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Cámara-Checa A, Perin F, Rubio-Alarcón M, Dago M, Crespo-García T, Rapún J, Marín M, Cebrián J, Gómez R, Bermúdez-Jiménez F, Monserrat L, Tamargo J, Caballero R, Jiménez-Jáimez J, Delpón E. A gain-of-function HCN4 mutant in the HCN domain is responsible for inappropriate sinus tachycardia in a Spanish family. Proc Natl Acad Sci U S A 2023; 120:e2305135120. [PMID: 38032931 PMCID: PMC10710060 DOI: 10.1073/pnas.2305135120] [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: 03/29/2023] [Accepted: 10/12/2023] [Indexed: 12/02/2023] Open
Abstract
In a family with inappropriate sinus tachycardia (IST), we identified a mutation (p.V240M) of the hyperpolarization-activated cyclic nucleotide-gated type 4 (HCN4) channel, which contributes to the pacemaker current (If) in human sinoatrial node cells. Here, we clinically study fifteen family members and functionally analyze the p.V240M variant. Macroscopic (IHCN4) and single-channel currents were recorded using patch-clamp in cells expressing human native (WT) and/or p.V240M HCN4 channels. All p.V240M mutation carriers exhibited IST that was accompanied by cardiomyopathy in adults. IHCN4 generated by p.V240M channels either alone or in combination with WT was significantly greater than that generated by WT channels alone. The variant, which lies in the N-terminal HCN domain, increased the single-channel conductance and opening frequency and probability of HCN4 channels. Conversely, it did not modify the channel sensitivity for cAMP and ivabradine or the level of expression at the membrane. Treatment with ivabradine based on functional data reversed the IST and the cardiomyopathy of the carriers. In computer simulations, the p.V240M gain-of-function variant increases If and beating rate and thus explains the IST of the carriers. The results demonstrate the importance of the unique HCN domain in HCN4, which stabilizes the channels in the closed state.
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Affiliation(s)
- Anabel Cámara-Checa
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Francesca Perin
- Department of Pediatric Cardiology, Virgen de las Nieves University Hospital, Granada18014, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada18014, Spain
| | - Marcos Rubio-Alarcón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - María Dago
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Teresa Crespo-García
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Josu Rapún
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - María Marín
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Jorge Cebrián
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Ricardo Gómez
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Francisco Bermúdez-Jiménez
- Department of Pediatric Cardiology, Virgen de las Nieves University Hospital, Granada18014, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada18014, Spain
- Centro Nacional de Investigaciones Cardiovasculares, Madrid28029, Spain
| | - Lorenzo Monserrat
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
- Health in Code Sociedad Limitada, A Coruña15008, Spain
| | - Juan Tamargo
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
| | - Ricardo Caballero
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
| | - Juan Jiménez-Jáimez
- Department of Pediatric Cardiology, Virgen de las Nieves University Hospital, Granada18014, Spain
- Instituto de Investigación Biosanitaria de Granada, Granada18014, Spain
| | - Eva Delpón
- Department of Pharmacology and Toxicology, School of Medicine, Universidad Complutense de Madrid, Instituto de Investigación Gregorio Marañón, 28040Madrid, Spain
- Centro de Investigación Biomédica en Red Enfermedades Cardiovasculares, Instituto de Salud Carlos III, Madrid28029, Spain
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2
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Varrias D, Sharma N, Hentz R, Ma R, Gurciullo D, Kleiman J, Kossack A, Wolf E, Lam B, Bimal T, Ansari U, Coleman KM, Mountantonakis SE. Clinical significance of unexplained persistent sinus tachycardia in women with structurally normal heart during the peripartum period. BMC Pregnancy Childbirth 2022; 22:677. [PMID: 36057572 PMCID: PMC9440559 DOI: 10.1186/s12884-022-05012-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Accepted: 08/30/2022] [Indexed: 11/23/2022] Open
Abstract
Background Persistent sinus tachycardia (ST) is frequently encountered during pregnancy and peripartum period and its etiology often remains elusive. We sought to examine the possible association between unexplained persistent ST and obstetric outcomes. Methods A case control study was conducted using chart review of women admitted in labor to one of 7 hospitals of Northwell Health between January 2015 to June 2021. After excluding women with structurally abnormal hearts, we identified patients with persistent ST during the peripartum period, defined as a heart rate of more than 100 bpm for more than 48 h. A control group was created by randomly subsampling those who did not meet the inclusion criteria for sinus tachycardia. Obstetric outcomes were measured as mother’s length of stay (LOS), pre-term labor (PTL), admission to the neonatal ICU (NICU), and whether she received cesarean-section (CS). Results Seventy-eight patients with persistent ST were identified, out of 141,769 women admitted for labor throughout the Northwell Health system. 23 patients with ST attributable to infection or hypovolemia from anemia requiring transfusion and 55 with unclear etiology were identified. After adjusting for age and parity, pregnant mothers with ST were 2.35 times more likely to have a CS than those without (95% CI: 1.46–3.81, p = 0.0005) and had 1.38 times the LOS (1.21- 1.56, p < 0.0001). Among mothers with ST, those with unexplained ST were 2.14 times more likely to have a CS (1.22–3.75, p = 0.008). Conclusion Among pregnant patients, patients with ST have higher rates of CS.This association is unclear, however potential mechanisms include catecholamine surge, indolent infection, hormonal fluctuations, and medications. More studies are needed to explore the mechanism of ST in pregnant woman to determine the clinical significance and appropriate management. Supplementary Information The online version contains supplementary material available at 10.1186/s12884-022-05012-3.
