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Mohanakumar S, Kelly B, Turquetto ALR, Alstrup M, Amato LP, Barnabe MSR, Silveira JBD, Amaral F, Manso PH, Jatene MB, Hjortdal VE. Functional lymphatic reserve capacity is depressed in patients with a Fontan circulation. Physiol Rep 2021; 9:e14862. [PMID: 34057301 PMCID: PMC8165731 DOI: 10.14814/phy2.14862] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 04/13/2021] [Indexed: 12/17/2022] Open
Abstract
Background Lymphatic abnormalities play a role in effusions in individuals with a Fontan circulation. Recent results using near‐infrared fluorescence imaging disclosed an increased contraction frequency of lymphatic vessels in Fontan patients compared to healthy controls. It is proposed that the elevated lymphatic pumping seen in the Fontan patients is necessary to maintain habitual interstitial fluid balance. Hyperthermia has previously been used as a tool for lymphatic stress test. By increasing fluid filtration in the capillary bed, the lymphatic workload and contraction frequency are increased accordingly. Using near‐infrared fluorescence imaging, the lymphatic functional reserve capacity in Fontan patients were explored with a lymphatic stress test. Methods Fontan patients (n = 33) were compared to a group of 15 healthy individuals of equal age, weight, and gender. The function of the superficial lymphatic vessels in the lower leg during rest and after inducing hyperthermia was investigated, using near‐infrared fluorescence imaging. Results Baseline values in the Fontan patients showed a 57% higher contraction frequency compared to the healthy controls (0.4 ± 0.3 min−1 vs. 0.3 ± 0.2 min−1, p = 0.0445). After inducing stress on the lymphatic vessels with hyperthermia the ability to increase contraction frequency was decreased in the Fontan patients compared to the controls (0.6 ± 0.5 min−1 vs. 1.2 ± 0.8 min−1, p = 0.0102). Conclusions Fontan patients had a higher lymphatic contraction frequency during normal circumstances. In the Fontan patients, the hyperthermia response is dampened indicating that the functional lymphatic reserve capacity is depressed. This diminished reserve capacity could be part of the explanation as to why some Fontan patients develop late‐onset lymphatic complications.
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Affiliation(s)
- Sheyanth Mohanakumar
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Radiology, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Cardiothoracic Surgery, Rigshospitalet, Copenhagen, Denmark
| | - Benjamin Kelly
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | - Mathias Alstrup
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Aarhus, Denmark.,Department of Clinical Medicine, Aarhus University, Aarhus, Denmark
| | | | | | | | - Fernando Amaral
- Ribeirão Preto Medical School - University of São Paulo, Ribeirão Preto, Brazil.,Pediatric and Adult Congenital Heart Disease Unit, Hospital das Clínicas, Ribeirão Preto, Brazil
| | - Paulo Henrique Manso
- Ribeirão Preto Medical School - University of São Paulo, Ribeirão Preto, Brazil.,Pediatric and Adult Congenital Heart Disease Unit, Hospital das Clínicas, Ribeirão Preto, Brazil
| | | | - Vibeke Elisabeth Hjortdal
- Department of Clinical Medicine, Aarhus University, Aarhus, Denmark.,Department of Cardiothoracic Surgery, Rigshospitalet, Copenhagen, Denmark
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Reduced Lymphatic Reserve in Heart Failure With Preserved Ejection Fraction. J Am Coll Cardiol 2021; 76:2817-2829. [PMID: 33303070 PMCID: PMC7724570 DOI: 10.1016/j.jacc.2020.10.022] [Citation(s) in RCA: 43] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/23/2020] [Revised: 10/02/2020] [Accepted: 10/12/2020] [Indexed: 12/11/2022]
Abstract
BACKGROUND Microvascular dysfunction plays an important role in the pathogenesis of heart failure with preserved ejection fraction (HFpEF). However, no mechanistic link between systemic microvasculature and congestion, a central feature of the syndrome, has yet been investigated. OBJECTIVES This study aimed to investigate capillary-interstitium fluid exchange in HFpEF, including lymphatic drainage and the potential osmotic forces exerted by any hypertonic tissue Na+ excess. METHODS Patients with HFpEF and healthy control subjects of similar age and sex distributions (n = 16 per group) underwent: 1) a skin biopsy for vascular immunohistochemistry, gene expression, and chemical (water, Na+, and K+) analyses; and 2) venous occlusion plethysmography to assess peripheral microvascular filtration coefficient (measuring capillary fluid extravasation) and isovolumetric pressure (above which lymphatic drainage cannot compensate for fluid extravasation). RESULTS Skin biopsies in patients with HFpEF showed rarefaction of small blood and lymphatic vessels (p = 0.003 and p = 0.012, respectively); residual skin lymphatics showed a larger diameter (p = 0.007) and lower expression of lymphatic differentiation and function markers (LYVE-1 [lymphatic vessel endothelial hyaluronan receptor 1]: p < 0.05; PROX-1 [prospero homeobox protein 1]: p < 0.001) compared with control subjects. In patients with HFpEF, microvascular filtration coefficient was lower (calf: 3.30 [interquartile range (IQR): 2.33 to 3.88] l × 100 ml of tissue-1 × min-1 × mm Hg-1 vs. 4.66 [IQR: 3.70 to 6.15] μl × 100 ml of tissue-1 × min-1 × mm Hg-1; p < 0.01; forearm: 5.16 [IQR: 3.86 to 5.43] l × 100 ml of tissue-1 × min-1 × mm Hg-1 vs. 5.66 [IQR: 4.69 to 8.38] μl × 100 ml of tissue-1 × min-1 × mm Hg-1; p > 0.05), in keeping with blood vascular rarefaction and the lack of any observed hypertonic skin Na+ excess, but the lymphatic drainage was impaired (isovolumetric pressure in patients with HFpEF vs. control subjects: calf 16 ± 4 mm Hg vs. 22 ± 4 mm Hg; p < 0.005; forearm 17 ± 4 mm Hg vs. 25 ± 5 mm Hg; p < 0.001). CONCLUSIONS Peripheral lymphatic vessels in patients with HFpEF exhibit structural and molecular alterations and cannot effectively compensate for fluid extravasation and interstitial accumulation by commensurate drainage. Reduced lymphatic reserve may represent a novel therapeutic target.
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Chen G, Du J, Jin H, Huang Y. Postural Tachycardia Syndrome in Children and Adolescents: Pathophysiology and Clinical Management. Front Pediatr 2020; 8:474. [PMID: 32974246 PMCID: PMC7468430 DOI: 10.3389/fped.2020.00474] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/01/2020] [Accepted: 07/06/2020] [Indexed: 12/21/2022] Open
Abstract
Postural tachycardia syndrome (POTS), characterized by chronic (≥6 months) orthostatic intolerance symptoms with a sustained and excessive heart rate increase while standing without postural hypotension, is common in children and adolescents. Despite the unclear pathogenesis of POTS, the present opinion is that POTS is a heterogeneous and multifactorial disorder that includes altered central blood volume, abnormal autonomic reflexes, "hyperadrenergic" status, damaged skeletal muscle pump activity, abnormal local vascular tension and vasoactive factor release, mast cell activation, iron insufficiency, and autoimmune dysfunction. A number of pediatric POTS patients are affected by more than one of these pathophysiological mechanisms. Therefore, individualized treatment strategies are initiated in the management of POTS, including basal non-pharmacological approaches (e.g., health education, the avoidance of triggers, exercise, or supplementation with water and salt) and special pharmacological therapies (e.g., oral rehydration salts, midodrine hydrochloride, and metoprolol). As such, the recent progress in the pathogenesis, management strategies, and therapeutic response predictors of pediatric POTS are reviewed here.
