tachycardia syndrome (POTS) is not satisfactory in children. Therefore, looking for suitable predictors of the therapeutic effects of ORS before treatment is extremely necessary to implement individualised treatment for paediatric patients with POTS. METHODS A retrospective case-control analysis of 130 patients (aged 5-18 years) who suffered from POTS with a 3-month treatment of ORS was conducted. A nomogram model was developed in the training set (n = 87) to predict the therapeutic response to ORS. Univariate analysis and logistic regression were applied to select the most useful predictors. ROC curves were applied to evaluate the discriminative performance of the nomogram model. The nomogram was then evaluated by calibration curves and the Hosmer-Lemeshow (H-L) test. The results were further validated using 1000 bootstrap resamples. External validation was performed in an independent validation set (n = 43). FINDINGS Among the ten variables with significant differences between the responders and non-responders in univariate analysis, five variables were found to be independently associated factors for ORS therapeutic efficacy among POTS children in the further logistic regression, including mean corpuscular haemoglobin concentration (MCHC), mean corpuscular volume (MCV), mean arterial pressure (MAP) at the first minute of the upright position, urine specific gravity (SG), and P-wave voltage peaking ratio (PWP). The nomogram model was established in the training set (AUC 0.926 [95% CI: 0.865-0.988], yielding a sensitivity of 87.8% and a specificity of 86.8%). The calibration curves showed good agreement between the prediction of the nomogram and actual observation in both the training and validation sets. The nomogram also effectively predicted the external validation set (sensitivity 82.1%, specificity 73.3%, and accuracy 79.1%). INTERPRETATION We established a feasible and high-precision nomogram model to predict the efficacy of ORS, which would help implement individualised treatment for children with POTS. FUNDING This study was supported by National High-Level Hospital Clinical Research Funding (Multi-centre Clinical Research Project of Peking University First Hospital) (2022CR59).
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Affiliation(s)
- Bowen Xu
- Department of Pediatrics, Peking University First Hospital, Beijing, China; Department of Cardiology, Beijing Children's Hospital, Beijing, China
| | - Yumeng Gao
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Qingyou Zhang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Xueying Li
- Department of Medical Statistics, Peking University First Hospital, Beijing, China
| | - Xueqin Liu
- Department of Pediatrics, Peking University First Hospital, Beijing, China
| | - Junbao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, China; State Key Laboratory of Vascular Homeostasis and Remodelling, Peking University, Beijing, China.
| | - Hongfang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China; State Key Laboratory of Vascular Homeostasis and Remodelling, Peking University, Beijing, China.
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He X, Sueyoshi E, Nagayama H, Koike H, Uetani M. The hemodynamics of adrenal veins with four-dimensional computed tomography using quantitative time-density curve: a study based on aldosteronism patients. Sci Rep 2023; 13:14348. [PMID: 37658182 PMCID: PMC10474258 DOI: 10.1038/s41598-023-41414-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 08/25/2023] [Indexed: 09/03/2023] Open
Abstract
Present study quantitatively analyzed adrenal venous flow using four-dimensional computed tomography (4D CT). We reviewed 4D CT images of 55 patients [mean age, 52 years ± 11 (standard deviation); 23 females] who underwent adrenal venous sampling between August 2017 and February 2021. Time-density curves were referred for the adrenal venous enhancement. The clinical factors affecting hemodynamics were assessed using uni- and multivariate linear regression analyses. The right and left adrenal veins (RAV and LAV, respectively) were visualized in all cases. Mean peak enhancement values in RAV and LAV were 247 ± 67 and 292 ± 70 Hounsfield units (P < 0.01), and were reached at 44.43 ± 6.86 and 45.39 ± 7.53 s (P < 0.01), respectively. The body mass index (BMI), plasma renin activity and potassium were significant factors influencing the peak enhancement of RAV blood flow [standardized regression coefficients, - 0.327 (P = 0.017), - 0.346 (P = 0.013), 0.426 (P = 0.016), respectively]. A linear relationship between sex and the time-to-peak was observed for RAV [standardized regression coefficient, 0.348 (P = 0.046)]. RAV had a lower contrast effect than LAV and reached its peak faster. BMI, plasma renin activity, and potassium were associated with flow density in RAV. Sex independently influenced the time-to-peak.
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Affiliation(s)
- Xi He
- Department of Radiological Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8521, Japan
| | - Eijun Sueyoshi
- Department of Radiology, Nagasaki Harbor Medical Center, Nagasaki, Japan.
| | - Hiroki Nagayama
- Department of Radiological Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8521, Japan
| | - Hirofumi Koike
- Department of Radiological Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8521, Japan
| | - Masataka Uetani
- Department of Radiological Sciences, Graduate School of Biomedical Sciences, Nagasaki University, 1-7-1 Sakamoto, Nagasaki, 852-8521, Japan
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Laurin JKH, Oyewunmi OA, Garland EM, Gamboa A, Nwazue VC, Paranjape SY, Black BK, Okamoto LE, Shibao CA, Biaggioni I, Robertson D, Diedrich A, Dupont WD, Sheldon RS, Raj SR. Adrenal gland response to adrenocorticotropic hormone is intact in patients with postural orthostatic tachycardia syndrome. Auton Neurosci 2023; 248:103105. [PMID: 37393658 DOI: 10.1016/j.autneu.2023.103105] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2023] [Revised: 05/18/2023] [Accepted: 06/20/2023] [Indexed: 07/04/2023]
Abstract
BACKGROUND Many patients with postural orthostatic tachycardia syndrome (POTS) are hypovolemic with plasma volume deficits of 10-30 %. Some also have low levels of aldosterone and diminished aldosterone-renin ratios despite elevations in angiotensin II, pointing to potential adrenal dysfunction. To assess adrenal gland responsiveness in POTS, we measured circulating levels of aldosterone and cortisol following adrenocorticotropin hormone (ACTH) stimulation. METHODS While on a low Na+ diet (∼10 mEq/day), 8 female patients with POTS and 5 female healthy controls (HC) received a low dose (1 μg) ACTH bolus following a baseline blood sample. After 60 min, a high dose (249 μg) infusion of ACTH was administered to ensure maximal adrenal response. Venous aldosterone and cortisol levels were sampled every 30 min for 2 h. RESULTS Aldosterone increased in both groups in response to ACTH but was not different between POTS vs. HC at 60 min (53.5 ng/dL [37.8-61.8 ng/dL] vs. 46.1 ng/dL [36.7-84.9 ng/dL]; P = 1.000) or maximally (56.4 ng/dL [49.2-67.1 ng/dL] vs. 49.5 ng/dL [39.1-82.8 ng/dL]; P = 0.524). Cortisol increased in both groups in response to ACTH but was not different in patients with POTS vs. HC at 60 min (39.9 μg/dL [36.1-47.7 μg/dL] vs. 39.3 μg/dL [35.4-46.6 μg/dL]; P = 0.724) or maximally (39.9 μg/dL [33.9-45.4 μg/dL] vs. 42.0 μg/dL [37.6-49.7 μg/dL]; P = 0.354). CONCLUSIONS ACTH appropriately increased the aldosterone and cortisol levels in patients with POTS. These findings suggest that the response of the adrenal cortex to hormonal stimulation is intact in patients with POTS.
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Affiliation(s)
- Jill K H Laurin
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Oyebimbola A Oyewunmi
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Emily M Garland
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Alfredo Gamboa
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Victor C Nwazue
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Sachin Y Paranjape
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Bonnie K Black
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Luis E Okamoto
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Cyndya A Shibao
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Italo Biaggioni
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David Robertson
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - André Diedrich
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, TN, USA
| | - William D Dupont
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Robert S Sheldon
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
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Spahic JM, Mattisson IY, Hamrefors V, Johansson M, Ricci F, Nilsson J, Melander O, Sutton R, Fedorowski A. Evidence for Impaired Renin Activity in Postural Orthostatic Tachycardia Syndrome. J Clin Med 2023; 12:4660. [PMID: 37510775 PMCID: PMC10380257 DOI: 10.3390/jcm12144660] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2023] [Revised: 07/09/2023] [Accepted: 07/11/2023] [Indexed: 07/30/2023] Open
Abstract
BACKGROUND Postural orthostatic tachycardia syndrome (POTS) is a heterogeneous condition predominantly affecting autonomic control of the cardiovascular system. Its extensive symptom diversity implies multi-organ involvement that interacts in ways still requiring full exploration. Current understanding of POTS pathophysiology suggests alterations in the renin-angiotensin-aldosterone system as a possible contributing factor. Therefore, we investigated the relationship between the activity of the renin-angiotensin-aldosterone system and hemodynamic parameters in a cohort of POTS patients and controls recruited at a tertiary referral center. METHODS The case-control study included 46 patients with POTS (27 ± 9 years), and 48 healthy controls (30 ± 9 years) without orthostatic intolerance. Plasma renin activity, expressed as angiotensin I generation, and plasma aldosterone were measured by enzyme-linked immunosorbent assay and were correlated with hemodynamic parameters obtained during active standing tests. RESULTS Renin activity was significantly downregulated in POTS patients compared to healthy individuals (median, 3406 ng/mL vs. 9949 ng/mL, p < 0.001), whereas aldosterone concentration did not differ between POTS and healthy controls (median, 218 pmol/L vs. 218 pmol/L, p = 0.26). A significant inverse correlation between renin activity and supine and orthostatic blood pressure levels was observed in healthy individuals (p < 0.05 for all), but not in POTS patients. CONCLUSIONS Renin activity, but not aldosterone concentration, is downregulated in patients with POTS. Moreover, renin activity in POTS is dissociated from supine and standing blood pressure levels in contrast to healthy individuals. These findings suggest impaired renin function in POTS, which may direct future therapeutic approaches.
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Affiliation(s)
| | - Ingrid Yao Mattisson
- Department of Internal Medicine, Skåne University Hospital, 214 28 Malmö, Sweden
| | - Viktor Hamrefors
- Department of Cardiology, Skåne University Hospital, 214 28 Malmö, Sweden
| | | | - Fabrizio Ricci
- Department of Clinical Sciences, Lund University, 214 28 Malmö, Sweden
- Department of Neuroscience, Imaging and Clinical Sciences, "G.d'Annunzio" University of Chieti-Pescara, Via dei Vestini 33, 66100 Chieti, Italy
- Fondazione Villa Serena per la Ricerca, 65013 Città Sant'Angelo, Italy
| | - Jan Nilsson
- Department of Clinical Sciences, Lund University, 214 28 Malmö, Sweden
| | - Olle Melander
- Department of Clinical Sciences, Lund University, 214 28 Malmö, Sweden
| | - Richard Sutton
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital Campus Du Cane Road, London W12 0HS, UK
| | - Artur Fedorowski
- Department of Clinical Sciences, Lund University, 214 28 Malmö, Sweden
- Department of Cardiology, Karolinska University Hospital, Department of Medicine, Karolinska Institute, 171 77 Stockholm, Sweden
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COVID-19 Induced Postural Orthostatic Tachycardia Syndrome (POTS): A Review. Cureus 2023; 15:e36955. [PMID: 37009342 PMCID: PMC10065129 DOI: 10.7759/cureus.36955] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/31/2023] [Indexed: 04/03/2023] Open
Abstract
POTS (Postural Orthostatic Tachycardia Syndrome) is a multisystem disorder characterized by the abnormal autonomic response to an upright posture, causing orthostatic intolerance and excessive tachycardia without hypotension. Recent reports suggest that a significant percentage of COVID-19 survivors develop POTS within 6 to 8 months of infection. Prominent symptoms of POTS include fatigue, orthostatic intolerance, tachycardia, and cognitive impairment. The exact mechanisms of post-COVID-19 POTS are unclear. Still, different hypotheses have been given, including autoantibody production against autonomic nerve fibers, direct toxic effects of SARS-CoV-2, or sympathetic nervous system stimulation secondary to infection. Physicians should have a high suspicion of POTS in COVID-19 survival when presented with symptoms of autonomic dysfunction and should conduct diagnostic tests like the Tilt table and others to confirm it. The management of COVID-19-related POTS requires a comprehensive approach. Most patients respond to initial non-pharmacological options, but when the symptoms become more severe and they do not respond to the non-pharmacological approach, pharmacological options are considered. We have limited understanding and knowledge of post-COVID-19 POTS, and further research is warranted to improve our understanding and formulate a better management plan.