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Affiliation(s)
- Dimitrios Varrias
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Nikhil Sharma
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Roland Hentz
- Feinstein Institutes For Medical Research, Manhasset, NY, USA
| | - Rosaline Ma
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Dillon Gurciullo
- Department of Obstetrics & Gynecology, Lenox Hill Hospital, Northwell Health System, New York, NY, USA
| | - Jeremy Kleiman
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Andrew Kossack
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Eliot Wolf
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Betty Lam
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Tia Bimal
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Umair Ansari
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
| | - Kristie M Coleman
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA.
| | - Stavros E Mountantonakis
- Department of Cardiology, Lenox Hill Hospital Heart & Lung, Northwell Health System, 100 East 77th Street, 2nd Floor, New York, NY, 10075, USA
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3
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Mayuga KA, Fedorowski A, Ricci F, Gopinathannair R, Dukes JW, Gibbons C, Hanna P, Sorajja D, Chung M, Benditt D, Sheldon R, Ayache MB, AbouAssi H, Shivkumar K, Grubb BP, Hamdan MH, Stavrakis S, Singh T, Goldberger JJ, Muldowney JAS, Belham M, Kem DC, Akin C, Bruce BK, Zahka NE, Fu Q, Van Iterson EH, Raj SR, Fouad-Tarazi F, Goldstein DS, Stewart J, Olshansky B. Sinus Tachycardia: a Multidisciplinary Expert Focused Review. Circ Arrhythm Electrophysiol 2022; 15:e007960. [PMID: 36074973 PMCID: PMC9523592 DOI: 10.1161/circep.121.007960] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Sinus tachycardia (ST) is ubiquitous, but its presence outside of normal physiological triggers in otherwise healthy individuals remains a commonly encountered phenomenon in medical practice. In many cases, ST can be readily explained by a current medical condition that precipitates an increase in the sinus rate, but ST at rest without physiological triggers may also represent a spectrum of normal. In other cases, ST may not have an easily explainable cause but may represent serious underlying pathology and can be associated with intolerable symptoms. The classification of ST, consideration of possible etiologies, as well as the decisions of when and how to intervene can be difficult. ST can be classified as secondary to a specific, usually treatable, medical condition (eg, pulmonary embolism, anemia, infection, or hyperthyroidism) or be related to several incompletely defined conditions (eg, inappropriate ST, postural tachycardia syndrome, mast cell disorder, or post-COVID syndrome). While cardiologists and cardiac electrophysiologists often evaluate patients with symptoms associated with persistent or paroxysmal ST, an optimal approach remains uncertain. Due to the many possible conditions associated with ST, and an overlap in medical specialists who see these patients, the inclusion of experts in different fields is essential for a more comprehensive understanding. This article is unique in that it was composed by international experts in Neurology, Psychology, Autonomic Medicine, Allergy and Immunology, Exercise Physiology, Pulmonology and Critical Care Medicine, Endocrinology, Cardiology, and Cardiac Electrophysiology in the hope that it will facilitate a more complete understanding and thereby result in the better care of patients with ST.
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Affiliation(s)
- Kenneth A. Mayuga
- Section of Cardiac Electrophysiology and Pacing, Department of Cardiovascular Medicine, Cleveland Clinic, Cleveland, OH
| | - Artur Fedorowski
- Karolinska Institutet & Karolinska University Hospital, Stockholm, Sweden
| | - Fabrizio Ricci
- Department of Neuroscience, Imaging and Clinical Sciences, “G.d’Annunzio” University of Chieti-Pescara, Chieti Scalo, Italy
| | | | | | | | | | | | - Mina Chung
- Section of Cardiac Electrophysiology and Pacing, Department of Cardiovascular Medicine, Cleveland Clinic, Phoenix, AZ
| | - David Benditt
- University of Minnesota Medical School, Minneapolis, MN
| | | | - Mirna B. Ayache
- MetroHealth Medical Center, Case Western Reserve University School of Medicine, Cleveland, OH
| | - Hiba AbouAssi
- Division of Endocrinology, Metabolism, and Nutrition, Duke University Medical Center, Durham, NC
| | | | | | | | | | - Tamanna Singh
- Department of Cardiovascular Medicine, Cleveland Clinic, OH
| | | | - James A. S. Muldowney
- Vanderbilt University Medical Center &Tennessee Valley Healthcare System, Nashville Campus, Department of Veterans Affairs, Nashville, TN
| | - Mark Belham
- Cambridge University Hospitals NHS FT, Cambridge, UK
| | - David C. Kem
- University of Oklahoma Health Sciences Center, Oklahoma City, OK
| | - Cem Akin
- University of Michigan, Ann Arbor, MI
| | | | - Nicole E. Zahka
- Cincinnati Children’s Hospital Medical Center, Cincinnati, OH
| | - Qi Fu
- Institute for Exercise and Environmental Medicine at Texas Health Presbyterian Hospital Dallas & University of Texas Southwestern Medical Center, Dallas, TX
| | - Erik H. Van Iterson
- Section of Preventive Cardiology & Rehabilitation, Robert and Suzanne Tomsich Department of Cardiovascular Medicine, Miller Family Heart, Vascular & Thoracic Institute, Cleveland Clinic Cleveland, OH
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
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4
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Hou CR, Olshansky B, Cortez D, Duval S, Benditt DG. Inappropriate sinus tachycardia: an examination of existing definitions. Europace 2022; 24:1655-1664. [DOI: 10.1093/europace/euac057] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2022] [Accepted: 04/10/2022] [Indexed: 11/15/2022] Open
Abstract
Abstract
Aims
Inappropriate sinus tachycardia (IST) is a syndrome characterized by an elevated sinus rate unassociated with known physiological, pathological, or pharmacological causes. Despite published consensus documents, IST definitions appear to vary in the literature. In this study, we reviewed IST publications to evaluate IST definition variability and ascertain the degree to which consensus definitions are being adopted.
Methods and results
English-language articles in PubMed, Ovid MEDLINE, Ovid Embase, and Google Scholar published from 1 January 1970 to 1 June 2021 with the title terms ‘inappropriate sinus tachycardia,’ ‘non-paroxysmal sinus tachycardia,’ or ‘permanent sinus tachycardia’ were searched. In each, the IST definition used, qualifying characteristics, and publications cited to support each definition were recorded. We identified 138 publications meeting the search criteria. Inappropriate sinus tachycardia definitions were provided in 114 of 138 articles (83%). A majority of definitions (92/114, 81%) used distinct heart rate (HR) thresholds. Among these, the most common threshold was ≥100 beats per minute (BPM) (75/92, 82%), mainly measured at rest (54/92, 59%). Most definitions (47/92, 51%) included a second criterion to qualify for IST; these were most often an HR threshold of 90 BPM measured over 24 h by ambulatory electrocardiogram (37/47, 79%). Diagnosis of exclusion was a common criterion (75/92, 82%) but symptom status was not (41/92, 45%). The 2015 Heart Rhythm Society IST consensus was commonly cited but adopted in only 37% of definitions published after 2015.