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Affiliation(s)
- Guozhen Chen
- Department of Pediatrics, Peking University First Hospital, Beijing, China
- Department of Pediatrics, The Affiliated Yantai Yuhuangding Hospital of Qingdao University, Yantai, China
- Research Unit of Clinical Diagnosis and Treatment of Pediatric Syncope and Cardiovascular Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Junbao Du
- Department of Pediatrics, Peking University First Hospital, Beijing, China
- Key Laboratory of Molecular Cardiovascular Science, The Ministry of Education, Beijing, China
| | - Hongfang Jin
- Department of Pediatrics, Peking University First Hospital, Beijing, China
- Research Unit of Clinical Diagnosis and Treatment of Pediatric Syncope and Cardiovascular Diseases, Chinese Academy of Medical Sciences, Beijing, China
| | - Yaqian Huang
- Department of Pediatrics, Peking University First Hospital, Beijing, China
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Mohanakumar S, Telinius N, Kelly B, Lauridsen H, Boedtkjer D, Pedersen M, de Leval M, Hjortdal V. Morphology and Function of the Lymphatic Vasculature in Patients With a Fontan Circulation. Circ Cardiovasc Imaging 2019; 12:e008074. [DOI: 10.1161/circimaging.118.008074] [Citation(s) in RCA: 38] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Sheyanth Mohanakumar
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark (S.M., N.T., B.K., V.H.)
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
| | - Niklas Telinius
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark (S.M., N.T., B.K., V.H.)
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
| | - Benjamin Kelly
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark (S.M., N.T., B.K., V.H.)
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
| | - Henrik Lauridsen
- Comparative Medicine Lab, Department of Clinical Medicine (H.L., M.P.), Aarhus University, Denmark
| | - Donna Boedtkjer
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
- Department of Biomedicine (D.B.), Aarhus University, Denmark
| | - Michael Pedersen
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
- Comparative Medicine Lab, Department of Clinical Medicine (H.L., M.P.), Aarhus University, Denmark
| | - Marc de Leval
- The Harley Street Clinic Children’s Hospital, London, United Kingdom (M.d.L.)
| | - Vibeke Hjortdal
- Department of Cardiothoracic and Vascular Surgery, Aarhus University Hospital, Denmark (S.M., N.T., B.K., V.H.)
- Department of Clinical Medicine (S.M., N.T., B.K., D.B., M.P., V.H.), Aarhus University, Denmark
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Cutsforth-Gregory JK, Sandroni P. Clinical neurophysiology of postural tachycardia syndrome. HANDBOOK OF CLINICAL NEUROLOGY 2019; 161:429-445. [PMID: 31307619 DOI: 10.1016/b978-0-444-64142-7.00066-7] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Postural tachycardia syndrome (POTS) is one of several disorders of orthostatic intolerance (OI). It is defined by the development of symptoms of cerebral hypoperfusion or sympathetic activation and a sustained heart rate increment of 30 beats/min or more (40 beats/min for teenagers) within 10min of standing or head-up tilt in the absence of orthostatic hypotension; the standing heart rate is often 120 beats/min or higher. POTS is approximately five times more common in women than men. This heterogeneous syndrome is caused by several pathophysiologic mechanisms (limited autonomic neuropathy, hyperadrenergic state, hypovolemia, venous pooling, deconditioning), which are not mutually exclusive. Anxiety and somatic hypervigilance play significant roles in POTS. Common comorbidities include visceral pain and dysmotility, chronic fatigue and fibromyalgia, migraine, joint hypermobility, mitral valve prolapse, and inappropriate sinus tachycardia. Patients with suspected POTS should undergo comprehensive cardiac and neurologic examinations and autonomic and laboratory tests to determine the most likely pathophysiologic basis of OI. The objectives of POTS management are to (1) increase the time that patients can stand, perform daily activities, and exercise and (2) avoid syncope. Management involves nonpharmacologic (fluid and salt loading, physical countermaneuvers, compression garments, exercise training) and pharmacologic (β-blockers, pyridostigmine, fludrocortisone, midodrine) approaches.
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Affiliation(s)
| | - Paola Sandroni
- Department of Neurology, Mayo Clinic, Rochester, MN, United States.
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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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Fortrat JO, de Holanda A, Zuj K, Gauquelin-Koch G, Gharib C. Altered Venous Function during Long-Duration Spaceflights. Front Physiol 2017; 8:694. [PMID: 28955249 PMCID: PMC5600926 DOI: 10.3389/fphys.2017.00694] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/21/2017] [Accepted: 08/29/2017] [Indexed: 11/16/2022] Open
Abstract
Aims: Venous adaptation to microgravity, associated with cardiovascular deconditioning, may contribute to orthostatic intolerance following spaceflight. The aim of this study was to analyze the main parameters of venous hemodynamics with long-duration spaceflight. Methods: Venous plethysmography was performed on 24 cosmonauts before, during, and after spaceflights aboard the International Space Station. Venous plethysmography assessed venous filling and emptying functions as well as microvascular filtration, in response to different levels of venous occlusion pressure. Calf volume was assessed using calf circumference measurements. Results: Calf volume decreased during spaceflight from 2.3 ± 0.3 to 1.7 ± 0.2 L (p < 0.001), and recovered after it (2.3 ± 0.3 L). Venous compliance, determined as the relationship between occlusion pressure and the change in venous volume, increased during spaceflight from 0.090 ± 0.005 to 0.120 ± 0.007 (p < 0.01) and recovered 8 days after landing (0.071 ± 0.005, arbitrary units). The index of venous emptying rate decreased during spaceflight from −0.004 ± 0.022 to −0.212 ± 0.033 (p < 0.001, arbitrary units). The index of vascular microfiltration increased during spaceflight from 6.1 ± 1.8 to 10.6 ± 7.9 (p < 0.05, arbitrary units). Conclusion: This study demonstrated that overall venous function is changed during spaceflight. In future, venous function should be considered when developing countermeasures to prevent cardiovascular deconditioning and orthostatic intolerance with long-duration spaceflight.
