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Iellamo F. Acute responses and chronic adaptations to exercise in humans: a look from the autonomic nervous system window. J Sports Med Phys Fitness 2024; 64:137-150. [PMID: 37791830 DOI: 10.23736/s0022-4707.23.15353-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/05/2023]
Abstract
The objective of this review was to give an overview on the current knowledge on the neural mechanisms of cardiovascular regulation during acute exercise and the autonomic adaptations brought about by chronic exercise, that is, exercise training. Evidence derived mainly from human studies, which supports the contribution of the different control mechanisms, namely the centralcommand, the reflex drive from active muscles and the arterial baroreflex, with the attendant modifications in autonomic nervous system activity, in determining the acute cardiovascular responses to exercise are discussed, along with some controversial issues and evolving concepts in exercise physiology. In particular, data that show how the various neural mechanisms involved in cardiovascular regulation during exercise are differently modulated by factors related to the muscular activity being performed, such as the type and intensity of exercise and the size of the active muscle masses are presented, stressing the plasticity of the neural network. Thereafter, the clinical implications pertaining neural cardiovascular adaptations to exercise training are presented and discussed, in the context of cardiac diseases. In particular, I will summarize a series of investigations performed in our laboratory that utilized a new training methodology and different exercise formats to quantify the training load in cardiac patients. The way by which individualized exercise training doses affects the autonomic nervous system and the cardiorespiratory adaptations is highlighted.
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Affiliation(s)
- Ferdinando Iellamo
- Department of Clinical Sciences and Translational Medicine, Tor Vergata University, Rome, Italy -
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2
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Marques KC, Quaresma JAS, Falcão LFM. Cardiovascular autonomic dysfunction in "Long COVID": pathophysiology, heart rate variability, and inflammatory markers. Front Cardiovasc Med 2023; 10:1256512. [PMID: 37719983 PMCID: PMC10502909 DOI: 10.3389/fcvm.2023.1256512] [Citation(s) in RCA: 8] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2023] [Accepted: 08/18/2023] [Indexed: 09/19/2023] Open
Abstract
Long COVID is characterized by persistent signs and symptoms that continue or develop for more than 4 weeks after acute COVID-19 infection. Patients with Long COVID experience a cardiovascular autonomic imbalance known as dysautonomia. However, the underlying autonomic pathophysiological mechanisms behind this remain unclear. Current hypotheses include neurotropism, cytokine storms, and inflammatory persistence. Certain immunological factors indicate autoimmune dysfunction, which can be used to identify patients at a higher risk of Long COVID. Heart rate variability can indicate autonomic imbalances in individuals suffering from Long COVID, and measurement is a non-invasive and low-cost method for assessing cardiovascular autonomic modulation. Additionally, biochemical inflammatory markers are used for diagnosing and monitoring Long COVID. These inflammatory markers can be used to improve the understanding of the mechanisms driving the inflammatory response and its effects on the sympathetic and parasympathetic pathways of the autonomic nervous system. Autonomic imbalances in patients with Long COVID may result in lower heart rate variability, impaired vagal activity, and substantial sympathovagal imbalance. New research on this subject must be encouraged to enhance the understanding of the long-term risks that cardiovascular autonomic imbalances can cause in individuals with Long COVID.
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Affiliation(s)
| | - Juarez Antônio Simões Quaresma
- Center for Biological Health Sciences, State University of Pará (UEPA), Belém, Brazil
- School of Medicine, São Paulo University (USP), São Paulo, Brazil
- Tropical Medicine Center, Federal University of Pará (UFPA), Belém, Brazil
| | - Luiz Fábio Magno Falcão
- Center for Biological Health Sciences, State University of Pará (UEPA), Belém, Brazil
- School of Medicine, São Paulo University (USP), São Paulo, Brazil
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3
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Longo S, Legramante JM, Rizza S, Federici M. Vasovagal syncope: An overview of pathophysiological mechanisms. Eur J Intern Med 2023; 112:6-14. [PMID: 37030995 DOI: 10.1016/j.ejim.2023.03.025] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/13/2022] [Revised: 03/09/2023] [Accepted: 03/23/2023] [Indexed: 04/10/2023]
Abstract
Syncope is a short-term transient loss of consciousness, characterized by rapid onset and complete spontaneous recovery. According to the 2018 European Society of Cardiology guidelines, three different types of syncope have been identified. However, all forms of syncope share a common final pathophysiological event, global cerebral hypoperfusion, which results from the inability of the circulatory system to maintain blood pressure at the level required to efficiently supply blood to the brain. The vasovagal syncope (VVS) is the most common form of syncope. Although, VVS is generally harmless, its frequent occurrence can negatively affect quality of life and increase the risk of adverse events. The pathophysiological mechanisms underlying VVS remain obscure. The multifaceted nature of VVS presents a veritable challenge to understanding this condition and developing preventative strategies. Thus, the aim of this review was to discuss the factors contributing to the pathogenesis of VVS and provide guidance for future research.
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Affiliation(s)
- Susanna Longo
- Department of Systems Medicine, University of Rome Tor Vergata, Via Montpellier 1, Rome 00133 ITALY
| | - Jacopo M Legramante
- Department of Systems Medicine, University of Rome Tor Vergata, Via Montpellier 1, Rome 00133 ITALY
| | - Stefano Rizza
- Department of Systems Medicine, University of Rome Tor Vergata, Via Montpellier 1, Rome 00133 ITALY
| | - Massimo Federici
- Department of Systems Medicine, University of Rome Tor Vergata, Via Montpellier 1, Rome 00133 ITALY.
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4
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Sánchez-Marín D, Trujano-Camacho S, Pérez-Plasencia C, De León DC, Campos-Parra AD. LncRNAs driving feedback loops to boost drug resistance: sinuous pathways in cancer. Cancer Lett 2022; 543:215763. [PMID: 35680071 DOI: 10.1016/j.canlet.2022.215763] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 05/18/2022] [Accepted: 05/27/2022] [Indexed: 11/16/2022]
Abstract
Feedback loops mediate signaling pathways to maintain cellular homeostasis. There are two types, positive and negative feedback loops. Both are subject to alterations, and consequently can become pathogenic in the development of diseases such as cancer. Long noncoding RNAs (lncRNAs) are regulators of signaling pathways through feedback loops hidden as the dark regulatory elements yet to be described with great impact on cancer tumorigenesis, development, and drug resistance. Several feedback loops have been studied in cancer, however, how they are regulated by lncRNAs is hardly evident, setting a trending topic in oncological research. In this review, we recapitulate and discuss the feedback loops that are regulated by lncRNAs to promote drug resistance. Furthermore, we propose additional strategies that allow us to identify, analyze and comprehend feedback loops regulated by lncRNAs to induce drug resistance or even to gain insight into novel feedback loops that are stimulated under the pressure of treatment and consequently increase its efficacy. This knowledge will be useful to optimize the therapeutic use of oncological drugs.
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Affiliation(s)
- David Sánchez-Marín
- Laboratorio de Genómica. Instituto Nacional de Cancerología (INCan). San Fernando 22 Col. Sección XVI, C.P. 14080, Ciudad de México, México.
| | - Samuel Trujano-Camacho
- Laboratorio de Genómica. Instituto Nacional de Cancerología (INCan). San Fernando 22 Col. Sección XVI, C.P. 14080, Ciudad de México, México.
| | - Carlos Pérez-Plasencia
- Laboratorio de Genómica. Instituto Nacional de Cancerología (INCan). San Fernando 22 Col. Sección XVI, C.P. 14080, Ciudad de México, México; Unidad de Biomedicina, FES-IZTACALA, Universidad Nacional Autónoma de México (UNAM), Tlalnepantla, 54090, Estado de México, México.
| | - David Cantú De León
- Unidad de Investigación Biomédica del Cáncer. Instituto Nacional de Cancerología (INCan). San Fernando 22 Col. Sección XVI, C.P. 14080, Ciudad de México, México.
| | - Alma D Campos-Parra
- Laboratorio de Genómica. Instituto Nacional de Cancerología (INCan). San Fernando 22 Col. Sección XVI, C.P. 14080, Ciudad de México, México.