Conclusions
Inappropriate sinus tachycardia definitions in current literature are inconsistent, and professional society consensus IST definitions have, to date, had limited impact.
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Affiliation(s)
- Cody R Hou
- Cardiac Arrhythmia Center, Cardiovascular Division, University of Minnesota , Mail Code 508, 420 Delaware St SE, Minneapolis, MN 55455 , USA
| | - Brian Olshansky
- Department of Medicine, University of Iowa , Iowa City, IA 52242 , USA
| | - Daniel Cortez
- Division of Pediatric Cardiology, Department of Pediatrics, University of California Davis Medical Center , Sacramento, CA 95616 , USA
| | - Sue Duval
- Cardiac Arrhythmia Center, Cardiovascular Division, University of Minnesota , Mail Code 508, 420 Delaware St SE, Minneapolis, MN 55455 , USA
| | - David G Benditt
- Cardiac Arrhythmia Center, Cardiovascular Division, University of Minnesota , Mail Code 508, 420 Delaware St SE, Minneapolis, MN 55455 , USA
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5
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Physical and mental health in young adults with heart disease - a national survey of Norwegian university students. Cardiol Young 2022; 32:257-265. [PMID: 34100351 DOI: 10.1017/s1047951121001815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
BACKGROUND Young adults with heart disease constitute a growing group with the risk of cognitive and physical impairment. The knowledge of their academic performance and mental and physical health is, however, scant. This study aimed to compare young adults with CHDs or arrhythmia with their peers. METHODS Information on physical health (Somatic Symptom Scale-8), mental health problems (Hopkins Symptoms Checklist-25), quality of life (Satisfaction With Life Scale), physical activity, and academic performance was collected online in a national cross-sectional survey in Norway among students in higher education (the SHoT2018 study). RESULTS Among 50,054 students, 172 (0.34%) reported CHD and 132 (0.26%) arrhythmias. Students reporting arrhythmias scored significantly higher than the control group on somatic symptoms (OR = 2.3 (95% CI: 1.62-3.27)), anxiety (OR = 1.60 (1.08-2.37)), depression (OR = 1.49 (1.05-2.11)), self-harm, and suicide attempt (OR = 2.72 (1.56-4.75)), and lower quality of life (OR 1.64 (1.16-2.32)) and more loneliness (OR = 1.99 (1.28-3.10)) compared to participants without heart disease. Participants with CHD reported an increased somatic symptom burden (OR = 1.58 (1.16-2.16)). Despite a tendency to a higher score, this group did not differ significantly from the control group on anxiety or depression, quality of life, or loneliness. However, the risk of self-harm thoughts and suicidality was significantly increased (OR for suicide attempt 2.22 (1.3-3.77)). There was no difference between the groups on academic performance. CONCLUSIONS Although Norwegian students with heart disease reported more somatic symptoms, their academic progress was not reduced compared to students without heart disease. Students with CHD or arrhythmias showed an increased risk of self-harm thoughts and suicidality.
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6
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Abstract
Inappropriate sinus tachycardia (IST) is a common observation in patients with post-COVID-19 syndrome (PCS) but has not yet been fully described to date. To investigate the prevalence and the mechanisms underlying IST in a prospective population of PCS patients. Consecutive patients admitted to the PCS Unit between June and December 2020 with a resting sinus rhythm rate ≥ 100 bpm were prospectively enrolled in this study and further examined by an orthostatic test, 2D echocardiography, 24-h ECG monitoring (heart rate variability was a surrogate for cardiac autonomic activity), quality-of-life and exercise capacity testing, and blood sampling. To assess cardiac autonomic function, a 2:1:1 comparative sub-analysis was conducted against both fully recovered patients with previous SARS-CoV-2 infection and individuals without prior SARS-CoV-2 infection. Among 200 PCS patients, 40 (20%) fulfilled the diagnostic criteria for IST (average age of 40.1 ± 10 years, 85% women, 83% mild COVID-19). No underlying structural heart disease, pro-inflammatory state, myocyte injury, or hypoxia were identified. IST was accompanied by a decrease in most heart rate variability parameters, especially those related to cardiovagal tone: pNN50 (cases 3.2 ± 3 vs. recovered 10.5 ± 8 vs. non-infected 17.3 ± 10; p < 0.001) and HF band (246 ± 179 vs. 463 ± 295 vs. 1048 ± 570, respectively; p < 0.001). IST is prevalent condition among PCS patients. Cardiac autonomic nervous system imbalance with decreased parasympathetic activity may explain this phenomenon.
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7
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Harnish PR, Shastri P, Grubb BP. Sick Sinus Syndrome Can Be Associated with Postural Tachycardia Syndrome and Inappropriate Sinus Tachycardia Syndrome. J Innov Card Rhythm Manag 2021; 12:4526-4531. [PMID: 34035985 PMCID: PMC8139308 DOI: 10.19102/icrm.2021.120503] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2020] [Accepted: 11/09/2020] [Indexed: 11/21/2022] Open
Abstract
As a known phenomenon, crossover between sinus node dysfunction and common atrial tachyarrhythmias—most notably, atrial fibrillation and atrial flutter—in older individuals has previously been seen. Here, we present one of the first case series demonstrating a similar relationship between sinus node dysfunction and much rarer etiologies of tachyarrhythmia—that is, postural tachycardia syndrome and inappropriate sinus tachycardia. The exact pathological mechanisms behind these arrhythmias as well as the observation of concurrent nodal dysfunction are poorly understood. Here, we propose both potential mechanistic pathways as well as an initial treatment algorithm for sinus node dysfunction based upon the existing evidence.