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Affiliation(s)
- Jacques-Olivier Fortrat
- UMR Centre National de la Recherche Scientifique, Faculté de Médecine d'Angers, 6214 Institut National de la Santé et de la Recherche Médicale, 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée)Angers, France
| | - Ana de Holanda
- UMR Centre National de la Recherche Scientifique, Faculté de Médecine d'Angers, 6214 Institut National de la Santé et de la Recherche Médicale, 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée)Angers, France
| | - Kathryn Zuj
- Faculty of Applied Health Sciences, University of WaterlooWaterloo, ON, Canada
| | | | - Claude Gharib
- Faculté de Médecine Lyon Est, Université Claude Bernard Lyon 1Lyon, France
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Vena D, Rubianto J, Popovic MR, Fernie GR, Yadollahi A. The Effect of Electrical Stimulation of the Calf Muscle on Leg Fluid Accumulation over a Long Period of Sitting. Sci Rep 2017; 7:6055. [PMID: 28729617 PMCID: PMC5519746 DOI: 10.1038/s41598-017-06349-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2017] [Accepted: 06/12/2017] [Indexed: 11/09/2022] Open
Abstract
Leg fluid accumulation during sedentary behaviours such as sitting can lead to leg edema and associated adverse health consequences. This study investigates the use calf muscle electrical stimulation (ES) to reduce seated leg fluid accumulation. Thirteen non-obese, normotensive men (mean age 51 yr.) with sleep apnea were enrolled in the study. Participants first lay supine for 30 minutes to equalize fluid distribution and then sat for 150 minutes. While seated, participants received either active or sham ES of the calf muscles, according to random assignment. Participants returned one-week later to cross over to the other study condition. Leg fluid was measured continuously while sitting using the bioelectrical impedance method. Fluid accumulation in the leg was reduced by more than 40% using active ES, compared to sham ES (∆ = 51.9 ± 8.8 ml vs. ∆ = 91.5 ± 8.9 ml, P < 0.001). In summary, calf muscle ES is an effective method for reducing accumulation of fluid during long sedentary periods and has potential use as a device for preventing leg edema to treat associated health consequences in at-risk groups and settings.
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Affiliation(s)
- Daniel Vena
- Toronto Rehabilitation Institute, University Health Network, Toronto, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Jonathan Rubianto
- Toronto Rehabilitation Institute, University Health Network, Toronto, Canada
| | - Milos R Popovic
- Toronto Rehabilitation Institute, University Health Network, Toronto, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Geoff R Fernie
- Toronto Rehabilitation Institute, University Health Network, Toronto, Canada
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada
| | - Azadeh Yadollahi
- Toronto Rehabilitation Institute, University Health Network, Toronto, Canada.
- Institute of Biomaterials and Biomedical Engineering, University of Toronto, Toronto, Canada.
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Lindenberger M, Länne T. Slower lower limb blood pooling in young women with orthostatic intolerance. Exp Physiol 2015; 100:2-11. [PMID: 25557726 DOI: 10.1113/expphysiol.2014.082867] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2014] [Accepted: 10/20/2014] [Indexed: 11/08/2022]
Abstract
NEW FINDINGS What is the central question of this study? Orthostatic stress is mostly caused by venous blood pooling in the lower limbs. Venous distension elicits sympathetic responses, and increased distension speed enhances the cardiovascular response. We examine whether lower limb blood pooling rate during lower body negative pressure is linked to orthostatic intolerance. What is the main finding and its importance? A similar amount of blood was pooled in the lower limb, but at a slower rate in women who developed signs of orthostatic intolerance. The difference in blood pooling rate increased with orthostatic stress and was most prominent at a presyncope-inducing level of lower body negative pressure. The findings have implications for the pathophysiology as well as treatment of orthostatic intolerance. Vasovagal syncope is common in young women, but its aetiology remains elusive. Orthostatic stress-induced lower limb blood pooling is linked with central hypovolaemia and baroreceptor unloading. Venous distension in the arm elicits a sympathetic response, which is enhanced with more rapid distension. Our aim was to study both the amount and the speed of lower limb pooling during orthostatic stress and its effects on compensatory mechanisms to maintain cardiovascular homeostasis in women with orthostatic intolerance. Twenty-seven healthy women, aged 20-27 years, were subjected to a lower body negative pressure (LBNP) of 11-44 mmHg. Five women developed symptoms of vasovagal syncope (orthostatic intolerant) and were compared with the remaining women, who tolerated LBNP well (orthostatic tolerant). Lower limb blood pooling, blood flow and compensatory mobilization of venous capacitance blood were measured. Lower body negative pressure induced equal lower limb blood pooling in both groups, but at a slower rate in orthostatic intolerant women (e.g. time to 50% of total blood pooling, orthostatic intolerant 44 ± 7 s and orthostatic tolerant 26 ± 2 s; P < 0.001). At presyncope-inducing LBNP, the mobilization of venous capacitance blood was both reduced (P < 0.05) and much slower in orthostatic intolerant women (P = 0.0007). Orthostatic intolerant women elicited blunted arterial vasoconstriction at low-grade LBNP, activating only cardiopulmonary baroreceptors, while orthostatic tolerant women responded with apparent vasoconstriction (P < 0.0001). In conclusion, slower lower limb blood pooling could contribute to orthostatic intolerance in women. Mobilization of venous capacitance blood from the peripheral to the central circulation was both slower and decreased; furthermore, reduced cardiopulmonary baroreceptor sensitivity was found in women who developed orthostatic intolerance. Further studies including women who experience syncope in daily life are needed.
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Affiliation(s)
- Marcus Lindenberger
- Department of Medical and Health Sciences, Linköping University, Linköping, Sweden; Department of Cardiology, County Council of Östergötland, Linköping, Sweden
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Rabbitts JA, Groenewald CB, Jacob AK, Low PA, Curry TB. Postural orthostatic tachycardia syndrome and general anesthesia: a series of 13 cases. J Clin Anesth 2011; 23:384-92. [PMID: 21802629 DOI: 10.1016/j.jclinane.2010.12.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/01/2009] [Revised: 11/02/2010] [Accepted: 12/08/2010] [Indexed: 10/17/2022]
Abstract
STUDY OBJECTIVE To investigate whether patients with postural orthostatic tachycardia syndrome (POTS) developed unexpected perioperative complications. DESIGN Retrospective case series. SETTING Academic medical center. MEASUREMENTS The records of 13 patients with POTS, who underwent surgical procedures during general anesthesia, were studied. Details of disease management, anesthetic induction, hemodynamic response to induction and intubation, intraoperative course, and immediate postoperative management were analyzed. MAIN RESULTS Three patients developed prolonged intraoperative hypotension, which was not associated with induction of anesthesia. All 13 patients were successfully treated and they recovered without complications. There were no unplanned hospital or intensive care admissions. CONCLUSIONS Intraoperative hypotension, but not tachycardia, was observed in three of 13 patients with POTS who received general anesthesia for a variety of surgical procedures using multiple medications and techniques.