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Trisvetova EL. Postural Orthostatic Tachycardia Syndrome as a Manifestation of Post-COVID-19 Syndrome. RATIONAL PHARMACOTHERAPY IN CARDIOLOGY 2022. [DOI: 10.20996/1819-6446-2022-04-11] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The pandemic of coronavirus infection, the complex and insufficiently studied mechanisms of which cause disorders in the functions of many organs and systems of the body, has led to the emergence of new problems that are far from being resolved. Researchers note the difficulty in predicting the course of the disease and outcome due to the detection of many symptoms that arose at the height of the disease and persisted for 3-6 months after recovery. The term "post-COVID-19syndrome" has appeared, reflecting the condition of a patient who has undergone COVID-19, with a negative PCR test, and with symptoms lasting more than 12 weeks from the onset of the disease, which cannot be explained by an alternative diagnosis. Postural orthostatic tachycardia as a manifestation of the post-COVID-19syndrome has been described in young women who have undergone coronavirus infection of varying severity. In the case of the development of the syndrome of postural orthostatic tachycardia, the quality of life deteriorates, and the ability to work of patients is limited. There is no evidence base for drug therapy of postural tachycardia syndrome, in most cases empirical drug and non-drug methods of treatment are used.
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Lo CWS, Tsui TKC, Ma RCW, Chan MHM, Ho CS. Quantitation of plasma angiotensin II in healthy Chinese subjects by a validated liquid chromatography tandem mass spectrometry method. Biomed Chromatogr 2022; 36:e5318. [PMID: 34981551 DOI: 10.1002/bmc.5318] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2021] [Revised: 12/09/2021] [Accepted: 12/13/2021] [Indexed: 11/06/2022]
Abstract
INTRODUCTION Quantitation of plasma angiotensin (Ang) II, the active mediator of the renin-angiotensin system (RAS), is challenging due to its low physiological concentration. We report a validated liquid chromatography-mass spectrometry (LCMS) method to overcome this challenge. METHOD Ang II was extracted from EDTA plasma by an offline solid-phase extraction procedure with Waters MAX μElution plate. LCMS quantitation was performed on the Waters TQS system, monitoring the 3+ ions of the peptide. The analytical performance of the LCMS method was validated. The stability of Ang II was studied with or without the presence of a protease inhibitor. Local reference intervals were established from 143 healthy normotensive subjects (57% female, 21-60 years old). RESULTS The Ang II LCMS method had a measurable range of 3.3 - 700 pmol/L. Between batch precision coefficient of variation was <7% over the Ang II concentrations of 8.6 - 110 pmol/L. No significant matrix interference and carryover was observed. There was no significant difference in Ang II concentration in EDTA blood and plasma for at least 2 hours and 1 hour at room temperature, respectively. Ang II was stable for at least one year when stored at -80 o C, with or without the protease inhibitor. Age-dependent Ang II reference intervals were established: 4.4-17.7 pmol/L (21-30 years) and 3.9-12.8 pmol/L (31-60 years). CONCLUSION The present LCMS method is suitable for quantitation of Ang II to study the RAS system. Ang II collected at room temperature into EDTA bottles was stable at -80 o C for at least 1 year. The first age-dependent reference intervals of plasma Ang II were established for a healthy normotensive Chinese population.
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Affiliation(s)
- Clara Wai-Shan Lo
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Statin, NT, Hong Kong
| | - Teresa Kam-Chi Tsui
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Statin, NT, Hong Kong
| | - Ronald Ching-Wan Ma
- Department of Medicine and Therapeutics, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong.,Li Ka Shing Institute of Health Sciences, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, NT, Hong Kong
| | - Michael Ho-Ming Chan
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Statin, NT, Hong Kong
| | - Chung-Shun Ho
- Department of Chemical Pathology, The Chinese University of Hong Kong, Prince of Wales Hospital, Statin, NT, Hong Kong
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Postural tachycardia syndrome (POTS) and antiphospholipid syndrome (APS): What do we know so far? Rev Neurol (Paris) 2021; 178:306-314. [PMID: 34895744 DOI: 10.1016/j.neurol.2021.10.006] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2021] [Revised: 10/05/2021] [Accepted: 10/05/2021] [Indexed: 11/21/2022]
Abstract
As part of the non-criteria clinical manifestations, postural orthostatic tachycardia syndrome (POTS), a multisystem autonomic dysfunction, can co-exist with antiphospholipid syndrome (APS). Several pieces of evidence hint on the autoimmune basis of POTS, and its possible association with several autoimmune diseases, including APS. Indeed, the evidence exists in the etiologies, symptomatology, and treatment options. Although infections, viral ones in particular, stress, and pregnancy are etiologies to both POTS and APS, the exact pathophysiological connection is still to be studied taking into consideration the activity of cytokines in both diseases. Nevertheless, certain immunomodulatory treatments used for the catastrophic or obstetrical forms of APS, such as intravenous immunoglobulins (IVIG) and steroids, have been also used for the treatment of POTS resistant to classical treatments. Therefore, our review aims to highlight the association between POTS and APS, shedding light on the common etiologies explaining the pathophysiology of the two disorders, the diagnostic approach to POTS as a possible clinical criterion of APS, and the treatment of APS in the context of treating POTS.
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Vernino S, Bourne KM, Stiles LE, Grubb BP, Fedorowski A, Stewart JM, Arnold AC, Pace LA, Axelsson J, Boris JR, Moak JP, Goodman BP, Chémali KR, Chung TH, Goldstein DS, Diedrich A, Miglis MG, Cortez MM, Miller AJ, Freeman R, Biaggioni I, Rowe PC, Sheldon RS, Shibao CA, Systrom DM, Cook GA, Doherty TA, Abdallah HI, Darbari A, Raj SR. Postural orthostatic tachycardia syndrome (POTS): State of the science and clinical care from a 2019 National Institutes of Health Expert Consensus Meeting - Part 1. Auton Neurosci 2021; 235:102828. [PMID: 34144933 DOI: 10.1016/j.autneu.2021.102828] [Citation(s) in RCA: 108] [Impact Index Per Article: 36.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2021] [Revised: 05/10/2021] [Accepted: 05/30/2021] [Indexed: 12/13/2022]
Abstract
Postural orthostatic tachycardia syndrome (POTS) is a chronic and often disabling disorder characterized by orthostatic intolerance with excessive heart rate increase without hypotension during upright posture. Patients often experience a constellation of other typical symptoms including fatigue, exercise intolerance and gastrointestinal distress. A typical patient with POTS is a female of child-bearing age, who often first displays symptoms in adolescence. The onset of POTS may be precipitated by immunological stressors such as a viral infection. A variety of pathophysiologies are involved in the abnormal postural tachycardia response; however, the pathophysiology of the syndrome is incompletely understood and undoubtedly multifaceted. Clinicians and researchers focused on POTS convened at the National Institutes of Health in July 2019 to discuss the current state of understanding of the pathophysiology of POTS and to identify priorities for POTS research. This article, the first of two articles summarizing the information discussed at this meeting, summarizes the current understanding of this disorder and best practices for clinical care. The evaluation of a patient with suspected POTS should seek to establish the diagnosis, identify co-morbid conditions, and exclude conditions that could cause or mimic the syndrome. Once diagnosed, management typically begins with patient education and non-pharmacologic treatment options. Various medications are often used to address specific symptoms, but there are currently no FDA-approved medications for the treatment of POTS, and evidence for many of the medications used to treat POTS is not robust.
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Affiliation(s)
- Steven Vernino
- Department of Neurology, UT Southwestern Medical Center, Dallas, TX, USA
| | - Kate M Bourne
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Lauren E Stiles
- Department of Neurology, Stony Brook University Renaissance School of Medicine, Stony Brook, NY, USA; Dysautonomia International, East Moriches, NY, USA
| | - Blair P Grubb
- Division of Cardiology, Department of Medicine, The University of Toledo Medical Center, USA
| | - Artur Fedorowski
- Department of Clinical Sciences, Lund University, Malmö, Sweden; Department of Cardiology, Skåne University Hospital, Malmö, Sweden
| | - Julian M Stewart
- Center for Hypotension, Departments of Pediatrics and Physiology, New York Medical College, Valhalla, NY, USA
| | - Amy C Arnold
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA; Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Laura A Pace
- Center for Genomic Medicine and Department of Pediatrics, Division of Medical Genetics and Genomics, University of Utah, Salt Lake City, UT, USA
| | - Jonas Axelsson
- Department of Clinical Immunology, Karolinska University Hospital, Stockholm, Sweden
| | | | - Jeffrey P Moak
- Department of Pediatrics, George Washington Univeristy School of Medicine and Health Sciences, Washington, DC, USA
| | - Brent P Goodman
- Neuromuscular Division, Department of Neurology, Mayo Clinic, Scottsdale, AZ, USA
| | - Kamal R Chémali
- Department of Neurology, Eastern Virginia Medical School, Division of Neurology, Neuromuscular and Autonomic Center, Sentara Healthcare, Norfolk, VA, USA
| | - Tae H Chung
- Department of Physical Medicine and Rehabilitation, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - David S Goldstein
- Autonomic Medicine Section, Clinical Neurosciences Program, Division of Intramural Research, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, USA
| | - Andre Diedrich
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine and Biomedical Engineering, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Mitchell G Miglis
- Department of Neurology and Neurological Sciences, Stanford University School of Medicine, Palo Alto, CA, USA
| | - Melissa M Cortez
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Amanda J Miller
- Department of Neural and Behavioral Sciences, Pennsylvania State University College of Medicine, Hershey, PA, USA
| | - Roy Freeman
- Department of Neurology, Harvard Medical School, Boston, MA, USA; Center for Autonomic and Peripheral Nerve Disorders, Beth Israel Deaconess Medical Center, Boston, MA, USA
| | - Italo Biaggioni
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Departments of Medicine and Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Peter C Rowe
- Department of Pediatrics, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Robert S Sheldon
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada
| | - Cyndya A Shibao
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Departments of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David M Systrom
- Pulmonary and Critical Care Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, MA, USA
| | - Glen A Cook
- Department of Neurology, Uniformed Services University, Bethesda, MD, USA
| | - Taylor A Doherty
- Division of Rheumatology, Allergy, and Immunology, Department of Medicine, University of California at San Diego, La Jolla, CA, USA
| | | | - Anil Darbari
- Pediatric Gastroenterology, Children's National Hospital, Department of Pediatrics, George Washington University School of Medicine and Health Sciences, Washington, DC, USA
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, AB, Canada; Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, TN, USA.
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Garland EM, Gamboa A, Nwazue VC, Celedonio JE, Paranjape SY, Black BK, Okamoto LE, Shibao CA, Biaggioni I, Robertson D, Diedrich A, Dupont WD, Raj SR. Effect of High Dietary Sodium Intake in Patients With Postural Tachycardia Syndrome. J Am Coll Cardiol 2021; 77:2174-2184. [PMID: 33926653 DOI: 10.1016/j.jacc.2021.03.005] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Revised: 03/08/2021] [Accepted: 03/09/2021] [Indexed: 02/07/2023]
Abstract
BACKGROUND High sodium intake is recommended for the treatment of postural tachycardia syndrome (POTS) to counteract the hypovolemia and elevated plasma norepinephrine that contribute to excessive orthostatic tachycardia, but evidence of its efficacy is not available. OBJECTIVES This study tested whether a high sodium (HS) diet reduces orthostatic tachycardia (Δ heart rate) and upright heart rate compared with a low sodium (LS) diet in POTS patients, and secondarily its effect on plasma volume (PV) and plasma norepinephrine. METHODS A total of 14 POTS patients and 13 healthy control subjects (HC), age 23 to 49 years, were enrolled in a crossover study with 6 days of LS (10 mEq sodium/day) or HS (300 mEq sodium/day) diet. Supine and standing heart rate, blood pressure, serum aldosterone, plasma renin activity, blood volume, and plasma norepinephrine and epinephrine were measured. RESULTS In POTS, the HS diet reduced upright heart rate and Δ heart rate compared with the LS diet. Total blood volume and PV increased, and standing norepinephrine decreased with the HS compared with the LS diet. However, upright heart rate, Δ heart rate, and upright norepinephrine remained higher in POTS than in HC on the HS diet (median 117 beats/min [interquartile range: 98 to 121 beats/min], 46 beats/min [interquartile range: 32 to 55 beats/min], and 753 pg/ml [interquartile range: 498 to 919 pg/ml] in POTS vs. 85 beats/min [interquartile range: 77 to 95 beats/min], 19 beats/min [interquartile range: 11 to 32 beats/min], and 387 pg/ml [interquartile range: 312 to 433 pg/ml] in HC, respectively), despite no difference in the measured PV. CONCLUSIONS In POTS patients, high dietary sodium intake compared with low dietary sodium intake increases plasma volume, lowers standing plasma norepinephrine, and decreases Δ heart rate. (Dietary Salt in Postural Tachycardia Syndrome; NCT01547117).