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Affiliation(s)
- Paul R Harnish
- Division of Cardiovascular Medicine, Department of Medicine, University of Toledo, Toledo, OH, USA
| | - Pinang Shastri
- Department of Medicine, University of Toledo, Toledo, OH, USA
| | - Blair P Grubb
- Division of Cardiovascular Medicine, Department of Medicine, University of Toledo, Toledo, OH, USA
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8
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Mikhailov AV, Kalyanasundaram A, Li N, Scott SS, Artiga EJ, Subr MM, Zhao J, Hansen BJ, Hummel JD, Fedorov VV. Comprehensive evaluation of electrophysiological and 3D structural features of human atrial myocardium with insights on atrial fibrillation maintenance mechanisms. J Mol Cell Cardiol 2020; 151:56-71. [PMID: 33130148 DOI: 10.1016/j.yjmcc.2020.10.012] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/24/2020] [Revised: 10/22/2020] [Accepted: 10/23/2020] [Indexed: 12/14/2022]
Abstract
Atrial fibrillation (AF) occurrence and maintenance is associated with progressive remodeling of electrophysiological (repolarization and conduction) and 3D structural (fibrosis, fiber orientations, and wall thickness) features of the human atria. Significant diversity in AF etiology leads to heterogeneous arrhythmogenic electrophysiological and structural substrates within the 3D structure of the human atria. Since current clinical methods have yet to fully resolve the patient-specific arrhythmogenic substrates, mechanism-based AF treatments remain underdeveloped. Here, we review current knowledge from in-vivo, ex-vivo, and in-vitro human heart studies, and discuss how these studies may provide new insights on the synergy of atrial electrophysiological and 3D structural features in AF maintenance. In-vitro studies on surgically acquired human atrial samples provide a great opportunity to study a wide spectrum of AF pathology, including functional changes in single-cell action potentials, ion channels, and gene/protein expression. However, limited size of the samples prevents evaluation of heterogeneous AF substrates and reentrant mechanisms. In contrast, coronary-perfused ex-vivo human hearts can be studied with state-of-the-art functional and structural technologies, such as high-resolution near-infrared optical mapping and contrast-enhanced MRI. These imaging modalities can resolve atrial arrhythmogenic substrates and their role in reentrant mechanisms maintaining AF and validate clinical approaches. Nonetheless, longitudinal studies are not feasible in explanted human hearts. As no approach is perfect, we suggest that combining the strengths of direct human atrial studies with high fidelity approaches available in the laboratory and in realistic patient-specific computer models would elucidate deeper knowledge of AF mechanisms. We propose that a comprehensive translational pipeline from ex-vivo human heart studies to longitudinal clinically relevant AF animal studies and finally to clinical trials is necessary to identify patient-specific arrhythmogenic substrates and develop novel AF treatments.
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Affiliation(s)
- Aleksei V Mikhailov
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Arrhythmology Research Department, Almazov National Medical Research Centre, Saint-Petersburg, Russia
| | - Anuradha Kalyanasundaram
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Ning Li
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Shane S Scott
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Esthela J Artiga
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Megan M Subr
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Jichao Zhao
- Auckland Bioengineering Institute, The University of Auckland, Auckland, New Zealand
| | - Brian J Hansen
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - John D Hummel
- Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Department of Internal Medicine, The Ohio State University Wexner Medical Center, Columbus, OH, USA
| | - Vadim V Fedorov
- Department of Physiology & Cell Biology, Bob and Corrine Frick Center for Heart Failure and Arrhythmia, The Ohio State University Wexner Medical Center, Columbus, OH, USA; Davis Heart and Lung Research Institute, The Ohio State University Wexner Medical Center, Columbus, OH, USA.
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9
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MacDonald EA, Rose RA, Quinn TA. Neurohumoral Control of Sinoatrial Node Activity and Heart Rate: Insight From Experimental Models and Findings From Humans. Front Physiol 2020; 11:170. [PMID: 32194439 PMCID: PMC7063087 DOI: 10.3389/fphys.2020.00170] [Citation(s) in RCA: 68] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Accepted: 02/13/2020] [Indexed: 12/22/2022] Open
Abstract
The sinoatrial node is perhaps one of the most important tissues in the entire body: it is the natural pacemaker of the heart, making it responsible for initiating each-and-every normal heartbeat. As such, its activity is heavily controlled, allowing heart rate to rapidly adapt to changes in physiological demand. Control of sinoatrial node activity, however, is complex, occurring through the autonomic nervous system and various circulating and locally released factors. In this review we discuss the coupled-clock pacemaker system and how its manipulation by neurohumoral signaling alters heart rate, considering the multitude of canonical and non-canonical agents that are known to modulate sinoatrial node activity. For each, we discuss the principal receptors involved and known intracellular signaling and protein targets, highlighting gaps in our knowledge and understanding from experimental models and human studies that represent areas for future research.
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Affiliation(s)
- Eilidh A. MacDonald
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
| | - Robert A. Rose
- Cumming School of Medicine, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, AB, Canada
| | - T. Alexander Quinn
- Department of Physiology and Biophysics, Dalhousie University, Halifax, NS, Canada
- School of Biomedical Engineering, Dalhousie University, Halifax, NS, Canada
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10
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Shabtaie SA, Witt CM, Asirvatham SJ. Natural history and clinical outcomes of inappropriate sinus tachycardia. J Cardiovasc Electrophysiol 2019; 31:137-143. [PMID: 31749258 DOI: 10.1111/jce.14288] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 10/24/2019] [Accepted: 11/16/2019] [Indexed: 12/17/2022]
Abstract
BACKGROUND Limited data are available regarding the demographics, disease associations, and long-term prognosis of patients with inappropriate sinus tachycardia (IST). OBJECTIVE To establish epidemiologic data for patients with IST, including symptom onset, comorbid disease, and long-term outcomes. METHODS We retrospectively reviewed all patients with an IST diagnosis at the Mayo Clinic (Rochester, MN) during a 20-year period (1998-2018). We extracted demographic data and clinical outcomes compared to an age and gender-matched control group with atrioventricular nodal reentry tachycardia (AVNRT). RESULTS Within the study period, a total of 305 patients with IST were identified (mean follow-up 3.5 years) with 92.1% female and mean age 33.2 ± 11.2 years. The most frequently identified circumstances triggering the condition included pregnancy (7.9%) and infectious illness (5.9%) while the most common comorbid conditions were depression (25.6%) and anxiety (24.6%). At diagnosis, the mean left ventricular ejection fraction (LVEF) was 62.3 ± 6.2%, with 77 patients having follow-up echocardiographic data. No significant difference in LVEF was seen after a mean 4.9 ± 4.3-year follow-up (baseline LVEF 59.8 ± 10.7% vs subsequent 61.4 ± 8.1%; P = .2971). Two deaths occurred within the study period, with one related to myocardial infarction and the other noncardiac; compared to an age and gender-matched AVNRT control group there was no excess mortality during the follow-up period. CONCLUSIONS In our study cohort, IST predominately affects young females with structurally normal hearts and modest coexistent psychiatric disease. In most cases of IST, a major event occurring just before or at the time of diagnosis could not be identified, although nearly 8% of patients first noted symptoms during or shortly after pregnancy. In our cohort, there was no evidence of cardiomyopathy or mortality related to IST.
