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Miglis MG, Syed N, Cortez MM, Viser FC, van Campen CLMC, Novak P. Is it time to move beyond blood pressure and heart rate during head-up tilt testing? Clin Auton Res 2024; 34:317-320. [PMID: 38755465 DOI: 10.1007/s10286-024-01036-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/31/2023] [Accepted: 04/30/2024] [Indexed: 05/18/2024]
Affiliation(s)
- Mitchell G Miglis
- Department of Neurology and Neurological Sciences, Stanford University, 213 Quarry Road, Palo Alto, CA, 94304, USA.
| | - Noor Syed
- Department of Neurology and Neurological Sciences, Stanford University, 213 Quarry Road, Palo Alto, CA, 94304, USA
| | - Melissa M Cortez
- Department of Neurology, University of Utah, Salt Lake City, UT, USA
| | - Frans C Viser
- Stichting CardioZorg, Planetenweg 5, 2132 HN, Hoofddorp, The Netherlands
| | | | - Peter Novak
- Department of Neurology, Brigham and Women's Faulkner Hospital, Harvard Medical School, Boston, MA, USA
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2
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Sharad B, Rivasi G, Hamrefors V, Johansson M, Ungar A, Sutton R, Brignole M, Parati G, Fedorowski A. Twenty-Four-Hour Ambulatory Blood Pressure Profile in Patients With Reflex Syncope and Matched Controls. J Am Heart Assoc 2023; 12:e028704. [PMID: 37026553 PMCID: PMC10227244 DOI: 10.1161/jaha.122.028704] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/24/2022] [Revised: 02/26/2023] [Accepted: 03/03/2023] [Indexed: 04/08/2023]
Abstract
Background Ambulatory blood pressure (BP) monitoring has long been used to monitor BP in hypertension and lately emerged as a useful tool to detect hypotensive susceptibility in reflex syncope. However, hemodynamic characteristics in reflex syncope have not been sufficiently explored. The present study investigated the differences between ambulatory BP monitoring profiles associated with reflex syncope and normal population. Methods and Results This is an observational study comparing ambulatory BP monitoring data from 50 patients with reflex syncope and 100 controls without syncope, age- and sex-matched 1:2. Mean 24-hour systolic (SBP) and diastolic BP, pulse pressure (24-hour PP), dipping status, and number of daytime SBP drops <90 to 100 mm Hg were analyzed. Variables associated with reflex syncope were investigated using multivariable logistic regression. Patients with reflex syncope displayed significantly lower 24-hour SBP (112.9±12.6 versus 119.3±11.5 mm Hg, P=0.002), higher 24-hour diastolic BP (85.2±9.6 versus 79.1±10.6 mm Hg, P<0.001), and markedly lower 24-hour PP (27.7±7.6 versus 40.3±9.0 mm Hg, P<0.001) compared with controls. Daytime SBP drops <90 mm Hg were more prevalent in patients with syncope (44% versus 17%, P<0.001). Daytime SBP drops <90 mm Hg, 24-hour PP <32 mm Hg, 24-hour SBP ≤110 mm Hg, and 24-hour diastolic BP ≥82 mm Hg were independently associated with reflex syncope, with 24-hour PP <32 mm Hg achieving the highest sensitivity (80%) and specificity (86%). Conclusions Patients with reflex syncope have lower 24-hour SBP but higher 24-hour diastolic BP and more frequent daytime SBP drops <90 mm Hg than individuals without syncope. Our results support the presence of lower SBP and PP in reflex syncope and suggest a role for ambulatory BP monitoring in the diagnostic work-up of this condition.
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Affiliation(s)
- Bashaaer Sharad
- Department of Clinical SciencesLund University, and Skåne University HospitalMalmöSweden
| | - Giulia Rivasi
- Division of Geriatric and Intensive Care MedicineUniversity of Florence and Azienda Ospedaliero Universitaria CareggiFlorenceItaly
| | - Viktor Hamrefors
- Department of Clinical SciencesLund University, and Skåne University HospitalMalmöSweden
- Department of CardiologySkåne University HospitalMalmöSweden
| | - Madeleine Johansson
- Department of Clinical SciencesLund University, and Skåne University HospitalMalmöSweden
- Department of CardiologySkåne University HospitalMalmöSweden
| | - Andrea Ungar
- Division of Geriatric and Intensive Care MedicineUniversity of Florence and Azienda Ospedaliero Universitaria CareggiFlorenceItaly
| | - Richard Sutton
- Department of Clinical SciencesLund University, and Skåne University HospitalMalmöSweden
- Department of Cardiology, National Heart & Lung Institute, Imperial CollegeHammersmith Hospital CampusLondonUnited Kingdom
| | - Michele Brignole
- IRCCS, Istituto Auxologico Italiano, Cardiology UnitS.Luca HospitalMilanItaly
- Department of Cardiovascular, Neural and Metabolic SciencesS.Luca HospitalMilanItaly
| | - Gianfranco Parati
- IRCCS, Istituto Auxologico Italiano, Cardiology UnitS.Luca HospitalMilanItaly
- Department of Cardiovascular, Neural and Metabolic SciencesS.Luca HospitalMilanItaly
| | - Artur Fedorowski
- Department of Clinical SciencesLund University, and Skåne University HospitalMalmöSweden
- Department of CardiologyKarolinska University HospitalStockholmSweden
- Department of MedicineKarolinska InstituteStockholmSweden
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3
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Sebastian SA, Co EL, Panthangi V, Jain E, Ishak A, Shah Y, Vasavada A, Padda I. Postural Orthostatic Tachycardia Syndrome (POTS): An Update for Clinical Practice. Curr Probl Cardiol 2022; 47:101384. [DOI: 10.1016/j.cpcardiol.2022.101384] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2022] [Accepted: 08/26/2022] [Indexed: 11/03/2022]
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4
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Jordan J, Limper U, Tank J. Cardiovascular autonomic nervous system responses and orthostatic intolerance in astronauts and their relevance in daily medicine. Neurol Sci 2022; 43:3039-3051. [PMID: 35194757 PMCID: PMC9018660 DOI: 10.1007/s10072-022-05963-7] [Citation(s) in RCA: 8] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2022] [Accepted: 02/17/2022] [Indexed: 11/12/2022]
Abstract
Background The harsh environmental conditions during space travel, particularly weightlessness, impose a major burden on the human body including the cardiovascular system. Given its importance in adjusting the cardiovascular system to environmental challenges, the autonomic nervous system has been in the focus of scientists and clinicians involved in human space flight. This review provides an overview on human autonomic research under real and simulated space conditions with a focus on orthostatic intolerance. Methods The authors conducted a targeted literature search using Pubmed. Results Overall, 120 articles were identified and included in the review. Conclusions Postflight orthostatic intolerance is commonly observed in astronauts and could pose major risks when landing on another celestial body. The phenomenon likely results from changes in volume status and adaptation of the autonomic nervous system to weightlessness. Over the years, various non-pharmacological and pharmacological countermeasures have been investigated. In addition to enabling safe human space flight, this research may have implications for patients with disorders affecting cardiovascular autonomic control on Earth.
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Affiliation(s)
- Jens Jordan
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany. .,Aerospace Medicine, Medical Faculty, University of Cologne, Cologne, Germany.
| | - Ulrich Limper
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany.,Department of Anesthesiology and Intensive Care Medicine, Merheim Medical Center, Hospitals of Cologne, University of Witten/Herdecke, Cologne, Germany
| | - Jens Tank
- Institute of Aerospace Medicine, German Aerospace Center DLR, Linder Hoehe, 51147, Cologne, Germany
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5
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Brignole M, Rivasi G, Sutton R, Kenny RA, Morillo CA, Sheldon R, Raj SR, Ungar A, Furlan R, van Dijk G, Hamdan M, Hamrefors V, Engström G, Park C, Soranna D, Zambon A, Parati G, Fedorowski A. Low-blood pressure phenotype underpins the tendency to reflex syncope. J Hypertens 2021; 39:1319-1325. [PMID: 33560050 PMCID: PMC8183486 DOI: 10.1097/hjh.0000000000002800] [Citation(s) in RCA: 33] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 12/04/2020] [Accepted: 12/30/2020] [Indexed: 02/04/2023]
Abstract
BACKGROUND We hypothesized that cardiovascular physiology differs in reflex syncope patients compared with the general population, predisposing such individuals to vasovagal reflex. METHODS In this multicohort cross-sectional study, we compared aggregate data of resting SBP, DBP, pulse pressure (PP) and heart rate (HR), collected from six community-based cohort studies (64 968 observations) with those from six databases of reflex syncope patients (6516 observations), subdivided by age decades and sex. RESULTS Overall, in male individuals with reflex syncope, SBP (-3.4 mmHg) and PP (-9.2 mmHg) were lower and DBP (+2.8 mmHg) and HR (+5.1 bpm) were higher than in the general population; the difference in SBP was higher at ages above 60 years. In female individuals, PP (-6.0 mmHg) was lower and DBP (+4.7 mmHg) and HR (+4.5 bpm) were higher than in the general population; differences in SBP were less pronounced, becoming evident only above 60 years. Compared with male individuals, SBP in female individuals exhibited slower increase until age 40 years, and then demonstrated steeper increase that continued throughout remaining life. CONCLUSION The patients prone to reflex syncope demonstrate a different resting cardiovascular haemodynamic profile as compared with a general population, characterized by lower SBP and PP, reflecting reduced venous return and lower stroke volume, and a higher HR and DBP, suggesting the activation of compensatory mechanisms. Our data contribute to a better understanding why some individuals with similar demographic characteristics develop reflex syncope and others do not. VIDEO ABSTRACT http://links.lww.com/HJH/B580.
