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Roy S, Lam MY, Panerai RB, Robinson TG, Minhas JS. Blood pressure variability at rest and during pressor challenges in patients with acute ischemic stroke. Blood Press Monit 2024:00126097-990000000-00111. [PMID: 38841869 DOI: 10.1097/mbp.0000000000000710] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/07/2024]
Abstract
INTRODUCTION Patients with acute ischemic stroke (AIS) have elevated blood pressure (BP) variability (BPV) and reduced baroreflex sensitivity (BRS) at rest for several days after initial stroke symptoms. We aimed to assess BPV and BRS in AIS patients during pressor challenge maneuvers in the acute and subacute phases of stroke. Pressor challenge maneuvers simulate day-to-day activities and can predict the quality of life. METHODS Continuous beat-to-beat BP and ECG in 15 AIS patients (mean age 69 ± 7.5 years) and 15 healthy controls (57 ± 16 years) were recorded at rest and during a 5-min rapid head positioning (RHP) paradigm. Patients were assessed within 24 h (acute phase) and 7 days (subacute phase) of stroke onset. Low frequency (LF) SBP power (measure of BPV), LF-α, and combined α-index (measure of BRS) were calculated from the recordings. RESULTS In the acute phase, at rest, LF-SBP power was higher (P = 0.024) and α-index was lower (P = 0.006) in AIS patients than in healthy controls. There was no change in LF-SBP during RHP in the patients but in healthy controls, it increased significantly (P = 0.018). In the subacute phase, at rest, the alpha-index increased (P = 0.037) and LF-SBP decreased (P = 0.029) significantly in the AIS patients, however, there was still no rise in the LF-SBP power during RHP (P = 0.240). CONCLUSION AIS patients have a high resting BPV. High resting BPV may be responsible for blunted BPV responses during pressor challenge maneuvers such as RHP, suggesting ongoing autonomic dysfunction and compromised quality of life.
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Affiliation(s)
- Sankanika Roy
- Department of Cardiovascular Sciences, University of Leicester
| | - Man Y Lam
- Department of Cardiovascular Sciences, University of Leicester
| | - Ronney B Panerai
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Thompson G Robinson
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
| | - Jatinder S Minhas
- Department of Cardiovascular Sciences, University of Leicester
- NIHR Leicester Biomedical Research Centre, British Heart Foundation Cardiovascular Research Centre, Glenfield Hospital, Leicester, UK
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Christensen AH, Wyller VB, Nygaard S, Rolid K, Nytrøen K, Gullestad L, Fiane A, Thaulow E, Saul JP, Døhlen G. Factors Associated With Sinoatrial Reinnervation After Heart Transplantation. Transplant Direct 2023; 9:e1553. [PMID: 37928482 PMCID: PMC10624457 DOI: 10.1097/txd.0000000000001553] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/07/2023] [Revised: 09/05/2023] [Accepted: 09/22/2023] [Indexed: 11/07/2023] Open
Abstract
Background Factors associated with sympathetic and parasympathetic sinoatrial reinnervation after heart transplantation (HTx) are inadequately studied. Methods Fifty transplant recipients were examined at 7 to 12 wk (index visit), 6, 12, 24, and 36 mo after HTx. Supine rest heart rate variability in the low-frequency (LF) domain (sympathetic and parasympathetic sinoatrial reinnervation) and the high-frequency (HF) domain (parasympathetic sinoatrial reinnervation) were measured repeatedly and related to selected recipient, donor, and perisurgical characteristics. We primarily aimed to identify index visit factors that affect the sinoatrial reinnervation process. Secondarily, we examined overall associations between indices of reinnervation and repeatedly measured recipient characteristics to generate new hypotheses regarding the consequences of reinnervation. Results LF and HF variability increased time dependently. In multivariate modeling, a pretransplant diagnosis of nonischemic cardiomyopathy (P = 0.038) and higher index visit handgrip strength (P = 0.028) predicted improved LF variability. Recipient age, early episodes of rejection, and duration of extracorporeal circulation were not associated with indices of reinnervation. Study average handgrip strength was positively associated with LF and HF variability (respectively, P = 0.005 and P = 0.029), whereas study average C-reactive protein was negatively associated (respectively, P = 0.015 and P = 0.008). Conclusions Indices of both sympathetic and parasympathetic sinoatrial reinnervation increased with time after HTx. A pretransplant diagnosis of nonischemic cardiomyopathy and higher index visit handgrip strength predicted higher indices of mainly sympathetic reinnervation, whereas age, rejection episodes, and duration of extracorporeal circulation had no association. HTx recipients with higher indices of reinnervation had higher average handgrip strength, suggesting a link between reinnervation and improved frailty. The more reinnervated participants had lower average C-reactive protein, suggesting an inhibitory effect of reinnervation on inflammation, possibly through enhanced function of the inflammatory reflex. These potential effects of reinnervation may affect long-term morbidity in HTx patients and should be scrutinized in future research.