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Affiliation(s)
| | - Chance M Witt
- Department of Cardiovascular Medicine, Mayo Clinic, Rochester, Minnesota
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12
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Kaczmarek K, Klingenheben T, Poddebska I, Urbanek I, Wranicz JK, Cygankiewicz I, Ptaszyński P. Baseline intrinsic heart rate and response to ivabradine treatment in patients with inappropriate sinus tachycardia. Ann Noninvasive Electrocardiol 2019; 25:e12709. [PMID: 31595620 PMCID: PMC7358846 DOI: 10.1111/anec.12709] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Accepted: 09/14/2019] [Indexed: 11/27/2022] Open
Abstract
BACKGROUND Treatment with ivabradine became a new therapeutic alternative for patients with inappropriate sinus tachycardia (IST). The aim was to determine a relation between intrinsic heart rate (IHR) and response to ivabradine treatment. METHODS Twenty-seven patients (mean age 37 ± 11; 23 women) with symptomatic IST despite medical treatment were recruited into the study. Resting ECG, 24-hr ECG monitoring (24hECG), exercise treadmill test, and symptoms evaluation were performed initially and after 60 days on ivabradine. IHR was acquired at baseline after pharmacological autonomic blockade. RESULTS Nineteen patients (70%) were classified as abnormal IHR group (AIHR) while eight showed normal IHR (NIHR). No significant differences in ECG parameters were found between NIHR and AIHR subgroups, while baseline exercise capacity was higher in AIHR patients (10.9 vs. 9.5 METs, p < .05). Ivabradine treatment resulted in significant reduction in resting heart rate, average 24hECG heart rate, improvement in exercise capacity and reduction of symptoms in both subgroups. Nevertheless, favorable influence of ivabradine was significantly more exaggerated in AIHR subgroup (HR 116 vs. 90 bpm, av. HR 98 vs. 79 bpm, 10.9 vs. 13.6 METS, EHRA score 3.1 vs. 1.1, p < .001 for all) than in NIHR patients (HR 112 vs. 98 bpm, av. HR 97 vs. 88 bpm, 9.5 vs. 11.1 METs, EHRA score 3.1 vs. 1.9; p < .05 for all). CONCLUSIONS Intrinsic heart rate may be useful in predicting response to ivabradine in patients with IST. More intense response to ivabradine in patients with AIHR may be attributed to different pathophysiological mechanisms underlying IST in AIHR and NIHR groups.
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Affiliation(s)
| | | | - Izabela Poddebska
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Irmina Urbanek
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Jerzy K Wranicz
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Iwona Cygankiewicz
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
| | - Pawel Ptaszyński
- Department of Electrocardiology, Medical University of Lodz, Lodz, Poland
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Affiliation(s)
- Brian Olshansky
- Professor Emeritus, Cardiology, University of Iowa Hospitals, 200 Hawkins Drive, Iowa, IA, USA
- Mercy Hospital-North Iowa, 1000 4th St SW, Mason, IA, USA
| | - Renee M Sullivan
- Medical Director, Clinical development Services, Covance, 2501 McGavock Pike, Nashville, TN, USA
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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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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: 105] [Impact Index Per Article: 17.5] [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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Moss R, Sachse FB, Moreno-Galindo EG, Navarro-Polanco RA, Tristani-Firouzi M, Seemann G. Modeling effects of voltage dependent properties of the cardiac muscarinic receptor on human sinus node function. PLoS Comput Biol 2018; 14:e1006438. [PMID: 30303952 PMCID: PMC6197694 DOI: 10.1371/journal.pcbi.1006438] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2017] [Revised: 10/22/2018] [Accepted: 08/15/2018] [Indexed: 11/25/2022] Open
Abstract
The cardiac muscarinic receptor (M2R) regulates heart rate, in part, by modulating the acetylcholine (ACh) activated K+ current IK,ACh through dissociation of G-proteins, that in turn activate KACh channels. Recently, M2Rs were noted to exhibit intrinsic voltage sensitivity, i.e. their affinity for ligands varies in a voltage dependent manner. The voltage sensitivity of M2R implies that the affinity for ACh (and thus the ACh effect) varies throughout the time course of a cardiac electrical cycle. The aim of this study was to investigate the contribution of M2R voltage sensitivity to the rate and shape of the human sinus node action potentials in physiological and pathophysiological conditions. We developed a Markovian model of the IK,ACh modulation by voltage and integrated it into a computational model of human sinus node. We performed simulations with the integrated model varying ACh concentration and voltage sensitivity. Low ACh exerted a larger effect on IK,ACh at hyperpolarized versus depolarized membrane voltages. This led to a slowing of the pacemaker rate due to an attenuated slope of phase 4 depolarization with only marginal effect on action potential duration and amplitude. We also simulated the theoretical effects of genetic variants that alter the voltage sensitivity of M2R. Modest negative shifts in voltage sensitivity, predicted to increase the affinity of the receptor for ACh, slowed the rate of phase 4 depolarization and slowed heart rate, while modest positive shifts increased heart rate. These simulations support our hypothesis that altered M2R voltage sensitivity contributes to disease and provide a novel mechanistic foundation to study clinical disorders such as atrial fibrillation and inappropriate sinus tachycardia. Heart rate regulation is dependent upon a delicate interplay between parasympathetic and sympathetic nerve activity at the level of the sinus node. Acetylcholine slows the heart rate by activating the M2 muscarinic receptor (M2R) that, in turn, opens the acetylcholine-activated potassium channel (IK,ACh) to slow the firing of the sinus node. Surprisingly, the M2R is sensitive to membrane potential and undergoes conformational changes throughout the cardiac action potential that alter the affinity for acetylcholine, with secondary consequences for IK,ACh activity. Here, we investigated the contribution of M2R voltage sensitivity to the rate and shape of the human sinus node action potential in physiological and pathophysiological conditions, using a Markovian model of the IK,ACh channel integrated into a computational model of human sinus node. The computational model allowed us to assess the effects of potential genetic variants that alter specific properties of voltage sensitivity. Our results indicate that alterations in the M2R voltage sensitivity play a significant role in the physiology and pathophysiology of the human sinus node and atria. Our computational model is relevant for future studies aimed at the design and development of anti-arrhythmic agents that specifically target the unique voltage-sensitive properties of M2R.