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Truijen J, Kim YS, Krediet CTP, Stok WJ, Kölgen RS, Colier WN, Secher NH, van Lieshout JJ. Orthostatic leg blood volume changes assessed by near-infrared spectroscopy. Exp Physiol 2011; 97:353-61. [PMID: 22090063 DOI: 10.1113/expphysiol.2011.061051] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Standing up shifts blood to dependent parts of the body, and blood vessels in the leg become filled. The orthostatic blood volume accumulation in the small vessels is relatively unknown, although these may contribute significantly. We hypothesized that in healthy humans exposed to the upright posture, volume accumulation in small blood vessels contributes significantly to the total fluid volume accumulated in the legs. Considering that near-infrared spectroscopy (NIRS) tracks postural blood volume changes within the small blood vessels of the lower leg, we evaluated the NIRS-determined changes in oxygenated (Δ[O(2)Hb]), deoxygenated (Δ[HHb]) and total haemoglobin tissue concentration (Δ[tHb]) and in total leg volume by strain-gauge plethysmography during 70 deg head-up tilt (HUT; n = 7). In a second experiment, spatial and temporal reproducibility were evaluated with three NIRS probes applied on two separate days (n = 8). In response to HUT, an initially fast increase in [O(2)Hb] was followed by a gradual decline, while [HHb] increased continuously. The increase in [tHb] during HUT was closely related to the increase in total leg volume (r(2) = 0.95 ± 0.03). After tilt back, [O(2)Hb] declined below and [HHb] remained above baseline, whereas all NIRS signals gradually returned to baseline. Spatial heterogeneity was observed, and for two probes [tHb] was highly correlated between days (r(2) = 0.92 ± 0.09 and 0.91 ± 0.12), but less for the third probe (r(2) = 0.44 ± 0.36). The results suggest a non-linear accumulation of blood volume in the small vessels of the leg, with an initial fast phase followed by a more gradual increase at least partly contributing to the relocation of fluid during orthostatic stress.
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Affiliation(s)
- J Truijen
- Department of Internal Medicine, Center for Heart Failure Research, Academic Medical Center, University of Amsterdam, The Netherlands
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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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Krishnan US, Taneja I, Gewitz M, Young R, Stewart J. Peripheral vascular adaptation and orthostatic tolerance in Fontan physiology. Circulation 2009; 120:1775-83. [PMID: 19841302 DOI: 10.1161/circulationaha.109.854331] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
BACKGROUND The Fontan circulation is critically dependent on elevated venous pressures to sustain effective venous return. We hypothesized that chronically increased systemic venous pressures lead to adaptive changes in regional and peripheral vessels to maintain cardiac output, especially when patients are upright. METHODS AND RESULTS Nine post-Fontan procedure patients (aged 13 to 24 years) and 6 age- and sex-matched controls were compared with techniques to measure circulatory responses (peripheral and compartmental blood flow, venous capacity, and microvascular filtration). Parameters studied included strain-gauge plethysmography measures of peripheral circulatory function, regional blood volume distribution by impedance plethysmography, and head-up tilt testing. Important differences between Fontan patients and controls were seen in several vascular compartments: (1) Calf capacitance was lower (median, 3.5 versus 5.5 mL/100 mL tissue; P=0.005), and resting venous pressure was higher (13.0 versus 10.5 mm Hg; P=0.004); (2) higher leg arterial resistance was observed (32.1 versus 22.2; P=0.03); (3) microvascular filtration pressures and threshold for edema were elevated; and (4) with head-up tilt testing, splanchnic flow was not reduced in Fontan patients versus controls (fractional change, +4% versus -32%; P=0.004), and splanchnic arterial resistance did not increase as expected (fractional change, +8% versus +79%; P=0.003). CONCLUSIONS Reduced venous compliance and increased filtration thresholds may act as adaptive mechanisms in maintaining venous return in Fontan circulation. Well-compensated Fontan subjects demonstrate superior orthostatic tolerance resulting from decreased compartmental fluid shifts in response to head-up tilt and higher vascular resistance. This results from increased venous stiffness and decreased splanchnic capacitance and may also be an adaptive mechanism to maintain venous return in these patients while standing.
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Affiliation(s)
- Usha S Krishnan
- Department of Pediatric Cardiology, New York Medical College, Valhalla, NY 10595, USA.
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16
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Fontenele JB, Félix FHC. Fibromyalgia and Related Medically Unexplained Symptoms: A Lost Link Between Cardiovascular and Nociception Modulation. ACTA ACUST UNITED AC 2009. [DOI: 10.1080/10582450802679904] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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17
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Postural tachycardia syndrome and reflex syncope: similarities and differences. J Pediatr 2009; 154:481-5. [PMID: 19324216 PMCID: PMC3810291 DOI: 10.1016/j.jpeds.2009.01.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/19/2008] [Revised: 12/02/2008] [Accepted: 01/06/2009] [Indexed: 11/24/2022]
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18
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Carew S, Connor MO, Cooke J, Conway R, Sheehy C, Costelloe A, Lyons D. A review of postural orthostatic tachycardia syndrome. Europace 2009; 11:18-25. [PMID: 19088364 DOI: 10.1093/europace/eun324] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022] Open
Abstract
A 21-year-old female reports an 18-month history of light-headedness on standing. This is often associated with palpitations and a feeling of intense anxiety. She has had two black-outs in the past 12 months. She is not taking any regular medications. Her supine blood pressure was 126/84 mmHg with a heart rate of 76 bpm, and her upright blood pressure was 122/80 mmHg with a heart rate of 114 bpm. A full system examination was otherwise normal. She had a 12-lead electrocardiogram performed which was unremarkable. She was referred for head-up tilt testing. She was symptomatic during the test and lost consciousness at 16 min. Figure 1 summarizes her blood pressure and heart rate response to tilting. A diagnosis of postural orthostatic tachycardia syndrome with overlapping vasovagal syncope was made.
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Affiliation(s)
- Sheila Carew
- Blood Pressure Unit, Mid Western Regional Hospital, Limerick, Ireland
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19
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All that shine is not gold: modelling the true relation between orthostatic intolerance, fibromyalgia and chronic fatigue syndromes. Clin Auton Res 2008; 18:298; author reply 299. [PMID: 18932009 DOI: 10.1007/s10286-008-0498-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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20
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Widmer RJ, Laurinec JE, Young MF, Mohiuddin MW, Laine GA, Quick CM. The origin of the biphasic flow response to local heat in skin. Microcirculation 2008; 15:349-57. [PMID: 18464163 DOI: 10.1080/10739680701745388] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
Abstract
OBJECTIVE Although it is well established that the application of local heat causes a biphasic increase in skin blood flow, the responsible microvessels have not been identified. METHODS A bifurcating network of arterioles (1st-5th orders, 60-15 mum, n = 10 per group) of the intact, unanesthetized, translucent bat wing were visualized on a transparent heat plate via intravital microscopy. Similar to previous bat wing studies, plate temperature was set at 25 degrees C for 10 min then increased to 37 degrees C for 20 min. Vessel diameter and red blood cell velocity were recorded and used to calculate resistance and blood flow. RESULTS The average flow response in arterioles was biphasic (p = 0.02) and proportional to the temporal decrease in total resistance calculated from 1st-5th order arterioles. Metarteriole (i.e., 5th order arteriole) resistance had the greatest impact on total resistance (-67.0 +/- 20.7%) and exhibited a biphasic trend that was opposed by temporal changes in resistance of 1st-4th order arterioles. CONCLUSION Metarterioles are not only necessary but sufficient to explain the origin of the biphasic flow response in skin blood flow.