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5
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Iellamo F, Perrone MA, Caminiti G, Volterrani M, Legramante JM. Post-exercise Hypotension in Patients With Coronary Artery Disease. Front Physiol 2021; 12:788591. [PMID: 35002770 PMCID: PMC8727444 DOI: 10.3389/fphys.2021.788591] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2021] [Accepted: 11/23/2021] [Indexed: 11/13/2022] Open
Abstract
Background: Blood pressure (BP) and hemodynamic changes occurring in the recovery phase after a single bout of exercise have not been extensively studied in coronary artery patients, despite the potential clinical implications of reducing BP through exercise. This study aimed at investigating the hemodynamic and arterial baroreflex mechanisms possibly involved in post-exercise hypotension (PEH) in patients with coronary artery disease.Methods: In 42 normotensive coronary artery patients undergone a Cardiac Rehabilitation Program, we evaluated before and after their daily exercise training session: blood pressure (BP) and heart rate (HR). In a subgroup (n = 29), daily BP profile was also evaluated by ambulatory BP monitoring. In those patients showing PEH (n = 15), we evaluated: Cardiac Output (CO), Stroke Volume (SV), total peripheral resistances (TPR), forearm (FVR) and calf (CVR) vascular resistances, and spontaneous baroreflex sensitivity (BRS).Results: After exercise TPR was significantly reduced with a similar contribution from CVR and FVR, whereas CO and SV significantly increased. BRS showed a significant reduction mainly due to a BRS decrease in response to hypertensive stimuli. Systolic BP (SBP) was significantly reduced for 12 h after the end of a single exercise session.Conclusion: These findings indicate that in coronary artery patients, the recovery phase after exercise is characterized by PEH which is mediated mainly by a generalized peripheral vasodilation and appears to influence BP behavior throughout the daily life. Finally, the cardiac component of the arterial baroreflex seems to contribute indirectly to BP reduction occurring after exercise.
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Affiliation(s)
- Ferdinando Iellamo
- Dipartimento di Scienze Cliniche e Medicina Traslazionale, Università Tor Vergata, Rome, Italy
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy
- *Correspondence: Ferdinando Iellamo,
| | - Marco Alfonso Perrone
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy
| | - Giuseppe Caminiti
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy
| | - Maurizio Volterrani
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy
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The effect of heart rate variability on blood pressure is augmented in spinal cord injury and is unaltered by exercise training. Clin Auton Res 2020; 31:293-301. [DOI: 10.1007/s10286-020-00677-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2019] [Accepted: 02/28/2020] [Indexed: 10/24/2022]
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Draghici AE, Taylor JA. Baroreflex autonomic control in human spinal cord injury: Physiology, measurement, and potential alterations. Auton Neurosci 2017; 209:37-42. [PMID: 28844537 DOI: 10.1016/j.autneu.2017.08.007] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2016] [Revised: 07/25/2017] [Accepted: 08/16/2017] [Indexed: 12/27/2022]
Abstract
The arterial baroreflex is a primary regulator of autonomic outflow to effectively regulate acute changes in blood pressure. After a spinal cord injury (SCI), regulation of autonomic function is disrupted, although the damage of the autonomic pathways may not necessarily be related to the severity of injury (i.e. level and completeness). Nonetheless, it can be assumed that there would be greater loss of sympathetic innervation with higher level of injury and that cardiac parasympathetic control would remain intact regardless of injury level. In those with SCI, impaired baroreflex regulation has implications not only for adequate pressure regulation, but also for long term cardiovascular health. In this review, we discuss the expected impact ofan SCI on baroreflex control and the studies that have investigated baroreflex sensitivity in this population. The data generally indicates that baroreflex sensitivity is lesser in those with chronic injuries. However, these findings are counter to the expected effect of an SCI and hence may indicate that the effect of an SCI on baroreflex control might be secondary to long term deconditioning and/or vascular stiffening of baroreceptive arteries. Furthermore, the alterations in the ability to regulate pressure do not impact the relationship between spontaneous heart rate and blood pressure variabilities. In addition, those with SCI are not adequately able to control blood pressure changes in response to orthostasis, resulting in frank hypotension in a significant proportion of those with high level injuries.
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Affiliation(s)
- Adina E Draghici
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, United States; Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States.
| | - J Andrew Taylor
- Department of Physical Medicine and Rehabilitation, Harvard Medical School, Boston, MA, United States; Cardiovascular Research Laboratory, Spaulding Rehabilitation Hospital, Cambridge, MA, United States
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Ondrusova K, Svacinova J, Javorka M, Novak J, Novakova M, Novakova Z. Impaired Baroreflex Function during Orthostatic Challenge in Patients after Spinal Cord Injury. J Neurotrauma 2017; 34:3381-3387. [PMID: 28605971 DOI: 10.1089/neu.2017.4989] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
The level of spinal cord injury (SCI) affects baroreflex regulation of blood pressure. While a parasympathetic cardiac chronotropic effect is preserved, baroreflex response could be impaired by sympathetic dysfunction under the SCI level. This study was aimed to evaluate the baroreflex function in SCI patients by the analysis of causal interaction between systolic blood pressure (SBP) and inter-beat intervals (IBI). Blood pressure was continuously recorded in 13 cervical SCI patients (CSCI), nine thoracic SCI (ThSCI) and 13 able-bodied controls (Con) during two phases: sitting (PS) and orthostatic challenge (PO). Beat-to-beat SBP and IBI sequences were obtained from continuous blood pressure recording. Closed loop of SBP-IBI interaction was mathematically opened by bivariate autoregressive model; causal coherence and baroreflex sensitivity (BRS) were calculated in baroreflex direction. Coherence quantifies causal synchronicity between SBP and IBI. The gain of transfer function from SBP to IBI represents BRS. PS (medians of CSCI/ThSCI/Con) coherence was 0.28/0.33/0.25 (no significant difference) and PS BRS was 6.98/7.54/6.66 (no difference). PO coherence was 0.18/0.58/0.45 (CSCI < ThCSI and Con; p < 0.01) and PO BRS was 2.38/5.87/6.22 (CSCI < ThCSI and Con; p < 0.01). For position change effect, there was no change in CSCI coherence; for ThSCI and Con, PS < PO (p < 0.05). For BRS in the CSCI group, PS < PO (p < 0.01); for ThSCI and Con, there was no change. BRS and coherence correlated negatively with SCI level (p < 0.01). In conclusion, baroreflex dysfunction in SCI patients was detected using causal analysis methods during orthostatic challenge only. Baroreflex dysfunction is probably an important mechanism of the more expressed blood pressure decrease associated with CSCI. The severity of autonomic dysfunction was related to SCI level.