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Affiliation(s)
- Robin Moss
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany
- Faculty of Medicine, Albert-Ludwigs University of Freiburg, Freiburg, Germany
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
| | - Frank B Sachse
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States of America
- Biomedical Engineering, University of Utah, Salt Lake City, Utah, United States of America
| | - Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Mexico
| | | | - Martin Tristani-Firouzi
- Nora Eccles Harrison Cardiovascular Research and Training Institute, University of Utah, Salt Lake City, Utah, United States of America
| | - Gunnar Seemann
- Institute for Experimental Cardiovascular Medicine, University Heart Centre Freiburg/Bad Krozingen, Freiburg, Germany
- Faculty of Medicine, Albert-Ludwigs University of Freiburg, Freiburg, Germany
- Institute of Biomedical Engineering, Karlsruhe Institute of Technology (KIT), Karlsruhe, Germany
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Yasin OZ, Vaidya VR, Chacko SR, Asirvatham SJ. Inappropriate Sinus Tachycardia: Current Challenges and Future Directions. J Innov Card Rhythm Manag 2018; 9:3239-3243. [PMID: 32479576 PMCID: PMC7252682 DOI: 10.19102/icrm.2018.090706] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Affiliation(s)
- Omar Z. Yasin
- Division of Cardiovascular Disease, Mayo Clinic, Rochester, MN, USA
| | | | | | - Samuel J. Asirvatham
- Division of Cardiovascular Disease, Mayo Clinic, Rochester, MN, USA
- Department of Pediatrics and Adolescent Medicine, Mayo Clinic, Rochester, MN, USA
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Zadourian A, Doherty TA, Swiatkiewicz I, Taub PR. Postural Orthostatic Tachycardia Syndrome: Prevalence, Pathophysiology, and Management. Drugs 2018; 78:983-994. [DOI: 10.1007/s40265-018-0931-5] [Citation(s) in RCA: 41] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Evaluation of postural tachycardia syndrome (POTS). Auton Neurosci 2018; 215:12-19. [PMID: 29705015 DOI: 10.1016/j.autneu.2018.04.004] [Citation(s) in RCA: 48] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 03/10/2018] [Accepted: 04/14/2018] [Indexed: 12/15/2022]
Abstract
The diagnostic evaluation of a patient with suspected postural tachycardia syndrome (POTS) requires a thoughtful diagnostic approach utilizing a careful clinical history and examination, laboratory, and autonomic testing. This article outlines the importance of a thorough history in identifying mechanism of symptom onset, clinical features, associated clinical conditions or disorders, and factors that may result in symptom exacerbation. The clinical examination involves an assessment of pupillary responses, an evaluation for sudomotor and vasomotor signs, and an assessment for joint hypermobility. Laboratory testing helps to exclude mimics of autonomic dysfunction, recognize conditions that may exacerbate symptoms, and to identify conditions that may cause or be associated with autonomic nervous system disease. The purpose of autonomic testing is to confirm a POTS diagnosis, exclude other causes of orthostatic intolerance, and may provide for characterization of POTS into neuropathic and hyperadrenergic subtypes. Other diagnostic studies, such as epidermal skin punch biopsy, exercise testing, radiographic studies, sleep studies, gastrointestinal motility studies, and urodynamic studies should be considered when clinically appropriate.
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Raj S, Sheldon R. Management of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia and Vasovagal Syncope. Arrhythm Electrophysiol Rev 2016; 5:122-9. [PMID: 27617091 PMCID: PMC5013178 DOI: 10.15420/aer.2016.7.2] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2016] [Accepted: 04/26/2016] [Indexed: 01/14/2023] Open
Abstract
Postural tachycardia syndrome (POTS), inappropriate sinus tachycardia (IST) and vasovagal syncope (VVS) are relatively common clinical syndromes that are seen by physicians in several disciplines. They are often not well recognised and are poorly understood by physicians, are associated with significant morbidity and cause significant frustration for both patients and their physicians. The 2015 Heart Rhythm Society Expert Consensus Statement on the Diagnosis and Treatment of Postural Tachycardia Syndrome, Inappropriate Sinus Tachycardia and Vasovagal Syncope provides physicians with an introduction to these disorders and initial recommendations on their investigation and treatment. Here we summarise the consensus statement to help physicians in the management of patients with these frequently distressing problems.
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Affiliation(s)
- Satish Raj
- Libin Cardiovascular Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
| | - Robert Sheldon
- Libin Cardiovascular Research Institute, Cumming School of Medicine, University of Calgary, Calgary, Canada
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Moreno-Galindo EG, Sanchez-Chapula JA, Tristani-Firouzi M, Navarro-Polanco RA. Pharmacological Conversion of a Cardiac Inward Rectifier into an Outward Rectifier Potassium Channel. Mol Pharmacol 2016; 90:334-40. [PMID: 27247338 DOI: 10.1124/mol.116.104950] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2016] [Accepted: 05/27/2016] [Indexed: 01/20/2023] Open
Abstract
Potassium (K(+)) channels are crucial for determining the shape, duration, and frequency of action-potential firing in excitable cells. Broadly speaking, K(+) channels can be classified based on whether their macroscopic current outwardly or inwardly rectifies, whereby rectification refers to a change in conductance with voltage. Outwardly rectifying K(+) channels conduct greater current at depolarized membrane potentials, whereas inward rectifier channels conduct greater current at hyperpolarized membrane potentials. Under most circumstances, outward currents through inwardly rectifying K(+) channels are reduced at more depolarized potentials. However, the acetylcholine-gated K(+) channel (KACh) conducts current that inwardly rectifies when activated by some ligands (such as acetylcholine), and yet conducts current that outwardly rectifies when activated by other ligands (for example, pilocarpine and choline). The perplexing and paradoxical behavior of KACh channels is due to the intrinsic voltage sensitivity of the receptor that activates KACh channels, the M2 muscarinic receptor (M2R). Emerging evidence reveals that the affinity of M2R for distinct ligands varies in a voltage-dependent and ligand-specific manner. These intrinsic receptor properties determine whether current conducted by KACh channels inwardly or outwardly rectifies. This review summarizes the most recent concepts regarding the intrinsic voltage sensitivity of muscarinic receptors and the consequences of this intriguing behavior on cardiac physiology and pharmacology of KACh channels.