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Affiliation(s)
- R Jay Widmer
- The Michael E. DeBakey Institute, Texas A&M University, College Station, Texas, USA
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21
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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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22
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Freeman R, Kaufmann H. DISORDERS OF ORTHOSTATIC TOLERANCE-ORTHOSTATIC HYPOTENSION, POSTURAL TACHYCARDIA SYNDROME, AND SYNCOPE. Continuum (Minneap Minn) 2007. [DOI: 10.1212/01.con.0000299966.05395.6c] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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23
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Lindenberger M, Länne T. Decreased capillary filtration but maintained venous compliance in the lower limb of aging women. Am J Physiol Heart Circ Physiol 2007; 293:H3568-74. [PMID: 17906110 DOI: 10.1152/ajpheart.00725.2007] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
There are sex-related differences in venous compliance and capillary filtration in the lower limbs, which to some extent can explain the susceptibility to orthostatic intolerance in young women. With age, venous compliance and capacitance are reduced in men. This study was designed to evaluate age-related changes in venous compliance and capillary filtration in the lower limbs of healthy women. Included in this study were 22 young and 12 elderly women (23.1 +/- 0.4 and 66.4 +/- 1.4 yr). Lower body negative pressure (LBNP) of 11, 22, and 44 mmHg created defined transmural pressure gradients in the lower limbs. A plethysmographic technique was used on the calf to assess venous capacitance and net capillary filtration. Venous compliance was calculated with the aid of a quadratic regression equation. No age-related differences in venous compliance and capacitance were found. Net capillary filtration and capillary filtration coefficient (CFC) were lower in elderly women at a LBNP of 11 and 22 mmHg (0.0032 vs. 0.0044 and 0.0030 vs. 0.0041 ml.100 ml(-1).min(-1).mmHg(-1), P < 0.001). At higher transmural pressure (LBNP, 44 mmHg), CFC increased by approximately 1/3 (0.010 ml.100 ml(-1).min(-1).mmHg(-1)) in the elderly (P < 0.001) but remained unchanged in the young women. In conclusion, no age-related decrease in venous compliance and capacitance was seen in women. However, a decreased CFC was found with age, implying reduced capillary function. Increasing transmural pressure increased CFC in the elderly women, indicating an increased capillary susceptibility to transmural pressure load in dependent regions. These findings differ from earlier studies on age-related effects in men, indicating sex-specific vascular aging both in the venous section and microcirculation.
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Affiliation(s)
- Marcus Lindenberger
- Division of Physiology, Department of Medicine and Care, University Hospital, Linköping University, SE 58185 Linköping, Sweden
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24
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Kooijman M, Poelkens F, Rongen GA, Smits P, Hopman MT. Leg blood flow measurements using venous occlusion plethysmography during head-up tilt. Clin Auton Res 2007; 17:106-11. [PMID: 17345054 PMCID: PMC1914255 DOI: 10.1007/s10286-007-0402-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/16/2006] [Accepted: 01/24/2007] [Indexed: 11/25/2022]
Abstract
We tested whether venous occlusion plethysmography (VOP) is an appropriate method to measure calf blood flow (CBF) during head-up tilt (HUT). CBF measured with VOP was compared with superficial femoral artery blood flow as measured by Doppler ultrasound during incremental tilt angles. Measurements of both methods correlated well (r = 0.86). Reproducibility of VOP was fair in supine position and 30° HUT (CV: 11%–15%). This indicates that VOP is an applicable tool to measure leg blood flow during HUT, especially up to 30° HUT.
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Affiliation(s)
- Miriam Kooijman
- Dept. of Physiology, Radboud University Nijmegen Medical Centre, Ïnstitute for Fundamental and Clinical Movement Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands
- Rehabilitation Centre, Sint Maartenskliniek, Nijmegen, The Netherlands
| | - Fleur Poelkens
- Dept. of Physiology, Radboud University Nijmegen Medical Centre, Ïnstitute for Fundamental and Clinical Movement Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands
| | - Gerard A. Rongen
- Dept. of Pharmacology-Toxicology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Paul Smits
- Dept. of Pharmacology-Toxicology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands
| | - Maria T.E. Hopman
- Dept. of Physiology, Radboud University Nijmegen Medical Centre, Ïnstitute for Fundamental and Clinical Movement Sciences, PO Box 9101, 6500 HB Nijmegen, The Netherlands
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Masuki S, Eisenach JH, Johnson CP, Dietz NM, Benrud-Larson LM, Schrage WG, Curry TB, Sandroni P, Low PA, Joyner MJ. Excessive heart rate response to orthostatic stress in postural tachycardia syndrome is not caused by anxiety. J Appl Physiol (1985) 2007; 102:896-903. [PMID: 17110507 DOI: 10.1152/japplphysiol.00927.2006] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Postural tachycardia syndrome (POTS) is characterized by excessive increases in heart rate (HR) without hypotension during orthostasis. The relationship between the tachycardia and anxiety is uncertain. Therefore, we tested whether the HR response to orthostatic stress in POTS is primarily related to psychological factors. POTS patients ( n = 14) and healthy controls ( n = 10) underwent graded venous pooling with lower body negative pressure (LBNP) to −40 mmHg while wearing deflated antishock trousers. “Sham” venous pooling was performed by 1) trouser inflation to 5 mmHg during LBNP and 2) vacuum pump activation without LBNP. HR responses to mental stress were also measured in both groups, and a questionnaire was used to measure psychological parameters. During LBNP, HR in POTS patients increased 39 ± 5 beats/min vs. 19 ± 3 beats/min in control subjects at −40 mmHg ( P < 0.01). LBNP with trouser inflation markedly blunted the HR responses in the patients (9 ± 2 beats/min) and controls (2 ± 1 beats/min), and there was no HR increase during vacuum application without LBNP in either group. HR responses during mental stress were not different in the patients and controls (18 ± 2 vs. 19 ± 1 beats/min; P > 0.6). Anxiety, somatic vigilance, and catastrophic cognitions were significantly higher in the patients ( P < 0.05), but they were not related to the HR responses during LBNP or mental stress ( P > 0.1). These results suggest that the HR response to orthostatic stress in POTS patients is not caused by anxiety but that it is a physiological response that maintains arterial pressure during venous pooling.