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Affiliation(s)
- Michele Brignole
- IRCCS Istituto Auxologico Italiano, Faint & Fall Programme, Ospedale San Luca, Milan
| | - Giulia Rivasi
- Syncope Unit, Division of Geriatrics and Intensive Care Unit, University of Florence and Careggi Hospital, Florence, Italy
| | - Richard Sutton
- National Heart and Lung Institute, Imperial College, Hammersmith Hospital Campus, Ducane Road, London, UK
| | - Rose Anne Kenny
- Chair Medical Gerontology, Syncope and Falls Unit, School of Medicine, St James Hospital and Trinity College, Dublin, Ireland
| | - Carlos A. Morillo
- Division of Cardiology, Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Robert Sheldon
- Division of Cardiology, Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Satish R. Raj
- Division of Cardiology, Department of Cardiac Sciences, Libin Cardiovascular Institute of Alberta, University of Calgary, Calgary, Alberta, Canada
| | - Andrea Ungar
- Syncope Unit, Division of Geriatrics and Intensive Care Unit, University of Florence and Careggi Hospital, Florence, Italy
| | - Raffaello Furlan
- Internal Medicine, Humanitas Clinical and Research Center-IRCCS, Department of Biomedical Sciences, Humanitas University, Rozzano, Italy
| | - Gert van Dijk
- Department of Neurology, Leiden University Medical Centre, Leiden, The Netherlands
| | - Mohamed Hamdan
- Department of Medicine, Division of Cardiovascular Medicine, University of Wisconsin School of Medicine and Public Health, Madison, Wisconsin, USA
| | - Viktor Hamrefors
- Department of Clinical Sciences, Lund University
- Department of Internal Medicine, Skåne University Hospital, Malmö, Sweden
| | | | - Chloe Park
- MRC Unit for Lifelong Health and Ageing, Institute of Cardiovascular Science, University College, London, UK
| | | | - Antonella Zambon
- IRCCS Istituto Auxologico Italiano, Biostatistics Unit
- Department of Statistics and quantitative methods, University of Milano-Bicocca
| | - Gianfranco Parati
- IRCCS Istituto Auxologico Italiano, Faint & Fall Programme, Ospedale San Luca, Milan
- Department of Medicine and Surgery, University of Milano Bicocca and IRCCS Istituto Auxologico Italiano, Ospedale San Luca, Milan, Italy
| | - Artur Fedorowski
- Department of Clinical Sciences, Lund University
- Department of Cardiology, Skåne University Hospital, Malmö, Sweden
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Kuchinskaya EA, Pevzner AV. [Lifestyle Modification as a Method of Treatment of Vasovagal Syncope]. ACTA ACUST UNITED AC 2020; 60:93-98. [PMID: 32245359 DOI: 10.18087/cardio.2020.1.n776] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 10/29/2019] [Indexed: 11/18/2022]
Abstract
Vasovagal syncope is the most common cause for loss of consciousness. The need for treatment of this condition is warranted by impaired quality of life and a risk of trauma due to the fall. At present, there are no medications with proven preventive effectiveness for vasovagal syncope as demonstrated by large randomized, placebo-controlled studies. At the same time, information about the pathogenesis of vasovagal reaction and provoking factors allows effective use of non-drug methods (such as patient education, physical exercise, maneuvers) in the management of patients with vasovagal syncope.
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Affiliation(s)
| | - A V Pevzner
- Russian Medical Research Center of Cardiology
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Xiang L, Hinojosa-Laborde C, Ryan KL, Rickards CA, Convertino VA. Time course of compensatory physiological responses to central hypovolemia in high- and low-tolerant human subjects. Am J Physiol Regul Integr Comp Physiol 2018; 315:R408-R416. [PMID: 29668322 DOI: 10.1152/ajpregu.00361.2017] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Lower body negative pressure (LBNP) simulates hemorrhage in human subjects. Most subjects (67%) exhibited high tolerance (HT) to hypovolemia, while the remainder (33%) had low tolerance (LT). To investigate the mechanisms for decompensation to central hypovolemia in HT and LT subjects, we characterized the time course of total peripheral resistance (TPR), heart rate (HR), and muscle sympathetic nerve activity (MSNA) during LBNP to tolerance determined by the onset of decompensation (presyncope, PS). We hypothesized that 1) maximum (Max) TPR, HR, and MSNA would coincide, and 2) PS would result from simultaneous decreases in TPR, HR, and MSNA in LT and HT subjects but occur earlier in LT than in HT subjects. Max TPR was lower and occurred earlier in LT ( n = 59) than in HT ( n = 113) subjects (LT: 24 ± 1 mmHg·min·1-1 at 756 ± 31 s; HT: 28 ± 1 mmHg·min·1-1 at 1,265 ± 37 s, P < 0.01). Max TPR occurred several minutes before PS. During subsequent decrease in TPR, HR and MSNA continued to increase. Max HR (LT: 111 ± 2 beat/min at 923 ± 27 s; HT: 130 ± 2 beats/min at 1489 ± 23 s, P < 0.01) occurred several seconds before PS. Higher MSNA ( P < 0.01) was attained in HT ( n = 10; 51 ± 5 bursts/min at max TPR; 54 ± 5 bursts/min at max HR) than LT subjects ( n = 4; 41 ± 8 bursts/min at max TPR; 39 ± 8 bursts/min at max HR). The onset of cardiovascular decompensation is a biphasic process in which vasodilation occurs before bradycardia and sympathetic withdrawal. This pattern was similar in LT and HT but occurred earlier in LT subjects. We conclude that sudden bradycardia plays a critical role in the determination of tolerance to central hypovolemia.
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Affiliation(s)
- Lusha Xiang
- United States Army Institute of Surgical Research, Joint Base San Antonio Fort Sam Houston, San Antonio, Texas
| | - Carmen Hinojosa-Laborde
- United States Army Institute of Surgical Research, Joint Base San Antonio Fort Sam Houston, San Antonio, Texas
| | - Kathy L Ryan
- United States Army Institute of Surgical Research, Joint Base San Antonio Fort Sam Houston, San Antonio, Texas
| | - Caroline A Rickards
- Institute for Cardiovascular and Metabolic Disease, University of North Texas Health Science Center , Fort Worth, Texas
| | - Victor A Convertino
- United States Army Institute of Surgical Research, Joint Base San Antonio Fort Sam Houston, San Antonio, Texas.,United States Army Medical Research and Materiel Command, Fort Detrick, Frederick, Maryland
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8
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Harrison JM, Gilchrist PT, Corovic TS, Bogetti C, Song Y, Bacon SL, Ditto B. Respiratory and hemodynamic contributions to emotion-related pre-syncopal vasovagal symptoms. Biol Psychol 2017; 127:46-52. [PMID: 28456564 DOI: 10.1016/j.biopsycho.2017.04.011] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2015] [Revised: 04/10/2017] [Accepted: 04/22/2017] [Indexed: 02/05/2023]
Abstract
Vasovagal reactions are conventionally understood as resulting from systemic changes in cardiovascular activity; however, there exists a complementary perspective focused on specific changes in cerebral vasoconstriction associated with hyperventilation-induced hypocapnia. The present study investigated the role of cardiovascular and respiratory activity in self-reported pre-syncopal vasovagal reactions to a surgery video in a sample of 49 healthy women. Participants who indicated more previous real-life episodes of dizziness reported experiencing significantly more symptoms in the laboratory consistent with a vasovagal response. They also showed lower total peripheral resistance and higher pre-ejection period in general, suggesting lower sympathetic nervous system activity. Significant decreases in end-tidal carbon dioxide (PETCO2) occurred during the surgery video among susceptible participants, without significant increases in respiration rate. Further, participants who experienced reductions from the neutral video in PETCO2, systolic blood pressure, or both, reported vasovagal symptoms during the surgery video. The results suggest that patterns of respiration associated with decreases in PETCO2 may contribute to vasovagal symptoms reported in non-clinical groups as well as those with blood-injection-injury phobia and are associated with susceptibility to dizziness.