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Affiliation(s)
- Anders H. Christensen
- Department of Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Pediatric Research, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Vegard B.B. Wyller
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Pediatrics, Akershus University Hospital, Norway
| | - Sissel Nygaard
- Department of Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, University of Oslo, Oslo, Norway
| | - Katrine Rolid
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Norway
- Center for Heart Failure Research, Oslo University Hospital, Norway
| | - Kari Nytrøen
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Lars Gullestad
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- KG Jebsen Cardiac Research Center and Center for Heart Failure Research, University of Oslo, Norway
- Center for Heart Failure Research, Oslo University Hospital, Norway
| | - Arnt Fiane
- Faculty of Medicine, University of Oslo, Oslo, Norway
- Department of Cardiothoracic Surgery, Oslo University Hospital, Rikshospitalet, Oslo, Norway
| | - Erik Thaulow
- Department of Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
- Faculty of Medicine, University of Oslo, Oslo, Norway
| | - J. Philip Saul
- Department of Pediatrics, West Virginia University, Morgantown, VA
| | - Gaute Døhlen
- Department of Pediatric Cardiology, Oslo University Hospital, Rikshospitalet, Oslo, Norway
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Mangalam M, Sadri A, Hayano J, Watanabe E, Kiyono K, Kelty-Stephen DG. Multifractal foundations of biomarker discovery for heart disease and stroke. Sci Rep 2023; 13:18316. [PMID: 37880302 PMCID: PMC10600152 DOI: 10.1038/s41598-023-45184-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 10/17/2023] [Indexed: 10/27/2023] Open
Abstract
Any reliable biomarker has to be specific, generalizable, and reproducible across individuals and contexts. The exact values of such a biomarker must represent similar health states in different individuals and at different times within the same individual to result in the minimum possible false-positive and false-negative rates. The application of standard cut-off points and risk scores across populations hinges upon the assumption of such generalizability. Such generalizability, in turn, hinges upon this condition that the phenomenon investigated by current statistical methods is ergodic, i.e., its statistical measures converge over individuals and time within the finite limit of observations. However, emerging evidence indicates that biological processes abound with nonergodicity, threatening this generalizability. Here, we present a solution for how to make generalizable inferences by deriving ergodic descriptions of nonergodic phenomena. For this aim, we proposed capturing the origin of ergodicity-breaking in many biological processes: cascade dynamics. To assess our hypotheses, we embraced the challenge of identifying reliable biomarkers for heart disease and stroke, which, despite being the leading cause of death worldwide and decades of research, lacks reliable biomarkers and risk stratification tools. We showed that raw R-R interval data and its common descriptors based on mean and variance are nonergodic and non-specific. On the other hand, the cascade-dynamical descriptors, the Hurst exponent encoding linear temporal correlations, and multifractal nonlinearity encoding nonlinear interactions across scales described the nonergodic heart rate variability more ergodically and were specific. This study inaugurates applying the critical concept of ergodicity in discovering and applying digital biomarkers of health and disease.
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Affiliation(s)
- Madhur Mangalam
- Division of Biomechanics and Research Development, Department of Biomechanics, and Center for Research in Human Movement Variability, University of Nebraska at Omaha, Omaha, NE, 68182, USA.
| | - Arash Sadri
- Lyceum Scientific Charity, Tehran, Iran
- Interdisciplinary Neuroscience Research Program, Students' Scientific Research Center, Tehran University of Medical Sciences, Tehran, P94V+8MF, Iran
| | - Junichiro Hayano
- Graduate School of Medicine, Nagoya City University, Nagoya, Aichi, 467-8601, Japan
| | - Eiichi Watanabe
- Division of Cardiology, Department of Internal Medicine, Fujita Health University Bantane Hospital, Nagoya, Aichi, 454-0012, Japan
| | - Ken Kiyono
- Graduate School of Engineering Science, Osaka University, Osaka, 560-8531, Japan
| | - Damian G Kelty-Stephen
- Department of Psychology, State University of New York at New Paltz, New Paltz, NY, 12561, USA
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Parati G, Bilo G, Kollias A, Pengo M, Ochoa JE, Castiglioni P, Stergiou GS, Mancia G, Asayama K, Asmar R, Avolio A, Caiani EG, De La Sierra A, Dolan E, Grillo A, Guzik P, Hoshide S, Head GA, Imai Y, Juhanoja E, Kahan T, Kario K, Kotsis V, Kreutz R, Kyriakoulis KG, Li Y, Manios E, Mihailidou AS, Modesti PA, Omboni S, Palatini P, Persu A, Protogerou AD, Saladini F, Salvi P, Sarafidis P, Torlasco C, Veglio F, Vlachopoulos C, Zhang Y. Blood pressure variability: methodological aspects, clinical relevance and practical indications for management - a European Society of Hypertension position paper ∗. J Hypertens 2023; 41:527-544. [PMID: 36723481 DOI: 10.1097/hjh.0000000000003363] [Citation(s) in RCA: 45] [Impact Index Per Article: 45.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
Blood pressure is not a static parameter, but rather undergoes continuous fluctuations over time, as a result of the interaction between environmental and behavioural factors on one side and intrinsic cardiovascular regulatory mechanisms on the other side. Increased blood pressure variability (BPV) may indicate an impaired cardiovascular regulation and may represent a cardiovascular risk factor itself, having been associated with increased all-cause and cardiovascular mortality, stroke, coronary artery disease, heart failure, end-stage renal disease, and dementia incidence. Nonetheless, BPV was considered only a research issue in previous hypertension management guidelines, because the available evidence on its clinical relevance presents several gaps and is based on heterogeneous studies with limited standardization of methods for BPV assessment. The aim of this position paper, with contributions from members of the European Society of Hypertension Working Group on Blood Pressure Monitoring and Cardiovascular Variability and from a number of international experts, is to summarize the available evidence in the field of BPV assessment methodology and clinical applications and to provide practical indications on how to measure and interpret BPV in research and clinical settings based on currently available data. Pending issues and clinical and methodological recommendations supported by available evidence are also reported. The information provided by this paper should contribute to a better standardization of future studies on BPV, but should also provide clinicians with some indications on how BPV can be managed based on currently available data.