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Affiliation(s)
- Emily M Garland
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Alfredo Gamboa
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Victor C Nwazue
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Jorge E Celedonio
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Sachin Y Paranjape
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Bonnie K Black
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Luis E Okamoto
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Cyndya A Shibao
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Italo Biaggioni
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - David Robertson
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Neurology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - André Diedrich
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Biomedical Engineering, School of Engineering, Vanderbilt University, Nashville, Tennessee, USA
| | - William D Dupont
- Department of Biostatistics, Vanderbilt University Medical Center, Nashville, Tennessee, USA
| | - Satish R Raj
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA; Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada.
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11
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Chopoorian AH, Wahba A, Celedonio J, Nwazue V, Smith EC, Garland EM, Paranjape S, Okamoto LE, Black BK, Biaggioni I, Raj SR, Gamboa A. Impaired Endothelial Function in Patients With Postural Tachycardia Syndrome. Hypertension 2021; 77:1001-1009. [PMID: 33486983 DOI: 10.1161/hypertensionaha.120.16238] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The purpose of this study is to evaluate endothelial function in postural tachycardia syndrome (PoTS), a poorly understood chronic condition characterized by a state of consistent orthostatic tachycardia (delta heart rate ≥30 beats per minute) upon standing without orthostatic hypotension. Nineteen patients with PoTS and 9 healthy controls were studied after 3 days of a fixed, caffeine-free, normal sodium (150 milliequivalents/day) diet. All participants underwent autonomic function testing, including sinus arrhythmia, valsalva maneuver, hyperventilation, cold pressor, handgrip, and a standing test with catecholamine measurements, followed by endothelial function testing. We analyzed 3 measures of endothelial function: percent brachial flow-mediated dilation, digital pulsatile arterial tonometry, and postischemic percent leg blood flow. Flow-mediated dilation was significantly lower in patients with PoTS (6.23±3.54% for PoTS) than in healthy controls (10.6±4.37% for controls versus, P=0.014). PoTS and controls had similar digital pulsatile arterial tonometry (1.93±0.40 arbitrary units for controls versus 2.13±0.63 arbitrary units for PoTS). PoTS had similar but suggestive percent leg blood flow to controls (313±158% for PoTS versus 468±236% for controls, P=0.098). Patients with PoTS have significantly reduced flow-mediated dilation compared with healthy controls, suggesting that PoTS is characterized by endothelial dysfunction in conduit arteries. Registration: URL: https://www.clinicaltrials.gov. Unique identifier: NCT01308099.
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Affiliation(s)
- Abby H Chopoorian
- From the Vanderbilt University School of Medicine (A.H.C.), Vanderbilt University Medical Center, Nashville, TN
| | - Amr Wahba
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Jorge Celedonio
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Victor Nwazue
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Emily C Smith
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Emily M Garland
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Sachin Paranjape
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Luis E Okamoto
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Bonnie K Black
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
| | - Italo Biaggioni
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN.,Department of Pharmacology, Vanderbilt University, Nashville, TN (I.B.)
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Alberta, Canada (S.R.R.)
| | - Alfredo Gamboa
- Vanderbilt Autonomic Dysfunction Center, Division of Clinical Pharmacology, Department of Medicine (A.W., J.C., V.N., E.C.S., E.M.G., S.P., L.E.O., B.K.B., I.B., A.G.), Vanderbilt University Medical Center, Nashville, TN
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Circadian rhythms of blood pressure and rate pressure product in children with postural tachycardia syndrome. Auton Neurosci 2020; 228:102715. [PMID: 32846397 DOI: 10.1016/j.autneu.2020.102715] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2020] [Revised: 08/03/2020] [Accepted: 08/07/2020] [Indexed: 12/13/2022]
Abstract
OBJECTIVE To investigate circadian rhythms of blood pressure (BP) and rate pressure product (RPP) in children with postural tachycardia syndrome (POTS) by performing 24-hour ambulatory blood pressure monitoring (24-h ABPM). METHODS 103 POTS children and 84 age- and gender-matched healthy children were enrolled and they got 24-h ABPM under usual routine of diurnal activity and nocturnal sleep. RESULTS Although the mean awake systolic BP (SBP), 24-h diastolic BP (DBP), awake DBP, asleep heart rate (HR) did not differ between two groups (P > 0.05), the mean 24-h and asleep SBP, asleep DBP, 24-h and awake HR, 24-h, awake and asleep RPP were significantly higher in POTS children (P < 0.01). Non-dipping BP was more prevalent in POTS children (67.0% vs. 46%, P < 0.001). The RPP of POTS and control children showed 24-h circadian variations with peak roughly occurring approximately 2 h after waking from nocturnal sleep. Compared with controls, the RPP values of POTS children were significantly higher during 2 h before and 3 h after waking (P < 0.05). For the RPP value of 1 h after waking, a cutoff value of 8995.6 bpm·mmHg yielded a sensitivity of 75.8% and a specificity of 65.4% for predicting POTS. CONCLUSIONS Abnormal circadian BP regulation is prevalent in POTS children. POTS children present with daily sympathetic hyperactivity, especially during nocturnal sleep and within 3 h after waking. And the excessive morning surge in RPP parallels with the morning surge of orthostatic HR increments and OI symptoms.
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13
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Abstract
Postural orthostatic tachycardia syndrome (POTS) is a clinically heterogeneous disorder with multiple contributing pathophysiologic mechanisms manifesting as symptoms of orthostatic intolerance in the setting of orthostatic tachycardia (increase in heart rate by at least 30 beats per minute upon assuming an upright position) without orthostatic hypotension. The three major pathophysiologic mechanisms include partial autonomic neuropathy, hypovolemia, and hyperadrenergic state. Patients often will exhibit overlapping characteristics from more than one of these mechanisms. The approach to the treatment of POTS centers on treating the underlying pathophysiologic mechanism. Stockings, abdominal binders, and vasoconstrictors are used to enhance venous return in partial neuropathic POTS. Exercise and volume expansion are the main treatment strategies for hypo-volemic POTS. For hyperadrenergic POTS, beta-blockers and avoidance of norepinephrine reuptake inhibitors is important. Attempts should be made to discern which pathophysiologic mechanism(s) may be afflicting patients so that treatment regimens can be individualized.
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Affiliation(s)
- Philip L. Mar
- Division of Cardiology, Department of Medicine, St. Louis University School of Medicine, St. Louis, Missouri 63110, USA
| | - Satish R. Raj
- Libin Cardiovascular Institute of Alberta, Department of Cardiac Sciences, Cumming School of Medicine, University of Calgary, Calgary, Alberta T2N 4Z6, Canada
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA
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14
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Autoimmunity in postural orthostatic tachycardia syndrome: Current understanding. Auton Neurosci 2018; 215:78-82. [DOI: 10.1016/j.autneu.2018.04.005] [Citation(s) in RCA: 60] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 04/25/2018] [Accepted: 04/25/2018] [Indexed: 01/01/2023]
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15
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Arnold AC, Ng J, Raj SR. Postural tachycardia syndrome - Diagnosis, physiology, and prognosis. Auton Neurosci 2018; 215:3-11. [PMID: 29523389 PMCID: PMC6113123 DOI: 10.1016/j.autneu.2018.02.005] [Citation(s) in RCA: 96] [Impact Index Per Article: 16.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/29/2017] [Revised: 02/22/2018] [Accepted: 02/25/2018] [Indexed: 11/29/2022]
Abstract
Postural tachycardia syndrome (POTS) is a heterogeneous clinical syndrome that has gained increasing interest over the past few decades due to its increasing prevalence and clinical impact on health-related quality of life. POTS is clinically characterized by sustained excessive tachycardia upon standing that occurs in the absence of significant orthostatic hypotension and other medical conditions and or medications, and with chronic symptoms of orthostatic intolerance. POTS represents one of the most common presentations of syncope and presyncope secondary to autonomic dysfunction in emergency rooms and in cardiology, neurology, and primary care clinics. The most sensitive method to detect POTS is a detailed medical history, physical examination with orthostatic vital signs or brief tilt table test, and a resting 12-lead electrocardiogram. Additional diagnostic testing may be warranted in selected patients based on clinical signs. While the precise etiology remains unknown, the orthostatic tachycardia in POTS is thought to reflect convergence of multiple pathophysiological processes, as a final common pathway. Based on this, POTS is often described as a clinical syndrome consisting of multiple heterogeneous disorders, with several underlying pathophysiological processes proposed in the literature including partial sympathetic neuropathy, hyperadrenergic state, hypovolemia, mast cell activation, deconditioning, and immune-mediated. These clinical features often overlap, however, making it difficult to categorize individual patients. Importantly, POTS is not associated with mortality, with many patients improving to some degree over time after diagnosis and proper treatment. This review will outline the current understanding of diagnosis, pathophysiology, and prognosis in POTS.
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Affiliation(s)
- Amy C Arnold
- Department of Neural and Behavioral Sciences, Penn State College of Medicine, 500 University Drive, Mail Code H109, Hershey, PA, USA; Autonomic Dysfunction Center, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jessica Ng
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - Satish R Raj
- Autonomic Dysfunction Center, Division of Clinical Pharmacology, Vanderbilt University Medical Center, Nashville, TN, USA; Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada.
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16
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Wagoner AL, Tarbell SE, Shaltout HA, Diz DI, Weese-Mayer DE, Fortunato JE. Chronic nausea and orthostatic intolerance: Diagnostic utility of orthostatic challenge duration, Nausea Profile Questionnaire, and neurohumoral measures. Neurogastroenterol Motil 2018; 30:e13433. [PMID: 30101470 PMCID: PMC8045406 DOI: 10.1111/nmo.13433] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/24/2018] [Revised: 05/31/2018] [Accepted: 06/28/2018] [Indexed: 12/21/2022]
Abstract
BACKGROUND Chronic nausea in pediatrics is a debilitating condition with unclear etiology. We aimed to define hemodynamic and neurohumoral characteristics of chronic nausea associated with orthostatic intolerance in order to improve identification and elucidate mechanism. METHODS Children (10-18 years) meeting Rome III criteria for functional dyspepsia with nausea and symptoms of orthostatic intolerance (OI) completed a Nausea Profile Questionnaire followed by prolonged (45 minutes rather than the traditional 10 minutes) head-upright tilt (HUT) (70° tilt up) test. Circulating catecholamines, vasopressin, aldosterone, renin, and angiotensins were measured supine and after 15 minutes into HUT. Beat-to-beat heart rate and blood pressure were continuously recorded to calculate their variability and baroreflex sensitivity. KEY RESULTS Within 10 and 45 minutes of HUT, 46% and 85% of subjects, respectively, had an abnormal tilt test (orthostatic hypotension, postural orthostatic tachycardia, or syncope). At 15 and 45 minutes of HUT, nausea was elicited in 42% and 65% of subjects respectively. Higher Nausea Profile Questionnaire scores correlated with positive HUT testing at 10 minutes (P = 0.004) and baroreflex sensitivity at 15 minutes (P ≤ 0.01). Plasma vasopressin rose 33-fold in subjects with HUT-induced nausea compared to twofold in those who did not experience HUT-induced nausea (P < 0.01). CONCLUSIONS AND INFERENCES In children with chronic nausea and OI, longer duration HUT elicited higher frequency of abnormal tilt testing and orthostatic-induced nausea. The Nausea Profile Questionnaire predicted the orthostatic response to tilt testing. Exaggerated vasopressin release differentiated patients with HUT-induced nausea (vs those without nausea), suggesting a possible mechanism for chronic nausea in childhood.
