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Alsaleh M, Talati A, Raj SR, Sheldon RS. Serotonin and vasovagal syncope. Clin Auton Res 2024:10.1007/s10286-024-01052-1. [PMID: 38980470 DOI: 10.1007/s10286-024-01052-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2024] [Accepted: 06/27/2024] [Indexed: 07/10/2024]
Abstract
PURPOSE The goal of this manuscript was to review the biological and clinical evidence that serotonin neurotransmission might play an important role in the physiology and treatment of vasovagal syncope. METHODS The authors reviewed PubMed and handsearches of secondary sources for papers related to the Bezold-Jarisch reflex and serotonin, the plausible involvement of the Bezold-Jarisch reflex in vasovagal syncope, and three lines of clinical evidence involving serotonin and the syncope. RESULTS The Bezold-Jarisch reflex was first described following the infusion of veratrum alkaloids into animals in the 19th century. The reflex is triggered by serotonin stimulation chemoreceptors and mechanoreceptors in the the left ventricle. The afferent component of the reflex is carried by unmyelinated type C vagal nerve fibers, which results in parasympathetic efferent stimulation that causes bradycardia. The similarity of the combination of hypotension and bradycardia in the Bezold-Jarisch reflex and in vasovagal syncope led to the suggestion that the reflex was the cause of the syndrome. Three lines of evidence implicate the serotonin 5HT3 receptors in the heart in the reflex. There is genetic and physiologic evidence for the serotonin 5HT1A and 5HT3 receptors and the serotonin reuptake transporter (SERT). Acute blockade of SERT induces vasovagal syncope in humans undergoing head-up tilt table testing, and SERT inhibition reduces hypotension and bradycardia during spinal anaesthesia. Finally, three randomized clinical trials of SERT inhibitors uniformly reported that they significantly reduce the likelihood of vasovagal syncope recurrences. CONCLUSION Multiple lines of evidence implicate serotonin neurotransmission in the cause of vasovagal syncope.
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Affiliation(s)
- Mohammed Alsaleh
- Department of Cardiac Sciences, Cumming School of Medicine, Libin Cardiovascular Institute, University of Calgary, GAA04 HRIC Building 3280 Hospital Drive Calgary, Calgary, AB, T2N 4Z6, Canada
| | - Aryan Talati
- Department of Cardiac Sciences, Cumming School of Medicine, Libin Cardiovascular Institute, University of Calgary, GAA04 HRIC Building 3280 Hospital Drive Calgary, Calgary, AB, T2N 4Z6, Canada
| | - Satish R Raj
- Department of Cardiac Sciences, Cumming School of Medicine, Libin Cardiovascular Institute, University of Calgary, GAA04 HRIC Building 3280 Hospital Drive Calgary, Calgary, AB, T2N 4Z6, Canada
| | - Robert S Sheldon
- Department of Cardiac Sciences, Cumming School of Medicine, Libin Cardiovascular Institute, University of Calgary, GAA04 HRIC Building 3280 Hospital Drive Calgary, Calgary, AB, T2N 4Z6, Canada.
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Fedorowski A, Kulakowski P, Brignole M, de Lange FJ, Kenny RA, Moya A, Rivasi G, Sheldon R, Van Dijk G, Sutton R, Deharo JC. Twenty-five years of research on syncope. Europace 2023; 25:euad163. [PMID: 37622579 PMCID: PMC10450792 DOI: 10.1093/europace/euad163] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2023] [Accepted: 05/30/2023] [Indexed: 08/26/2023] Open
Abstract
Over the last 25 years, the Europace journal has greatly contributed to dissemination of research and knowledge in the field of syncope. More than 400 manuscripts have been published in the journal. They undoubtedly improved our understanding of syncope. This symptom is now clearly differentiated from other forms of transient loss of consciousness. The critical role of vasodepression and/or cardioinhibition as final mechanisms of reflex syncope is emphasized. Current diagnostic approach sharply separates between cardiac and autonomic pathways. Physiologic insights have been translated, through rigorously designed clinical trials, into non-pharmacological or pharmacological interventions and interventional therapies. The following manuscript is intended to give the reader the current state of the art of knowledge of syncope by highlighting landmark contributions of the Europace journal.