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Affiliation(s)
- Shizue Masuki
- Dept. of Anesthesiology, Mayo Clinic and Foundation, Rochester, MN 55905, USA
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26
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Thieben MJ, Sandroni P, Sletten DM, Benrud-Larson LM, Fealey RD, Vernino S, Lennon VA, Shen WK, Low PA. Postural orthostatic tachycardia syndrome: the Mayo clinic experience. Mayo Clin Proc 2007; 82:308-13. [PMID: 17352367 DOI: 10.4065/82.3.308] [Citation(s) in RCA: 137] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
OBJECTIVE To evaluate the prevalence and pathogenetic mechanisms of postural orthostatic tachycardia syndrome (POTS). PATIENTS AND METHODS We reviewed the medical records of patients with POTS seen at the Mayo Clinic in Rochester, Minn, from January 1, 1993, through December 31, 2003. All patients were required to have had a full autonomic reflex screen. The results of the following additional tests were evaluated: thermoregulatory sweat test, plasma catecholamine measurement, serum ganglionic (a3) acetylcholine receptor antibody detection, and 24-hour urinary sodium measurement. RESULTS We identified 152 patients (86.8% female; mean +/- SD age, 30.2+/-10.3 years) with a mean duration of symptoms of 4.1 years. The mean orthostatic heart rate increment was 44 beats/min. Half the patients had sudomotor abnormalities (apparent on both the quantitative sudomotor axon reflex test and thermoregulatory sweat test), and 34.9% had significant adrenergic impairment, indicating that at least half of the patients had a neuropathic pattern of POTS. In 13.8% of patients, onset was subacute, and ganglionic acetylcholine receptor antibody was detected in 14.6%, suggesting an autoimmune origin in at least 1 in 7 patients. Hyperadrenergic status was documented in 29.0% of patients (standing plasma norepinephrine level 2600 pg/mL), and at least 28.9% were presumably hypovolemic (24-hour urinary sodium level <100 mEq/24h). The lack of correlation between urinary sodium and standing norepinephrine levels suggests that mechanisms other than hypovolemia accounted for the hyperadrenergic state. CONCLUSION Our findings suggest a neuropathic basis for at least half the cases of POTS and that a substantial percentage of cases may be autoimmune. Hyperadrenergic and hypovolemic correlates are likely compensatory or exacerbating.
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Affiliation(s)
- Mark J Thieben
- Autonomic Disorders Center, Department of Neurology, Mayo Clinic College of Medicine, Rochester, Minn 55905, USA
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Stewart JM, Glover JL, Medow MS. Increased plasma angiotensin II in postural tachycardia syndrome (POTS) is related to reduced blood flow and blood volume. Clin Sci (Lond) 2006; 110:255-63. [PMID: 16262605 PMCID: PMC4511483 DOI: 10.1042/cs20050254] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/17/2023]
Abstract
POTS (postural tachycardia syndrome) is associated with low blood volume and reduced renin and aldosterone; however, the role of Ang (angiotensin) II has not been investigated. Previous studies have suggested that a subset of POTS patients with increased vasoconstriction related to decreased bioavailable NO (nitric oxide) have decreased blood volume. Ang II reduces bioavailable NO and is integral to the renin-Ang system. Thus, in the present study, we investigated the relationship between blood volume, Ang II, renin, aldosterone and peripheral blood flow in POTS patients. POTS was diagnosed by 70 degrees upright tilt, and supine calf blood flow, measured by venous occlusion plethysmography, was used to subgroup POTS patients. A total of 23 POTS patients were partitioned; ten with low blood flow, eight with normal flow and five with high flow. There were ten healthy volunteers. Blood volume was measured by dye dilution. All biochemical measurements were performed whilst supine. Blood volume was decreased in low-flow POTS (2.14 +/- 0.12 litres/m2) compared with controls (2.76 +/- 0.20 litres/m2), but not in the other subgroups. PRA (plasma renin activity) was decreased in low-flow POTS compared with controls (0.49 +/- 0.12 compared with 0.90 +/- 0.18 ng of Ang I.ml(-1).h(-1) respectively), whereas plasma Ang II was increased (89 +/- 20 compared with 32 +/- 4 ng/l), but not in the other subgroups. PRA correlated with aldosterone (r = +0.71) in all subjects. PRA correlated negatively with blood volume (r = -0.72) in normal- and high-flow POTS, but positively (r = +0.65) in low-flow POTS. PRA correlated positively with Ang II (r = +0.76) in normal- and high-flow POTS, but negatively (r = -0.83) in low-flow POTS. Blood volume was negatively correlated with Ang II (r = -0.66) in normal- and high-flow POTS and in five low-flow POTS patients. The remaining five low-flow POTS patients had reduced blood volume and increased Ang II which was not correlated with blood volume. The data suggest that plasma Ang II is increased in low-flow POTS patients with hypovolaemia, which may contribute to local blood flow dysregulation and reduced NO bioavailability.
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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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Diehl RR. Continuous progression of orthostatic tachycardia as a further feature of the postural tachycardia syndrome. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2006; 28:975-9. [PMID: 16176538 DOI: 10.1111/j.1540-8159.2005.00215.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
BACKGROUND The clinical diagnosis of the postural tachycardia syndrome (POTS) includes the demonstration of an upright heart rate (HR) of at least 30 beats per minute (bpm) above supine HR. The dynamic behavior of HR during the course of standing has not yet been studied systematically in POTS. METHODS HR and arterial blood pressure (ABP) were continuously monitored in 17 POTS patients and in 24 age-matched controls at rest and during an 11-minute phase of 80 degrees tilt. RESULTS ABP values at different time intervals of the protocol did not differ between the subgroups with the exception of higher diastolic pressures in POTS after 5 and 10 minutes of tilt. POTS patients showed a higher resting HR (80.6 +/- 17.0 bpm vs 67.8 +/- 10.9 bpm in controls, P < 0.05) and there was a continuous HR acceleration in the course of the 11-minute tilt phase. In control subjects, the tilt-induced HR increase was nearly completed after 1 minute with only a minimal further rise between minute 1 and minute 10 (from 83.7 +/- 11.5 to 85.3 +/- 11.9 bpm vs from 106.1 +/- 15.6 to 120.1 +/- 13.8 bpm in POTS). CONCLUSIONS Continuously progressing orthostatic tachycardia can serve as an additional criterion in the diagnosis of POTS. It may be related to the recently observed increased orthostatic capillary filtration rate in POTS.
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Affiliation(s)
- Rolf R Diehl
- Autonomic Laboratory, Department of Neurology, Krupp Hospital, Alfried-Krupp-Strasse 21, 45117 Essen, Germany.
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Abstract
Sinus tachycardia is the most common rhythm disturbance encountered in clinical practice. Primary sinus tachycardia without an underlying secondary cause, despite often being associated with troublesome symptoms, is often neglected leading to multiple consultations and frustration on part of both the practitioner and the patient. The fact that primary sinus tachycardias are a heterogeneous group of disorders is seldom appreciated; hence, a firm diagnosis is rarely reached and management is haphazard. Furthermore, there may be prognostic implications for prolonged or recurrent sinus tachycardia, making it imperative that this group of arrhythmias receive adequate and appropriate attention. Normal sinus tachycardia (i.e., secondary), inappropriate sinus tachycardia, postural orthostatic tachycardia syndrome (POTS) and sinus node reentry tachycardia make up this group of arrhythmias. Their definitions, clinical features, diagnostic criteria, pathophysiologic mechanisms, and optimum management are discussed in this review.
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Affiliation(s)
- Shamil Yusuf
- Department of Cardiovascular Medicine, St. Georges Hospital Medical School, London, UK.