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Affiliation(s)
- Ashley L. Wagoner
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, NC
| | - Sally E. Tarbell
- Section of Pediatric Gastroenterology, Hepatology and Nutrition, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
- Department of Psychiatry and Behavioral Sciences, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
- Department of Psychiatry and Behavioral Sciences, Northwestern University Feinberg School of Medicine, Chicago, IL
| | - Hossam A. Shaltout
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, NC
- Obstetrics and Gynecology and School of Medicine, Winston-Salem, NC
- SurgeryWake Forest School of Medicine, Winston-Salem, NC
| | - Debra I. Diz
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, NC
- SurgeryWake Forest School of Medicine, Winston-Salem, NC
| | - Debra E. Weese-Mayer
- Center for Autonomic Medicine in Pediatrics, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL
- Stanley Manne Children’s Research Institute, Chicago, IL
| | - John E. Fortunato
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, NC
- Section of Pediatric Gastroenterology, Hepatology and Nutrition, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
- Center for Autonomic Medicine in Pediatrics, Ann & Robert H. Lurie Children’s Hospital of Chicago, Chicago, IL
- Department of Pediatrics, Northwestern University Feinberg School of Medicine, Chicago, IL
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Nagiub M, Moskowitz W, Fortunato J. Systematic literature review of pathophysiology of postural orthostatic tachycardia syndrome (angiotensin II receptor subtype imbalance theory). PROGRESS IN PEDIATRIC CARDIOLOGY 2018. [DOI: 10.1016/j.ppedcard.2018.01.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
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18
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Fu Q, Levine BD. Exercise and non-pharmacological treatment of POTS. Auton Neurosci 2018; 215:20-27. [PMID: 30001836 DOI: 10.1016/j.autneu.2018.07.001] [Citation(s) in RCA: 73] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 06/29/2018] [Accepted: 07/01/2018] [Indexed: 12/11/2022]
Abstract
Recent research has demonstrated that cardiovascular deconditioning (i.e., cardiac atrophy and hypovolemia) contributes significantly to the Postural Orthostatic Tachycardia Syndrome (POTS) and its functional disability. Therefore, physical reconditioning with exercise training and volume expansion via increased salt and fluid intake should be initiated early in the course of treatment for patients with POTS if possible. The use of horizontal exercise (e.g., rowing, swimming, recumbent bike, etc.) at the beginning is a critical strategy, allowing patients to exercise while avoiding the upright posture that elicits their POTS symptoms. As patients become increasingly fit, the duration and intensity of exercise should be progressively increased, and upright exercise can be gradually added as tolerated. Supervised training is preferable to maximize functional capacity. Other non-pharmacological interventions, which include: 1) chronic volume expansion via sleeping in the head-up position; 2) reduction in venous pooling during orthostasis by lower body compression garments extending at least to the xiphoid or with an abdominal binder; and 3) physical countermeasure maneuvers, such as squeezing a rubber ball, leg crossing, muscle pumping, squatting, negative-pressure breathing, etc., may also be effective in preventing orthostatic intolerance and managing acute clinical symptoms in POTS patients. However, randomized clinical trials are needed to evaluate the efficacies of these non-pharmacological treatments of POTS.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX, USA.
| | - Benjamin D Levine
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, The University of Texas Southwestern Medical Center, Dallas, TX, USA
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Stewart JM, Pianosi P, Shaban MA, Terilli C, Svistunova M, Visintainer P, Medow MS. Postural Hyperventilation as a Cause of Postural Tachycardia Syndrome: Increased Systemic Vascular Resistance and Decreased Cardiac Output When Upright in All Postural Tachycardia Syndrome Variants. J Am Heart Assoc 2018; 7:e008854. [PMID: 29960989 PMCID: PMC6064900 DOI: 10.1161/jaha.118.008854] [Citation(s) in RCA: 26] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/07/2018] [Accepted: 06/07/2018] [Indexed: 12/15/2022]
Abstract
BACKGROUND Postural tachycardia syndrome (POTS) is a heterogeneous condition. We stratified patients previously evaluated for POTS on the basis of supine resting cardiac output (CO) or with the complaint of platypnea or "shortness of breath" during orthostasis. We hypothesize that postural hyperventilation is one cause of POTS and that hyperventilation-associated POTS occurs when initial reduction in CO is sufficiently large. We also propose that circulatory abnormalities normalize with restoration of CO2. METHODS AND RESULTS Fifty-eight enrollees with POTS were compared with 16 healthy volunteer controls. Low CO in POTS was defined by a resting supine CO <4 L/min. Patients with shortness of breath had hyperventilation with end tidal CO2 <30 Torr during head-up tilt table testing. There were no differences in height or weight between control patients and patients with POTS or differences between the POTS groups. Beat-to-beat blood pressure was measured by photoplethysmography, and CO was measured by ModelFlow. Systemic vascular resistance was defined as mean arterial blood pressure/CO. End tidal CO2 and cerebral blood flow velocity of the middle cerebral artery were only reduced during head-up tilt in the hyperventilation group, whereas blood pressure was increased compared with control. We corrected the reduced end tidal CO2 in hyperventilation by addition of exogenous CO2 into a rebreathing apparatus. With added CO2, heart rate, blood pressure, CO, and systemic vascular resistance in hyperventilation became similar to control. CONCLUSIONS We conclude that all POTS is related to decreased CO, decreased central blood volume, and increased systemic vascular resistance and that a variant of POTS is consequent to postural hyperventilation.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY
- Department of Physiology, New York Medical College, Valhalla, NY
| | - Paul Pianosi
- Paediatric Respiratory Medicine, King's College Hospital National Health Service Foundation Trust, London, United Kingdom
| | - Mohamed A Shaban
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Courtney Terilli
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Maria Svistunova
- Department of Pediatrics, New York Medical College, Valhalla, NY
| | - Paul Visintainer
- Epidemiology and Biostatistics, Baystate Medical Center, University of Massachusetts School of Medicine, Worcester, MA
| | - Marvin S Medow
- Department of Pediatrics, New York Medical College, Valhalla, NY
- Department of Physiology, New York Medical College, Valhalla, NY
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20
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Yu X, Li H, Murphy TA, Nuss Z, Liles J, Liles C, Aston CE, Raj SR, Fedorowski A, Kem DC. Angiotensin II Type 1 Receptor Autoantibodies in Postural Tachycardia Syndrome. J Am Heart Assoc 2018; 7:JAHA.117.008351. [PMID: 29618472 PMCID: PMC6015435 DOI: 10.1161/jaha.117.008351] [Citation(s) in RCA: 50] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Background Both the adrenergic and renin‐angiotensin systems contribute to orthostatic circulatory homeostasis, which is impaired in postural orthostatic tachycardia syndrome (POTS). Activating autoantibodies to the α1‐adrenergic and β1/2‐adrenergic receptors have previously been found in sera from patients with POTS. We hypothesized that patients with POTS might also harbor activating autoantibodies to the angiotensin II type 1 receptor (AT1R) independently of antiadrenergic autoimmunity. This study examines a possible pathophysiological role for AT1R autoantibodies in POTS. Methods and Results Serum immunoglobulin G from 17 patients with POTS, 6 patients with recurrent vasovagal syncope, and 10 normal controls was analyzed for the ability to activate AT1R and alter AT1R ligand responsiveness in transfected cells in vitro. Of 17 subjects with POTS, 12 demonstrated significant AT1R antibody activity in immunoglobulin G purified from their serum. No significant AT1R antibody activity was found in the subjects with vasovagal syncope or healthy subjects. AT1R activation by POTS immunoglobulin G was specifically blocked by the AT1R blocker losartan. Moreover, POTS immunoglobulin G significantly shifted the angiotensin II dosage response curve to the right, consistent with an inhibitory effect. All subjects with POTS were positive for one or both autoantibodies to the AT1R and α1‐adrenergic receptor. Conclusions Most patients with POTS harbor AT1R antibody activity. This supports the concept that AT1R autoantibodies and antiadrenergic autoantibodies, acting separately or together, may exert a significant impact on the cardiovascular pathophysiological characteristics in POTS.
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Affiliation(s)
- Xichun Yu
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Hongliang Li
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Taylor A Murphy
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Zachary Nuss
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Jonathan Liles
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Campbell Liles
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
| | - Christopher E Aston
- Department of Pediatrics, University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta University of Calgary, Alberta, Canada.,Department of Medicine, Autonomic Dysfunction Center, Vanderbilt University, Nashville, TN
| | - Artur Fedorowski
- Department of Clinical Sciences, Lund University, Lund, Sweden.,Department of Cardiology, Skåne University Hospital, Malmö, Sweden
| | - David C Kem
- Department of Medicine, University of Oklahoma Health Sciences Center and VA Medical Center, Oklahoma City, OK
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Stewart JM, Boris JR, Chelimsky G, Fischer PR, Fortunato JE, Grubb BP, Heyer GL, Jarjour IT, Medow MS, Numan MT, Pianosi PT, Singer W, Tarbell S, Chelimsky TC. Pediatric Disorders of Orthostatic Intolerance. Pediatrics 2018; 141:peds.2017-1673. [PMID: 29222399 PMCID: PMC5744271 DOI: 10.1542/peds.2017-1673] [Citation(s) in RCA: 108] [Impact Index Per Article: 18.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 09/06/2017] [Indexed: 01/18/2023] Open
Abstract
Orthostatic intolerance (OI), having difficulty tolerating an upright posture because of symptoms or signs that abate when returned to supine, is common in pediatrics. For example, ∼40% of people faint during their lives, half of whom faint during adolescence, and the peak age for first faint is 15 years. Because of this, we describe the most common forms of OI in pediatrics and distinguish between chronic and acute OI. These common forms of OI include initial orthostatic hypotension (which is a frequently seen benign condition in youngsters), true orthostatic hypotension (both neurogenic and nonneurogenic), vasovagal syncope, and postural tachycardia syndrome. We also describe the influences of chronic bed rest and rapid weight loss as aggravating factors and causes of OI. Presenting signs and symptoms are discussed as well as patient evaluation and testing modalities. Putative causes of OI, such as gravitational and exercise deconditioning, immune-mediated disease, mast cell activation, and central hypovolemia, are described as well as frequent comorbidities, such as joint hypermobility, anxiety, and gastrointestinal issues. The medical management of OI is considered, which includes both nonpharmacologic and pharmacologic approaches. Finally, we discuss the prognosis and long-term implications of OI and indicate future directions for research and patient management.
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Affiliation(s)
| | | | | | | | - John E. Fortunato
- Ann and Robert H. Lurie Children’s Hospital of Chicago, Chicago, Illinois
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McNeely BD, Meade RD, Fujii N, Seely AJE, Sigal RJ, Kenny GP. Fluid replacement modulates oxidative stress- but not nitric oxide-mediated cutaneous vasodilation and sweating during prolonged exercise in the heat. Am J Physiol Regul Integr Comp Physiol 2017; 313:R730-R739. [PMID: 28931548 PMCID: PMC5814697 DOI: 10.1152/ajpregu.00284.2017] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Revised: 09/11/2017] [Accepted: 09/11/2017] [Indexed: 01/29/2023]
Abstract
The roles of nitric oxide synthase (NOS), reactive oxygen species (ROS), and angiotensin II type 1 receptor (AT1R) activation in regulating cutaneous vasodilation and sweating during prolonged (≥60 min) exercise are currently unclear. Moreover, it remains to be determined whether fluid replacement (FR) modulates the above thermoeffector responses. To investigate, 11 young men completed 90 min of continuous moderate intensity (46% V̇o2peak) cycling performed at a fixed rate of metabolic heat production of 600 W (No FR condition). On a separate day, participants completed a second session of the same protocol while receiving FR to offset sweat losses (FR condition). Cutaneous vascular conductance (CVC) and local sweat rate (LSR) were measured at four intradermal microdialysis forearm sites perfused with: 1) lactated Ringer (Control); 2) 10 mM NG-nitro-l-arginine methyl ester (l-NAME, NOS inhibition); 3) 10 mM ascorbate (nonselective antioxidant); or 4) 4.34 nM losartan (AT1R inhibition). Relative to Control (71% CVCmax at both time points), CVC with ascorbate (80% and 83% CVCmax) was elevated at 60 and 90 min of exercise during FR (both P < 0.02) but not at any time during No FR (all P > 0.31). In both conditions, CVC was reduced at end exercise with l-NAME (60% CVCmax; both P < 0.02) but was not different relative to Control at the losartan site (76% CVCmax; both P > 0.19). LSR did not differ between sites in either condition (all P > 0.10). We conclude that NOS regulates cutaneous vasodilation, but not sweating, irrespective of FR, and that ROS influence cutaneous vasodilation during prolonged exercise with FR.