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Affiliation(s)
- Gianfranco Parati
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Grzegorz Bilo
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Anastasios Kollias
- Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece
| | - Martino Pengo
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Juan Eugenio Ochoa
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
| | - Paolo Castiglioni
- IRCCS Fondazione Don Carlo Gnocchi, Milan
- Department of Biotechnology and Life Sciences (DBSV), University of Insubria, Varese
| | - George S Stergiou
- Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece
| | | | - Kei Asayama
- Department of Hygiene and Public Health, Teikyo University School of Medicine, Tokyo, Japan
- Department of Cardiovascular Sciences, University of Leuven, and Research Unit Hypertension and Cardiovascular Epidemiology, KU Leuven, Belgium
- Tohoku Institute for the Management of Blood Pressure, Sendai, Japan
| | - Roland Asmar
- Foundation-Medical Research Institutes, Geneva, Switzerland
| | - Alberto Avolio
- Department of Biomedical Sciences, Faculty of Medicine and Health Sciences, Macquarie University, Sydney, NSW, Australia
| | - Enrico G Caiani
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
- Department of Electronics, Information, and Bioengineering, Politecnico di Milano, Italy
| | - Alejandro De La Sierra
- Hypertension Unit, Department of Internal Medicine, Hospital Mútua Terrassa, University of Barcelona, Barcelona, Spain
| | | | - Andrea Grillo
- Department of Medicine, Surgery and Health Sciences, University of Trieste, Italy
| | - Przemysław Guzik
- Department of Cardiology -Intensive Therapy, University School of Medicine in Poznan, Poznan, Poland
| | - Satoshi Hoshide
- Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University School of Medicine, Tochigi, Japan
| | - Geoffrey A Head
- Baker Heart and Diabetes Institute, Melbourne Victoria Australia
| | - Yutaka Imai
- Tohoku Institute for the Management of Blood Pressure, Sendai, Japan
| | - Eeva Juhanoja
- Chronic Disease Prevention Unit, National Institute for Health and Welfare, Turku
- Department of Oncology; Division of Medicine, Turku University Hospital, University of Turku, Turku, Finland
| | - Thomas Kahan
- Karolinska Institute, Department of Clinical Sciences, Division of Cardiovascular Medicine, Department of Cardiology, Danderyd University Hospital Corporation, Stockholm, Sweden
| | - Kazuomi Kario
- Division of Cardiovascular Medicine, Department of Medicine, Jichi Medical University School of Medicine, Tochigi, Japan
| | | | | | - Konstantinos G Kyriakoulis
- Hypertension Center STRIDE-7, National and Kapodistrian University of Athens, School of Medicine, Third Department of Medicine, Sotiria Hospital, Athens, Greece
| | - Yan Li
- Department of Cardiovascular Medicine, Shanghai Key Laboratory of Hypertension and Medical Genomics, National Research Centre for Translational Medicine
- Shanghai Institute of Hypertension, Ruijin Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Efstathios Manios
- Department of Clinical Therapeutics, National and Kapodistrian University of Athens, School of Medicine, Alexandra Hospital Athens, Greece
| | - Anastasia S Mihailidou
- Department of Cardiology and Kolling Institute, Royal North Shore Hospital, St Leonards; Faculty of Medicine and Health Sciences, Macquarie University, Sydney, Australia
| | | | - Stefano Omboni
- Clinical Research Unit, Italian Institute of Telemedicine, Varese, Italy
- Department of Cardiology, Sechenov First Moscow State Medical University, Moscow, Russian Federation
| | - Paolo Palatini
- Department of Medicine. University of Padova, Padua, Italy
| | - Alexandre Persu
- Division of Cardiology, Department of Cardiovascular Diseases, Cliniques Universitaires Saint-Luc and Pole of Cardiovascular Research, Institut de Recherche Expérimentale et Clinique, Université Catholique de Louvain, Brussels, Belgium
| | - Athanasios D Protogerou
- Cardiovascular Prevention and Research Unit, Department of Pathophysiology, Medical School, National and Kapodistrian University of Athens, Laiko General Hospital, Athens, Greece
| | - Francesca Saladini
- Department of Medicine. University of Padova, Padua, Italy
- Cardiology Unit, Cittadella Town Hospital, Padova, Italy
| | - Paolo Salvi
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
| | - Pantelis Sarafidis
- Department of Nephrology, Hippokration Hospital, Aristotle University of Thessaloniki, Greece
| | - Camilla Torlasco
- Istituto Auxologico Italiano, IRCCS, Department of Cardiovascular Neural and Metabolic Sciences, Milan
| | - Franco Veglio
- Internal Medicine Division and Hypertension Unit, Department of Medical Sciences, University of Turin, Turin, Italy
| | - Charalambos Vlachopoulos
- Hypertension and Cardiometabolic Syndrome Unit, 1 Department of Cardiology, Medical School, National & Kapodistrian University of Athens, Hippokration Hospital, Athens, Greece
| | - Yuqing Zhang
- Department of Cardiology, Fu Wai Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, China
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Krzesiński P, Marczyk J, Wolszczak B, Gielerak GG, Accardi F. Quantitative Complexity Theory (QCT) in Integrative Analysis of Cardiovascular Hemodynamic Response to Posture Change. Life (Basel) 2023; 13:life13030632. [PMID: 36983787 PMCID: PMC10052206 DOI: 10.3390/life13030632] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2023] [Revised: 02/19/2023] [Accepted: 02/22/2023] [Indexed: 03/30/2023] Open
Abstract
The explanation of physiological mechanisms involved in adaptation of the cardiovascular system to intrinsic and environmental demands is crucial for both basic science and clinical research. Computational algorithms integrating multivariable data that comprehensively depict complex mechanisms of cardiovascular reactivity are currently being intensively researched. Quantitative Complexity Theory (QCT) provides quantitative and holistic information on the state of multi-functional dynamic systems. The present paper aimed to describe the application of QCT in an integrative analysis of the cardiovascular hemodynamic response to posture change. Three subjects that underwent head-up tilt testing under beat-by-beat hemodynamic monitoring (impedance cardiography) were discussed in relation to the complexity trends calculated using QCT software. Complexity has been shown to be a sensitive marker of a cardiovascular hemodynamic response to orthostatic stress and vasodilator administration, and its increase has preceded changes in standard cardiovascular parameters. Complexity profiling has provided a detailed assessment of individual hemodynamic patterns of syncope. Different stimuli and complexity settings produce results of different clinical usability.