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Affiliation(s)
| | - Jana Svacinova
- 1 Department of Physiology, Masaryk University , Brno, Czech Republic
| | - Michal Javorka
- 2 Department of Physiology, Comenius University in Bratislava , Martin, Slovakia .,3 Biomedical Center Martin, Comenius University in Bratislava , Martin, Slovakia
| | - Jan Novak
- 1 Department of Physiology, Masaryk University , Brno, Czech Republic
| | - Marie Novakova
- 1 Department of Physiology, Masaryk University , Brno, Czech Republic .,4 International Clinical Research Center, St. Anne's University Hospital Brno , Brno, Czech Republic
| | - Zuzana Novakova
- 1 Department of Physiology, Masaryk University , Brno, Czech Republic
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Bellia A, Iellamo F, De Carli E, Andreadi A, Padua E, Lombardo M, Annino G, Campoli F, Tartaglione S, D'Ottavio S, Della-Morte D, Lauro D. Exercise individualized by TRIMPi method reduces arterial stiffness in early onset type 2 diabetic patients: A randomized controlled trial with aerobic interval training. Int J Cardiol 2017; 248:314-319. [PMID: 28716522 DOI: 10.1016/j.ijcard.2017.06.065] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/26/2017] [Revised: 06/02/2017] [Accepted: 06/15/2017] [Indexed: 12/11/2022]
Abstract
BACKGROUND Arterial stiffness (AS) and baroreflex sensitivity (BRS) are subclinical markers of vascular diseases in type 2 diabetes (T2D). We evaluated the effects of aerobic interval training (AIT), with loads prescribed according to individual heart rate and lactate profiling obtained during a baseline treadmill test (TRIMPi method), on AS and BRS in patients with early-onset T2D without cardiovascular complications. POPULATION STUDY AND METHODS Twenty-two sedentary overweight T2D patients (aged 57±7years) were randomized to 12-weeks open-label of supervised AIT by TRIMPi (n=8) or unsupervised physical activity as per usual care (SOC) (n=11). Following parameters were evaluated (pre- and post-): anthropometrics; six-minute walking test (6MWT); fasting glucose, insulin, HbA1c; Pulse Wave Velocity (PWV) and Augmentation Index (AIxHR75) using radial approach (SphigmoCor System); BRS using Finapress method. RESULTS Both interventions significantly improved distance walked during 6MWT (AIT 52±21m; SOC 39±24m, p<0.001 for both). PWV significantly improved with AIT (p<0.001) whereas did not vary with SOC (p=0.47). Similar trend was observed for AIxHR75. Resulting percent changes from baseline were significantly better for AIT vs SOC, in both PWV (-15.8±2.1 vs +1.50±3.4%, p<0.001) and AIxHR75 (-28.9±3.2% vs +12.7±2.4%, p<0.001). BRS similarly improved in both groups (p<0.001 for both), as well as body weight, HbA1c and blood pressure. CONCLUSION In sedentary T2D patients, 12-weeks AIT individualized by TRIMPi method improved AS to a greater extent than usual recommendation on physical activity, whilst exerting comparable effects on exercise capacity, glycemic control and body weight. Further researches are needed to ascertain durability of these effects.
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Affiliation(s)
- Alfonso Bellia
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy; Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Ferdinando Iellamo
- Department of Clinical Sciences and Translational Medicine, University "Tor Vergata", Rome, Italy; Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS) San Raffaele Pisana, Rome, Italy
| | - Elisa De Carli
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy
| | | | - Elvira Padua
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Mauro Lombardo
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Giuseppe Annino
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy
| | - Francesca Campoli
- Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Sara Tartaglione
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy
| | - Stefano D'Ottavio
- Department of Clinical Sciences and Translational Medicine, University "Tor Vergata", Rome, Italy
| | - David Della-Morte
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy; Department of Human Sciences and Promotion of the Quality of Life, San Raffaele Roma Open University, Rome, Italy
| | - Davide Lauro
- Department of Systems Medicine, University "Tor Vergata", Rome, Italy.
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Panzarino M, Gravina A, Carosi V, Crobeddu P, Tiroli A, Lombardi R, D'Ottavio S, Galante A, Legramante JM. Cardiovascular and hemodynamic responses to adapted physical exercises in very old adults. Aging Clin Exp Res 2017; 29:419-426. [PMID: 27324693 DOI: 10.1007/s40520-016-0598-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Accepted: 05/25/2016] [Indexed: 11/28/2022]
Abstract
BACKGROUND Aging is characterized by a physiological reduction in physical activity, which is inversely correlated with survival. AIMS Aim of the present study is to evaluate the cardiovascular, central hemodynamic and autonomic responses to a single bout of adapted physical exercise in octogenarian subjects. METHODS We studied cardiovascular, hemodynamic and autonomic responses to adapted physical activity in 33 subjects by a noninvasive methodology (Nexfin®, Edwards Lifesciences Corporation). RESULTS Our octogenarians presented a significant increase in mean arterial pressure (p < 0.01) and heart rate (p < 0.005) in response to exercise, while both are reduced during the early recovery phase. Central hemodynamic showed a significant increase in stroke volume (p < 0.05), cardiac output (p < 0.01) and left ventricle contractility index (p < 0.01), whereas systemic vascular resistance showed a significant decrease (p < 0.001). We found a reduction in baroreflex control of the sinus node during exercise. DISCUSSION Our data demonstrate that in very old people adapted physical activity is able to activate cardiovascular system and to induce a postexercise hypotension similarly to adults. The baroreflex control of sinus node seems to contribute in the physiological mechanism of these cardiovascular adaptations. CONCLUSIONS In very old people, physical activity induces cardiovascular and hemodynamic responses not significantly different from those induced in adult even though some cautions particularly in the early recovery phase after exercise should be exercised.
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Affiliation(s)
- Michele Panzarino
- Advanced Technology in Rehabilitation Medicine, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
- Corso di Scienze Motorie, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
| | - Angela Gravina
- Medicina e Chirurgia d'accettazione e d'urgenza, Ospedale Maria Vittoria, via Cibrario 72, 10144, Turin, Italy
| | - Veronica Carosi
- Scuola di Specializzazione di Medicina Interna, Dipartimento di Medicina, Università degli Studi di Padova, Via Giustiniani 2, 35128, Padua, Italy
| | - Patrizio Crobeddu
- Divisione di Riabilitazione Cardiologica, San Raffaele, via di San Silvestro 67, Montecompatri, 00040, Rome, Italy
| | - Alessia Tiroli
- Dipartimento di Emergenza, Policlinico di Tor Vergata, Università "Tor Vergata", viale Oxford 81, 00133, Rome, Italy
| | - Roberto Lombardi
- Corso di Scienze Motorie, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
| | - Stefano D'Ottavio
- Advanced Technology in Rehabilitation Medicine, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
- Corso di Scienze Motorie, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
- Dipartimento di Medicina dei Sistemi, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy
| | - Alberto Galante
- Divisione di Riabilitazione Cardiologica, San Raffaele, via di San Silvestro 67, Montecompatri, 00040, Rome, Italy
| | - Jacopo M Legramante
- Dipartimento di Emergenza, Policlinico di Tor Vergata, Università "Tor Vergata", viale Oxford 81, 00133, Rome, Italy.
- Dipartimento di Medicina dei Sistemi, Università "Tor Vergata", via Montpellier 1, 00133, Rome, Italy.
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Xie L, Liu B, Wang X, Mei M, Li M, Yu X, Zhang J. Effects of different stresses on cardiac autonomic control and cardiovascular coupling. J Appl Physiol (1985) 2016; 122:435-445. [PMID: 27979981 DOI: 10.1152/japplphysiol.00245.2016] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 10/24/2016] [Accepted: 12/07/2016] [Indexed: 12/21/2022] Open
Abstract
The objective of this study was to investigate the impacts of different stresses on time-varying autonomic reactivity and cardiovascular coupling. In total, 25 male subjects were recruited. RR intervals (RRI), systolic and diastolic blood pressure (SBP, DBP), stroke volume (SV), cardiac output (CO), and systemic vascular resistance (SVR) values were collected during rest, mental arithmetic task (MAT), and cold pressor test (CPT). Baroreflex sensitivity (BRS) was derived using the transfer function method. Continuous wavelet transformation of RRI was used to describe the time-variant patterns of autonomic neural activities. Wavelet cross correlation and phase synchronization were used to estimate the amplitude and phase coupling between RRI and SBP. MAT was characterized by increased heart rate (HR), SBP, DBP, and CO with decreased BRS attributable to prolonged parasympathetic withdrawal. Moreover, cardiovascular coupling was disrupted in MAT. These results indicated that baroreflex was depressed, and the top-down system started to take action under mental stress. In CPT, SBP, DBP, and SVR increased significantly, whereas HR and BRS remained unchanged. The increase of sympathetic activity was transient, and cardiovascular coupling did not change in CPT. Intriguingly, the frequency of the maximum cross-correlation coefficient in the low-frequency band (0.04-0.15 Hz) was significantly decreased in CPT, which may be due to the change of resonance frequency of the baroreflex loop.NEW & NOTEWORTHY The study is the first to compare the time-variant pattern of autonomic nervous activities and cardiovascular coupling between the mental arithmetic task (MAT) and the cold pressor test (CPT). Our results demonstrated that MAT and CPT elicited different time-varying patterns of autonomic neural activities and cardiovascular synchronization. Both the amplitude and phase consistency of blood pressure and heart rate decreased in MAT. CPT may affect the harmonic frequency of the baroreflex loop.