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Affiliation(s)
- Brendan D McNeely
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Robert D Meade
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
| | - Naoto Fujii
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
- Faculty of Health and Sports Science, University of Tsukuba, Tsukuba, Japan
| | - Andrew J E Seely
- Thoracic Surgery and Critical Care Medicine, Ottawa Hospital Research Institute, University of Ottawa, Ontario, Canada
| | - Ronald J Sigal
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; and
- Departments of Medicine, Cardiac Sciences and Community Health Sciences, Faculties of Medicine and Kinesiology University of Calgary, Calgary, Alberta, Canada
| | - Glen P Kenny
- Human and Environmental Physiology Research Unit, University of Ottawa, Ottawa, Canada;
- Clinical Epidemiology Program, Ottawa Hospital Research Institute, Ottawa, Ontario, Canada; and
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Differences in neurohumoral and hemodynamic response to prolonged head-up tilt between patients with high and normal standing norepinephrine forms of postural orthostatic tachycardia syndrome. Auton Neurosci 2017; 205:110-114. [PMID: 28522107 DOI: 10.1016/j.autneu.2017.05.007] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2016] [Revised: 04/18/2017] [Accepted: 05/10/2017] [Indexed: 11/24/2022]
Abstract
OBJECTIVE To investigate the optimal timing for blood sample collection of catecholamines and the possible correlations between neurohumoral and hemodynamic responses to prolonged head-up tilt (HUT) in postural orthostatic tachycardia syndrome (POTS). METHODS Nineteen patients underwent a 30-minute, 70° HUT test. Blood samples (norepinephrine (NE), epinephrine and dopamine) were taken in the 10th minute of supine, and 10th, 20th and 30th minutes of HUT. RESULTS There were no significant differences in the proportion of high and normal standing NE patients in the different time points. Mean NE (nmol/L) values in 10th, 20th and 30th minute of HUT were 4.37, 4.87, and 4.35 in the high standing NE, and 2.49, 2.59 and 2.88 in the normal standing NE group. High standing NE patients had higher blood pressure (BP) during the first 6min of HUT (2nd minute after the HUT systolic BP (sBP): 118.29±15.65 vs. 95.70±13.43, p=0.004; diastolic BP (dBP): 78.71±6.68 vs. 65.10±9.04, p=0.003), while normal standing NE patients exhibited a drop in BP compared to resting values during the same time period. The normal standing NE group exhibited a progressive increase in norepinephrine values during the HUT. CONCLUSION One blood sample taken at the 10th minute of HUT correctly identifies high and normal standing NE POTS patients, but a small number of patients (1 out of 19, 5.2%) can be misidentified. High and normal standing NE POTS patients display distinctly different neurohumoral and hemodynamic responses to HUT.
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Abstract
Postural tachycardia syndrome (POTS) represents a common form of orthostatic intolerance that disproportionately affects young women from puberty through adulthood. Patients with POTS have day-to-day orthostatic symptoms with the hallmark feature of an excessive, sustained, and symptomatic rise in heart rate during orthostatic testing. Although considerable overlap exists, three subtypes of POTS have been described: neuropathic, hyperadrenergic, and hypovolemic forms. The wide spectrum of symptoms and comorbidities can make treatment particularly challenging. Volume expansion with fluid and salt, exercise, and education constitute a reasonable initial therapy for most patients. Several medicines are also available to treat orthostatic intolerance and the associated comorbidities. Defining the POTS subtypes clinically in each patient may help to guide medicine choices. A multidisciplinary approach to overall management of the patient with POTS is advised. This review highlights several aspects of POTS with a specific focus on adolescent and young adult patients. [Pediatr Ann. 2017;46(4):e145-e154.].
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Tudor KI, Sakakibara R, Panicker JN. Neurogenic lower urinary tract dysfunction: evaluation and management. J Neurol 2016; 263:2555-2564. [DOI: 10.1007/s00415-016-8212-2] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2016] [Accepted: 06/18/2016] [Indexed: 12/20/2022]
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Khan AW, Corcoran SJ, Esler M, El-Osta A. Epigenomic changes associated with impaired norepinephrine transporter function in postural tachycardia syndrome. Neurosci Biobehav Rev 2016; 74:342-355. [PMID: 27345145 DOI: 10.1016/j.neubiorev.2016.06.015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 06/05/2016] [Accepted: 06/15/2016] [Indexed: 01/20/2023]
Abstract
The postural tachycardia syndrome (POTS) is characterised clinically by symptoms of light-headedness, palpitations, fatigue and exercise intolerance occurring with standing and relieved by lying down. Symptoms occur in association with an inappropriate rise in heart rate in the absence of a fall in blood pressure with the assumption of standing. The pathophysiology of POTS is complicated and poorly understood. Plasma norepinephrine (NE) is often elevated in patients with POTS, resulting in consideration of dysfunction of the norepinephrine transporter (NET) encoded by SLC6A2 gene. Whilst some studies have implicated a defect in the SLC6A2 gene, the cause of reduced SLC6A2 expression and function remains unclear. The search to explain the molecular mechanism of NET dysfunction has focused on genetic variation in the SLC6A2 gene and remains inconclusive. More recent studies show epigenetic mechanisms implicated in the regulation of SLC6A2 expression. In this article, we discuss the epigenetic mechanisms involved in SLC6A2 repression and highlight the potential therapeutic application of targeting these mechanisms in POTS.
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Affiliation(s)
- Abdul Waheed Khan
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia.
| | - Susan J Corcoran
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia.
| | - Murray Esler
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia.
| | - Assam El-Osta
- Baker IDI Heart and Diabetes Institute, The Alfred Medical Research and Education Precinct, Melbourne, Victoria 3004, Australia; Department of Pathology, The University of Melbourne, Parkville, Victoria, Australia; Central Clinical School, Faculty of Medicine, Monash University, Victoria, Australia.
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Abstract
Postural tachycardia syndrome (POTS) is a form of chronic orthostatic intolerance for which the hallmark physiological trait is an excessive increase in heart rate with assumption of upright posture. The orthostatic tachycardia occurs in the absence of orthostatic hypotension and is associated with a >6-month history of symptoms that are relieved by recumbence. The heart rate abnormality and orthostatic symptoms should not be caused by medications that impair autonomic regulation or by debilitating disorders that can cause tachycardia. POTS is a "final common pathway" for a number of overlapping pathophysiologies, including an autonomic neuropathy in the lower body, hypovolemia, elevated sympathetic tone, mast cell activation, deconditioning, and autoantibodies. Not only may patients be affected by more than one of these pathophysiologies but also the phenotype of POTS has similarities to a number of other disorders, e.g., chronic fatigue syndrome, Ehlers-Danlos syndrome, vasovagal syncope, and inappropriate sinus tachycardia. POTS can be treated with a combination of non-pharmacological approaches, a structured exercise training program, and often some pharmacological support.
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Wagoner AL, Shaltout HA, Fortunato JE, Diz DI. Distinct neurohumoral biomarker profiles in children with hemodynamically defined orthostatic intolerance may predict treatment options. Am J Physiol Heart Circ Physiol 2016; 310:H416-25. [PMID: 26608337 PMCID: PMC4888538 DOI: 10.1152/ajpheart.00583.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/23/2015] [Accepted: 11/23/2015] [Indexed: 12/31/2022]
Abstract
Studies of adults with orthostatic intolerance (OI) have revealed altered neurohumoral responses to orthostasis, which provide mechanistic insights into the dysregulation of blood pressure control. Similar studies in children with OI providing a thorough neurohumoral profile are lacking. The objective of the present study was to determine the cardiovascular and neurohumoral profile in adolescent subjects presenting with OI. Subjects at 10-18 yr of age were prospectively recruited if they exhibited two or more traditional OI symptoms and were referred for head-up tilt (HUT) testing. Circulating catecholamines, vasopressin, aldosterone, renin, and angiotensins were measured in the supine position and after 15 min of 70° tilt. Heart rate and blood pressure were continuously measured. Of the 48 patients, 30 patients had an abnormal tilt. Subjects with an abnormal tilt had lower systolic, diastolic, and mean arterial blood pressures during tilt, significantly higher levels of vasopressin during HUT, and relatively higher catecholamines and ANG II during HUT than subjects with a normal tilt. Distinct neurohumoral profiles were observed when OI subjects were placed into the following groups defined by the hemodynamic response: postural orthostatic tachycardia syndrome (POTS), orthostatic hypotension (OH), syncope, and POTS/syncope. Key characteristics included higher HUT-induced norepinephrine in POTS subjects, higher vasopressin in OH and syncope subjects, and higher supine and HUT aldosterone in OH subjects. In conclusion, children with OI and an abnormal response to tilt exhibit distinct neurohumoral profiles associated with the type of the hemodynamic response during orthostatic challenge. Elevated arginine vasopressin levels in syncope and OH groups are likely an exaggerated response to decreased blood flow not compensated by higher norepinephrine levels, as observed in POTS subjects. These different compensatory mechanisms support the role of measuring neurohumoral profiles toward the goal of selecting more focused and mechanistic-based treatment options for pediatric patients with OI.
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Affiliation(s)
- Ashley L Wagoner
- Neuroscience Graduate Program, Wake Forest Graduate School of Arts and Sciences, Winston-Salem, North Carolina; Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - Hossam A Shaltout
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of Obstetrics and Gynecology, Wake Forest School of Medicine, Winston-Salem, North Carolina
| | - John E Fortunato
- Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina; and Department of Pediatrics, Virginia Commonwealth University School of Medicine, Richmond, Virginia
| | - Debra I Diz
- Neuroscience Graduate Program, Wake Forest Graduate School of Arts and Sciences, Winston-Salem, North Carolina; Hypertension and Vascular Research Center, Wake Forest School of Medicine, Winston-Salem, North Carolina; Department of General Surgery, Wake Forest School of Medicine, Winston-Salem, North Carolina; and
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Crnošija L, Krbot Skorić M, Adamec I, Lovrić M, Junaković A, Mišmaš A, Miletić V, Šprljan Alfirev R, Pavelić A, Habek M. Hemodynamic profile and heart rate variability in hyperadrenergic versus non-hyperadrenergic postural orthostatic tachycardia syndrome. Clin Neurophysiol 2015; 127:1639-1644. [PMID: 26386646 DOI: 10.1016/j.clinph.2015.08.015] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2015] [Revised: 08/04/2015] [Accepted: 08/31/2015] [Indexed: 11/28/2022]
Abstract
OBJECTIVES To investigate differences in hemodynamic profile between hyperadrenergic and non-hyperadrenergic postural orthostatic tachycardia syndrome (POTS) in response to head-up tilt test (HUTT). METHODS Ten patients with hyperadrenergic and 33 patients with non-hyperadrenergic POTS underwent HUTT consisting of a 10-min supine phase and 30-min 70° tilted phase. Heart rate (HR), systolic and diastolic blood pressure (dBP), and heart rate variability (HRV) parameters of the two groups were compared. RESULTS Hyperadrenergic patients had higher supine HR (82.6 ± 16.3 bpm vs. 73.8 ± 10.4 bpm, p=0.048). Supine HRV analysis showed significantly lower cardiac vagal activity and possible predominance of cardiac sympathetic activity in the hyperadrenergic group. Non-hyperadrenergic patients had lower dBP during the first four minutes of tilt. Furthermore, 60% of non-hyperadrenergic patients had lower average dBP in the 1st minute of tilted phase when compared to supine values, whereas only 2 of 10 hyperadrenergic patients exhibited the same response. Syncope or intolerable symptoms, causing early ending of HUTT, developed earlier in the non-hyperadrenergic group (8.9 ± 6.8 min vs. 21.2 ± 3.5 min, p=0.001). CONCLUSION Hyperadrenergic and non-hyperadrenergic type of POTS seem to have distinctly different response to HUTT. SIGNIFICANCE This study has shown significant differences in hemodynamic response to HUTT between hyperadrenergic and non-hyperadrenergic type of POTS indicating possible differences in their pathophysiology.
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Affiliation(s)
- Luka Crnošija
- School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Magdalena Krbot Skorić
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Ivan Adamec
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Mila Lovrić
- University Hospital Centre Zagreb, Department of Laboratory Diagnostics, Zagreb, Croatia
| | - Anamari Junaković
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Antonija Mišmaš
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Vladimir Miletić
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Rujana Šprljan Alfirev
- University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia
| | - Antun Pavelić
- School of Medicine, University of Zagreb, Zagreb, Croatia
| | - Mario Habek
- School of Medicine, University of Zagreb, Zagreb, Croatia; University Hospital Center Zagreb, Department of Neurology, Referral Center for Autonomic Nervous System Disorders, Zagreb, Croatia.