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Affiliation(s)
- Paweł Krzesiński
- Departament of Cardiology and Internal Diseases, Military Institute of Medicine, 04-141 Warsaw, Poland
| | | | | | - Grzegorz Gerard Gielerak
- Departament of Cardiology and Internal Diseases, Military Institute of Medicine, 04-141 Warsaw, Poland
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Strong evidence for parasympathetic sinoatrial reinnervation after heart transplantation. J Heart Lung Transplant 2021; 41:898-909. [PMID: 34924265 DOI: 10.1016/j.healun.2021.11.005] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2021] [Revised: 10/26/2021] [Accepted: 11/09/2021] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Heart transplantation (HTx) surgically denervates the heart. We examined indices of sinoatrial reinnervation, with emphasis on (1) the occurrence and timing of parasympathetic reinnervation, and (2) the consequences of reinnervation for heart rate (HR) responsiveness and arterial baroreceptor sensitivity. METHODS Fifty HTx recipients were prospectively followed for 36 months after surgery. Hemodynamic variables and heart rate variability were continuously recorded at supine rest, 60 degrees head-up-tilt, during the Valsalva maneuver and during handgrip isometric exercise. RESULTS Suggesting parasympathetic reinnervation: at baseline rest, root of the mean squared differences of successive RR intervals increased from median 3.9(5.9) to 7.1(5.1) ms (p < 0.001); high-frequency power increased from 4.0(12) to 5.7(18.9) ms2 (p = 0.018); and baroreceptor sensitivity increased from 0.04(0.36) to 1.3(2.4) ms/mmHg (p < 0.001). Suggesting sympathetic reinnervation: at baseline rest low-frequency power increased from 0.49(2.5) to 7.5(18.1) ms2 (p < 0.001); and HR responses to sympathetic stimulation during (1) head-up tilt increased from 1.9(4.2) to 9.1(8.2) bpm (p < 0.001), (2) Valsalva increased from 1.6(1.4) to 8.3(10.8) bpm (p < 0.001) and (3) handgrip increased from 0.3(0.6) to 1.9(5.1) bpm (p < 0.001). Signs of sympathetic reinnervation emerged within 6 months, while signs of parasympathetic reinnervation emerged by 24 months. CONCLUSIONS Root of the mean squared differences of successive RR intervals, high-frequency and low-frequency variability, HR responsiveness and arterial baroreflex sensitivity all increased after HTx, suggesting functional parasympathetic and sympathetic sinoatrial reinnervation. Accordingly, the pathological regulatory state present in heart transplant recipients, which is responsible for a host of functional and clinical abnormalities, is being partially offset over time by restored autonomic control of the heart in many heart transplant recipients.
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Quantitative Complexity Theory Used in the Prediction of Head-Up Tilt Testing Outcome. Cardiol Res Pract 2021; 2021:8882498. [PMID: 34603772 PMCID: PMC8486546 DOI: 10.1155/2021/8882498] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/25/2020] [Revised: 05/29/2021] [Accepted: 09/08/2021] [Indexed: 11/17/2022] Open
Abstract
Background Head-up tilt testing (HUTT), a well-established tool in the diagnosis of vasovagal syncope, is time-consuming, and every provoked vasovagal reaction may result in consolidating the reflex mechanism. Therefore, identification of parameters that could shorten the duration of HUTT and prevent fainting is desirable. Quantitative complexity theory (QCT) may provide holistic information on the cardiovascular reaction in HUTT. The aim of the present article was to evaluate the prognostic value of complexity in comparison with traditional haemodynamic parameters (HR and BP) in predicting the HUTT outcome. Methods Eighty-one healthy volunteers (74 men; mean age: 37.8 years) were included in this retrospective analysis of data collected within the project realized in Department of Cardiology and Internal Diseases, Military Institute of Medicine between January 2012 and October 2014. The subjects underwent HUTT, with beat-to-beat haemodynamic monitoring with a Niccomo™. The chosen haemodynamic parameters (including BP, HR, stroke volume, cardiac output, systemic vascular resistance) have been used in complexity analysis. Results HUTT was positive in 54 (66.7%) study participants. The values of complexity were already higher in fainting subjects than those were in nonfainting ones 300 s before HUTT termination (HUTT_end), with a significant upward trend starting 150 s before (pre)syncope. An area under the curve (AUC) over 0.700 was observed for complexity from 120 s before HUTT_end, with a sensitivity of 63% and specificity of 78% at this time point. The prognostic value of complexity was superior to that of the HR and mean arterial pressure (MAP). Conclusions Complexity has been shown to be a sensitive marker of cardiovascular haemodynamic response to orthostatic stress and proved to be superior over HR and BP in predicting HUTT outcomes.
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Abstract
BACKGROUND Heart transplantation (HTx) surgically transects all connections to the heart, including the autonomic nerves. We prospectively examined signs, timing and consequences of early sympathetic and parasympathetic sinoatrial reinnervation, as well as explored indirect evidence of afferent cardiopulmonary reinnervation. METHODS Fifty HTx recipients were assessed at 2.5, 6, and 12 mo after HTx. For comparison, 50 healthy controls were examined once. Continuous, noninvasive recordings of hemodynamic variables and heart rate variability indices were performed at supine rest, 0.2 Hz controlled breathing, 60° head-up-tilt, during the Valsalva maneuver and during handgrip isometric exercise. RESULTS In HTx recipients, supine low-frequency heart rate variability gradually increased; supine high-frequency variability did not change; heart rate variability indices during controlled breathing remained unaltered; heart rate responses during tilt and isometric exercise gradually increased; the tachycardia response during Valsalva maneuver increased, while the bradycardia response remained unchanged; and indices of baroreflex sensitivity improved. Responses remained low compared to healthy controls. A negative correlation between indices of preload and heart rate response during head-up tilt emerged at 12 mo. CONCLUSIONS Results suggest that sympathetic reinnervation of the sinoatrial node starts within 6 mo after HTx and strengthens during the first year. No evidence of early parasympathetic reinnervation was found. Indirect signs of afferent reinnervation of cardiopulmonary low-pressure baroreceptors emerged at 12 mo. Better sympathetic sinoatrial control improved heart rate responsiveness to orthostatic challenge and isometric exercise, as well as heart rate buffering of blood pressure fluctuations.