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Affiliation(s)
- Johanna M Harrison
- Laboratory for Cardiovascular Psychophysiology, Department of Psychology, McGill University, 1205 Ave. Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada.
| | - Philippe T Gilchrist
- Wolfson College, University of Cambridge, Cambridge CB3 9BB, United Kingdom; MRC/BHF Cardiovascular Epidemiology Unit, Department of Public Health and Primary Care, University of Cambridge, Strangeways Research Laboratory, 2 Wort's Causeway, Cambridge, CB1 8RN, United Kingdom
| | - Tiana S Corovic
- Laboratory for Cardiovascular Psychophysiology, Department of Psychology, McGill University, 1205 Ave. Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Curtis Bogetti
- Laboratory for Cardiovascular Psychophysiology, Department of Psychology, McGill University, 1205 Ave. Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Yuqing Song
- Laboratory for Cardiovascular Psychophysiology, Department of Psychology, McGill University, 1205 Ave. Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
| | - Simon L Bacon
- Department of Exercise Science, Concordia University, 7141 Sherbrooke St. West, Montreal, Quebec, H4 B 1R6, Canada
| | - Blaine Ditto
- Laboratory for Cardiovascular Psychophysiology, Department of Psychology, McGill University, 1205 Ave. Docteur Penfield, Montreal, Quebec, H3A 1B1, Canada
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9
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Fu Q, Levine BD. Syncope prevention in blood donors: when to do what? Transfusion 2016; 56:2399-2402. [DOI: 10.1111/trf.13775] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Accepted: 07/18/2016] [Indexed: 11/30/2022]
Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine; Texas Health Presbyterian Hospital Dallas; Dallas TX
| | - Benjamin D. Levine
- Institute for Exercise and Environmental Medicine; Texas Health Presbyterian Hospital Dallas; Dallas TX
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Nilsson D, Sutton R, Melander O, Fedorowski A. Spontaneous vs nitroglycerin-induced vasovagal reflex on head-up tilt: Are there neuroendocrine differences? Heart Rhythm 2016; 13:1674-8. [DOI: 10.1016/j.hrthm.2016.03.018] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Indexed: 10/21/2022]
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Patel K, Rössler A, Lackner HK, Trozic I, Laing C, Lorr D, Green DA, Hinghofer-Szalkay H, Goswami N. Effect of postural changes on cardiovascular parameters across gender. Medicine (Baltimore) 2016; 95:e4149. [PMID: 27428203 PMCID: PMC4956797 DOI: 10.1097/md.0000000000004149] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
Abstract
INTRODUCTION We investigated the effect of postural changes on various cardiovascular parameters across gender. Twenty-eight healthy subjects (16 male, 12 female) were observed at rest (supine) and subjected to 3 interventions; head-down tilt (HDT), HDT with lower body negative pressure (HDT+ LBNP at -30 mm Hg), and head-up tilt (HUT), each for 10 minutes separated by a 10 minutes recovery period. METHODS Measurements were recorded for heart rate (HR), standard deviation of the normal-to-normal intervals, root mean square of successive differences between the normal-to-normal intervals, heart rate variability-low frequency (LFRRI), heart rate variability-high frequency (HFRRI), low frequency/high frequency ratio (LFRRI/HFRRI), systolic blood pressure (SBP), mean arterial pressure (MAP), diastolic blood pressure (DBP), total peripheral resistance index (TPRI), stroke index (SI), cardiac index (CI), index of contractility (IC), left ventricular work index, and left ventricular ejection time. RESULTS Across all cardiovascular parameters, there was a significant main effect of the intervention applied but there was no significant main effect of gender across all parameters. CONCLUSIONS The results suggest that there are no specific gender differences in regards to the measured variables under the conditions of this study. Furthermore, these results suggest that in healthy subjects, there appears to be evidence that LBNP partially elicits similar cardiovascular responses to HUT, which supports the use of LBNP as an intervention to counteract the effects of central hypovolemia.
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Affiliation(s)
- Kieran Patel
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
- Kings College, London, UK
| | - Andreas Rössler
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Helmut Karl Lackner
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Irhad Trozic
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Charles Laing
- Kings College, London, UK
- Institute of Aerospace Medicine, German Aerospace Center (DLR), Cologne, Germany
| | - David Lorr
- Department of Neurophsiology, University of Linkoping, Sweden
| | - David A Green
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Helmut Hinghofer-Szalkay
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
| | - Nandu Goswami
- Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Graz, Austria
- Correspondence: Nandu Goswami Gravitational Physiology and Medicine Research Unit, Institute of Physiology, Medical University of Graz, Harrachgasse 21/ V, 8010 Graz, Austria (e-mail: )
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12
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Disgust stimuli reduce heart rate but do not contribute to vasovagal symptoms. J Behav Ther Exp Psychiatry 2016; 51:116-22. [PMID: 26851836 DOI: 10.1016/j.jbtep.2016.01.005] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Revised: 12/09/2015] [Accepted: 01/27/2016] [Indexed: 11/23/2022]
Abstract
BACKGROUND AND OBJECTIVES The vasovagal response demonstrates a unique form of stress response, common in medical settings yet provoked by a variety of blood-injury-injection stimuli. This study aimed to better understand the psychophysiological mechanisms of the vasovagal response.. METHODS 16 undergraduates with and 42 without a self-reported history of fainting watched five 3-5 min videos with different emotional content. One documentary clip (Neutral condition) described a campus environmental project while another (Blood/Injury) depicted portions of an open heart surgery. Three additional clips were also used, including Medical, Threat, and Contamination stimuli. Vasovagal symptoms and physiological variables were assessed during each video. RESULTS As predicted, while the disgust-related stimuli (Blood/Injury, Medical, Contamination) were associated with generally lower heart rate, the Blood/Injury video produced the highest symptoms and the only significant difference between previous fainters and non-fainters. The physiological measures also revealed that participants with a fainting history experienced higher stroke volume and lower systolic blood pressure throughout, as well as several main effects of video. LIMITATIONS An additional decrease in systolic blood pressure and respiration produced by watching the Blood/Injury video may have been sufficient to trigger symptoms in some, though results also suggest that systemic variables do not entirely explain susceptibility to symptoms. More careful evaluation of regional blood flow may be required. CONCLUSIONS Participants who had previously experienced strong vasovagal responses displayed what appeared to be an anticipatory response to the Blood/Injury video. Finally, disgust stimuli may reduce heart rate but do not appear to contribute to vasovagal symptoms.
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Wieling W, Jardine DL, de Lange FJ, Brignole M, Nielsen HB, Stewart J, Sutton R. Cardiac output and vasodilation in the vasovagal response: An analysis of the classic papers. Heart Rhythm 2015; 13:798-805. [PMID: 26598322 DOI: 10.1016/j.hrthm.2015.11.023] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/30/2015] [Indexed: 11/17/2022]
Abstract
The simple faint is secondary to hypotension and bradycardia resulting in transient loss of consciousness. According to Ohm's law applied to the circulation, BP = SVR × CO, hypotension can result from a decrease in systemic vascular resistance (SVR), cardiac output (CO), or both. It is important to understand that when blood pressure (BP) is falling, SVR and CO do not change reciprocally as they do in the steady state. In 1932, Lewis, assuming that decreased SVR alone accounted for hypotension, defined "the vasovagal response" along pathophysiologic lines to denote the association of vasodilation with vagal-induced bradycardia in simple faint. Studies performed by Barcroft and Sharpey-Schafer between 1940 and 1950 used volume-based plethysmography to demonstrate major forearm vasodilation during extreme hypotension and concluded that the main mechanism for hypotension was vasodilation. Plethysmographic measurements were intermittent and not frequent enough to capture rapid changes in blood flow during progressive hypotension. However, later investigations by Weissler, Murray, and Stevens performed between 1950 and 1970 used invasive beat-to-beat BP measurements and more frequent measurements of CO using the Fick principle. They demonstrated that CO significantly fell before syncope, and little vasodilation occurred until very late in the vasovagal reaction Thus, since the 1970s, decreasing cardiac output rather than vasodilation has been regarded as the principal mechanism for the hypotension of vasovagal syncope.
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Affiliation(s)
- Wouter Wieling
- Department of Internal Medicine, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands.
| | - David L Jardine
- Department of Medicine, Christchurch School of Medicine, University of Otago, Otago, New Zealand
| | - Frederik J de Lange
- Heart Centre, Department of Clinical and Experimental Cardiology, Academic Medical Centre, University of Amsterdam, Amsterdam, The Netherlands
| | - Michele Brignole
- Department of Cardiology, Arrhythmologic Centre, Ospedali del Tigullio, Lavagna, Italy
| | - Henning B Nielsen
- Department of Anaesthesia, Rigshospitalet, University of Copenhagen, Copenhagen, Denmark
| | - Julian Stewart
- Departments of Pediatrics, Physiology and Medicine, New York Medical College, Valhalla, New York
| | - Richard Sutton
- National Heart & Lung institute, Imperial College, London, United Kingdom
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14
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Wieling W, van Dijk N, Thijs RD, de Lange FJ, Krediet CTP, Halliwill JR. Physical countermeasures to increase orthostatic tolerance. J Intern Med 2015; 277:69-82. [PMID: 24697914 DOI: 10.1111/joim.12249] [Citation(s) in RCA: 56] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- W Wieling
- Department of Internal Medicine, Academic Medical Centre University of Amsterdam, Amsterdam, the Netherlands
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Wieling W, de Lange FJ, Jardine DL. The heart cannot pump blood that it does not receive. Front Physiol 2014; 5:360. [PMID: 25278907 PMCID: PMC4166953 DOI: 10.3389/fphys.2014.00360] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2014] [Accepted: 09/02/2014] [Indexed: 12/03/2022] Open
Affiliation(s)
- Wouter Wieling
- Department of Internal Medicine, Academic Medical Centre, University of Amsterdam Amsterdam, Netherlands
| | - Frederik J de Lange
- Department of Cardiology, Academic Medical Centre, University of Amsterdam Amsterdam, Netherlands
| | - David L Jardine
- Department of General Medicine, Christchurch Hospital, University of Otago Christchurch, New Zealand
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Pathophysiology of neurally mediated syncope: Role of cardiac output and total peripheral resistance. Auton Neurosci 2014; 184:24-6. [PMID: 25081417 DOI: 10.1016/j.autneu.2014.07.004] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Revised: 07/07/2014] [Accepted: 07/09/2014] [Indexed: 11/24/2022]
Abstract
Syncope is a common clinical condition occurring even in otherwise healthy people without underlying cardiovascular disease. Neurally mediated syncope is by far the most common cause of syncope in individuals without any structural heart disease. Based on traditional wisdom, loss of sympathetic tone with relaxation of vascular smooth muscle is the key mechanism underlying the pathophysiology of syncope, especially in patients without an acute decrease in heart rate. However, this concept has recently been challenged. Some microneurographic studies indicate that sympathetic withdrawal may not always be a prerequisite even for the development of classic "vasodepressor" forms of syncope. Conversely, a decrease in cardiac output appears to be a determinant factor for syncope in most circumstances. This article reviews the relative contribution of cardiac output versus sympathetic vasoconstriction in neurally mediated syncope in otherwise healthy individuals. It is suggested that a moderate to severe fall in cardiac output with or without vasodilatation may contribute to syncope.