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Affiliation(s)
- Lin Xie
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
| | - Binbin Liu
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
| | - Xiaoni Wang
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
| | - Mengqi Mei
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
| | - Mengjun Li
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
| | - Xiaolin Yu
- Department of Information Engineering, Officers College of CAPF, Chengdu, China
| | - Jianbao Zhang
- Key Laboratory of Biomedical Information Engineering of Education Ministry, Xi'an Jiaotong University, Xi'an, China; and
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12
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Fortrat JO, Levrard T, Courcinous S, Victor J. Self-Organization of Blood Pressure Regulation: Experimental Evidence. Front Physiol 2016; 7:112. [PMID: 27065880 PMCID: PMC4814514 DOI: 10.3389/fphys.2016.00112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/11/2016] [Indexed: 11/13/2022] Open
Abstract
Blood pressure regulation is a prime example of homeostatic regulation. However, some characteristics of the cardiovascular system better match a non-linear self-organized system than a homeostatic one. To determine whether blood pressure regulation is self-organized, we repeated the seminal demonstration of self-organized control of movement, but applied it to the cardiovascular system. We looked for two distinctive features peculiar to self-organization: non-equilibrium phase transitions and hysteresis in their occurrence when the system is challenged. We challenged the cardiovascular system by means of slow, 20-min Tilt-Up and Tilt-Down tilt table tests in random order. We continuously determined the phase between oscillations at the breathing frequency of Total Peripheral Resistances and Heart Rate Variability by means of cross-spectral analysis. We looked for a significant phase drift during these procedures, which signed a non-equilibrium phase transition. We determined at which head-up tilt angle it occurred. We checked that this angle was significantly different between Tilt-Up and Tilt-Down to demonstrate hysteresis. We observed a significant non-equilibrium phase transition in nine healthy volunteers out of 11 with significant hysteresis (48.1 ± 7.5° and 21.8 ± 3.9° during Tilt-Up and Tilt-Down, respectively, p < 0.05). Our study shows experimental evidence of self-organized short-term blood pressure regulation. It provides new insights into blood pressure regulation and its related disorders.
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Affiliation(s)
- Jacques-Olivier Fortrat
- CaDyWec Associated Lab, Faculté de Médecine d'Angers, UMR Centre National De La Recherche Scientifique 6214 Institut national de la santé et de la recherche médicale 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée) Angers, France
| | - Thibaud Levrard
- CaDyWec Associated Lab, Faculté de Médecine d'Angers, UMR Centre National De La Recherche Scientifique 6214 Institut national de la santé et de la recherche médicale 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée) Angers, France
| | - Sandrine Courcinous
- CaDyWec Associated Lab, Faculté de Médecine d'Angers, UMR Centre National De La Recherche Scientifique 6214 Institut national de la santé et de la recherche médicale 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée) Angers, France
| | - Jacques Victor
- CaDyWec Associated Lab, Faculté de Médecine d'Angers, UMR Centre National De La Recherche Scientifique 6214 Institut national de la santé et de la recherche médicale 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée) Angers, France
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Fortrat JO, Gharib C. Self-Organization of Blood Pressure Regulation: Clinical Evidence. Front Physiol 2016; 7:113. [PMID: 27065881 PMCID: PMC4812062 DOI: 10.3389/fphys.2016.00113] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2015] [Accepted: 03/11/2016] [Indexed: 11/19/2022] Open
Abstract
The pathogenesis of vasovagal syncope has remained elusive despite many efforts to identify an underlying dysfunction. Catastrophe theory explains the spontaneous occurrence of sudden events in some mathematically complex systems known as self-organized systems poised at criticality. These systems universally exhibit a power law initially described in earthquake occurrence: the Gutenberg Richter law. The magnitude plotted against the total number of earthquakes of at least this magnitude draw a straight line on log-log graph. We hypothesized that vasovagal syncope is a catastrophe occurring spontaneously in the cardiovascular system. We counted the number and magnitude (number of beats) of vasovagal reactions (simultaneous decreases in both blood pressure and heart rate on consecutive beats) in 24 patients with vasovagal symptoms during a head-up tilt test and 24 paired patients with no symptoms during the test. For each patient, we checked whether vasovagal reaction occurrence followed the Gutenberg Richter law. The occurrence followed the Gutenberg Richter law in 43 patients (correlation coefficient |r| = 0.986 ± 0.001, mean ± SEM) out of 48, with no difference between patients with and without symptoms. We demonstrated that vasovagal syncope matches a catastrophe model occurring in a self-organized cardiovascular complex system poised at criticality. This is a new vision of cardiovascular regulation and its related disorders.
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Affiliation(s)
- Jacques-Olivier Fortrat
- UMR Centre National de la Recherche Scientifique 6214 Institut National de la Santé et de la Recherche Médicale 1083 (Biologie Neurovasculaire et Mitochondriale Intégrée), Faculté de Médecine d'Angers Angers, France
| | - Claude Gharib
- Université Claude Bernard Lyon 1, Faculté de Médecine Lyon EstLyon, France; Centre International d'OstéopathieSaint Etienne, France
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Sarabadani Tafreshi A, Klamroth-Marganska V, Nussbaumer S, Riener R. Real-Time Closed-Loop Control of Human Heart Rate and Blood Pressure. IEEE Trans Biomed Eng 2015; 62:1434-1442. [DOI: 10.1109/tbme.2015.2391234] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
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Ahn S, Solfest J, Rubchinsky LL. Fine temporal structure of cardiorespiratory synchronization. Am J Physiol Heart Circ Physiol 2014; 306:H755-63. [DOI: 10.1152/ajpheart.00314.2013] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Cardiac and respiratory rhythms are known to exhibit a modest degree of phase synchronization, which is affected by age, diseases, and other factors. We study the fine temporal structure of this synchrony in healthy young, healthy elderly, and elderly subjects with coronary artery disease. We employ novel time-series analysis to explore how phases of oscillations go in and out of the phase-locked state at each cycle of oscillations. For the first time we show that cardiorespiratory system is engaged in weakly synchronized dynamics with a very specific temporal pattern of synchrony: the oscillations go out of synchrony frequently, but return to the synchronous state very quickly (usually within just 1 cycle of oscillations). Properties of synchrony depended on the age and disease status. Healthy subjects exhibited more synchrony at the higher (1:4) frequency-locking ratio between respiratory and cardiac rhythms, whereas subjects with coronary artery disease exhibited relatively more 1:2 synchrony. However, multiple short desynchronization episodes prevailed regardless of the age and disease status. The same average synchrony level could be alternatively achieved with few long desynchronizations, but this was not observed in the data. This implies functional importance of short desynchronization dynamics. These dynamics suggest that a synchronous state is easy to create if needed but is also easy to break. Short desynchronization dynamics may facilitate the mutual coordination of cardiac and respiratory rhythms by creating intermittent synchronous episodes. It may be an efficient background dynamics to promote adaptation of cardiorespiratory coordination to various external and internal factors.