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Lund MT, Salomonsson M, Jonassen TEN, Holstein-Rathlou NH. A method for assessment of the dynamic response of the arterial baroreflex. Acta Physiol (Oxf) 2018; 222. [PMID: 28872781 DOI: 10.1111/apha.12962] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2017] [Revised: 07/11/2017] [Accepted: 08/30/2017] [Indexed: 11/28/2022]
Abstract
AIM The baroreflex is a key mechanism in cardiovascular regulation, and alterations in baroreceptor function are seen in many diseases, including heart failure, obesity and hypertension. We propose a new method for analysing baroreceptor function from continuous blood pressure (BP) and heart rate (HR) in both health and disease. METHODS Forty-eight-hour data series of BP and HR were collected with telemetry. Sprague Dawley rats on standard chow (n = 11) served as controls, while rats on a high-fat, high-fructose (HFHC) diet (n = 6) constituted the obese-hypertensive model. A third group of rats underwent autonomic blockade (n = 6). An autoregressive-moving-average with exogenous inputs (ARMAX) model was applied to the data and compared with the α-coefficient. RESULTS Autonomic blockade caused a significant reduction in the strength of the baroreflex as estimated by ARMAX [ARMAX- baroreflex sensitivity (BRS)] -0.03 ± 0.01 vs. -0.19 ± 0.04 bpm heartbeat-1) . Both methods showed a ~50% reduction in BRS in the obese-hypertensive group compared with control (body weight 531 ± 27 vs. 458 ± 19 g, P < 0.05; mean arterial pressure 119 ± 3 vs. 102 ± 1 mmHg, P < 0.05; ARMAX-BRS -0.08 ± 0.01 vs. -0.15 ± 0.01 bpm heartbeat-1 , P < 0.05; α-coefficient BRS 0.51 ± 0.07 vs. 0.89 ± 0.07 ms mmHg-1 , P < 0.05). The ARMAX method additionally showed the open-loop gain of the baroreflex to be reduced by ~50% in the obese-hypertensive group (-2.3 ± 0.3 vs. -4.1 ± 0.3 bpm, P < 0.05), while the rate constant was similar between groups. CONCLUSION The ARMAX model represents an efficient method for estimating several aspects of the baroreflex. The open-loop gain of the baroreflex was attenuated in obese-hypertensive rats compared with control, while the time response was similar. The algorithm can be applied to other species including humans.
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Affiliation(s)
- M. T. Lund
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - M. Salomonsson
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
| | - T. E. N. Jonassen
- Department of Biomedical Sciences; University of Copenhagen; Copenhagen N Denmark
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Blood pressure changes after high- and low-salt diets: are intermittent arm measures and beat-by-beat finger measures equivalent? J Hum Hypertens 2014; 29:430-5. [PMID: 25427990 DOI: 10.1038/jhh.2014.110] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2014] [Revised: 09/22/2014] [Accepted: 10/20/2014] [Indexed: 11/08/2022]
Abstract
The assessment of sodium sensitivity requires to measure the difference in mean arterial pressure (MAP) at the end of sodium-loading (SLoad) and sodium-depletion (SDepl) maneuvers with an arm-cuff manometer. Aim of this study is to evaluate whether MAP measuring devices based on the volume-clamp method at the finger can also be used for assessing sodium sensitivity. Sixty-eight normotensive volunteers underwent SLoad and SDepl diets in random order. MAP was simultaneously measured at the end of each diet with arm (Spacelabs 90207) and finger (Portapres model-2) cuff devices. The sodium sensitivity was assessed as the difference in MAP at the end of SLoad and SDepl diets (ΔMAP), and as salt-sensitivity index (SSI; SSI = ΔMAP divided by the difference in urinary-sodium-excretion rate at the end of the diets). Discrepancies between finger and arm-cuff devices in ΔMAP or SSI were evaluated by Bland and Altman analysis. Even if discrepancies between devices had null-fixed bias, results showed a significant proportional bias and large limits of agreement (between -25 and 25 mm Hg for ΔMAP, between -196 and 180 mm Hg mol(-1) per day for SSI). The SSI distribution over the group was larger, flatter and less symmetric if derived from finger-cuff rather than arm-cuff devices, and this influenced substantially the identification of salt-sensitive individuals. Therefore, the response of MAP to SLoad/SDepl diets and consequently the assessment of the salt-sensitivity condition depends importantly on the measurement site, and brachial measures should be preferred for consistency with literature and normative data.
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Frequency range extension of spectral analysis of pulse rate variability based on Hilbert-Huang transform. Med Biol Eng Comput 2014; 52:343-51. [PMID: 24435320 DOI: 10.1007/s11517-013-1135-5] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 12/21/2013] [Indexed: 10/25/2022]
Abstract
Heart rate variability (HRV) is a well-accepted indicator for neural regulatory mechanisms in cardiovascular circulation. Its spectrum analysis provides the powerful means of observing the modulation between sympathetic and parasympathetic nervous system. The timescale of HRV is limited by discrete beat-to-beat time intervals; therefore, the exploration region of frequency band of HRV spectrum is relatively narrow. It had been proved that pulse rate variability (PRV) is a surrogate measurement of HRV in most of the circumstances. Moreover, arterial pulse wave contains small oscillations resulting from complex regulation of cardiac pumping function and vascular tone at higher frequency range. This study proposed a novel instantaneous PRV (iPRV) measurement based on Hilbert-Huang transform. Fifteen healthy subjects participated in this study and received continuous blood pressure wave recording in supine and passive head-up tilt. The result showed that the very-high-frequency band (0.4-0.9 Hz) varied during head-up tilt and had strong correlation (r = 0.77) with high-frequency band and medium correlation (r = 0.643) with baroreflex sensitivity. The very-high-frequency band of iPRV helps for the exploration of non-stationary autoregulation and provides the non-stationary spectral evaluation of HRV without distortion or information loss.