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Pruett WA, Husband LD, Husband G, Dakhlalla M, Bellamy K, Coleman TG, Hester RL. A population model of integrative cardiovascular physiology. PLoS One 2013; 8:e74329. [PMID: 24058546 PMCID: PMC3772858 DOI: 10.1371/journal.pone.0074329] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2013] [Accepted: 07/31/2013] [Indexed: 11/19/2022] Open
Abstract
We present a small integrative model of human cardiovascular physiology. The model is population-based; rather than using best fit parameter values, we used a variant of the Metropolis algorithm to produce distributions for the parameters most associated with model sensitivity. The population is built by sampling from these distributions to create the model coefficients. The resulting models were then subjected to a hemorrhage. The population was separated into those that lost less than 15 mmHg arterial pressure (compensators), and those that lost more (decompensators). The populations were parametrically analyzed to determine baseline conditions correlating with compensation and decompensation. Analysis included single variable correlation, graphical time series analysis, and support vector machine (SVM) classification. Most variables were seen to correlate with propensity for circulatory collapse, but not sufficiently to effect reasonable classification by any single variable. Time series analysis indicated a single significant measure, the stressed blood volume, as predicting collapse in situ, but measurement of this quantity is clinically impossible. SVM uncovered a collection of variables and parameters that, when taken together, provided useful rubrics for classification. Due to the probabilistic origins of the method, multiple classifications were attempted, resulting in an average of 3.5 variables necessary to construct classification. The most common variables used were systemic compliance, baseline baroreceptor signal strength and total peripheral resistance, providing predictive ability exceeding 90%. The methods presented are suitable for use in any deterministic mathematical model.
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Affiliation(s)
- William A. Pruett
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Leland D. Husband
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Graham Husband
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Muhammad Dakhlalla
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Kyle Bellamy
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Thomas G. Coleman
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
| | - Robert L. Hester
- Department of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, Mississippi, United States of America
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Abstract
The rich cardiology literature of the past 100 years in which the most important forms of syncope are described - including vasodepressor syncope, postural orthostatic hypotension, and Morgagni-Stokes-Adams syncope - is fascinating. These conditions were of interest to some of our most astute clinicians who were also excellent writers. We thus have available for review the remarkable description of patients with these entities written by clinicians such as Soma Weiss, Sir Thomas Lewis, Laurence Ellis, David Sherf, Milton Shy, and Glenn Drager. In their detailed clinical descriptions we identify the pertinent symptoms and signs we see in our patients today years later. A group of brilliant basic physiologists and cardiologists was able to explain the altered physiology responsible for the clinical presentations of syncope patients. Basic investigations were done by investigators such as Arnold Weissler, James Warren, J. Erlanger and clinical cardiologists including John Parkinson, Cornelio Papp, and William Evans to name just a few. Between the early precise clinical descriptions and the subsequent thorough definition of the altered physiology, a surprisingly complete understanding of these clinical entities was established 50 years ago. It took another generation before clinicians developed methods of caring for patients with these clinical entities. The development of implantable devices, e.g., pacemakers and defibrillators, for use in Morgagni-Adams-Stokes attacks is the best example of curative therapies catching up with clinical diagnoses. Other more simple relevant therapies were developed for patients with vasodepressor syncope and postural orthostatic hypotension. Finally, the development and acceptance of clinical guidelines for the treatment of these conditions brought the original clinical observations and description of altered physiology into focus and ushered in a new generation of improved care for these patients.
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Dos Santos RQ, Smidt L, Suzigan BH, De Souza LV, Barbisan JN. Efficacy of lower limb compression in the management of vasovagal syncope--randomized, crossover study. PACING AND CLINICAL ELECTROPHYSIOLOGY: PACE 2013; 36:451-5. [PMID: 23305349 DOI: 10.1111/pace.12069] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2012] [Revised: 10/31/2012] [Accepted: 11/04/2012] [Indexed: 11/30/2022]
Abstract
INTRODUCTION Vasovagal syncope (VS) is the most prevalent cause of transient loss of consciousness. The treatment consists of lifestyle modifications and pacemaker in some patients. The purpose of this study is to evaluate the effect of measures to compress the lower limbs in patients with recurrent episodes of VS submitted to the tilt-test (TT). METHODS AND RESULTS Twenty patients, average age 30.5 years (15-75), 13 (65%) female, with a clinical diagnosis of VS and previous TT with a positive result and who had at least one episode of syncope during the last year, were included in this placebo-controlled randomized crossover study. The patients underwent two consecutive TT, at a 1-hour interval, with and without compression by pneumatic compression boots with 40 mmHg at the heels and 30 mmHg for the legs. The blood pressure (BP) and heart rate (HR) of these patients were monitored continuously. The outcome assessors were blinded. The results of the TT were positive in 13 (65%) of the patients in the control groups and in two (10%) of the patients with compression (P < 0.0001). Throughout the test, the systolic BP was not different among the groups. On the other hand, the HR measures showed a difference only in the tilted position at 2 minutes, of 73 ± 16 beats per minute (bpm) in the control group and of 69 ± 16 bpm (P = 0.047) in the compression group. CONCLUSION Compression of the lower limbs is very effective to render the TT negative in patients with a diagnosis of VS.
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NICHOLLS D, HARRON D, SHANKS R. ACUTE AND CHRONIC CARDIOVASCULAR EFFECTS OF INDORAMIN AND PRAZOSIN IN NORMAL MAN. Br J Clin Pharmacol 2012. [DOI: 10.1111/j.1365-2125.1981.tb00296.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
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Abstract
This article reviews microneurographic research on sympathetic neural control in women under both physiological and pathophysiological conditions across the lifespan. Specifically, the effects of sex, age, race, the menstrual cycle, oral contraceptives, estrogen replacement therapy, and normal pregnancy on neural control of blood pressure in healthy women are reviewed. In addition, sympathetic neural activity during neurally mediated (pre)syncope, the Postural Orthostatic Tachycardia Syndrome (POTS), obesity, the Polycystic Ovary Syndrome (PCOS), gestational hypertension, and preeclampsia, chronic essential hypertension, heart failure, and myocardial infarction in women are also reviewed briefly. It is suggested that microneurographic studies provide valuable information regarding autonomic circulatory control in women of different ages and in most cases, excessive sympathetic activation is associated with specific medical conditions regardless of age and sex. In some situations, sympathetic inhibition or withdrawal may be the underlying mechanism. Information gained from previous and recent microneurographic studies has significant clinical implications in women's health, and in some cases could be used to guide therapy if more widely available.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, and UT Southwestern Medical Center Dallas, TX, USA
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Rozenberg J, Wieling W, Schon IK, Westerhof B, Frampton C, Jardine D. MSNA during prolonged post-faint hypotension. Clin Auton Res 2012; 22:167-73. [PMID: 22415156 PMCID: PMC3412950 DOI: 10.1007/s10286-012-0159-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2011] [Accepted: 02/14/2012] [Indexed: 11/02/2022]
Abstract
BACKGROUND Following tilt-induced syncope, blood pressure usually recovers rapidly after tilt back to the horizontal position. However, in some patients, hemodynamic recovery is delayed, a condition recently termed "prolonged post-faint hypotension" (PPFH). The mechanism is thought to be mediated by increased vagal outflow rather than exaggerated peripheral vasodilatation and sympathetic withdrawal. To date, no muscle sympathetic nerve activity (MSNA) recordings have been reported in this condition, so we aimed to confirm that neither vasodilatation nor MSNA withdrawal was responsible. OBJECTIVES To retrospectively select patients with satisfactory recordings of continuous BP and MSNA during tilt-induced syncope. To compare hemodynamic and MSNA profiles in patients with PPFH to patients with normal recovery (NR) after tilt-back. METHODS All patients were studied in Christchurch, New Zealand, between 1998 and 2008 using continuous arterial BP monitoring, and microneurographic recordings of MSNA from the right leg. Only patients with satisfactory BP and MSNA data throughout baseline, head-up tilt and presyncope were selected. Stroke volume (SV), cardiac output (CO), and total peripheral resistance (TPR) were derived using Modelflow. After baseline measurements, patients were tilted to the head-up 60° position and given GTN spray if asymptomatic after 20 min. Following the onset of presyncope, patients were tilted slowly back to the horizontal. PPFH was defined as systolic BP <85 mmHg for at least 2 min after tilt-back. Measurements were averaged at baseline, early tilt, presyncope, early and late recovery. Within-group comparisons were made between baseline and all other time points. Between-group comparisons were made over all time points. RESULTS Patients with PPFH (7 males, age 46 ± 5 years, n = 8) and with NR (8 males, age 47 ± 6 years, n = 8) were selected. Presyncope was provoked by GTN in 4/8 patients in each group. In both groups, MAP remained below baseline during early and late recovery: PPFH 84 ± 5 versus 51 ± 5 and 64 ± 5 mmHg (p = 0.001, p = 0.001); NR 104 ± 5 versus 83 ± 5 and 93 ± 5 mmHg (p = 0.001, p = 0.03). However, MAP and HR were lower in the PPFH group (p = 0.004, p = 0.023). During early recovery, CO remained below baseline only in the PPFH group (p = 0.001), whereas TPR remained constant in both groups. In both groups, all MSNA indices tended to remain above baseline levels during early and late recovery. PPFH 25 ± 2 increased to 31 ± 6 and 29 ± 4 bursts/min (p = 0.09, 0.02); NR 23 ± 3 increased to 33 ± 3 and 34 ± 3 bursts/min (p = 0.06, 0.01). CONCLUSIONS PPFH does not appear to be mediated by exaggerated vasodilatation or sympathetic withdrawal. Delayed recovery of cardiac output by increased vagal outflow is a more likely mechanism.