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Affiliation(s)
- Sungwoo Ahn
- Department of Mathematical Sciences and Center for Mathematical Biosciences, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana; and
| | - Jessica Solfest
- Department of Mathematical Sciences and Center for Mathematical Biosciences, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana; and
| | - Leonid L. Rubchinsky
- Department of Mathematical Sciences and Center for Mathematical Biosciences, Indiana University-Purdue University Indianapolis, Indianapolis, Indiana; and
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana
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Sapoznikov D, Dranitzki Elhalel M, Rubinger D. Heart rate response to blood pressure variations: sympathetic activation versus baroreflex response in patients with end-stage renal disease. PLoS One 2013; 8:e78338. [PMID: 24124623 PMCID: PMC3790707 DOI: 10.1371/journal.pone.0078338] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2013] [Accepted: 09/18/2013] [Indexed: 11/29/2022] Open
Abstract
Background Continuous systolic blood pressure (SBP) and interbeat intervals (IBI) recordings reveal sequences of consecutive beats in which SBP and heart rate change in opposite direction, representing negative feedback baroreflex mechanisms, as well as sequences in which SBP and heart rate change in the same direction (non-baroreflex), believed to represent feedforward control mechanisms. The present study was undertaken to assess the relationship between baroreflex and non-baroreflex sequences in end stage renal insufficiency. Methodology/Principal Findings Continuous beat-to-beat SBP and IBI monitoring was performed in patients on chronic hemodialysis (HD, n=72), in age-matched patients after renal transplantation (TX, n=41) and healthy (control) individuals (C, n=34). The proportion of baroreflex and nonbaroreflex episodes and the b coefficients (the regression line slope of SBP-IBI correlation) were determined using a newly developed 1 minute sliding window method, the classical sequence technique and the "Z" coefficient method. Analysis using the 1 minute sliding window showed an increased proportion of baroreflex episodes in controls and HD, and predominance of nonbaroreflex episodes in TX. An increased proportion of nonbaroreflex episodes in TX patients relative to HD was also revealed by the "Z" method. Baroreflex and nonbaroreflex b coefficients obtained by all methods were markedly decreased in HD. This alteration was reversed at least partly in TX. In HD, both baroreflex and nonbaroreflex b coefficients were inversely correlated to age and CRP levels; in TX, the nonbaroreflex b coefficient was influenced by the type of calcineurin inhibitor. Conclusion/Significance Renal status affects the contribution of baroreflex and nonbaroreflex mechanisms and the strength of SBP-IBI relationship. The predominant contribution of nonbaroreflex mechanisms in TX may be suggestive of enhanced central sympathetic control. Our data may be relevant for understanding of the pathogenesis and selection of appropriate treatment of post-transplant hypertension.
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Affiliation(s)
- Dan Sapoznikov
- Nephrology and Hypertension Services, Department of Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Michal Dranitzki Elhalel
- Nephrology and Hypertension Services, Department of Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel
| | - Dvora Rubinger
- Nephrology and Hypertension Services, Department of Medicine, Hadassah Hebrew University Medical Center, Jerusalem, Israel
- * E-mail:
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Cardiovascular control and stabilization via inclination and mobilization during bed rest. Med Biol Eng Comput 2013; 52:53-64. [PMID: 24096595 DOI: 10.1007/s11517-013-1119-5] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2012] [Accepted: 09/25/2013] [Indexed: 10/26/2022]
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Phillips AA, Krassioukov AV, Ainslie PN, Warburton DE. Baroreflex Function after Spinal Cord Injury. J Neurotrauma 2012; 29:2431-45. [DOI: 10.1089/neu.2012.2507] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Affiliation(s)
- Aaron A. Phillips
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
| | - Andrei V. Krassioukov
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
- Division of Physical Medicine and Rehabilitation, Department of Medicine, University of British Columbia, British Columbia, Canada
| | - Philip N. Ainslie
- School of Health and Exercise Sciences, Faculty of Health and Social Development, University of British Columbia Okanagan, Kelowna, British Columbia, Canada
| | - Darren E.R. Warburton
- Cardiovascular Physiology and Rehabilitation Laboratory, Physical Activity Promotion and Chronic Disease Prevention Unit, University of British Columbia, British Columbia, Canada
- Experimental Medicine Program, Faculty of Medicine, University of British Columbia, British Columbia, Canada
- International Collaboration of Repair Discoveries, University of British Columbia, British Columbia, Canada
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Patil AG, Chile RH, Hamde ST. Statistical analysis of RR series variability in spinal cord injured persons. J Med Eng Technol 2012; 36:180-4. [PMID: 22420781 DOI: 10.3109/03091902.2012.663053] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Disabled persons with spinal cord injury are prone to cardiovascular dysfunction and an increased risk of cardiovascular disease. Rehabilitation of the disabled person is a critical task as it involves multiple therapies. Physical exercise is an important component of rehabilitation, and depends on cardiovascular health. Reduced RR variability is a marker of poor cardiac health. Time domain RR variability analysis of 38 normal healthy subjects and 20 spinal cord injured subjects has been carried out and compared. In this study, RR intervals were recorded in three different modes or positions: supine, sitting and five-second rhythm respiration. At a time of 150 s RR interval data were acquired in each mode and analysed. Statistical parameters (mean, HR, STD, NN50 and pNN50) were calculated. It was observed that most of the indices were significantly and substantially altered in spinal cord injured persons.
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Affiliation(s)
- A G Patil
- Shri Bhagubhai Mafatlal Polytechnic, Vile Parle (West), Mumbai, India.
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West CR, Mills P, Krassioukov AV. Influence of the neurological level of spinal cord injury on cardiovascular outcomes in humans: a meta-analysis. Spinal Cord 2012; 50:484-92. [DOI: 10.1038/sc.2012.17] [Citation(s) in RCA: 100] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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Iellamo F, Manzi V, Caminiti G, Sposato B, Massaro M, Cerrito A, Rosano G, Volterrani M. Dose-response relationship of baroreflex sensitivity and heart rate variability to individually-tailored exercise training in patients with heart failure. Int J Cardiol 2011; 166:334-9. [PMID: 22078985 DOI: 10.1016/j.ijcard.2011.10.082] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/06/2011] [Accepted: 10/18/2011] [Indexed: 12/21/2022]
Abstract
BACKGROUND Heart Rate Variability (HRV) and Baroreflex Sensitivity (BRS) are impaired in patients with Chronic Heart Failure (CHF) and carry negative prognosis. Exercise training improves these parameters. However, the relationship between exercise training with HRV and BRS has been investigated without regard for individual training loads. We tested the hypothesis that in CHF patients changes in HRV and BRS are dose-response related to individual volume/intensity training load (TL). METHODS Twenty patients with stable postinfarction CHF under optimal medical treatment were randomized to either aerobic continuous training (ACT) or aerobic interval training (AIT) for 12weeks. Individualized TL was monitored by the Training Impulses (TRIMPi) method, which was determined using the individual HR and lactate profiling determined during a treadmill test at baseline. HRV (standard deviation of mean R-R interval) and BRS were assessed at rest and 3weeks apart, throughout the study. RESULTS HRV, BRS and R-R interval increased significantly with training, being very highly correlated to the dose of exercise with a second-order regression model (r(2) ranged from 0.75 to 0.96; P<0.001), resembling a bell-shaped in the ACT, and an asymptotic-shaped curve in the AIT groups, respectively. These changes were accompanied by a significant increase in functional capacity. No significant differences were detected between ACT and AIT in any variable. CONCLUSIONS These results suggest that improvements in HRV and BRS by exercise training in CHF patients are dose related to TL in a non-linear fashion on an individual basis, with optimal results at moderate doses of exercise.
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Affiliation(s)
- Ferdinando Iellamo
- Istituto di Ricovero e Cura a Carattere Scientifico San Raffaele Pisana, Rome, Italy.
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Cloutier F, Lauschke JL, Carrive P. Compensatory mechanisms to maintain blood pressure in paraplegic rats: implication of central tachykinin NK-1 and NK-3 receptors? Neuropeptides 2010; 44:199-207. [PMID: 20096457 DOI: 10.1016/j.npep.2009.12.012] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/04/2009] [Revised: 12/14/2009] [Accepted: 12/18/2009] [Indexed: 11/25/2022]
Abstract
People with high level spinal cord injury (SCI) suffer from both hypotension and spontaneous hypertension due to loss of supraspinal control of spinal sympathetic outflow. Few reports have addressed whether any changes occur in central regulation of blood pressure (BP) and heart rat (HR) at the supraspinal level. Central tachykinin NK-1 and NK-3 receptors are located in many cardiovascular areas in the brain and are known to modulate BP and HR. This study examined the intracerebroventricular (i.c.v.) effects of the selective NK-1 receptor agonist [Sar(9), Met(O(2))(11)]SP (65pmol, n=6) and NK-3 receptor agonist senktide (650pmol, n=6) on mean arterial pressure (MAP) and HR before and after complete spinal cord transection at thoracic level 4 (T4). [Sar(9), Met(O(2))(11)]SP evoked increases in MAP and HR which were still present 4days after the T4 SCI. Further analysis using the beta(1)-adrenoceptor antagonist atenolol (10mgkg(-1)) revealed an increased contribution of HR in the MAP increase after SCI. For senktide, 2 and 5weeks after T4 SCI, the rise in MAP induced by senktide was significantly increased in magnitude and was similar to a normal response at 8weeks. These effects were accompanied by a bradycardia, which was still present and amplified at 8weeks. Our results reveal a transient potentiation of the senktide-mediated MAP effect and a greater contribution of the HR in MAP increase by [Sar(9), Met(O(2))(11)]SP in T4 transected rats. Although the significance of these changes remains to be established. This suggest a reorganization of supraspinal mechanisms regulating BP and HR after a high level SCI. Central NK-1 and NK-3 receptors might therefore contribute to the maintenance of MAP following high thoracic SCI.