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Kauppila E, Vanninen E, Kaurijoki S, Karhunen L, Pietiläinen KH, Rissanen A, Tiihonen J, Pesonen U, Kaprio J. Influence of serotonin transporter gene polymorphism (5-HTTLPR polymorphism) on the relation between brain 5-HT transporter binding and heart rate corrected cardiac repolarization interval. PLoS One 2013; 8:e50303. [PMID: 23341873 PMCID: PMC3544835 DOI: 10.1371/journal.pone.0050303] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2012] [Accepted: 10/18/2012] [Indexed: 12/31/2022] Open
Abstract
Objective Serotonin transporter gene polymorphism (5-HTTLPR polymorphism) predicts the degree of structural and functional connectivity in the brain, and less consistently the degree of vulnerability for anxiety and depressive disorders. It is less known how 5-HTTLPR polymorphism influences on the coupling between brain and neuronal cardiovascular control. The present study demonstrates the impact of 5-HTTLPR polymorphism on the relations between heart rate (HR) corrected cardiac repolarization interval (QTc interval) and the brain 5-HTT binding. Material and Methods Thirty healthy young adults (fifteen monozygotic twin pairs) (mean age 26±1.3 years, 16 females) were imagined with single-photon emission computed tomography (SPECT) using iodine-123 labeled 2β-carbomethoxy-3β-(4-iodophenyl) nortropane (nor-β-CIT). Continuous ECG recording was obtained from each participant at supine rest. Signal averaged QTc interval on continuous ECG was calculated and compared with the brain imaging results. Results In the two groups [l homozygotes (n = 16, 10 females), s carriers (n = 14, 8 female)] HR and the length of QTc interval were not influenced by 5-HTTLPR polymorphism. There were no significant relations between HR and 5-HTT binding in the brain. There were significant associations between QTc interval and nor-β-CIT binding in the brain in l homozygotes, but not in s carriers (correlations for QTc interval and nor-β-CIT binding of striatum, thalamus and right temporal region were −0.8–−0.9, (p<0.0005), respectively). Conclusion The finding of longer QTc interval with less 5-HTT binding availability in major serotonergic binding sites in l homozygotes, but not in s carriers, implicate to differentiated control of QTc interval by 5-HTTLPR polymorphism.
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Affiliation(s)
- Esa Kauppila
- Department of Clinical Physiology and Nuclear Medicine, Kuopio University Hospital and University of Eastern Finland, Kuopio, Finland.
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Driehuys B, Martinez-Jimenez S, Cleveland ZI, Metz GM, Beaver DM, Nouls JC, Kaushik SS, Firszt R, Willis C, Kelly KT, Wolber J, Kraft M, McAdams HP. Chronic obstructive pulmonary disease: safety and tolerability of hyperpolarized 129Xe MR imaging in healthy volunteers and patients. Radiology 2011; 262:279-89. [PMID: 22056683 DOI: 10.1148/radiol.11102172] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
PURPOSE To evaluate the safety and tolerability of inhaling multiple 1-L volumes of undiluted hyperpolarized xenon 129 ((129)Xe) followed by up to a 16-second breath hold and magnetic resonance (MR) imaging. MATERIALS AND METHODS This study was approved by the institutional review board and was HIPAA compliant. Written informed consent was obtained. Forty-four subjects (19 men, 25 women; mean age, 46.1 years ± 18.8 [standard deviation]) were enrolled, consisting of 24 healthy volunteers, 10 patients with chronic obstructive pulmonary disease (COPD), and 10 age-matched control subjects. All subjects received three or four 1-L volumes of undiluted hyperpolarized (129)Xe, followed by breath-hold MR imaging. Oxygen saturation, heart rate and rhythm, and blood pressure were continuously monitored. These parameters, along with respiratory rate and subjective symptoms, were assessed after each dose. Subjects' serum biochemistry and hematology were recorded at screening and at 24-hour follow-up. A 12-lead electrocardiogram (ECG) was obtained at these times and also within 2 hours prior to and 1 hour after (129)Xe MR imaging. Xenon-related symptoms were evaluated for relationship to subject group by using a χ(2) test and to subject age by using logistic regression. Changes in vital signs were tested for significance across subject group and time by using a repeated-measures multivariate analysis of variance test. RESULTS The 44 subjects tolerated all xenon inhalations, no subjects withdrew, and no serious adverse events occurred. No significant changes in vital signs (P > .27) were observed, and no subjects exhibited changes in laboratory test or ECG results at follow-up that were deemed clinically important or required intervention. Most subjects (91%) did experience transient xenon-related symptoms, most commonly dizziness (59%), paresthesia (34%), euphoria (30%), and hypoesthesia (30%). All symptoms resolved without clinical intervention in 1.6 minutes ± 0.9. CONCLUSION Inhalation of hyperpolarized (129)Xe is well tolerated in healthy subjects and in those with mild or moderate COPD. Subjects do experience mild, transient, xenon-related symptoms, consistent with its known anesthetic properties.
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Affiliation(s)
- Bastiaan Driehuys
- Department of Radiology, Center for In-Vivo Microscopy, Duke University Medical Center, 311 Research Dr, Durham, NC 27710, USA.
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Abstract
PURPOSE In our previous study to investigate autonomic nervous system (ANS) activity due to radio frequency (RF) radiation using heart rate variability (HRV), drowsiness was observed in approximately half of all subjects. Therefore, the usage of HRV with unwanted drowsiness could falsely indicate the effects of RF radiation by mobile phones on the ANS. The objective of this study was to determine which posture is appropriate for accurate HRV analysis for provocation study. MATERIALS AND METHODS A total of 52 healthy subjects (25 males and 27 females) participated in this experiment. We measured the number of times a subject showed drowsiness or sleep deprivation due to awakening, and analyzed HRV six times over 30 minutes in sitting and recumbent postures, using power spectrum. RESULTS We employed the ratio of low frequency power to high frequency power (LFP/HFP) to analyze the changes in the ANS. The number of sleep deprivation occurrences in the sitting posture was significantly less than that in the recumbent posture (p<0.01), resulting in smaller increase of LFP/HFP. Although LFP/HFP of the two postures varied with time without any provocation, it was more stable in sitting than in recumbent postures. CONCLUSION A sitting posture is preferable to a recumbent posture for analyzing HRV, because of decreased drowsiness and sleep deprivation, thereby decreasing variation of LFP/HFP during experiment. Considering the drowsiness, it is also recommended that any experiment should be completed within 15 minutes, if possible.