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Differential Diagnosis of Vasovagal Syncope: Postural Orthostatic Tachycardia. VASOVAGAL SYNCOPE 2015. [PMCID: PMC7123721 DOI: 10.1007/978-3-319-09102-0_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 11/04/2022]
Abstract
Postural tachycardia syndrome (POTS) is a syndrome defined as an increase in heart rate (HR) of ≥30 bpm within 10 min of assuming an upright posture in the absence of orthostatic hypotension (decrease in blood pressure (BP) >20/10 mmHg). The prevalence of POTS has been estimated as 500,000–3,000,000 patients in the USA. Because it affects mainly women between 13 and 50 years of age, the impact on productivity at work and lifestyle can be devastating. Considerable clinical overlap exists between POTS and vasovagal syncope (VVS) with patients experiencing similar orthostatic symptoms related to insufficient adaptation to blood volume shifts during upright posture. Nevertheless, differences emerge during head up tilt table testing. In patients with POTS, during upright tilt, sympathetic tone increases, there is an early and sustained tachycardia, and patients complain of presyncope without frank syncope. In contrast, patients with VVS experience delayed symptoms and abrupt drops in BP and HR and are more likely to lose consciousness. Treatment of POTS includes exercise and medications directed at decreasing sympathetic tone or increasing blood volume.
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31
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Mar PL, Raj SR. Neuronal and hormonal perturbations in postural tachycardia syndrome. Front Physiol 2014; 5:220. [PMID: 24982638 PMCID: PMC4059278 DOI: 10.3389/fphys.2014.00220] [Citation(s) in RCA: 35] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2014] [Accepted: 05/26/2014] [Indexed: 11/13/2022] Open
Abstract
The Postural Tachycardia Syndrome (POTS) is the most common disorder seen in autonomic clinics. Cardinal hemodynamic feature of this chronic and debilitating disorder of orthostatic tolerance is an exaggerated orthostatic tachycardia (≥30 bpm increase in HR with standing) in the absence of orthostatic hypotension. There are multiple pathophysiological mechanisms that underlie POTS. Some patients with POTS have evidence of elevated sympathoneural tone. This hyperadrenergic state is likely a driver of the excessive orthostatic tachycardia. Another common pathophysiological mechanism in POTS is a hypovolemic state. Many POTS patients with a hypovolemic state have been found to have a perturbed renin-angiotensin-aldosterone profile. These include inappropriately low plasma renin activity and aldosterone levels with resultant inadequate renal sodium retention. Some POTS patients have also been found to have elevated plasma angiotensin II (Ang-II) levels, with some studies suggesting problems with decreased angiotensin converting enzyme 2 activity and decreased Ang-II degradation. An understanding of these pathophysiological mechanisms in POTS may lead to more rational treatment approaches that derive from these pathophysiological mechanisms.
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Affiliation(s)
- Philip L Mar
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine Nashville, TN, USA
| | - Satish R Raj
- Departments of Medicine and Pharmacology, Vanderbilt University School of Medicine Nashville, TN, USA
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Del Pozzi AT, Pandey A, Medow MS, Messer ZR, Stewart JM. Blunted cerebral blood flow velocity in response to a nitric oxide donor in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2014; 307:H397-404. [PMID: 24878770 DOI: 10.1152/ajpheart.00194.2014] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cognitive deficits are characteristic of postural tachycardia syndrome (POTS). Intact nitrergic nitric oxide (NO) is important to cerebral blood flow (CBF) regulation, neurovascular coupling, and cognitive efficacy. POTS patients often experience defective NO-mediated vasodilation caused by oxidative stress. We have previously shown dilation of the middle cerebral artery in response to a bolus administration of the NO donor sodium nitroprusside (SNP) in healthy volunteers. In the present study, we hypothesized a blunted middle cerebral artery response to SNP in POTS. We used combined transcranial Doppler-ultrasound to measure CBF velocity and near-infrared spectroscopy to measure cerebral hemoglobin oxygenation while subjects were in the supine position. The responses of 17 POTS patients were compared with 12 healthy control subjects (age: 14-28 yr). CBF velocity in POTS patients and control subjects were not different at baseline (75 ± 3 vs. 71 ± 2 cm/s, P = 0.31) and decreased to a lesser degree with SNP in POTS patients (to 71 ± 3 vs. 62 ± 2 cm/s, P = 0.02). Changes in total and oxygenated hemoglobin (8.83 ± 0.45 and 8.13 ± 0.48 μmol/kg tissue) were markedly reduced in POTS patients compared with control subjects (14.2 ± 1.4 and 13.6 ± 1.6 μmol/kg tissue), primarily due to increased venous efflux. The data indicate reduced cerebral oxygenation, blunting of cerebral arterial vasodilation, and heightened cerebral venodilation. We conclude, based on the present study outcomes, that decreased bioavailability of NO is apparent in the vascular beds, resulting in a downregulation of NO receptor sites, ultimately leading to blunted responses to exogenous NO.
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Affiliation(s)
- Andrew T Del Pozzi
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Akash Pandey
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Marvin S Medow
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Zachary R Messer
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
| | - Julian M Stewart
- Departments of Pediatrics and Physiology, New York Medical College, Center for Hypotension, Hawthorne, New York
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Reynolds GK, Lewis DP, Richardson AM, Lidbury BA. Comorbidity of postural orthostatic tachycardia syndrome and chronic fatigue syndrome in an Australian cohort. J Intern Med 2014; 275:409-17. [PMID: 24206536 DOI: 10.1111/joim.12161] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
OBJECTIVE Patients with chronic fatigue syndrome (CFS) are frequently diagnosed with comorbid postural orthostatic tachycardia syndrome (POTS), suggesting a shared pathogenesis. The aim of this study was to examine the relationship between demographic characteristics, autonomic functioning and fatigue levels amongst CFS patients with and without comorbid POTS. DESIGN AND SETTING All patients presenting to the CFS Discovery Clinic between 2009 and 2012 completed a 20-min standing task as part of their initial assessment. Heart rate and pulse pressure were recorded at baseline, at 2-min intervals poststanding, at the end of the task and following a recovery period. Average heart rate and pulse pressure variability were calculated from this data. Age, gender, length of illness and self-reported fatigue scores were also recorded. POTS patients were diagnosed by an orthostatic increase in heart rate >30 beats per min, concomitant symptoms of orthostatic intolerance and no orthostatic hypotension. Differences in autonomic functioning between POTS and CFS patients were compared using independent samples t-tests, whilst logistic and linear regressions were performed to examine the contribution of autonomic functioning to task completion and perceived fatigue, respectively. RESULTS Comorbidity of CFS and POTS (CFS-POTS) was observed in 11% (33/306) of patients. CFS-POTS patients were significantly younger (P < 0.001), had a shorter length of illness (P = 0.034), experienced greater task difficulty (P = 0.002) and were able to stand for significantly shorter periods compared to the CFS-only patients (P < 0.001). CFS-POTS patients experienced significantly lower baseline diastolic blood pressure (P = 0.002), significantly higher heart rate and lower pulse pressures at each standing measurement. Early heart rate changes (P = 0.002) and overall heart rate change (P < 0.001) were significant predictors of completion status, whereas heart rate variability (P < 0.001) and female gender (P < 0.001) were significant predictors of increased perceived task difficulty. CONCLUSIONS Haemodynamic and demographic differences between CFS-POTS and CFS-only patients suggest that the former group reflects a distinct subgroup of the CFS population. The findings highlight the utility of screening younger patients with fatigue for POTS, and identified heart rate variability as an important marker of fatigue for CFS patients in general.
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Affiliation(s)
- G K Reynolds
- Department of Genome Biology, The John Curtin School of Medical Research, The Australian National University, Canberra, Australian Capital Territory, Australia
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Ives CT, Kimpinski K. Higher postural heart rate increments on head-up tilt correlate with younger age but not orthostatic symptoms. J Appl Physiol (1985) 2013; 115:525-8. [DOI: 10.1152/japplphysiol.00292.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Reports have shown that younger individuals present with higher postural heart rate increments on head-up tilt (HUT). However, a correlation between the degree of heart rate increment and symptoms of orthostatic intolerance has not been determined. The objective of this study was to determine whether higher postural heart rate increments during HUT correlate with symptoms of orthostatic intolerance in healthy subjects. Postural heart rate increment on HUT did not differ between men and women ( P = 0.48) but did show a significant decrease by age group ( P < 0.0001). There was a significant negative correlation between heart rate increment on HUT and age [ r = −0.63 (−0.73, −0.51), r2 = 0.400; P < 0.0001]. There was a significant difference with respect to symptoms of orthostatic intolerance by sex ( P = 0.03) but not age ( P = 0.58). There was no significant correlation between either symptoms of orthostatic intolerance and age [ r = −0.13 (−0.31, 0.06), r2 = 0.017; P = 0.17] or heart rate increment on HUT and symptoms of orthostatic intolerance [ r = 0.15 (−0.04, 0.33), r2 = 0.022; P = 0.13]. The results demonstrate that higher postural heart rate increments in younger individuals do not result in an increase in orthostatic intolerance. This highlights the potential need for a reevaluation of the diagnostic criteria for postural orthostatic tachycardia syndrome in younger individuals.
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Affiliation(s)
- Colleen T. Ives
- Department of Clinical Neurological Sciences, University Hospital, London Health Sciences Centre, London, Ontario, Canada; and
| | - Kurt Kimpinski
- Department of Clinical Neurological Sciences, University Hospital, London Health Sciences Centre, London, Ontario, Canada; and
- Schulich School of Medicine & Dentistry, Western University, London, Ontario, Canada
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Stewart JM. Update on the theory and management of orthostatic intolerance and related syndromes in adolescents and children. Expert Rev Cardiovasc Ther 2013; 10:1387-99. [PMID: 23244360 DOI: 10.1586/erc.12.139] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Orthostasis means standing upright. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. 'Initial orthostatic hypotension' on rapid standing is a normal form of OI. However, other people experience OI that seriously interferes with quality of life. These include episodic acute OI, in the form of postural vasovagal syncope, and chronic OI, in the form of postural tachycardia syndrome. Less common is neurogenic orthostatic hypotension, which is an aspect of autonomic failure. Normal orthostatic physiology and potential mechanisms for OI are discussed, including forms of sympathetic hypofunction, forms of sympathetic hyperfunction and OI that results from regional blood volume redistribution. General and specific treatment options are proposed.
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Affiliation(s)
- Julian M Stewart
- Departments of Pediatrics, Physiology and Medicine, The Maria Fareri Childrens Hospital and New York Medical College, Valhalla, NY, USA.
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Peggs KJ, Nguyen H, Enayat D, Keller NR, Al-Hendy A, Raj SR. Gynecologic disorders and menstrual cycle lightheadedness in postural tachycardia syndrome. Int J Gynaecol Obstet 2012; 118:242-6. [PMID: 22721633 DOI: 10.1016/j.ijgo.2012.04.014] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2011] [Revised: 04/16/2012] [Accepted: 04/22/2012] [Indexed: 12/21/2022]
Abstract
OBJECTIVE To assess differences in gynecologic history and lightheadedness during menstrual cycle phases among patients with POTS and healthy control women. METHODS In a prospective, questionnaire-based study carried out at Paden Autonomic Dysfunction Center, Vanderbilt University, between April 2005 and January 2009, a custom-designed questionnaire was administered to patients with POTS (n=65) and healthy individuals (n=95). The results were analyzed via Fisher exact test and Mann-Whitney U test. RESULTS Patients with POTS reported increased lightheadedness through all phases of the menstrual cycle phases as compared with healthy controls. Both groups experienced the greatest lightheadedness during menses, and a decrease in lightheadedness during the follicular phase. Patients with POTS reported a higher incidence of gynecologic diseases as compared with healthy controls. CONCLUSION The severity of lightheadedness was found to vary during the menstrual cycle, which may relate to changes in estrogen levels. Patients with POTS also reported an increase in estrogen-related gynecologic disease.