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Affiliation(s)
- Frank Cloutier
- Neural Injury Research Unit, School of Anatomy, University New South Wales Sydney, Australia.
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Legramante JM, Valentini F, Magrini A, Palleschi G, Sacco S, Iavicoli I, Pallante M, Moscone D, Galante A, Bergamaschi E, Bergamaschi A, Pietroiusti A. Cardiac autonomic regulation after lung exposure to carbon nanotubes. Hum Exp Toxicol 2009; 28:369-75. [PMID: 19755448 DOI: 10.1177/0960327109105150] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
The ultrafine (UF) component of airborne pollution may impair cardiovascular autonomic control, a high-risk condition for cardiovascular adverse events. Since engineered nanoparticles, such as single-walled carbon nanotubes (SWCNTs) share physicochemical properties with UF, they might have similar adverse effects. Aim of the study was to evaluate arterial baroreflex function (BRF) at baseline, 24 h after the first instillation, immediately before the second one, and 2 weeks later, in adult Wystar-Kyoto conscious rats undergoing two intratracheal instillations of SWCNT (eight rats) or phosphate buffer saline (PBS) (five rats) at 2-week interval. During each session, 30-min continuous recording of arterial pressure and pulse interval was performed by a telemetered catheter implanted in the abdominal aorta of the rats. BRF was studied by the sequence technique. SWCNTs dispersed in PBS (1 mg/ml) were administered immediately after sonication (1 microg/g body weight). A significant decrease in the number of baroreflex sequences (from 498 +/- 27.1 at baseline to 287 +/- 40.2 at the recording performed after 4 weeks; P < 0.05) was observed in SWCNT-instilled rats, whereas no significant change was detected in controls. These data suggest that SWCNTs may alter the BRF, thus affecting the autonomic cardiovascular control regulation.
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Affiliation(s)
- J M Legramante
- Department of Internal Medicine, Tor Vergata University Rome, Italy
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Caminiti G, Volterrani M, Iellamo F, Marazzi G, Massaro R, Miceli M, Mammi C, Piepoli M, Fini M, Rosano GMC. Effect of long-acting testosterone treatment on functional exercise capacity, skeletal muscle performance, insulin resistance, and baroreflex sensitivity in elderly patients with chronic heart failure a double-blind, placebo-controlled, randomized study. J Am Coll Cardiol 2009; 54:919-27. [PMID: 19712802 DOI: 10.1016/j.jacc.2009.04.078] [Citation(s) in RCA: 347] [Impact Index Per Article: 23.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/10/2009] [Revised: 04/08/2009] [Accepted: 04/29/2009] [Indexed: 02/02/2023]
Abstract
OBJECTIVES This study investigated the effect of a 12-week long-acting testosterone administration on maximal exercise capacity, ventilatory efficiency, muscle strength, insulin resistance, and baroreflex sensitivity (BRS) in elderly patients with chronic heart failure (CHF). BACKGROUND CHF is characterized by a metabolic shift favoring catabolism and impairment in skeletal muscle bulk and function that could be involved in the pathophysiology of heart failure. METHODS Seventy elderly patients with stable CHF-median age 70 years, ejection fraction 31.8 +/- 7%-were randomly assigned to receive testosterone (n = 35, intramuscular injection every 6 weeks) or placebo (n = 35), both on top of optimal medical therapy. At baseline and at the end of the study, all patients underwent echocardiogram, cardiopulmonary exercise test, 6-min walk test (6MWT), quadriceps maximal voluntary contraction (MVC), and isokinetic strength (peak torque) and BRS assessment (sequences technique). RESULTS Baseline peak oxygen consumption (VO(2)) and quadriceps isometric strength showed a direct relation with serum testosterone concentration. Peak VO(2) significantly improved in testosterone but was unchanged in placebo. Insulin sensitivity was significantly improved in testosterone. The MVC and peak torque significantly increased in testosterone but not in placebo. The BRS significantly improved in testosterone but not in placebo. Increase in testosterone levels was significantly related to improvement in peak VO(2) and MVC. There were no significant changes in left ventricular function either in testosterone or placebo. CONCLUSIONS These results suggest that long-acting testosterone therapy improves exercise capacity, muscle strength, glucose metabolism, and BRS in men with moderately severe CHF. Testosterone benefits seem to be mediated by metabolic and peripheral effects.
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Affiliation(s)
- Giuseppe Caminiti
- Centre for Clinical and Basic Research, Cardiovascular Research Unit, Department of Medical Sciences, IRCCS San Raffaele Pisana, Rome, Italy
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Nollo G, Faes L, Antolini R, Porta A. Assessing causality in normal and impaired short-term cardiovascular regulation via nonlinear prediction methods. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2009; 367:1423-40. [PMID: 19324717 DOI: 10.1098/rsta.2008.0275] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
We investigated the ability of mutual nonlinear prediction methods to assess causal interactions in short-term cardiovascular variability during normal and impaired conditions. Directional interactions between heart period (RR interval of the ECG) and systolic arterial pressure (SAP) short-term variability series were quantified as the cross-predictability (CP) of one series given the other, and as the predictability improvement (PI) yielded by the inclusion of samples of one series into the prediction of the other series. Nonlinear prediction was performed through global approximation (GA), approximation with locally constant models (LA0) and approximation with locally linear models (LA1) of the nonlinear function linking the samples of the two series, on patients with neurally mediated syncope and control subjects. Causality measures were evaluated in the two directions (from SAP to RR and from RR to SAP) in the supine (SU) position, in the upright position after head-up tilt (early tilt, ET) and after prolonged upright posture (late tilt, LT). While the trends for the GA, LA0 and LA1 methods were substantially superimposable, PI elicited better than CP the prevalence of causal coupling from RR to SAP during SU. Both CP and PI noted a marked decrease in coupling in both causal directions in syncope subjects during LT, documenting the impairment of cardiovascular regulation in the minutes just preceding syncope.
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Legramante JM, Sacco S, Raimondi G, Di Lecce VN, Pallante M, Di Nardo P, Galante A. Investigating feedforward neural regulation of circulation from analysis of spontaneous arterial pressure and heart rate fluctuations in conscious rats. Am J Physiol Heart Circ Physiol 2009; 296:H202-10. [DOI: 10.1152/ajpheart.00358.2008] [Citation(s) in RCA: 7] [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
It has been suggested in anesthetized animals that the occurrence of sequences of consecutive beats characterized by systolic arterial pressure (SAP) and RR or pulse interval (PI) changing in the opposite direction (SAP+/RR− and SAP−/RR+, nonbaroreflex sequences) might represent the expression of neural cardiovascular regulatory mechanisms operating with feedforward characteristics. The aim of the present study was to study nonbaroreflex sequences in a more physiological experimental model, i.e., in conscious freely moving rats. We studied conscious rats before and after 1) complete autonomic blockade ( n = 12), 2) sympathetic blockade ( n = 10), 3) α ( n = 7)- and β ( n = 8)-adrenergic blockade, and 4) parasympathetic blockade ( n = 10). Nonbaroreflex sequences were defined as three or more beats in which SAP and PI of the following beat changed in the opposite direction. Complete autonomic blockade reduced the number of nonbaroreflex sequences (95.6 ± 9.0 vs. 45.2 ± 4.1, P < 0.001), as did sympathetic blockade (80.9 ± 12.6 vs. 30.9 ± 6.1, P < 0.001). The selective α-receptor blockade did not induce significant changes (80.9 ± 12.5 in baseline vs. 79.0 ± 14.7 after prazosin), whereas β-receptor blockade significantly reduced nonbaroreflex sequence occurrence (80.9 ± 12.5 in baseline vs. 48.9 ± 15.3 after propranolol). Parasympathetic blockade produced a significant increase of nonbaroreflex sequences (95.1 ± 6.9 vs. 136.0 ± 12.4, P < 0.01). These results demonstrate the physiological role of the nonbaroreflex sequences as an expression of a feedforward type of short-term cardiovascular regulation able to interact dynamically with the feedback mechanisms of baroreflex origin in the neural control of the sinus node.