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Affiliation(s)
- J Rozenberg
- Department of Internal Medicine, Academic Medical Center, University of Amsterdam, Amsterdam, The Netherlands.
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Fu Q, Verheyden B, Wieling W, Levine BD. Cardiac output and sympathetic vasoconstrictor responses during upright tilt to presyncope in healthy humans. J Physiol 2012; 590:1839-48. [PMID: 22331415 DOI: 10.1113/jphysiol.2011.224998] [Citation(s) in RCA: 70] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Syncope is a common clinical condition occurring even in healthy people without manifest cardiovascular disease. The purpose of this study was to determine the role of cardiac output and sympathetic vasoconstriction in neurally mediated (pre)syncope. Twenty-five subjects (age 15–51) with no history of recurrent syncope but who had presyncope during 60 deg upright tilt were studied; 10 matched controls who completed 45 min tilting were analysed retrospectively. Beat-to-beat haemodynamics (Modelflow), muscle sympathetic nerve activity (MSNA) and sympathetic baroreflex sensitivity (MSNA–diastolic pressure relation) were measured. MSNA, haemodynamic responses and baroreflex sensitivity during early tilting were not different between presyncopal subjects and controls. Hypotension was mediated by a drop in cardiac output in all presyncopal subjects, accompanied by a decrease in total peripheral resistance in 16 of them (64%, group A). In the other 9 subjects, total peripheral resistance was well maintained even at presyncope (36%, group B). Cardiac output was smaller (3.26 ± 0.34 (SEM) vs. 5.02 ± 0.40 l min(−1), P = 0.01), while total peripheral resistance was greater (1327 ± 117 vs. 903 ± 80 dyn s cm(−5), P < 0.01) in group B than group A at presyncope. The steeper fall in cardiac output in group B was due to a drop in heart rate. MSNA decreased rapidly at presyncope after the onset of hypotension. Thus, a moderate fall in cardiac output with coincident vasodilatation or a marked fall in cardiac output with no changes in peripheral vascular resistance may contribute to (pre)syncope. However, an intrinsic impairment of vasomotor responsiveness and sympathetic baroreflex function is not the cause of neurally mediated (pre)syncope in this population.
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Affiliation(s)
- Qi Fu
- Institute for Exercise and Environmental Medicine, Texas Health Presbyterian Hospital Dallas, Dallas, TX 75231, USA
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Wieling W, Rozenberg J, Go-Schön IK, Karemaker JM, Westerhof BE, Jardine DL. Hemodynamic mechanisms underlying prolonged post-faint hypotension. Clin Auton Res 2011; 21:405-13. [PMID: 21796352 PMCID: PMC3210950 DOI: 10.1007/s10286-011-0134-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2011] [Accepted: 06/09/2011] [Indexed: 11/29/2022]
Abstract
OBJECTIVE During hypotension induced by tilt-table testing, low presyncopal blood pressure (BP) usually recovers within 1 min after tilt back. However, in some patients prolonged post faint hypotension (PPFH) is observed. We assessed the hemodynamics underlying PPFH in a retrospective study. METHODS Seven patients (2 females, aged 31-72 years) experiencing PPFH were studied. PPFH was defined as a systolic BP below 85 mmHg for at least 2 min after tilt back. In 6 out of 7 presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60° head-up tilt position following head-up tilt for 20 min. Continuous BP was monitored and stroke volume (SV) was computed from pressure pulsations. Cardiac output (CO) was calculated from SV × heart rate (HR); and total peripheral resistance (TPR) from mean BP/CO. Left ventricular contractility was estimated by dP/dt (max) of finger pressure pulse. RESULTS Systolic BP (SYS), diastolic BP (DIAS) and HR during PPFH were lower compared to baseline: SYS 75 ± 14 versus 121 ± 18 mmHg, DIAS 49 ± 9 versus 71 ± 9 mmHg and HR 52 ± 14 versus 67 ± 12 beats/min (p < 0.05). Marked hypotension was associated with a 47% fall in CO 3.1 ± 0.6 versus 5.9 ± 1.3 L/min (p < 0.05) and decreases in dP/dt, 277 ± 77 versus 759 ± 160 mmHg/s (p < 0.05). The difference in TPR was not significant 1.1 ± 0.3 versus 1.0 ± 0.3 MU (p = 0.229). In four patients, we attempted to treat PPFH by 30° head-down tilt. This intervention increased SYS only slightly (to 89 ± 12 mmHg). INTERPRETATION PPFH seems to be mediated by severe cardiac depression.
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Affiliation(s)
- Wouter Wieling
- Department of Medicine, Academic Medical Centre, University of Amsterdam, The Netherlands.
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Lagi A, Cencetti S, Cartei A. What Happens before Syncope? Study of the Time Frame Preceding Vasovagal Syncope. ISRN CARDIOLOGY 2011; 2011:659787. [PMID: 22347649 PMCID: PMC3262513 DOI: 10.5402/2011/659787] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/21/2011] [Accepted: 03/18/2011] [Indexed: 11/30/2022]
Abstract
Objective. The events characterizing the very last part of the vasovagal crisis has not been determined. The aim of the study was to analyze the variations in respiratory pattern preceding the vaso-vagal syncope full-blown and the relationship between cardiovascular functions in order to assess the temporal sequence. Methods. Eleven consecutive patients were studied. Heart rate, arterial pressure, respiratory frequency, tidal volume, carbon dioxide, and oxygen saturation in time domain from supine and standing recordings were analyzed. Results. The respiratory activity is different in the time frame preceding syncope, both in VT and breathing rate, and that the increase of the lung ventilation does not influence the baroreflex control during the presyncopal period but may be cause of the baroreflex failure during the full-blown syncope.
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Affiliation(s)
- Alfonso Lagi
- Dipartimento di Medicina Interna, Ospedale Santa Maria Nuova, Piazza S. Maria Nuova, 50100 Firenze, Italy
| | - Simone Cencetti
- Dipartimento di Medicina Interna, Ospedale Santa Maria Nuova, Piazza S. Maria Nuova, 50100 Firenze, Italy
| | - Alessandro Cartei
- Dipartimento di Medicina Interna, Ospedale Santa Maria Nuova, Piazza S. Maria Nuova, 50100 Firenze, Italy
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Ritz T, Meuret AE, Ayala ES. The psychophysiology of blood-injection-injury phobia: looking beyond the diphasic response paradigm. Int J Psychophysiol 2010; 78:50-67. [PMID: 20576505 DOI: 10.1016/j.ijpsycho.2010.05.007] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2010] [Revised: 04/29/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
Abstract
Blood-injection-injury (BII) phobia is an anxiety disorder that may be accompanied by vasovagal fainting during confrontation with the feared stimuli. The underlying pattern of autonomic regulation has been characterized as a diphasic response, with initial increases in heart rate and blood pressure that are typical of a fight-flight response, and subsequent drops in blood pressure and/or heart rate that may precipitate vasovagal fainting. Tensing skeletal muscles of the arms, legs, and trunk (applied tension) has been proposed as a technique to cope with this dysregulation. This review critically examines the empirical basis for the diphasic response and its treatment by applied tension in BII phobia. An alternative perspective on the psychophysiology of BII phobia and vasovagal fainting is offered by focusing on hypocapnia that leads to cerebral blood flow reductions, a perspective supported by research on neurocardiogenic and orthostatically-induced syncope. The evidence may indicate a role for respiration-focused coping techniques in BII phobia.
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Affiliation(s)
- Thomas Ritz
- Department of Psychology, Southern Methodist University, P.O. Box 750442, Dallas, TX 75275-0442, USA.