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Affiliation(s)
- Kiffany J Peggs
- Paden Autonomic Dysfunction Service, Division of Clinical Pharmacology, Department of Medicine, Vanderbilt University School of Medicine, Nashville, USA
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Abstract
Sympathetic circulatory control is key to the rapid cardiovascular adjustments that occur within seconds of standing upright (orthostasis) and which are required for bipedal stance. Indeed, patients with ineffective sympathetic adrenergic vasoconstriction rapidly develop orthostatic hypotension, prohibiting effective upright activities. One speaks of orthostatic intolerance (OI) when signs, such as hypotension, and symptoms, such as lightheadedness, occur when upright and are relieved by recumbence. The experience of transient mild OI is part of daily life. However, many people experience episodic acute OI as postural faint or chronic OI in the form of orthostatic tachycardia and orthostatic hypotension that significantly reduce the quality of life. Potential mechanisms for OI are discussed including forms of sympathetic hypofunction, forms of sympathetic hyperfunction, and OI that results from regional blood volume redistribution attributable to regional adrenergic hypofunction.
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Affiliation(s)
- Julian M Stewart
- Departments of Physiology, Pediatrics and Medicine, New York Medical College, Valhalla, NY, USA. mail:
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Mustafa HI, Raj SR, Diedrich A, Black BK, Paranjape SY, Dupont WD, Williams GH, Biaggioni I, Robertson D. Altered systemic hemodynamic and baroreflex response to angiotensin II in postural tachycardia syndrome. Circ Arrhythm Electrophysiol 2012; 5:173-80. [PMID: 22247480 DOI: 10.1161/circep.111.965343] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND Postural tachycardia syndrome (POTS) is characterized by excessive orthostatic tachycardia and significant functional disability. We have previously found that patients with POTS have increases in plasma angiotensin II (Ang II) that are twice as high as healthy subjects despite normal blood pressures (BPs). In this study, we assess systemic and renal hemodynamic and functional responses to Ang II infusion in patients with POTS compared with healthy controls. METHODS AND RESULTS Following a 3-day sodium-controlled diet, we infused Ang II (3 ng/kg per minute) for 1 hour in patients with POTS (n=15) and healthy controls (n=13) in the supine position. All study subjects were women with normal BP. Ages were similar for patients with POTS and controls (mean±SEM, 30±2 versus 26±1 years; P=0.11). We measured the changes from baseline mean arterial pressure, renal plasma flow, plasma renin activity, aldosterone, urine sodium, and baroreflex sensitivity in both groups. In response to Ang II infusion, patients with POTS had a blunted increase compared with controls in mean arterial pressure (10±1 versus 14±1 mm Hg, P=0.01) and diastolic BP (9±1 versus 13±1 mm Hg, P=0.01) but not systolic BP (13±2 versus 15±2 mm Hg, P=0.40). Renal plasma flow decreased similarly with Ang II infusion in patients with POTS versus controls (-166±20 versus -181±17 mL/min per 1.73 kg/m(2), P=0.58). Postinfusion, the decrease in plasma renin activity (-0.9±0.2 versus -0.6±0.2 ng/mL per hour, P=0.43) and the increase in aldosterone (17±1 versus 15±2 pg/mL, P=0.34) were similar in both groups. The decrease in urine sodium excretion was similar in patients with POTS and controls (-49±12 versus -60±16 mEq/g creatinine, P=0.55). The spontaneous baroreflex sensitivity at baseline was significantly lower in patients with POTS compared with controls (10.1±1.2 versus 16.8±1.5 ms/mm Hg, P=0.003), and it was further reduced with Ang II infusion. CONCLUSIONS Patients with POTS have blunted vasopressor response to Ang II and impaired baroreflex function. This impaired vasoconstrictive response might be exaggerated with upright posture and may contribute to the subsequent orthostatic tachycardia that is the hallmark of this disorder. Clinical Trial Registration- URL: http://www.clinicaltrials.gov. Unique identifier: NCT00962949.
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Affiliation(s)
- Hossam I Mustafa
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, TN 37232-2195, USA
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Stewart JM, Nafday A, Ocon AJ, Terilli C, Medow MS. Cutaneous constitutive nitric oxide synthase activation in postural tachycardia syndrome with splanchnic hyperemia. Am J Physiol Heart Circ Physiol 2011; 301:H704-11. [PMID: 21642500 DOI: 10.1152/ajpheart.00171.2011] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Models of microgravity are linked to excessive constitutive nitric oxide (NO) synthase (NOS), splanchnic vasodilation, and orthostatic intolerance. Normal-flow postural tachycardia syndrome (POTS) is a form of chronic orthostatic intolerance associated with splanchnic hyperemia. To test the hypothesis that there is excessive constitutive NOS in POTS, we determined whether cutaneous microvascular neuronal NO and endothelial NO are increased. We performed two sets of experiments in POTS and control subjects aged 21.4 ± 2 yr. We used laser-Doppler flowmetry to measure the cutaneous response to local heating as an indicator of bioavailable neuronal NO. To test for bioavailable endothelial NO, we infused intradermal acetylcholine through intradermal microdialysis catheters and used the selective neuronal NOS inhibitor l-N(ω)-nitroarginine-2,4-L-diamino-butyric amide (N(ω), 10 mM), the selective inducible NOS inhibitor aminoguanidine (10 mM), the nonspecific NOS inhibitor nitro-l-arginine (NLA, 10 mM), or Ringer solution. The acetylcholine dose response and the NO-dependent plateau of the local heating response were increased in POTS compared with those in control subjects. The local heating plateau was significantly higher, 98 ± 1%maximum cutaneous vascular conductance (%CVC(max)) in POTS compared with 88 ± 2%CVC(max) in control subjects but decreased to the same level with N(ω) (46 ± 5%CVC(max) in POTS compared with 49 ± 4%CVC(max) in control) or with NLA (45 ± 3%CVC(max) in POTS compared with 47 ± 4%CVC(max) in control). Only NLA blunted the acetylcholine dose response, indicating that NO produced by endothelial NOS was released by acetylcholine. Aminoguanidine was without effect. This is consistent with increased endothelial and neuronal NOS activity in normal-flow POTS.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, New York, New York, USA.
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Stewart JM, Ocon AJ, Medow MS. Ascorbate improves circulation in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2011; 301:H1033-42. [PMID: 21622825 DOI: 10.1152/ajpheart.00018.2011] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
Low flow postural tachycardia syndrome (LFP) is associated with vasoconstriction, reduced cardiac output, increased plasma angiotensin II, reduced bioavailable nitric oxide (NO), and oxidative stress. We tested whether ascorbate would improve cutaneous NO and reduce vasoconstriction when delivered systemically. We used local cutaneous heating to 42°C and laser Doppler flowmetry to assess NO-dependent conductance (%CVC(max)) to sodium ascorbate and the systemic hemodynamic response to ascorbic acid in 11 LFP patients and in 8 control subjects (aged 23 ± 2 yr). We perfused intradermal microdialysis catheters with sodium ascorbate (10 mM) or Ringer solution. Predrug heat response was reduced in LFP, particularly the NO-dependent plateau phase (56 ± 6 vs. 88 ± 7%CVC(max)). Ascorbate increased baseline skin flow in LFP and control subjects and increased the LFP plateau response (82 ± 6 vs. 92 ± 6 control). Systemic infusion experiments used Finometer and ModelFlow to estimate relative cardiac index (CI) and forearm and calf venous occlusion plethysmography to estimate blood flows, peripheral arterial and venous resistances, and capacitance before and after infusing ascorbic acid. CI increased 40% after ascorbate as did peripheral flows. Peripheral resistances were increased (nearly double control) and decreased by nearly 50% after ascorbate. Calf capacitance and venous resistance were decreased compared with control but normalized with ascorbate. These data provide experimental support for the concept that oxidative stress and reduced NO possibly contribute to vasoconstriction and venoconstriction of LFP.
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Affiliation(s)
- Julian M Stewart
- Department of Physiology, New York Medical College, Valhalla, New York 10532, USA.
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Mustafa HI, Garland EM, Biaggioni I, Black BK, Dupont WD, Robertson D, Raj SR. Abnormalities of angiotensin regulation in postural tachycardia syndrome. Heart Rhythm 2011; 8:422-8. [PMID: 21266211 DOI: 10.1016/j.hrthm.2010.11.009] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2010] [Accepted: 11/04/2010] [Indexed: 12/12/2022]
Abstract
BACKGROUND Postural tachycardia syndrome (POTS) is a disorder characterized by excessive orthostatic tachycardia and significant functional disability. We previously reported that POTS patients have low blood volume and inappropriately low plasma renin activity (PRA) and aldosterone. In this study, we sought to more fully characterize the renin-angiotensin-aldosterone system (RAAS) to gain a better understanding of the pathophysiology of POTS. OBJECTIVE The purpose of this study was to prospectively assess the plasma levels of angiotensin (Ang) peptides and their relationship to other RAAS components in patients with POTS compared with healthy controls. METHODS Heart rate, PRA, Ang I, Ang II, Ang (1-7), and aldosterone were measured in POTS patients (n = 38) and healthy controls (n = 13) while they were consuming a sodium-controlled diet. RESULTS POTS patients had larger orthostatic increases in heart rate than did controls (52 ± 3 [mean ± SEM] bpm vs 27 ± 6 bpm, P = .001). Plasma Ang II was significantly higher in POTS patients (43 ± 3 pg/mL vs 28 ± 3 pg/mL, P = .006), whereas plasma Ang I and angiotensin 1-7 [Ang-(1-7)] were similar between groups. Despite the twofold increase of Ang II, POTS patients trended to lower PRA levels than did controls (0.9 ± 0.1 ng/mL/h vs 1.6 ± 0.5 ng/mL/h, P = .268) and lower aldosterone levels (4.6 ± 0.8 pg/mL vs 10.0 ± 3.0 pg/mL, P = .111). Estimated angiotensin-converting enzyme-2 (ACE2) activity was significantly lower in POTS patients than in controls (0.25 ± 0.02 vs 0.33 ± 0.03, P = .038). CONCLUSION Some patients with POTS have inappropriately high plasma Ang II levels, with low estimated ACE2 activity. We propose that these abnormalities in Ang regulation may play a key role in the pathophysiology of POTS in some patients.
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Affiliation(s)
- Hossam I Mustafa
- Division of Clinical Pharmacology, Vanderbilt University School of Medicine, Nashville, Tennessee 37232-2195, USA
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Fu Q, Vangundy TB, Galbreath MM, Shibata S, Jain M, Hastings JL, Bhella PS, Levine BD. Cardiac origins of the postural orthostatic tachycardia syndrome. J Am Coll Cardiol 2010; 55:2858-68. [PMID: 20579544 DOI: 10.1016/j.jacc.2010.02.043] [Citation(s) in RCA: 208] [Impact Index Per Article: 14.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/03/2009] [Revised: 01/06/2010] [Accepted: 02/01/2010] [Indexed: 11/29/2022]
Abstract
OBJECTIVES The purpose of this study was to test the hypothesis that a small heart coupled with reduced blood volume contributes to the postural orthostatic tachycardia syndrome (POTS) and that exercise training improves this syndrome. BACKGROUND Patients with POTS have marked increases in heart rate during orthostasis. However, the underlying mechanisms are unknown and the effective therapy is uncertain. METHODS Twenty-seven POTS patients underwent autonomic function tests, cardiac magnetic resonance imaging, and blood volume measurements. Twenty-five of them participated in a 3-month specially designed exercise training program with 19 completing the program; these patients were re-evaluated after training. Results were compared with those of 16 healthy controls. RESULTS Upright heart rate and total peripheral resistance were greater, whereas stroke volume and cardiac output were smaller in patients than in controls. Baroreflex function was similar between groups. Left ventricular mass (median [25th, 75th percentiles], 1.26 g/kg [1.12, 1.37 g/kg] vs. 1.45 g/kg [1.34, 1.57 g/kg]; p < 0.01) and blood volume (60 ml/kg [54, 64 ml/kg] vs. 71 ml/kg [65, 78 ml/kg]; p < 0.01) were smaller in patients than in controls. Exercise training increased left ventricular mass and blood volume by approximately 12% and approximately 7% and decreased upright heart rate by 9 beats/min [1, 17 beats/min]. Ten of 19 patients no longer met POTS criteria after training, whereas patient quality of life assessed by the 36-item Short-Form Health Survey was improved in all patients after training. CONCLUSIONS Autonomic function was intact in POTS patients. The marked tachycardia during orthostasis was attributable to a small heart coupled with reduced blood volume. Exercise training improved or even cured this syndrome in most patients. It seems reasonable to offer POTS a new name based on its underlying pathophysiology, the "Grinch syndrome," because in this famous children's book by Dr. Seuss, the main character had a heart that was "two sizes too small."