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Relationships between physiological responses and presyncope symptoms during tilting up in patients with spinal cord injury. Med Biol Eng Comput 2008; 46:681-8. [DOI: 10.1007/s11517-008-0322-2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/22/2006] [Accepted: 01/21/2008] [Indexed: 11/25/2022]
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Silvani A, Grimaldi D, Vandi S, Barletta G, Vetrugno R, Provini F, Pierangeli G, Berteotti C, Montagna P, Zoccoli G, Cortelli P. Sleep-dependent changes in the coupling between heart period and blood pressure in human subjects. Am J Physiol Regul Integr Comp Physiol 2008; 294:R1686-92. [PMID: 18272662 DOI: 10.1152/ajpregu.00756.2007] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether in human subjects, the pattern of coupling between the spontaneous fluctuations of heart period (HP) and those of systolic blood pressure (SBP) differs among wake-sleep states. Polysomnographic recordings and finger blood pressure measurements were performed for 48 h in 15 nonobese adults without sleep-disordered breathing. The cross-correlation function (CCF) between the fluctuations of HP and SBP at frequencies <0.15 Hz was computed during quiet wakefulness (QW), light (stages 1 and 2) and deep (stages 3 and 4) nonrapid-eye-movement sleep (NREMS), and rapid-eye-movement sleep (REMS). A positive correlation between HP and the previous SBP values, which is the expected result of baroreflex feedback control, was observed in the sleep states but not in QW. In deep NREMS, the maximum CCF value was significantly higher than in any other state, suggesting the greatest baroreflex contribution to the coupling between HP and SBP. A negative correlation between HP and the subsequent SBP values was also observed in each state, consistent with the mechanical feed-forward action of HP on SBP and with central autonomic commands. The contribution of these mechanisms to the coupling between HP and SBP, estimated from the minimum CCF value, was significantly lower in deep NREMS than either in light NREMS or QW. These results indicate that the pattern of coupling between HP and SBP at low frequencies differs among wake-sleep states in human subjects, with deep NREMS entailing the highest feedback contribution of the baroreflex and a low effectiveness of feed-forward mechanisms.
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Affiliation(s)
- Alessandro Silvani
- Dipartimento di Fisiologia Umana e Generale, Università di Bologna, Bologna, Italy.
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Berteotti C, Asti V, Ferrari V, Franzini C, Lenzi P, Zoccoli G, Silvani A. Central and baroreflex control of heart period during the wake-sleep cycle in spontaneously hypertensive rats. Am J Physiol Regul Integr Comp Physiol 2007; 293:R293-8. [PMID: 17459912 DOI: 10.1152/ajpregu.00086.2007] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated whether the relative contribution of the baroreflex and central commands to the control of heart period differs between spontaneously hypertensive rats (SHR) and Wistar-Kyoto normotensive rats (WKY) during physiological behavior. Rats were instrumented with an arterial catheter and with electrodes for discriminating wakefulness, nonrapid eye movement sleep (NREMS), and rapid eye movement sleep (REMS). The cross-correlation function (CCF) between spontaneous fluctuations of heart period and mean arterial pressure was computed at frequencies <0.2 Hz. The baroreflex determines a positive correlation between heart period and previous pressure values. This pattern was observed in the CCF during quiet wakefulness (QW) and NREMS, and in QW, it was accompanied by a pronounced negative correlation between heart period and subsequent pressure values. The relative baroreflex contribution to the control of heart period, estimated from the positive peak value of the CCF, was lower in SHR than in WKY during QW but not during NREMS. During REMS, the CCF showed a negative correlation between heart period and both previous and subsequent pressure values, reflecting the prevalence of central autonomic commands. The relative contribution of central commands to the control of heart period, estimated from the negative peak value of the CCF, was lower in SHR than in WKY during REMS. These results suggest that during QW and REMS, the control of heart period exerted by the baroreflex and central commands, respectively, is less effective in SHR than in WKY. This difference is not apparent in a behavioral state of autonomic stability such as NREMS.
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Affiliation(s)
- Chiara Berteotti
- Dipartimento di Fisiologia Umana e Generale, Università di Bologna, Piazza di Porta San Donato 2, 40126 Bologna, Italy
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Iellamo F, Sala-Mercado JA, Ichinose M, Hammond RL, Pallante M, Ichinose T, Stephenson LW, O'Leary DS. Spontaneous baroreflex control of heart rate during exercise and muscle metaboreflex activation in heart failure. Am J Physiol Heart Circ Physiol 2007; 293:H1929-36. [PMID: 17604328 DOI: 10.1152/ajpheart.00564.2007] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In heart failure (HF), there is a reduced baroreflex sensitivity at rest, and during dynamic exercise there is enhanced muscle metaboreflex activation (MRA). However, how the arterial baroreflex modulates HR during exercise is unknown. We tested the hypothesis that spontaneous baroreflex sensitivity (SBRS) is attenuated during exercise in HF and that MRA further depresses SBRS. In seven conscious dogs we measured heart rate (HR), cardiac output, and left ventricular systolic pressure at rest and during mild and moderate dynamic exercise, before and during MRA (via imposed reductions of hindlimb blood flow), and before and after induction of HF (by rapid ventricular pacing). SBRS was assessed by the sequences method. In control, SBRS was reduced from rest with a progressive resetting of the baroreflex stimulus-response relationship in proportion to exercise intensity and magnitude of MRA. In HF, SBRS was significantly depressed in all settings; however, the changes with exercise and MRA occurred with a pattern similar to the control state. As in control, the baroreflex stimulus-response relationship showed an intensity- and muscle metaboreflex (MMR)-dependent rightward and upward shift. The results of this study indicate that HF induces an impairment in baroreflex control of HR at rest and during exercise, although the effects of exercise and MRA on SBRS occur with a similar pattern as in control, indicating the persistence of some vagal activity.
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31
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Garstang SV, Miller-Smith SA. Autonomic Nervous System Dysfunction After Spinal Cord Injury. Phys Med Rehabil Clin N Am 2007; 18:275-96, vi-vii. [PMID: 17543773 DOI: 10.1016/j.pmr.2007.02.003] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
The autonomic nervous system (ANS) plays a key role in the regulation of many physiologic processes, mediated by supraspinal control from centers in the central nervous system. The role of autonomic dysfunction in persons with spinal cord injuries is crucial to understand because many aspects of the altered physiology seen in these individuals are directly caused by ANS dysregulation.
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Affiliation(s)
- Susan V Garstang
- Department of Physical Medicine and Rehabilitation, UMNDJ-New Jersey Medical School, 30 Bergen Street, ADMC 101, Newark, NJ 07039, USA.