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Sympatho-vagal responses in patients with sleep and typical vasovagal syncope. Clin Sci (Lond) 2009; 117:345-53. [PMID: 19281451 DOI: 10.1042/cs20080497] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Sleep syncope is a recently described form of vasovagal syncope that interrupts sleep. The pathophysiology of this condition is uncertain but a ‘central’ non-baroreflex-mediated trigger has been suggested. In the present study, we tested the hypothesis that patients with sleep syncope have abnormal sympatho-vagal responses to non-baroreflex, but normal responses to baroreflex stimuli. We collected historical data from SS patients (patients with vasovagal syncope with sleep syncope; n=16) and NSS patients (patients with vasovagal syncope without sleep syncope; n=35), including demography, and triggers and symptoms during syncope. MBP (mean blood pressure), HR (heart rate) and MSNA (muscle sympathetic nerve activity) in SS patients were compared with NSS patients and matched controls (n=16) during HG (handgrip), CPTs (cold pressor tests), HUT (head-up tilting) and tilt-induced pre-syncope. Patients and controls were of similar age and gender distribution [SS patients, age 46.0±4 years (69% female); NSS patients, 47.3±4 years (63% female); controls, 43.7±5 years (69% female)]. Compared with NSS patients, SS patients reported more fainting episodes: (i) triggered by phobias (75 compared with 37%; P=0.001); (ii) while in the horizontal position (44 compared with 6%; P=0.001); and (iii) associated with abdominal symptoms (69 compared with 9%; P=0.001). Compared with controls, the MBP response to HG was attenuated in SS patients (P=0.016), and MSNA (burst frequency and incidence) responses to CPT were attenuated in both syncope groups (SS, P=0.011 and 0.003 respectively; NSS, P=0.021 and 0.049 respectively). MSNA responses to HUT did not differ. For both non-baroreflex and baroreflex responses, there were no differences in any of the MSNA indices between the syncope groups. Patients with vasovagal syncope, with or without sleep syncope, have very similar sympatho-vagal responses to both non-baroreflex and baroreflex stimuli. This is consistent with sleep syncope being a subform of vasovagal syncope. Attenuation of sympathetic responses to non-baroreflex pathways may be important in the mechanism of vasovagal syncope.
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Lewis RP. Arnold M. Weissler, MD, FACC, FRSM. Clin Cardiol 2009; 32:E55-7. [PMID: 19434685 PMCID: PMC6653324 DOI: 10.1002/clc.20328] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/01/2007] [Accepted: 10/02/2007] [Indexed: 07/19/2024] Open
Affiliation(s)
- Richard P Lewis
- Internal Medicine, The Ohio State University College of Medicine, Columbus, Ohio, USA.
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Abstract
Stimuli related to blood, injury and illness (BII) evoke a unique psychophysiological response, with signs of both sympathetic and parasympathetic arousal. Fainting, which occurs commonly in BII phobias, may represent the extreme of this reponse pattern. Data from the assessment and cognitive–behavioural treatment of a BII phobic subject are presented. At assessment the patient showed a massive bradycardia and near loss of consciousness on exposure to blood. This responded rapidly to treatment, although with some desynchrony between subjective and autonomic responses.
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Verheyden B, Liu J, van Dijk N, Westerhof BE, Reybrouck T, Aubert AE, Wieling W. Steep fall in cardiac output is main determinant of hypotension during drug-free and nitroglycerine-induced orthostatic vasovagal syncope. Heart Rhythm 2008; 5:1695-701. [PMID: 19084808 DOI: 10.1016/j.hrthm.2008.09.003] [Citation(s) in RCA: 74] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Accepted: 09/02/2008] [Indexed: 10/21/2022]
Abstract
BACKGROUND How much of the hypotension occurring during postural syncope is cardiac output-mediated and how much can be ascribed to a fall in systemic vascular resistance are unknown. The contribution of both determinants may be influenced by the use of vasoactive drugs. OBJECTIVE The purpose of this study was to assess the determinants of hypotension during drug-free and nitroglycerine (NTG)-induced vasovagal presyncope in routine tilt table testing. METHODS In this retrospective study, a total of 56 patients (37 female; age 36 +/- 19 years) with suspected vasovagal syncope and a positive tilt test at two clinical centers were selected. In 29 patients, presyncope was provoked by 0.4 mg sublingual NTG, administered in the 60 degrees head-up tilt position. In the other 27 patients, presyncope was provoked by passive tilt alone. Finger arterial pressure was monitored continuously, and left ventricular stroke volume was computed from pressure pulsations. RESULTS After NTG administration, heart rate rose, and peak heart rate was similar in all patients. Use of NTG did not affect circulatory patterns precipitating a vasovagal response. On average in all patients, marked hypotension was mediated by an approximately 50% fall in cardiac output, whereas systemic vascular resistance was well maintained until presyncope. CONCLUSION Hypotension during routine tilt testing is cardiac output-mediated, and the mechanism appears independent of the use of 0.4 mg sublingual NTG. The study data challenge the conventional idea of systemic vasodilation as the overriding cause of hypotension during postural syncope.
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Affiliation(s)
- Bart Verheyden
- Laboratory of Experimental Cardiology, University Hospital Gasthuisberg, KU Leuven, Leuven, Belgium.
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Pancheva MV, Panchev VS, Suvandjieva AV. Improved orthostatic tolerance by leg crossing and muscle tensing: indisputable evidence for the arteriovenous pump existence. J Appl Physiol (1985) 2006; 101:1271-2; author reply 1272. [PMID: 16763102 DOI: 10.1152/japplphysiol.00434.2006] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
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Krediet CTP, de Bruin IGJM, Ganzeboom KS, Linzer M, van Lieshout JJ, Wieling W. Leg crossing, muscle tensing, squatting, and the crash position are effective against vasovagal reactions solely through increases in cardiac output. J Appl Physiol (1985) 2005; 99:1697-703. [PMID: 16227457 DOI: 10.1152/japplphysiol.01250.2004] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
Tensing of lower body muscles without or with leg crossing (LBMT, LCMT), whole body tensing (WBT), squatting, and sitting with the head bent between the knees (“crash position,” HBK) are believed to abort vasovagal reactions. The underlying mechanisms are unknown. To study these interventions in patients with a clinical history of vasovagal syncope and a vasovagal reaction during routine tilt table testing, we measured blood pressure (BP) continuously with Finapres and derived heart rate, stroke volume, cardiac output (CO), and total peripheral resistance using Modelflow. In series A ( n = 12) we compared LBMT to LCMT. In series B ( n = 9), WBT was compared with LCMT. In series C ( n = 14) and D ( n = 9), we tested squatting and HBK. All maneuvers caused an increase in BP, varying from a systolic rise from 77 ± 8 to 104 ± 18 mmHg ( P < 0.05) in series A during LBMT to a rise from 70 ± 10 to 123 ± 9 mmHg ( P < 0.05) in series B during LCMT. In each maneuver, the BP increase started within 3–5 s from start of the maneuver. In all maneuvers, there was an increase in CO varying from 54 ± 12% of baseline to 94 ± 21% in WBT to a rise from 65 ± 17% to 110 ± 22% in LCMT in series A. No maneuver caused significant change in total peripheral resistance. We conclude that the mechanism underlying the effects of these maneuvers is exclusively an increase in CO.
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Affiliation(s)
- C T Paul Krediet
- Academic Medical Center/Univ. of Amsterdam, Dept. of Internal Medicine, Amsterdam, The Netherlands.
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Chan WL, Lu TM, Wang JJ, Jiau SS, Kong CW. Hemodynamic significance of heart rate in neurally mediated syncope. Clin Cardiol 2005; 27:635-40. [PMID: 15562934 PMCID: PMC6654538 DOI: 10.1002/clc.4960271111] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
BACKGROUND Vasovagal and vasodepressor syncope are used interchangeably in the literature to describe the common faint syndrome, now collectively named neurally mediated syncope. The significance of heart rate (HR) in these reflex-induced reactions remains unclear. HYPOTHESIS The study was undertaken to investigate the hemodynamic significance of HR in tilt-induced neurally mediated syncope. METHODS In all, 113 patients with syncope of unknown etiology were studied by head-up tilt test with invasive hemodynamic monitoring. Thirty-five patients (15 women, 20 men, age range 21 to 72 years) developed syncope and were enrolled for analysis. The hemodynamic data were compared between patients who developed bradycardia (vasovagal group, n = 15) and those without bradycardia (vasodepressor group, n = 20). RESULTS The baseline hemodynamic data (mean +/- standard deviation) and the hemodynamic responses after 10-min headup tilt were similar between patients in the vasovagal and vasodepressor groups. During syncope, patients with vasovagal reaction developed hypotension and paradoxical bradycardia (HR = 52.4 +/- 5.9 beats/min), while patients with vasodepressor reaction developed a precipitous drop in arterial blood pressure with inappropriate HR (105 +/- 21 beats/min) compensation. Patients with vasovagal syncope manifested a significantly lower cardiac index and a significantly higher systemic vascular resistance index than patients with vasodepressor syncope (1.47 +/- 0.29 vs. 1.97 +/- 0.41 1/min/m2, p < 0.001 and 2098 +/- 615 vs. 1573 +/- 353 dynes x s x cm(-5) x m2, p < 0.003, respectively). A positive correlation existed between HR and cardiac index (r = 0.44, p = 0.008) during syncope in the patients studied. CONCLUSIONS These findings suggest that the hemodynamic characteristics of vasovagal and vasodepressor reactions are different, and that HR plays a significant role in neurally mediated syncope.
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Affiliation(s)
- Wan Leong Chan
- Division of Cardiology, Department of Medicine, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan, ROC.
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Affiliation(s)
- Arnaud J J Aerts
- Department of Cardiology, Atrium Medisch Centrum Heerlen, the Netherlands.