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Affiliation(s)
- Ki Chang Nam
- Clinical Trials Center for Medical Devices, Yonsei University Health System, Seoul, Korea
- Department of Medical Engineering, Yonsei University College of Medicine, Seoul, Korea
| | - Min Kyung Kwon
- Department of Medical Engineering, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 Project for Medical Science, Yonsei University, Seoul, Korea
| | - Deok Won Kim
- Department of Medical Engineering, Yonsei University College of Medicine, Seoul, Korea
- Brain Korea 21 Project for Medical Science, Yonsei University, Seoul, Korea
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Jíra M, Závodná E, Honzíková N, Nováková Z, Vašků A, Izakovičová Hollá L, Fišer B. Association of eNOS gene polymorphisms T-786C and G894T with blood pressure variability in man. Physiol Res 2010; 60:193-7. [PMID: 20945955 DOI: 10.33549/physiolres.931887] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
The aim of this study was to evaluate the association of single nucleotide polymorphisms (SNPs) T-786C and G894T in the gene encoding eNOS with blood pressure variability (BPV) in man. Blood pressure was recorded beat-to-beat at rest three times in periods of one week (5 min, Finapres, breathing at 0.33 Hz) in 152 subjects (19-24 years). Systolic (SBPV(0.1r)/SBPV(0.1a)) and diastolic (DBPV(0.1r)/DBPV(0.1a)) blood pressure variabilities in relative (r.u.) and absolute (mm Hg(2)/Hz) units were determined by the spectral method as spectral power at the frequency of 0.1 Hz. Genotypes of both polymorphisms were detected using polymerase chain reaction and restriction analysis using enzymes Msp I and Ban II. Significant differences were observed in BPV among genotypes of T-786C SNP (p<0.05; Kruskal-Wallis), and among haplotypes of both SNPs (p<0.05; Kruskal-Wallis) as well. In T-786C SNP, carriers of less frequent allele (CC homozygotes and TC heterozygotes) showed significantly greater SBPV(0.1r) and SBPV(0.1a) compared to TT homozygotes (Mann-Whitney; p<0.05). The G894T variant showed no significant differences, but, both SNPs were in linkage disequilibrium (D'=0.37; p<0.01). Carriers of haplotype CT/CT (CC homozygotes of -786C/T and TT homozygotes of G894T) displayed significantly greater SBPV(0.1r), SBPV(0.1a) and DBPV(0.1a) compared to carriers of other haplotype combinations (Kruskal-Wallis; p=0.015, p=0.048, and p=0.026, respectively). In conclusion, the haplotype formed by less frequent alleles of both eNOS variants was associated with increased systolic and diastolic BPV in this study.
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Affiliation(s)
- M Jíra
- Department of Physiology, Masaryk University, Brno, Czech Republic
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Dantas E, Gonçalves C, Silva A, Rodrigues S, Ramos M, Andreão R, Pimentel E, Lunz W, Mill J. Reproducibility of heart rate variability parameters measured in healthy subjects at rest and after a postural change maneuver. Braz J Med Biol Res 2010; 43:982-8. [DOI: 10.1590/s0100-879x2010007500101] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2009] [Accepted: 09/08/2010] [Indexed: 11/22/2022] Open
Affiliation(s)
- E.M. Dantas
- Universidade Federal do Espírito Santo, Brasil
| | | | | | | | - M.S. Ramos
- Centro Federal de Educação Tecnológica do Espírito Santo, Brasil
| | - R.V. Andreão
- Centro Federal de Educação Tecnológica do Espírito Santo, Brasil
| | | | - W. Lunz
- Universidade Federal do Espírito Santo, Brasil
| | - J.G. Mill
- Universidade Federal do Espírito Santo, Brasil
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Dietrich A, Rosmalen JGM, Althaus M, van Roon AM, Mulder LJM, Minderaa RB, Oldehinkel AJ, Riese H. Reproducibility of heart rate variability and baroreflex sensitivity measurements in children. Biol Psychol 2010; 85:71-8. [PMID: 20553793 DOI: 10.1016/j.biopsycho.2010.05.005] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 05/19/2010] [Accepted: 05/20/2010] [Indexed: 10/19/2022]
Abstract
Despite their extensive use, the reproducibility of cardiac autonomic measurements in children is not well-known. We investigated the reproducibility of short-term continuous measurements of heart rate (HR), heart rate variability (HRV, time and frequency domain), and spontaneous baroreflex sensitivity (BRS, frequency domain) in the supine and standing position in 57 children (11.2+/-0.7 years, 52.6% boys). Reproducibility between two sessions within a two-week interval was evaluated by intraclass correlation coefficients (ICCs), standard error of measurement, coefficients of variation (CVs), limits of agreement, and Bland-Altman plots. HR and HRV were moderately-to-highly (ICC=.63-.79; CV=5.7%-9.7%) and BRS moderately (ICC=.49-.63; CV=11.4%-14.0%) reproducible. While the BRS measurements were slightly less reproducible than the HR and HRV measurements, all can be reliably applied in research, thus implicating sufficient capacity to detect real differences between children. Still, clinical studies focusing on individual changes in cardiac autonomic functioning need to address the considerable random variations that may occur between test-retest measurements.
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Affiliation(s)
- Andrea Dietrich
- Department of Psychiatry, Child and Adolescent Psychiatry, University Medical Center Groningen, University of Groningen, Groningen, The Netherlands.