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Texas 75231, USA
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Fu Q, VanGundy TB, Shibata S, Auchus RJ, Williams GH, Levine BD. Menstrual cycle affects renal-adrenal and hemodynamic responses during prolonged standing in the postural orthostatic tachycardia syndrome. Hypertension 2010; 56:82-90. [PMID: 20479333 DOI: 10.1161/hypertensionaha.110.151787] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Approximately 500,000 American premenopausal women have the postural orthostatic tachycardia syndrome (POTS). We tested the hypothesis that in POTS women during orthostasis, activation of the renin-angiotensin-aldosterone system is greater, leading to better compensated hemodynamics in the midluteal phase (MLP) than in the early follicular phase of the menstrual cycle. Ten POTS women and 11 healthy women (controls) consumed a constant diet 3 days before testing. Hemodynamics and renal-adrenal hormones were measured while supine and during 2-hour standing. We found that blood pressure was similar, heart rate and total peripheral resistance were greater, and cardiac output and stroke volume were lower in POTS subjects than in controls during 2-hour standing. In controls, hemodynamic parameters were indistinguishable between menstrual phases. In POTS subjects, cardiac output and stroke volume were lower and total peripheral resistance was greater in the early follicular phase than MLP after 30 minutes of standing; however, blood pressure and heart rate were similar between phases. Plasma renin activity (9+/-6 [SD] versus 13+/-9 ng/mL per hour; P=0.04) and aldosterone (43+/-22 versus 55+/-25 ng/dL; P=0.02) were lower in the early follicular phase than MLP in POTS subjects after 2 hours of standing. Catecholamine responses were similar between phases. The percentage rate of subjects having presyncope was greater in the early follicular phase than MLP for both groups (chi(2) P<0.01). These results suggest that the menstrual cycle modulates the renin-angiotensin-aldosterone system and affects hemodynamics during orthostasis in POTS. The high estrogen and progesterone in the MLP are associated with greater increases in renal-adrenal hormones and presumably more volume retention, which improve late-standing tolerance in these patients.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, Tex 75231, USA.
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Chronic fatigue syndrome: comments on deconditioning, blood volume and resulting cardiac function. Clin Sci (Lond) 2009; 118:121-3. [PMID: 19534728 DOI: 10.1042/cs20090327] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Cardiovascular and autonomic dysfunction have been suggested to underlie the symptoms accompanying CFS (chronic fatigue syndrome). In the present issue of Clinical Science, Hurwitz and co-workers have investigated whether deficits were present in cardiac output and blood volume in a cohort of patients with CFS and if these were linked to illness severity and sedentary lifestyle. The results clearly demonstrate reduced cardiac stroke volume and cardiac output in more severely afflicted patients with CFS, which is primarily attributable to a measurable reduction in blood volume. Similar findings are observed in microgravity and bed rest deconditioning, in forms of orthostatic intolerance and, to a lesser extent, in sedentary people. The circulatory consequences of reduced cardiac output may help to account for many of the findings of the syndrome.
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Stewart JM, Ocon AJ, Clarke D, Taneja I, Medow MS. Defects in cutaneous angiotensin-converting enzyme 2 and angiotensin-(1-7) production in postural tachycardia syndrome. Hypertension 2009; 53:767-74. [PMID: 19289653 DOI: 10.1161/hypertensionaha.108.127357] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Postural tachycardia syndrome (POTS) is associated with increased plasma angiotensin II (Ang II). Ang II administered in the presence of NO synthase inhibition with nitro-L-arginine (NLA) and Ang II type 1 receptor blockade with losartan produces vasodilation during local heating in controls. We tested whether this angiotensin-mediated vasodilation occurs in POTS and whether it is related to angiotensin-converting enzyme 2 (ACE2) and Ang-(1-7). We used local cutaneous heating to 42 degrees C and laser Doppler Flowmetry to assess NO-dependent conductance at 4 calf sites in 12 low-flow POTS and in 12 control subjects 17.6 to 25.5 years of age. We perfused Ringer's solution through intradermal microdialysis catheters and performed local heating. We perfused one catheter with NLA (10 mmol/L)+losartan (2 microg/L) and repeated heating, and NLA+losartan+Ang II (10 micromol/L), repeating heating a third time. A second catheter received NLA+losartan+Ang II, heated, perfused NLA+losartan+Ang II+DX600 (1 mmol/L; a selective ACE2 inhibitor), and reheated. A third catheter received NLA+losartan+Ang II, heated, perfused NLA+losartan+Ang II+Ang-(1-7) (100 micromol/L), and reheated. The fourth catheter received Ang-(1-7) then reheated a second time only. Angiotensin-mediated vasodilation was present in control but not POTS. Ang-mediated dilation was eliminated by DX600, indicating an ACE2-related effect. Ang-mediated vasodilation was restored in POTS by Ang-(1-7). When administered alone during locally mediated heating, Ang-(1-7) improved the NO-dependent local heating response. ACE2 effects are blunted in low-flow POTS and restored by the ACE2 product Ang-(1-7). Data imply impaired catabolism of Ang II through the ACE2 pathway. Vasoconstriction in POTS may result from a reduction in Ang-(1-7) and an increase in Ang II.
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Affiliation(s)
- Julian M Stewart
- The Center for Pediatric Hypotension, Suite 1600 S, 19 Bradhurst Ave, New York Medical College, Hawthorne, NY 10532, USA.
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Stewart JM, Taneja I, Raghunath N, Clarke D, Medow MS. Intradermal angiotensin II administration attenuates the local cutaneous vasodilator heating response. Am J Physiol Heart Circ Physiol 2008; 295:H327-34. [PMID: 18469148 DOI: 10.1152/ajpheart.00126.2008] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The vasodilation response to local cutaneous heating is nitric oxide (NO) dependent and blunted in postural tachycardia but reversed by angiotensin II (ANG II) type 1 receptor (AT(1)R) blockade. We tested the hypothesis that a localized infusion of ANG II attenuates vasodilation to local heating in healthy volunteers. We heated the skin of a calf to 42 degrees C and measured local blood flow to assess the percentage of maximum cutaneous vascular conductance (%CVC(max)) in eight healthy volunteers aged 19.5-25.5 years. Initially, two experiments were performed; in one, Ringer solution was perfused in three catheters, the response to heating was measured, 2 microg/l losartan, 10 mM nitro-l-arginine (NLA), or NLA + losartan was added to perfusate, and the heat response was remeasured; in another, 10 microM ANG II was given, the heat response was measured, losartan, NLA, or NLA + losartan was added to ANG II, and the heat response was reassessed. The heat response decreased with ANG II, particularly the plateau phase (47 +/- 5 vs. 84 +/- 3 %CVC(max)). Losartan increased baseline conductance in both experiments (from 8 +/- 1 to 20 +/- 2 and 12 +/- 1 to 24 +/- 3). Losartan increased the ANG II response (83 +/- 4 vs. 91 +/- 6 in Ringer). NLA decreased both angiotensin and Ringer responses (31 +/- 4 vs. 43 +/- 3). NLA + losartan blunted the Ringer response (48 +/- 2), but the ANG II response (74 +/- 5) increased. In a second set of experiments, we used dose responses to ANG II (0.1 nM to 10 microM) with and without NLA + losartan to confirm graded responses. Sodium ascorbate (10 mM) restored the ANG II-blunted heating plateau. NO synthase and AT(1)R inhibition cause an NO-independent angiotensin-mediated vasodilation with local heating. ANG II mediates the AT(1)R blunting of local heating, which is not exclusively NO dependent, and is improved by antioxidant supplementation.
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Stewart JM, Taneja I, Medow MS. Reduced body mass index is associated with increased angiotensin II in young women with postural tachycardia syndrome. Clin Sci (Lond) 2007; 113:449-57. [PMID: 17624938 PMCID: PMC3896076 DOI: 10.1042/cs20070104] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
Altered peripheral haemodynamics, decreased cardiac output, decreased blood volume and increased AngII (angiotensin II) have been reported in POTS (postural tachycardia syndrome). Recent findings indicate that BMI (body mass index) may be reduced. In the present study, we investigated the hypothesis that reduced BMI is associated with haemodynamic abnormalities in POTS and that this is related to AngII. We studied 52 patients with POTS, aged 14-29 years, compared with 36 control subjects, aged 14-27 years. BMI was not significantly reduced on average in the POTS patients, but was reduced in patients with decreased peripheral blood flow. POTS patients were then subdivided on the basis of BMI, and supine haemodynamics were measured. There was no difference in blood volume or cardiac output once BMI or body mass were accounted for. When POTS patients with BMI <50th percentile were compared with controls, calf blood flow [1.63+/-0.31 compared with 3.58+/-0.67 ml(-1).min(-1).(100 ml of tissue)(-1)] and maximum venous capacity (3.87+/-0.32 compared with 4.98+/-0.36 ml/100 ml of tissue) were decreased, whereas arterial resistance [56+/-0.5 compared with 30+/-4 mmHg.ml(-1).min(-1).(100 ml of tissue)(-1)] and venous resistance [1.23+/-0.17 compared with 0.79+/-0.11 mmHg.ml(-1).min(-1).(100 ml of tissue)(-1)] were increased. Similar findings were also observed when POTS patients with BMI <50th percentile were compared with POTS patients with BMI >50th percentile. There was no relationship between blood flow, resistance or maximum venous capacity with BMI in control subjects. BMI was inversely related to plasma AngII concentrations in those POTS patients with decreased peripheral blood flow, consistent with cachectic properties of the octapeptide. Patients with low-flow POTS had decreased body mass, but decreased body mass alone cannot account for findings of peripheral vasoconstriction. In conclusion, the findings suggest that reduced body mass relates to increased plasma AngII.
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Affiliation(s)
- Julian M Stewart
- Center for Pediatric Hypotension, New York Medical College, Valhalla, NY 10595, USA.
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Stewart JM, Taneja I, Glover J, Medow MS. Angiotensin II type 1 receptor blockade corrects cutaneous nitric oxide deficit in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2007; 294:H466-73. [PMID: 17993594 DOI: 10.1152/ajpheart.01139.2007] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Low-flow postural tachycardia syndrome (POTS) is associated with increased plasma angiotensin II (ANG II) and reduced neuronal nitric oxide (NO), which decreases NO-dependent vasodilation. We tested whether the ANG II type 1 receptor (AT(1)R) antagonist losartan would improve NO-dependent vasodilation in POTS patients. Furthermore, if the action of ANG II is dependent on NO, then the NO synthase inhibitor nitro-L-arginine (NLA) would reverse this improvement. We used local heating of the skin of the left calf to 42 degrees C and laser-Doppler flowmetry to assess NO-dependent conductance [percent maximum cutaneous vascular conductance (%CVC(max))] in 12 low-flow POTS patients aged 22.5 +/- 0.8 yr and in 15 control subjects aged 22.0 +/- 1.3 yr. After measuring the baseline local heating response at three separate sites, we perfused individual intradermal microdialysis catheters at those sites with 2 microg/l losartan, 10 mM NLA, or losartan + NLA. The predrug heat response was reduced in POTS, particularly the plateau phase reflecting NO-dependent vasodilation (50 +/- 5 vs. 91 +/- 7 %CVC(max); P < 0.001 vs. control). Losartan increased baseline flow in both POTS and control subjects (from 6 +/- 1 to 21 +/- 3 vs. from 10 +/- 1 to 21 +/- 2 %CVC(max); P < 0.05 compared with predrug). The baseline increase was blunted by NLA. Losartan increased the POTS heat response to equal the control subject response (79 +/- 7 vs. 88 +/- 6 %CVC(max); P = 0.48). NLA decreased both POTS and control subject heat responses to similar conductances (38 +/- 4 vs. 38 +/- 3 %CVC(max); P < 0.05 compared with predrug). The addition of NLA to losartan reduced POTS and control subject conductances compared with losartan alone (48 +/- 3 vs. 53 +/- 2 %CVC(max)). The data suggest that the reduction in cutaneous NO-dependent vasodilation in low-flow POTS is corrected by AT(1)R blockade.
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Affiliation(s)
- Julian M Stewart
- The Center for Pediatric Hypotension, New York Medical College, 19 Bradhurst Avenue, Hawthorne, NY 10532, USA.
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