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Affiliation(s)
- Artur Fedorowski
- Department of Cardiology, Karolinska University Hospital, Eugeniavägen 3, 171 76 Solna, Stockholm, Sweden
- Department of Medicine, Karolinska Institute, Solnavägen 1, 171 77 Solna, Stockholm, Sweden
- Department of Clinical Sciences, Lund University, 214 28 Malmö, Sweden
| | - Piotr Kulakowski
- Department of Cardiology, Medical Centre for Postgraduate Education, Grochowski Hospital, Ul. Grenadierow 51/59, 04-073 Warsaw, Poland
| | - Michele Brignole
- Department of Cardiology, S. Luca Hospital, IRCCS, Istituto Auxologico Italiano, Piazzale Brescia 20, 20149 Milan, Italy
| | - Frederik J de Lange
- Department of Clinical and Experimental Cardiology, Heart Center, Amsterdam Cardiovascular Sciences, Amsterdam UMC, University of Amsterdam, Meibergdreef 9, 1105 AZ Amsterdam, The Netherlands
| | - Rose Anne Kenny
- The Irish Longitudinal Study on Ageing, Trinity College Dublin, 152-160 Pearse St, Dublin, Ireland
- Mercer Institute for Successful Ageing, St. James Hospital, James St, Dublin 8, D08 NHY1Ireland
| | - Angel Moya
- Department of Cardiology, Hospital Universitari Dexeus, Carrer de Sabino Arana 5-19, 08028 Barcelona, Spain
| | - Giulia Rivasi
- Division of Geriatric and Intensive Care Medicine, University of Florence and Azienda Ospedaliero-Universitaria Careggi, Largo Brambilla 3, 50139 Florence, Italy
| | - Robert Sheldon
- Department of Cardiac Sciences, University of Calgary, Libin Cardiovascular Institute, 3310 Hospital Drive NW, Calgary, Alberta T2N 4N1, Canada
| | - Gert Van Dijk
- Department of Neurology, Canisius Wilhelmina Hospital, Weg door Jonkerbos 100, 6532 SZ, Nijmegen, The Netherlands
| | - Richard Sutton
- Department of Cardiology, Hammersmith Hospital, National Heart & Lung Institute, Imperial College, Du Cane Road, London, W12 0HS, United Kingdom
| | - Jean-Claude Deharo
- Assistance Publique − Hôpitaux de Marseille, Centre Hospitalier Universitaire La Timone, Service de Cardiologie, Marseille, France and Aix Marseille Université, C2VN, 264 Rue Saint-Pierre, 13005 Marseille, France
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Sandhu RK, Raj SR, Hamzeh R, Sheldon RS. The Seventh Prevention of Syncope Trial (POST VII)-A randomized clinical trial of atomoxetine for the prevention of vasovagal syncope: Rationale and study design. Am Heart J 2023; 262:49-54. [PMID: 37100187 DOI: 10.1016/j.ahj.2023.04.012] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/25/2022] [Revised: 03/30/2023] [Accepted: 04/18/2023] [Indexed: 05/14/2023]
Abstract
BACKGROUND Vasovagal syncope (VVS) is common, recurs, and is associated with markedly reduced quality of life, anxiety, and frequent injuries. The few pharmacological therapies for VVS proven to have a moderate benefit in reducing recurrences are limited to patients without coexisting conditions such as hypertension or heart failure. Although there is some data to suggest Atomoxetine, a norepinephrine reuptake transport inhibitor (NET), may be a promising treatment option, an adequately powered randomized placebo-controlled trial is needed. STUDY DESIGN POST VII is a multicenter, randomized, double-blind, placebo-controlled, crossover study that will randomize 180 patients with VVS and at least 2 syncopal spells in the preceding year to a target daily dose of atomoxetine 80 mg daily or to a matching placebo, with an observation period of 6 months in each phase and with a 1-week washout period between phases. The primary end point will be the proportion of patients with at least one syncope recurrence in each arm analyzed with an intention-to-treat approach. The secondary end points include total syncope burden, quality of life, cost, and cost-effectiveness. POWER CALCULATIONS Assuming a 33% relative risk reduction in syncope recurrence with atomoxetine, and a dropout rate of 16%, the enrollment of 180 patients will give an 85% power of reaching a positive conclusion about atomoxetine, with P = .05. CONCLUSIONS This will be the first adequately powered trial to determine whether atomoxetine is effective in preventing VVS. If proven effective, atomoxetine might become the first-line pharmacological treatment for recurrent VVS.
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Affiliation(s)
- Roopinder K Sandhu
- Smidt Heart Institute, Cedars-Sinai Hospital, Los Angeles, CA; Division of Cardiology, University of Alberta, Edmonton, Alberta, Canada.
| | - Satish R Raj
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Rasha Hamzeh
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
| | - Robert S Sheldon
- Department of Cardiac Sciences, Libin Cardiovascular Institute, Cumming School of Medicine, University of Calgary, Calgary, Alberta, Canada
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