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Jardine DL, Melton IC, Crozier IG, English S, Bennett SI, Frampton CM, Ikram H. Decrease in cardiac output and muscle sympathetic activity during vasovagal syncope. Am J Physiol Heart Circ Physiol 2002; 282:H1804-9. [PMID: 11959646 DOI: 10.1152/ajpheart.00640.2001] [Citation(s) in RCA: 64] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The importance of cardiac output (CO) to blood pressure level during vasovagal syncope is unknown. We measured thermodilution CO, mean blood pressure (MBP), and leg muscle mean sympathetic nerve activity (MSNA) each minute during 60 degrees head-up tilt in 26 patients with recurrent syncope. Eight patients tolerated tilt (TT) for 45 min (mean age 60 +/- 5 yr) and 15 patients developed syncope during tilt (TS) (mean age 58 +/- 4 yr, mean tilt time 15.4 +/- 2 min). In TT patients, CO decreased during the first minute of tilt (from 3.2 +/- 0.2 to 2.5 +/- 0.3 l x min(-1) x m(-2), P = 0.001) and thereafter remained stable between 2.5 +/- 0.3 (P = 0.001) and 2.4 +/- 0.2 l x min(-1) x m(-2) (P = 0.004) at 5 and 45 min, respectively. In TS patients, CO decreased during the first minute (from 3.3 +/- 0.2 to 2.7 +/- 0.1 l x min(-1) x m(-2), P = 0.02) and was stable until 7 min before syncope, falling to 2.0 +/- 0.2 at syncope (P = 0.001). Regression slopes for CO versus time during tilt were -0.01 min(-1) in TT versus -0.1 l x min(-1) x m(-2) x min(-1) in TS (P = 0.001). However, MBP was more closely correlated to total peripheral resistance (R = 0.56, P = 0.001) and MSNA (R = 0.58, P = 0.001) than CO (R = 0.32, P = 0.001). In vasovagal reactions, a progressive decline in CO may contribute to hypotension some minutes before syncope occurs.
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Affiliation(s)
- D L Jardine
- Department of General Medicine, Christchurch Hospital, Christchurch, New Zealand.
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Convertino VA, Sather TM. Effects of cholinergic and beta-adrenergic blockade on orthostatic tolerance in healthy subjects. Clin Auton Res 2000; 10:327-36. [PMID: 11324988 DOI: 10.1007/bf02322256] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
Cardiovascular responses during a graded lower body negative pressure (LBNP) protocol were compared before and after atropine and propranolol administration to test the hypothesis that both sympathetic and parasympathetic control of cardio-acceleration are associated with syncopal predisposition to orthostatic stress in healthy subjects. Eleven men were categorized into two groups having high (HT, N = 6) or low (LT, N = 5) tolerance based on their total time before the onset of presyncopal symptoms. HT and LT groups were similar in physical characteristics, fitness, and baseline cardiovascular measurements. Atropine treatment had no effect on LBNP tolerance or mean arterial pressure at presyncope, despite an atropine-induced increase in heart rate. Propranolol treatment reduced (p<0.05) LBNP tolerance in both groups. Diminished LBNP tolerance after propranolol administration was associated with reductions in cardiac output, whereas increase in systemic peripheral resistance from baseline to presyncope was unaffected by propranolol. Reduction in cardiac output and LBNP tolerance after beta blockade reflected a chronotropic effect because lower LBNP tolerance for the HT (-50%) and LT (-39%) groups was associated with dramatic reductions (p <0.05) in the magnitude of LBNP-induced tachycardia without significant effects on stroke volume at presyncope. Absence of an atropine-induced difference in cardiac output and systemic peripheral resistance between HT and LT groups failed to support the notion that cardiac vagal withdrawal represents a predominant mechanism that could account for differences in orthostatic tolerance. Because a reduction in LBNP tolerance in both HT and LT groups after propranolol treatment was most closely associated with reduced tachycardia, the data suggest that a primary autonomically mediated mechanism for maintenance of mean arterial pressure and orthostatic tolerance in healthy subjects is beta adrenergic-induced tachycardia.
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Affiliation(s)
- V A Convertino
- United States Army Institute of Surgical Research, Fort Sam Houston, Texas 78234-6315, USA.
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Castro PF, Larrain G, Pérez O, Corbalán R. Chronic hyperventilation syndrome associated with syncope and coronary vasospasm. Am J Med 2000; 109:78-80. [PMID: 10991750 DOI: 10.1016/s0002-9343(00)00356-9] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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Benditt DG, Samniah N. Respiratory changes during the evolving vasovagal faint: physiologic and clinical implications. J Cardiovasc Electrophysiol 2000; 11:612-5. [PMID: 10868732 DOI: 10.1111/j.1540-8167.2000.tb00021.x] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Shen WK, Low PA, Rea RF, Lohse CM, Hodge DO, Hammill SC. Distinct hemodynamic profiles in patients with vasovagal syncope: a heterogeneous population. J Am Coll Cardiol 2000; 35:1470-7. [PMID: 10807449 DOI: 10.1016/s0735-1097(00)00567-2] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVE The objective was to investigate mechanisms of vasovagal syncope by identifying laboratory techniques that characterize cardiovascular profiles in patients with vasovagal syncope. BACKGROUND The triggering mechanisms of vasovagal syncope are complex. The patient population is likely heterogeneous. We hypothesized that distinct hemodynamic profiles are definable with provocative maneuvers. METHODS Three groups of subjects were matched for age and gender: 16 patients with a history of syncope and an inducible vasovagal response during passive tilt table testing (70 degrees, 45 min, group I), 16 with a history of syncope, negative passive tilt table testing but positive isoproterenol tilt table testing (0.05 microg/kg per min, 70 degrees, 10 min, group II), and 16 control subjects. Beat-to-beat hemodynamic functions were determined noninvasively by photo-plethysmography and impedance cardiography. RESULTS At baseline, hemodynamic functions were not different among the three groups (supine). In response to tilt before any symptoms developed, total peripheral resistance decreased 9% +/- 14% in group I from baseline supine to tilt position but increased 27% +/- 18% in group II and 28% +/- 17% in controls (p < 0.001). Responses to isoproterenol were not significantly different between group II and controls in supine position. In response to tilt during isoproterenol infusion before any symptoms developed, total peripheral resistance decreased 24% +/- 20% in group II and increased 20% +/- 48% in controls (p = 0.002). CONCLUSIONS Group I patients may have impaired ability to increase vascular resistance during orthostatic stress. The inability to overcome isoproterenol-induced vasodilatation during tilt is important in triggering a vasovagal response in group II patients. These data suggest that the population with vasovagal response is heterogeneous. Distinct hemodynamic profiles in response to various provocative maneuvers are definable with noninvasive, continuous monitoring techniques.
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Affiliation(s)
- W K Shen
- Division of Cardiovascular Diseases and Internal Medicine, Mayo Clinic and Mayo Foundation, Rochester, Minnesota 55905, USA
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Aerts AJ, Dendale P, Daniels C, Meyvisch P, Kaufman L, Strobel G, Block P. Intravenous nitrates for pharmacological stimulation during head-up tilt testing in patients with suspected vasovagal syncope and healthy controls. Pacing Clin Electrophysiol 1999; 22:1593-8. [PMID: 10598961 DOI: 10.1111/j.1540-8159.1999.tb00377.x] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
Nitrates may be used for pharmacological stimulation during tilt testing for the diagnosis of vasovagal syncope. In this study we assessed the diagnostic value of intravenous nitrates during tilt testing in patients with a typical history of vasovagal syncope. Twenty patients and 23 controls were tilted at 700 for a maximum duration of 30 minutes. After a 10-minute baseline supine phase, the test started with a continuous nitrate infusion at 1 microg/kg/min and increased every 5 minutes by 1 microg/kg/min, to a maximum of 6 microg/kg/min at the end of the test. The test was ended if the subjects developed a positive response (syncope or presyncope). Nineteen patients (95%) and 17 (74%) of the controls had a positive response. At test end sensitivity was 95%, but specificity was 26% and accuracy was 58%. Receiver operator characteristics (ROC) analysis revealed a maximum accuracy of 79% at 18 minutes, with a sensitivity of 80% and a specificity of 78%. Intravenous nitrates during tilt testing in patients with typical clinical criteria of vasovagal syncope is highly effective in provoking vasovagal syncope. Based on the ROC analysis, a maximum accuracy of 79% was attained at 18 minutes (at a dose of 4 microg/kg/min), suggesting a good diagnostic performance when tilt duration is limited to this point. A positive result requiring more than 18 minutes of stimulated tilting should be interpreted with caution, due to the accompanying considerable decrease of specificity.
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Affiliation(s)
- A J Aerts
- Department of Cardiology, Atrium Medisch Centrum, Heerlen, The Netherlands
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Robertson RM, Medina E, Shah N, Furlan R, Mosqueda-Garcia R. Neurally mediated syncope: pathophysiology and implications for treatment. Am J Med Sci 1999; 317:102-9. [PMID: 10037113 DOI: 10.1097/00000441-199902000-00004] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
Neurally mediated syncope may occur in patients whose hemodynamic picture does not fit the characteristics of orthostatic intolerance as described elsewhere in this issue. Nonetheless, patients who suffer from neurocardiogenic or vasovagal syncope may be seriously incapacitated by their episodes of syncope or presyncope. Although it has been assumed that vagal activation as a result of stimulation of ventricular mechanoreceptors is essential to the production of these episodes, several critical observations are presented that suggest that other mechanisms may also be operative in some patient subsets. In addition, evidence is presented that the sympathetic responses of many of these patients may be reduced rather than increased and that abnormal baroreflex responsiveness may also play an causative role. These findings suggest new avenues for therapy in this field in which carefully controlled, randomized, double-blind trials are scarce.