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Brady PA, Low PA, Shen WK. Inappropriate Sinus Tachycardia, Postural Orthostatic Tachycardia Syndrome, and Overlapping Syndromes. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2005; 28:1112-21. [PMID: 16221272 DOI: 10.1111/j.1540-8159.2005.00227.x] [Citation(s) in RCA: 55] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
BACKGROUND Inappropriate sinus tachycardia (IAST) and postural orthostatic tachycardia syndrome (POTS) are syndrome complexes with some distinctive features, overlapping clinical manifestations, and potential common mechanisms. Pathogenesis of these overlapping syndromes is poorly understood. Diagnostic and therapeutic approaches have not been standardized. PURPOSE This article provides an overview of the definition, clinical presentation, and proposed mechanisms of IAST and other overlapping syndromes. A stepwise diagnostic approach is suggested. A multidisciplinary management scheme is outlined. METHODS A MEDLINE search for English-language articles on IAST, POTS, and chronic orthostatic intolerance published up to 2005 was performed. Published data incorporated with our clinical experience were synthesized and presented in this review. RESULTS The population of IAST is heterogeneous and underlying mechanisms are complex and likely multifactorial. Evidence suggests that both cardiac and extracardiac causes are plausible. Regional and limited autonomic neuropathies, at least in part, can provide a mechanism-based explanation of the cardiovascular indices and clinical symptoms in a significant number of patients with IAST. The regional abnormalities can be detected by autonomic testing. Among patients with IAST and evidence of autonomic dysregulation, an integrated autonomic, cardiovascular, and psychiatric management approach appears to be logical and rational when appropriate. Sinus node ablation could be considered in patients with persistent IAST in the absence of autonomic neuropathy and multisystem symptoms. Data from long-term outcomes are lacking. CONCLUSION The current understanding of IAST mechanisms is incomplete and management approach is not adequate. Significant effort needed in clinical research to improve therapeutic outcome.
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Affiliation(s)
- Peter A Brady
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic College of Medicine and Mayo Foundation, Rochester, Minnesota 55905, USA
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Stewart JM, Medow MS, Glover JL, Montgomery LD. Persistent splanchnic hyperemia during upright tilt in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2005; 290:H665-73. [PMID: 16143646 PMCID: PMC4513355 DOI: 10.1152/ajpheart.00784.2005] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Previous investigations have allowed for stratification of patients with postural tachycardia syndrome (POTS) on the basis of peripheral blood flow. One such subset, comprising "normal-flow POTS" patients, is characterized by normal peripheral resistance and blood volume in the supine position but thoracic hypovolemia and splanchnic blood pooling in the upright position. We studied 32 consecutive 14- to 22-yr-old POTS patients comprising 13 with low-flow POTS, 14 with normal-flow POTS, and 5 with high-flow POTS and 12 comparably aged healthy volunteers. We measured changes in impedance plethysmographic (IPG) indexes of blood volume and blood flow within thoracic, splanchnic, pelvic (upper leg), and lower leg regional circulations in the supine posture and during incremental tilt to 20 degrees, 35 degrees, and 70 degrees. We validated IPG measures of thoracic and splanchnic blood flow against indocyanine green dye-dilution measurements. We validated IPG leg blood flow against venous occlusion plethysmography. Control subjects developed progressive vasoconstriction with incremental tilt. Splanchnic blood flow was increased in the supine position in normal-flow POTS, despite marked peripheral vasoconstriction, and did not change during incremental tilt, producing progressive splanchnic hypervolemia. Absolute hypovolemia was present in low-flow POTS, all supine flows and volumes were reduced, there was no vasoconstriction with tilt in all segments, and segmental volumes tended to increase uniformly throughout tilt. Lower body (pelvic and leg) flows were increased in high-flow POTS at all angles, with consequent lower body hypervolemia during tilt. Our main finding is selective and maintained orthostatic splanchnic vasodilation in normal-flow POTS, despite marked peripheral vasoconstriction in these same patients. Local splanchnic vasoregulatory factors may counteract vasoconstriction and venoconstriction in these patients. Lower body vasoconstriction in high-flow POTS was abnormal, and vasoconstriction in low-flow POTS was sustained at initially elevated supine levels.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, NY, USA.
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Nickander KK, Carlson PJ, Urrutia RA, Camilleri M, Low PA. A screen of candidate genes and influence of β2-adrenergic receptor genotypes in postural tachycardia syndrome. Auton Neurosci 2005; 120:97-103. [PMID: 15946904 DOI: 10.1016/j.autneu.2005.05.001] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/07/2004] [Revised: 04/29/2005] [Accepted: 05/03/2005] [Indexed: 11/29/2022]
Abstract
OBJECTIVE To screen candidate genes, encoding beta2-adrenergic receptor (beta2AR), alpha2C-adrenergic receptor (alpha(2C)AR), norepinephrine transporter (NET), and mitochondrial complex I (COI), for common single nucleotide polymorphisms (SNPs) in patients with postural tachycardia syndrome (POTS); alterations could potentially cause or aggravate orthostatic tachycardia and to relate beta2AR SNPs, known to effect venomotor tone, to heart rate (HR) and blood pressure measurements during 10-min head-up tilt. METHODS (a) DNA extraction from leukocytes of 29 patients with POTS; (b) Denaturing high performance liquid chromatography analysis to screen for the 12-bp deletion (Del322-325) in alpha(2C)AR and for the alanine to proline mutation at amino acid 457 (Ala457Pro) in NET; (c) Systematic direct sequence analysis to screen for SNPs in beta2AR, NET, and COI. RESULTS Three common polymorphisms were abundant in at least one allele in beta2AR resulting in a cysteine to arginine in the 5' promoter region (72% of patients), an arginine to glycine at amino acid-16 (Gly16; 86%), and a glutamine to glutamic acid at amino acid-27 (Glu27; 66%), a frequency that was no different to the normal Caucasian population. Orthostatic HR was significantly greater in patients with Glu27. Diastolic blood pressure (DBP) was significantly lower in a subset of patients with Gly16 whose HR were > or =120 beats/min with head-up tilt. All patients did not show the Ala457Pro mutation of NET; all sequence variants detected in alpha(2C)AR, NET, and COI were not considered causally related to POTS. CONCLUSIONS Of the candidate genes screened, none harbored a SNP considered to be causally related to POTS. There was significant association of HR and DBP with SNPs of the gene encoding beta2AR; Gly16 or Glu27 could aggravate orthostatic tachycardia by excessive venous pooling.
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Affiliation(s)
- Kim K Nickander
- Department of Neurology, Mayo Clinic and Foundation, 200 First Street SW, Rochester, Minnesota 55905, USA
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics and Physiology, New York Medical College Valhalla, New York, USA.
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Stewart JM, McLeod KJ, Sanyal S, Herzberg G, Montgomery LD. Relation of postural vasovagal syncope to splanchnic hypervolemia in adolescents. Circulation 2004; 110:2575-81. [PMID: 15492310 DOI: 10.1161/01.cir.0000145543.88293.21] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
BACKGROUND The mechanisms of simple faint remain elusive. We propose that postural fainting is related to excessive thoracic hypovolemia and splanchnic hypervolemia during orthostasis compared with healthy subjects. METHODS AND RESULTS We studied 34 patients 12 to 22 years old referred for multiple episodes of postural faint and 11 healthy subjects. Subjects were studied in the supine position and during upright tilt to 70 degrees for 30 minutes and subgrouped into S+, historical fainters who fainted during testing (n=24); S-, historical fainters who did not faint during testing (n=10); and control subjects. Supine venous occlusion plethysmography showed no differences between blood flows of the forearm and calf in S+, S-, or control. Cardiac index, total peripheral resistance, and blood volume were not different. Using impedance plethysmography, we assessed blood redistribution during upright tilt. This demonstrated decreased thoracic blood volume and increased splanchnic, pelvic, and leg blood volumes for all subjects. However, thoracic blood volume was decreased in S+ compared with control volume, correlating well with the maximum upright heart rate. Splanchnic volume was decreased in the S+ and S- groups, correlating with the change in thoracic blood volume. Pelvic and leg volume changes were similar for all groups and uncorrelated to thoracic blood volume. CONCLUSIONS Enhanced postural thoracic hypovolemia and splanchnic hypervolemia are associated with postural simple faint.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, The Center for Pediatric Hypotension, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA.