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Affiliation(s)
- Eloy G Moreno-Galindo
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Jose A Sanchez-Chapula
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Martin Tristani-Firouzi
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
| | - Ricardo A Navarro-Polanco
- Centro Universitario de Investigaciones Biomédicas, Universidad de Colima, Colima, Colima, México (E.G.M.-G., J.A.S.-C., R.A.N.-P.); Nora Eccles Harrison Cardiovascular Research and Training Institute, and Division of Pediatric Cardiology, University of Utah, Salt Lake City, Utah (M.T.-F.)
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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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Baruscotti M, Bianco E, Bucchi A, DiFrancesco D. Current understanding of the pathophysiological mechanisms responsible for inappropriate sinus tachycardia: role of the If "funny" current. J Interv Card Electrophysiol 2016; 46:19-28. [PMID: 26781742 DOI: 10.1007/s10840-015-0097-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/10/2015] [Accepted: 12/28/2015] [Indexed: 01/01/2023]
Abstract
BACKGROUND Together with the afferent branches of the autonomic nervous system, the sinoatrial node (SAN) forms a functional unit whose function is to fire rhythmic action potentials at a rate optimal for coping with the metabolic needs of the body. Dysfunctional behavior of this complex unit may thus result in SAN rhythm disorders. Among these disorders, there is the inappropriate sinus tachycardia (IST) which occurs when an unjustified fast SAN rate is present. METHODS We here present a critical review of the role of pacemaker f/HCN channels in cardiac rhythm generation and modulation and their involvement in IST. RESULTS Recent evidence demonstrates that a familial form of IST is associated with a gain-of-function mutation in the HCN4 pacemaker channel (R524Q) which confers an increased sensitivity to the second messenger cAMP, a key mediator in sympathetic modulation. CONCLUSIONS This finding is consistent with the general view that hypersympathetic tone is one of the causes of IST and introduces the novel concept of defective funny channel-dependent tachyarrhythmias.
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Affiliation(s)
- Mirko Baruscotti
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy.
| | - Elisabetta Bianco
- Cardiovascular Department, "Ospedali Riuniti di Trieste", University Hospital, Trieste, Italy
| | - Annalisa Bucchi
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy
| | - Dario DiFrancesco
- Department of Biosciences, Centro Interuniversitario di Medicina Molecolare e Biofisica Applicata, University of Milano, via Celoria 26, 20133, Milano, Italy.
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Balakrishnan M, Chakravarthy VS, Guhathakurta S. Simulation of Cardiac Arrhythmias Using a 2D Heterogeneous Whole Heart Model. Front Physiol 2015; 6:374. [PMID: 26733873 PMCID: PMC4685512 DOI: 10.3389/fphys.2015.00374] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2015] [Accepted: 11/23/2015] [Indexed: 01/11/2023] Open
Abstract
Simulation studies of cardiac arrhythmias at the whole heart level with electrocardiogram (ECG) gives an understanding of how the underlying cell and tissue level changes manifest as rhythm disturbances in the ECG. We present a 2D whole heart model (WHM2D) which can accommodate variations at the cellular level and can generate the ECG waveform. It is shown that, by varying cellular-level parameters like the gap junction conductance (GJC), excitability, action potential duration (APD) and frequency of oscillations of the auto-rhythmic cell in WHM2D a large variety of cardiac arrhythmias can be generated including sinus tachycardia, sinus bradycardia, sinus arrhythmia, sinus pause, junctional rhythm, Wolf Parkinson White syndrome and all types of AV conduction blocks. WHM2D includes key components of the electrical conduction system of the heart like the SA (Sino atrial) node cells, fast conducting intranodal pathways, slow conducting atriovenctricular (AV) node, bundle of His cells, Purkinje network, atrial, and ventricular myocardial cells. SA nodal cells, AV nodal cells, bundle of His cells, and Purkinje cells are represented by the Fitzhugh-Nagumo (FN) model which is a reduced model of the Hodgkin-Huxley neuron model. The atrial and ventricular myocardial cells are modeled by the Aliev-Panfilov (AP) two-variable model proposed for cardiac excitation. WHM2D can prove to be a valuable clinical tool for understanding cardiac arrhythmias.
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Affiliation(s)
- Minimol Balakrishnan
- Department of Biotechnology, Indian Institute of Technology MadrasChennai, India
| | | | - Soma Guhathakurta
- Department of Engineering Design, Indian Institute of Technology MadrasChennai, India
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Clinical presentation of inappropriate sinus tachycardia and differential diagnosis. J Interv Card Electrophysiol 2015; 46:33-41. [PMID: 26329720 DOI: 10.1007/s10840-015-0051-z] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/17/2015] [Accepted: 08/14/2015] [Indexed: 10/23/2022]
Abstract
Inappropriate sinus tachycardia (IST) is a syndrome characterized by a sinus tachycardia not related to a medical condition, to a physiological response, or to medication or drugs and associated with symptoms, often invalidating and altering the quality of life of affected patients. It occurs predominantly in adolescents and young adults, and in the female sex. The diagnosis requires a complete work-up in order to exclude other causes of sinus tachycardia and one or several additional tests: 24-h ECG ambulatory recordings, echocardiogram, exercise testing, and autonomous nervous system assessment. It should be differentiated from the postural orthostatic tachycardia syndrome, with which it shares a number of symptoms, and other supraventricular tachycardias originating in the high right atrium. An electrophysiological study should be considered in selected cases in order to differentiate IST from other supraventricular tachycardias. The mechanism is still unclear, and possible etiologies may include intrinsic abnormality of the sinus node, autonomic dysfunction, hypersensitivity of the sinus node to catecholamines, blunted vagal system, or a combination of the above. The authors emphasize the wide spectrum of clinical presentations and the need to better define the IST and the criteria required to ascertain its diagnosis.