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Ino-Oka E, Sekino H, Kajikawa S, Inooka H, Imai Y, Hashimoto J. Involvement of Carotid Baroreceptor Function in Blood Pressure Control in the Chronic Phase: Effect on 24-Hour Ambulatory Blood Pressure. Clin Exp Hypertens 2009; 30:69-78. [DOI: 10.1080/10641960701815895] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Meyhoff CS, Haarmark C, Kanters JK, Rasmussen LS. Is it possible to predict hypotension during onset of spinal anesthesia in elderly patients? J Clin Anesth 2009; 21:23-9. [DOI: 10.1016/j.jclinane.2008.06.015] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/17/2007] [Revised: 06/16/2008] [Accepted: 06/19/2008] [Indexed: 10/21/2022]
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Krabbendam I, Jacobs LCA, Lotgering FK, Spaanderman MEA. Venous response to orthostatic stress. Am J Physiol Heart Circ Physiol 2008; 295:H1587-93. [PMID: 18708445 DOI: 10.1152/ajpheart.00571.2008] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Head-up tilt (HUT) induces a reduction in preload, which is thought to be restored through sympathetic venoconstriction, reducing unstressed volume (V(u)) and venous compliance (VeC). In this study, we assessed venous inflow and outflow responses and their reproducibility and determined the relation with autonomic function during HUT. Eight healthy non-pregnant women were subjected to 20 degrees head-down tilt to 60 degrees HUT at 20 degrees intervals. At each rotational step, we randomly assessed forearm pressure-volume (P-V) curves (venous occlusion plethysmography) during inflow (VeC(IN)) and outflow [venous emptying rate (VER(OUT))]. VeC(IN) was defined as the ratio of the slope of the volume-time curve and pressure-time curve, with direct intravenous pressure measurement. VER(OUT) was determined using the derivate of a quadratic regression model using cuff pressure. We defined V(u) as the y-intercept of the P-V curve. We calculated, for both methods, the coefficients of reproducibility (CR) and variation (CV). Vascular sympathetic activity was determined by spectral analysis. VeC(IN) decreased at each rotational step compared with the supine position (P<0.05), whereas VER(OUT) increased. CR of VeC(IN) was higher in the supine position than VER(OUT) but lower during HUT. CV varied between 19% and 25% (VeC(IN)) and between 12% and 21% (VER(OUT)). HUT decreased V(u). The change in VeC(IN) and VER(OUT) correlated with the change in vascular sympathetic activity (r= -0.36, P<0.01, and r=0.48, P<0.01). This is the first study in which a reproducible reduction in VeC(IN) and V(u) and a rise in VER(OUT) during HUT are documented. The alterations in venous characteristics relate to changes in vascular sympathetic activity.
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Affiliation(s)
- Ineke Krabbendam
- Department of Obstetrics and Gynecology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands.
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Kobayashi H. Inter- and Intra-Individual Variations of Heart Rate Variability in Japanese Males. J Physiol Anthropol 2007; 26:173-7. [PMID: 17435361 DOI: 10.2114/jpa2.26.173] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Abstract
Spectral components of heart rate variability (HRV) were repeatedly measured (4-8 measurements; mean: 6 measurements) in 75 healthy Japanese male subjects (age range: 20-61) under two postural conditions (standing and supine). Low-frequency (LF) and high-frequency (HF) components and mean heart rate (HR) were analyzed with special reference to individual variations, which were classified into two types: inter- (interV) and intra-individual variations (intraV). The percent contributions and coefficients of variations were calculated for both interV and intraV. Percent contributions of intraV (intraV%) of HR with standing and supine postures were 15.8 and 12.9%, respectively. The intraV% of HF and LF on standing were 31.5 and 26.5%, while those in the supine posture were 27.8 and 35.5%, respectively. The coefficients of interV (interCV) and intraV (intraCV) were also calculated. The interCVs of HR, HF, and LF on standing were 14.9, 41.4, and 48.4%, while those in the supine posture registered 16.2, 42.9, and 44.2%, respectively. The intraCVs of HR, HF, and LF on standing were 5.0, 19.7, and 21.2%, while those in the supine posture indicated 4.7, 20.1, and 23.0%, respectively. We also calculated the interV and intraV of logarithmic-transformed HRV indexes. The log-transformation remarkably diminished both variables: interCV and intraCV registered 14-16 and 6-7%, respectively. Although interV variations were considerably large, intraV variations of HRV were negligibly small. The HRV indexes decreased with age, although HR remained unchanged. The coefficients of determination (r2) were 14-34%. In the case of log-transformed HRV indexes, the coefficients of determination registered 9-15%, suggesting that 14-34% (raw) or 9-15% (log) of the observed interV may be due to variations in age.
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Wecht JM, Weir JP, Bauman WA. Blunted heart rate response to vagal withdrawal in persons with tetraplegia. Clin Auton Res 2006; 16:378-83. [PMID: 17066256 DOI: 10.1007/s10286-006-0367-y] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2006] [Accepted: 07/13/2006] [Indexed: 11/29/2022]
Abstract
Cardiovascular autonomic mechanisms control heart rate (HR) and determination of heart rate variability (HRV) permits the quantitative assessment of relative shifts in autonomic cardiac control during head-up tilt (HUT). The study herein used HRV techniques to determine the vagal and sympathetic contribution to the change in HR during HUT in persons with tetraplegia (T; n = 7) paraplegia (P; n = 7) and a non-spinal cord injured (non-SCI; n = 8) control group. Heart rate (HR) was continuously monitored and cardiovascular autonomic responses were assessed for 5-minutes at supine and at 45 degrees HUT. Change associated with tilt from supine to 45 degrees HUT was calculated for HR (deltaHR), high & low frequency HRV (HF & LF) and the LF/HF ratio. HR and LF power were lower in the T compared to the P and non-SCI groups at 45 degrees HUT, whereas there were no group differences for HF at 45 degrees HUT. The LF/HF ratio was lower in the T compared to the non-SCI group at 45 degrees HUT. The relationship between delta HR and delta HF response differed between groups (significant group x delta HF interaction) such that the slope of this relationship was reduced in the T (-1.026: 95% CI: -2.623 to 0.571) compared with the non-SCI (-6.985: 95% CI: -11.25 to 2.72) and P (-5.218: 95% CI: -8.197 to -2.239) groups. There was no significant interaction effect for the relationships between deltaHR and deltaLF or deltaLF/HF. In summary, although the magnitude of vagal withdrawal was comparable among the groups, the increase in HR was attenuated in the group with tetraplegia, which may reflect reduced sympathetic cardiac modulation or altered SA node responsiveness to vagal withdrawal.
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Affiliation(s)
- Jill M Wecht
- Veterans Affairs Medical Center, SCI, Bronx, NY, USA.
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