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Stewart JM, Karman C, Montgomery LD, McLeod KJ. Plantar vibration improves leg fluid flow in perimenopausal women. Am J Physiol Regul Integr Comp Physiol 2004; 288:R623-9. [PMID: 15472009 DOI: 10.1152/ajpregu.00513.2004] [Citation(s) in RCA: 65] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Recent studies have indicated that plantar-based vibration may be an effective approach for the prevention and treatment of osteoporosis. We addressed the hypothesis of whether the plantar vibration operated by way of the skeletal muscle pump, resulting in enhanced blood and fluid flow to the lower body. We combined plantar stimulation with upright tilt table testing in 18 women aged 46-63 yr. We used strain-gauge plethysmography to measure calf blood flow, venous capacitance, and the microvascular filtration relation, as well as impedance plethysmography to examine changes in leg, splanchnic, and thoracic blood flow while supine at a 35 degrees upright tilt. A vibrating platform was placed on the footboard of a tilt table, and measurements were made at 0, 15, and 45 Hz with an amplitude of 0.2 g point to point, presented in random order. Impedance-measured supine blood flows were significantly (P = 0.05) increased in the calf (30%), pelvic (26%), and thoracic regions (20%) by plantar vibration at 45 Hz. Moreover, the 25-35% decreases in calf and pelvic blood flows associated with upright tilt were reversed by plantar vibration, and the decrease in thoracic blood flow was significantly attenuated. Strain-gauge measurements showed an attenuation of upright calf blood flow. In addition, the microvascular filtration relation was shifted with vibration, producing a pronounced increase in the threshold for edema, P(i), due to enhanced lymphatic flow. Supine values for P(i) increased from 24 +/- 2 mmHg at 0 Hz to 27 +/- 3 mmHg at 15 Hz, and finally to 31 +/- 2 mmHg at 45 Hz (P < 0.01). Upright values for P(i) increased from 25 +/- 3 mmHg at 0 Hz, to 28 +/- 4 mmHg at 15 Hz, and finally to 35 +/- 4 mmHg at 45 Hz. The results suggest that plantar vibration serves to significantly enhance peripheral and systemic blood flow, peripheral lymphatic flow, and venous drainage, which may account for the apparent ability of such stimuli to influence bone mass.
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Affiliation(s)
- Julian M Stewart
- Depts. of Pediatrics and Physiology, The Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA.
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Stewart JM, Montgomery LD. Regional blood volume and peripheral blood flow in postural tachycardia syndrome. Am J Physiol Heart Circ Physiol 2004; 287:H1319-27. [PMID: 15117717 PMCID: PMC4515760 DOI: 10.1152/ajpheart.00086.2004] [Citation(s) in RCA: 71] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Variants of postural tachycardia syndrome (POTS) are associated with increased ["high-flow" POTS (HFP)], decreased ["low-flow" POTS (LFP)], and normal ["normal-flow" POTS (NFP)] blood flow measured in the lower extremities while subjects were in the supine position. We propose that postural tachycardia is related to thoracic hypovolemia during orthostasis but that the patterns of peripheral blood flow relate to different mechanisms for thoracic hypovolemia. We studied 37 POTS patients aged 14-21 yr: 14 LFP, 15 NFP, and 8 HFP patients and 12 healthy control subjects. Peripheral blood flow was measured in the supine position by venous occlusion strain-gauge plethysmography of the forearm and calf to subgroup patients. Using indocyanine green techniques, we showed decreased cardiac index (CI) and increased total peripheral resistance (TPR) in LFP, increased CI and decreased TPR in HFP, and unchanged CI and TPR in NFP while subjects were supine compared with control subjects. Blood volume tended to be decreased in LFP compared with control subjects. We used impedance plethysmography to assess regional blood volume redistribution during upright tilt. Thoracic blood volume decreased, whereas splanchnic, pelvic, and leg blood volumes increased, for all subjects during orthostasis but were markedly lower than control for all POTS groups. Splanchnic volume was increased in NFP and LFP. Pelvic blood volume was increased in HFP only. Calf volume was increased above control in HFP and LFP. The results support the hypothesis of (at least) three pathophysiologic variants of POTS distinguished by peripheral blood flow related to characteristic changes in regional circulations. The data demonstrate enhanced thoracic hypovolemia during upright tilt and confirm that POTS is related to inadequate cardiac venous return during orthostasis.
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Affiliation(s)
- Julian M Stewart
- Department of Pediatrics, New York Medical College, Valhalla, New York 10595, USA.
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Stewart JM, Medow MS, Montgomery LD, McLeod K. Decreased skeletal muscle pump activity in patients with postural tachycardia syndrome and low peripheral blood flow. Am J Physiol Heart Circ Physiol 2003; 286:H1216-22. [PMID: 14576081 DOI: 10.1152/ajpheart.00738.2003] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Standing translocates thoracic blood volume into the dependent body. The skeletal muscle pump participates in preventing orthostatic intolerance by enhancing venous return. We investigated the hypothesis that skeletal muscle pump function is impaired in postural tachycardia (POTS) associated with low calf blood flow (low-flow POTS) and depends in general on muscle blood flow. We compared 12 subjects that have low-flow POTS with 10 controls and 7 patients that have POTS and normal calf blood flow using strain-gauge plethysmography to measure peripheral blood flow, venous capacitance, and calf muscle pump function. Blood volume was estimated by dye dilution. We found that calf circumference was reduced in low-flow POTS (32 +/- 1 vs. 39 +/- 3 and 43 +/- 3 cm) and, compared with controls and POTS patients with normal blood flow, is related to the reduced fraction of calf venous capacity emptied during voluntary muscle contraction (ejection fraction, 0.52 +/- 0.07 vs. 0.76 +/- 0.07 and 0.80 +/- 0.06). We found that blood flow was linearly correlated (r(p) = 0.69) with calf circumference (used as a surrogate for muscle mass). Blood volume measurements were 2.2 +/- 0.3 in low-flow POTS vs. 2.6 +/- 0.5 in controls (P = 0.17) and 2.4 +/- 0.7 in normal-flow POTS patients. Decreased calf blood flow may reduce calf size in POTS and thereby impair the upright ejective ability of the skeletal muscle pump and further contribute to overall reduced blood flow and orthostatic intolerance in these patients.
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Affiliation(s)
- Julian M Stewart
- Center for Pediatric Hypotension and Division of Pediatric Cardiology, Suite 618, Munger Pavilion, New York Medical College, Valhalla, NY 10595, USA.
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