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Pellegrini CN, Scheinman MM. Epidemiology and definition of inappropriate sinus tachycardia. J Interv Card Electrophysiol 2015; 46:29-32. [PMID: 26310298 DOI: 10.1007/s10840-015-0039-8] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 07/21/2015] [Indexed: 11/28/2022]
Abstract
Inappropriate sinus tachycardia (IST) is a clinical syndrome lacking formal diagnostic criteria. It is generally defined as an elevated resting heart rate (HR; >90-100 bpm) with an exaggerated response to physical or emotional stress and a clearly sinus mechanism. Clinical manifestations are broad from a complete lack of symptoms to incapacitating incessant tachycardia. Now understood to be relatively prevalent, it is observed to have a generally benign prognosis, though symptoms may persist for years. Whether IST is a single discrete entity or a heterogeneous condition with overlap to other syndromes such as postural orthostatic tachycardia syndrome remains a matter of debate.
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Affiliation(s)
- Cara N Pellegrini
- San Francisco VA Medical Center, 4150 Clement Street, 111C, San Francisco, CA, 94121, USA. .,University of California San Francisco, San Francisco, CA, USA.
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Olshansky B, Sullivan RM. Conventional management of inappropriate sinus tachycardia. J Interv Card Electrophysiol 2015; 46:43-5. [DOI: 10.1007/s10840-015-0034-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/11/2015] [Accepted: 06/22/2015] [Indexed: 02/04/2023]
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Neurogenic hyperadrenergic orthostatic hypotension: a newly recognized variant of orthostatic hypotension in older adults with elevated norepinephrine (noradrenaline). Clin Sci (Lond) 2015; 129:107-16. [PMID: 25706983 DOI: 10.1042/cs20140766] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
Patients with neurogenic orthostatic hypotension (OH) typically have impaired sympathetic nervous system tone and therefore low levels of upright plasma norepinephrine (NE) (noradrenaline). We report a subset of patients who clinically have typical neurogenic OH but who paradoxically have elevated upright levels of plasma NE. We retrospectively studied 83 OH patients evaluated at the Vanderbilt Autonomic Dysfunction Center between August 2007 and May 2013. Based on standing NE, patients were dichotomized into a hyperadrenergic OH group [hyperOH: upright NE ≥ 3.55 nmol/l (600 pg/ml), n=19] or a non-hyperadrenergic OH group [nOH: upright NE < 3.55 nmol/l (600 pg/ml), n=64]. Medical history and data from autonomic testing, including the Valsalva manoeuvre (VM), were analysed. HyperOH patients had profound orthostatic falls in blood pressure (BP), but less severe than in nOH [change in SBP (systolic blood pressure): -53 ± 31 mmHg compared with -68 ± 33 mmHg, P=0.050; change in DBP (diastolic blood pressure): -18 ± 23 mmHg compared with -30 ± 17 mmHg, P=0.01]. The expected compensatory increase in standing heart rate (HR) was similarly blunted in both hyperOH and nOH groups [84 ± 15 beats per minute (bpm) compared with 82 ± 14 bpm; P=0.6]. HyperOH patients had less severe sympathetic failure as evidenced by smaller falls in DBP during phase 2 of VM and a shorter VM phase 4 BP recovery time (16.5 ± 8.9 s compared with 31.6 ± 16.6 s; P<0.001) than nOH patients. Neurogenic hyperOH patients have severe neurogenic OH, but have less severe adrenergic dysfunction than nOH patients. Further work is required to understand whether hyperOH patients will progress to nOH or whether this represents a different disorder.
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Meyer C, Mühlsteff J, Drexel T, Eickholt C, Kelm M, Zahiragic L, Ziegler D. POTS following traumatic stress: interacting central and intracardiac neural control? J Diabetes Complications 2015; 29:459-61. [PMID: 25708501 DOI: 10.1016/j.jdiacomp.2015.02.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 02/05/2015] [Accepted: 02/06/2015] [Indexed: 10/24/2022]
Abstract
Cardiovascular autonomic dysfunction is one of the most overlooked complications in patients with diabetes. We report the case of a 19-year-old woman with a 4-year history of diabetes referred due to palpitations and light-headedness following traumatic stress. Rise of heart rate and blood pressure during tilt table testing indicated hyperadrenergic postural orthstatic tachycardia syndrome (POTS). Elevated blood pressure variability, an indirect parameter of increased sympathetic activity, remained almost stable during orthostatic stress. Short-term treatment with ivabradine in combination with psychosocial support alleviated POTS-related symptoms. Our findings suggest that traumatic stress in patients with type 1 diabetes mellitus might translate into disturbed neural heart rate control due to a central, ephemeral alteration in autonomic balance.
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Affiliation(s)
- Christian Meyer
- Department of Cardiology/Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Eppendorf, Hamburg, Germany; DZHK (German Centre for Cardiovascular Research), Partner Site Hamburg/Kiel/Lübeck, Germany; Department of Cardiology, Pulmology and Angiology, Heinrich-Heine-University Duesseldorf, Germany.
| | - Jens Mühlsteff
- Philips Research Europe, Patient Care Solutions, Eindhoven, Netherlands
| | - Thomas Drexel
- Department of Cardiology/Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Eppendorf, Hamburg, Germany
| | - Christian Eickholt
- Department of Cardiology/Electrophysiology, cNEP, cardiac Neuro- and Electrophysiology research group, University Heart Center, University Hospital Eppendorf, Hamburg, Germany; Department of Cardiology, Pulmology and Angiology, Heinrich-Heine-University Duesseldorf, Germany
| | - Malte Kelm
- Department of Cardiology, Pulmology and Angiology, Heinrich-Heine-University Duesseldorf, Germany
| | - Lejla Zahiragic
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Duesseldorf, Germany; Department of Metabolic Diseases, Heinrich Heine University Duesseldorf, Germany
| | - Dan Ziegler
- Institute for Clinical Diabetology, German Diabetes Center, Leibniz Center for Diabetes Research, Heinrich Heine University Duesseldorf, Germany; Department of Metabolic Diseases, Heinrich Heine University Duesseldorf, Germany
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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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