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Affiliation(s)
- R M Robertson
- Autonomic Dysfunction Center, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee 37232, USA.
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ZOHMAN LR. Idiopathic postural hypotension. Case report including hemodynamic measurements before and after acute digitalization. Am J Cardiol 1998; 8:135-9. [PMID: 13788740 DOI: 10.1016/0002-9149(61)90188-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
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Yamanouchi Y, Shehadeh AA, Fouad-Tarazi FM. Usefulness of plasma catecholamines during head-up tilt as a measure of sympathetic activation in vasovagal patients. Pacing Clin Electrophysiol 1998; 21:1539-45. [PMID: 9725151 DOI: 10.1111/j.1540-8159.1998.tb00240.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Vasovagal syncope is a common clinical disorder which has been traditionally related to a vasovagal reflex precipitated by an initial excess sympathetic stimulation. We hypothesized that the increase in plasma catecholamines during head-up tilt is more accentuated in patients with tilt induced vasovagal syncope. To test this hypothesis, plasma catecholamines were measured in supine posture and during head-up tilt in patients with a history suggestive of vasovagal syncope. Of these, 13 had a normal response to tilt (nonvasovagal group; age 41 +/- 19 [SD]years) and 11 had a vasovagal response to tilt (vasovagal group; 39 +/- 20 years). In the supine posture at rest, plasma epinephrine and norepinephrine were not significantly different between the nonvasovagal and the vasovagal groups (39 +/- 28 ng/L vs 46 +/- 38 ng/L, P = 0.5792, 335 +/- 158 ng/L vs 304 +/- 124 ng/L, P = 0.6007, respectively). Furthermore, the tilt induced changes in plasma epinephrine and norepinephrine were not different between the two groups (20 +/- 20 ng/L vs 35 +/- 55 ng/L, P = 0.3562, 264 +/- 158 ng/L vs 242 +/- 205 ng/L, P = 0.7724, respectively) suggesting that differences in the hemodynamic response to tilt are not predictable by the supine levels of circulating plasma catecholamines, and that the extent of plasma catecholamines increase during tilt does not determine the hemodynamic outcome of the tilt test. Since orthostatic changes of plasma catecholamines could be influenced by volume factors, we assessed plasma renin activity and aldosterone as surrogates of blood volume. Baseline plasma renin activity and aldosterone were not significantly different between the two groups. We conclude that inasmuch as plasma catecholamines reflect the status of sympathetic activity, our data do not support the hypothesis that accentuation of sympathetic activity precedes necessarily the tilt induced vasovagal syncope. However, one should take in consideration that multiple factors may influence catecholamine levels and catecholamines kinetics. A hyperresponsiveness of beta-receptors to catecholamines in patients with vasovagal syncope may be suggested but needs to be tested.
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Affiliation(s)
- Y Yamanouchi
- Department of Cardiology, Cleveland Clinic Foundation, Ohio 44195-5069, USA
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Lipsitz LA, Morin R, Gagnon M, Kiely D, Medina A. Vasomotor instability preceding tilt-induced syncope: does respiration play a role? J Appl Physiol (1985) 1997; 83:383-90. [PMID: 9262431 DOI: 10.1152/jappl.1997.83.2.383] [Citation(s) in RCA: 25] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
This study aimed to determine whether alterations in cardiovascular dynamics before syncope are related to changes in spontaneous respiration. Fifty-two healthy subjects underwent continuous heart rate (HR), arterial blood pressure (BP), and respiratory measurements during 10-min periods of spontaneous and paced breathing (0.25 Hz) in the supine and 60 degrees head-up tilt positions. Data were evaluated by power spectrum and transfer function analyses. During tilt, 27 subjects developed syncope or presyncope and 25 remained asymptomatic. Subjects with tilt-induced syncope had significantly greater increases in low-frequency (0.04-0. 15 Hz) systolic BP, diastolic BP, and HR power during tilt than the asymptomatic subjects (P </= 0.01). This difference was present during spontaneous but not paced breathing. However, average tidal volume, respiratory rate, minute ventilation, proportion of breaths below 0.15 Hz, and low-frequency respiratory power during tilt did not differ between syncopal and nonsyncopal subjects. Transfer magnitudes between low-frequency respiration and BP, and between BP and interbeat interval, were also similar between groups. Thus vasomotor instability before syncope is not related to alterations in respiration or the cardiovagal baroreflex but may reflect oscillating central sympathetic outflow to the vasculature.
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Affiliation(s)
- L A Lipsitz
- Hebrew Rehabilitation Center for Aged Research and Training Institute, Boston, Massachusetts 02131, USA.
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Abstract
The current knowledge regarding the pathophysiologic basis of the vasodepressor response was reviewed. The balance of evidence indicates that the mechanoreceptor hypothesis seems unlikely to be the sole afferent alteration that leads to the vasodepressor response. Alternative afferent mechanisms should include neurohumoral mediated sympathoinhibition triggered by opioid mechanisms as well as impaired endothelial and NO responses to orthostatic stress in susceptible individuals. It is possible that impaired cardiovagal and sympathetic outflow control of arterial baroreceptors is enhanced by the aforementioned mechanisms. The role of central sympathoinhibition and vagal excitation triggered directly from pathways within the temporal lobe or triggered by alterations in regional cerebral blood flow should be considered as potential alternative mechanisms. Efferent autonomic outflow during vasodepressor syncope include sympathetic neural outflow withdrawal in addition to activation of parasympathetic outflow to the heart and abdominal viscera. Further human research is needed to understand the underlying mechanisms that result in the described neural and vascular responses.
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Affiliation(s)
- C A Morillo
- Department of Medicine, Universidad Industrial de Santander, Colombia
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Shen WK, Hammill SC, Munger TM, Stanton MS, Packer DL, Osborn MJ, Wood DL, Bailey KR, Low PA, Gersh BJ. Adenosine: potential modulator for vasovagal syncope. J Am Coll Cardiol 1996; 28:146-54. [PMID: 8752807 DOI: 10.1016/0735-1097(96)00100-3] [Citation(s) in RCA: 69] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
OBJECTIVES This study examined the hypothesis that adenosine could provoke a vasovagal response in susceptible patients. Mechanisms of the vasovagal response were further explored by studying the adenosine-mediated reactions. BACKGROUND Increased sympathetic activity is frequently observed before vasovagal syncope. Recent studies have demonstrated that adenosine, in addition to its direct bradycardiac and vasodilatory effects, can increase sympathetic discharge by activating cardiovascular afferent nerves. METHODS The effects of adenosine and head-up tilt-table testing with or without isoproterenol were prospectively evaluated in 85 patients examined for syncope after negative results of electrophysiologic testing (51 men and 34 women, mean [+/- SD] age 61 +/- 17 years). Adenosine bolus injections of 6 mg and 12 mg were sequentially administered to patients in the upright position. The same protocol was implemented in 14 normal control subjects (7 men and 7 women, mean [+/- SD] age 38 +/- 10 years). RESULTS Transient hypertension or tachycardia was observed in 57 (67%) and 20 (24%) patients after administration of 6 mg and 12 mg of adenosine, respectively, during the immediate phase (first 15 s), suggesting direct sympathetic activation. Hypotension and reflex tachycardia were observed in all patients during the delayed phase (15 to 60 s after adenosine injection), suggesting baroreceptor unloading. A vasovagal response was induced in 22 (26%) and 29 (34%) patients after adenosine administration and during tilt-table testing. Inducibility of a vasovagal response by these two methods was comparable (p = 0.12). Of the control subjects, one (7%) had a vasovagal response after adenosine administration and one (7%) had a positive response during tilt-table testing. CONCLUSIONS These observations support the idea that adenosine is an endogenous modulator of the cardiac excitatory afferent nerves. Sympathetic activation by adenosine can be direct (i.e., cardiac excitatory afferent nerves) and indirect (i.e., vasodilation and reflex sympathetic activation). Adenosine could be an important modulator in triggering a vasovagal response in susceptible patients during examination for syncope.
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Affiliation(s)
- W K Shen
- Division of Cardiovascular Diseases and Internal Medicine, Section of Biostatistics and Peripheral Neuropathy Research Laboratory, Mayo Clinic, Rochester, Minnesota 55905, USA
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Abstract
Although dangling is a common nursing intervention, little research has been conducted to test its effectiveness or to compare various dangling methods. By contrast, abundant information is available about orthostatic responses. In this article the authors explain the physiologic principles underlying orthostatic responses, focusing on blood volume distribution and the role of the mechanoreceptors, discuss typical and atypical responses to dangling and standing, describe clinical manifestations of orthostatic hypotension and syncope, present research-based practice guidelines, and, provide specific recommendations for future research. Because of the wide variability in heart rate and blood pressure responses to orthostasis, the authors stress the importance of signs and symptoms such as nausea, pallor, dizziness, visual dimming, and impaired consciousness in assessing orthostatic tolerance. Studying rituals such as dangling can advance nursing practice, improve patient outcomes, and move nursing to a research-based practice.
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Affiliation(s)
- E H Winslow
- University of Texas at Arlington, School of Nursing, Arlington 76019, USA
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