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32
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Raimondi G, Contini S, Maria Legramante J, Bocchino M, Sacco S, Pallante M, Cazzola M, Saltini C. Autonomic nervous system dysfunction in the course of active pulmonary tuberculosis. Respir Med 2007; 101:1804-8. [PMID: 17399973 DOI: 10.1016/j.rmed.2007.02.008] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/30/2006] [Revised: 02/03/2007] [Accepted: 02/12/2007] [Indexed: 11/18/2022]
Abstract
BACKGROUND Functional alterations of the autonomic nervous system have been described in relation to chronic hypoxemia in chronic obstructive pulmonary diseases. Aim of the present study was to investigate the occurrence of neuro-vegetative dysfunction during active tuberculosis in the absence of hypoxemia. MATERIALS AND METHODS Fifteen patients affected by pulmonary tuberculosis under standard therapy and 17 matched controls were enrolled. Activation of the sympathetic system was induced by the tilt-up test. Systolic and diastolic arterial pressures and the R-R interval were monitored for 15 min by Finapres and ECG. The baroreflex sensitivity was evaluated by the spontaneous sequences method. RESULTS Systolic and diastolic pressures were significantly higher at basal conditions and showed a less increase during the tilt test in tuberculosis patients compared to healthy controls. The basal R-R interval was shorter and its reduction during the tilt test was less evident in patients. The baroreflex sensitivity was decreased in patients at basal conditions and its reduction during the tilt test was less evident than in controls. CONCLUSIONS Our preliminary results suggest the presence in tuberculosis patients of an altered autonomic cardiovascular regulation, which is a reduced function of the baroreflex control of the sinus node.
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Affiliation(s)
- Gianfranco Raimondi
- Postgraduate School of Respiratory Medicine, University of Rome Tor Vergata, Rome, Italy
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33
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Tanhoffer RA, Yamazaki RK, Nunes EA, Pchevozniki AI, Pchevozniki AM, Nogata C, Aikawa J, Bonatto SJ, Brito G, Lissa MD, Fernandes LC. Glutamine concentration and immune response of spinal cord-injured rats. J Spinal Cord Med 2007; 30:140-6. [PMID: 17591226 PMCID: PMC2031944 DOI: 10.1080/10790268.2007.11753925] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
BACKGROUND/OBJECTIVES Glutamine plays a key role in immune response. Spinal cord injury (SCI) leads to severe loss of muscle mass and to a high incidence of infections. This study investigated the acute effect of SCI (2 and 5 days) on the plasma glutamine and skeletal muscle concentrations and immune responses in rats. METHODS A total of 29 adult male Wistar rats were divided as follows: control (C; n = 5), sham-operated (S2; n = 5) and spinal cord-transected (T2; n = 7). They were killed on day 2 after surgery/transection (acute phase). Another set was sham-operated (S5; n = 5), spinal cord-transected (T5; n = 7), and killed at day 5 after surgery/transection (secondary phase). Blood was collected; the white portion of the epitrochlearis and gastrocnemius muscles and the red portion of soleus muscles were dissected to measure the glutamine concentration. Gut-associated lymphocytes and peritoneal macrophages were obtained for immune parameters measurements. RESULTS Glutamine concentration in the plasma, gastrocnemius, and soleus muscles in rats with SCI were significantly reduced but not in the epitrochlearis muscle in the acute (2 days) and secondary (5 days) phases. Phagocytic response was reduced in the acute phase but increased in the secondary phase in rats with SCI. Superoxide production, on the other hand, was significantly increased at days 2 and 5 after SCI, and CD8+ lymphocytes subset decreased significantly on days 2 and 5. CONCLUSIONS Our results showed reduction in plasma glutamine and skeletal muscle concentrations after spinal cord transection. They also suggest that SCI and glutamine reduction contribute to an alteration in immune competence.
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Affiliation(s)
- Ricardo A Tanhoffer
- Department of Physiology, Laboratory of Cellular Metabolism, Universidade Federal do Parana, Centro Politecnico-Jardim das Americas, Setor de Ciencias Biologicas, Curitiba, Parana, Brazil.
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Iellamo F. Prognostic role of baroreflex control of heart rate: further insights from dynamic assessment of baroreceptor-cardiac reflex? J Hypertens 2007; 25:51-3. [PMID: 17143172 DOI: 10.1097/hjh.0b013e3280113d4c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/23/2022]
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35
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Castiglioni P, Di Rienzo M, Veicsteinas A, Parati G, Merati G. Mechanisms of blood pressure and heart rate variability: an insight from low-level paraplegia. Am J Physiol Regul Integr Comp Physiol 2006; 292:R1502-9. [PMID: 17122332 DOI: 10.1152/ajpregu.00273.2006] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
It is still unclear whether the low-frequency oscillation in heart rate is generated by an endogenous neural oscillator or by a baroreflex resonance. Our aim was to investigate this issue by analyzing blood pressure and heart rate variability and the baroreflex function in paraplegic subjects with spinal cord injury below the fourth thoracic vertebra. These subjects were selected because they represent a model of intact central neural drive to the heart, with a partially impaired autonomic control of the vessels. In our study, arterial blood pressure and ECG were recorded in 33 able-bodied controls and in 33 subjects with spinal cord lesions between the fifth thoracic and the fourth lumbar vertebra 1) during supine rest (lowest sympathetic activation), 2) sitting on a wheelchair (light sympathetic activation), and 3) during exercise (moderate sympathetic activation). Blood pressure and heart rate spectra, coherence, and baroreflex function (sequence technique) were estimated in each condition. Compared with controls, paraplegic subjects showed a reduction of the low-frequency power of blood pressure and heart rate, and, unlike controls, a 0.1-Hz peak did not appear in their spectra. Sympathetic activation increased the 0.1-Hz peak of blood pressure and heart rate and the coherence at 0.1 Hz in controls only. Paraplegic subjects also had significantly lower baroreflex effectiveness and greater blood pressure variability. In conclusion, the disappearance of the 10-s oscillation of heart rate and blood pressure in subjects with spinal cord lesion supports the hypothesis of the baroreflex nature of this phenomenon.
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Affiliation(s)
- Paolo Castiglioni
- Centro di Bioingegneria, Fondazione Don C. Gnocchi ONLUS IRCCS, Via Capecelatro 66, 20135 Milano, Italy.
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Aslan SC, Randall DC, Donohue KD, Knapp CF, Patwardhan AR, McDowell SM, Taylor RF, Evans JM. Blood pressure regulation in neurally intact human vs. acutely injured paraplegic and tetraplegic patients during passive tilt. Am J Physiol Regul Integr Comp Physiol 2006; 292:R1146-57. [PMID: 17082357 DOI: 10.1152/ajpregu.00225.2006] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated autonomic control of cardiovascular function in able-bodied (AB), paraplegic (PARA), and tetraplegic (TETRA) subjects in response to head-up tilt following spinal cord injury. We evaluated spectral power of blood pressure (BP), baroreflex sensitivity (BRS), baroreflex effectiveness index (BEI), occurrence of systolic blood pressure (SBP) ramps, baroreflex sequences, and cross-correlation of SBP with heart rate (HR) in low (0.04-0.15 Hz)- and high (0.15-0.4 Hz)-frequency regions. During tilt, AB and PARA effectively regulated BP and HR, but TETRA did not. The numbers of SBP ramps and percentages of heartbeats involved in SBP ramps and baroreflex sequences increased in AB, were unchanged in PARA, and declined in TETRA. BRS was lowest in PARA and declined with tilt in all groups. BEI was greatest in AB and declined with tilt in all groups. Low-frequency power of BP and the peak of the SBP/HR cross-correlation magnitude were greatest in AB, increased during tilt in AB, remained unchanged in PARA, and declined in TETRA. The peak cross-correlation magnitude in HF decreased with tilt in all groups. Our data indicate that spinal cord injury results in decreased stimulation of arterial baroreceptors and less engagement of feedback control as demonstrated by lower 1) spectral power of BP, 2) number (and percentages) of SBP ramps and barosequences, 3) cross-correlation magnitude of SBP/HR, 4) BEI, and 5) changes in delay between SBP/HR. Diminished vasomotion and impaired baroreflex regulation may be major contributors to decreased orthostatic tolerance following injury.
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Affiliation(s)
- Sevda C Aslan
- Center for Biomedical Engineering, Wenner-Gren Research Laboratory, University of Kentucky, Lexington, KY 40506-0070, USA
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Gulli G, Claydon VE, Cooper VL, Hainsworth R. R–R interval–blood pressure interaction in subjects with different tolerances to orthostatic stress. Exp Physiol 2005; 90:367-75. [PMID: 15665146 DOI: 10.1113/expphysiol.2004.029496] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
In addition to the gain, the time delay in the input-output response in a feedback system is crucial for the maintenance of its stability. Patients with posturally related (vasovagal) syncope have inadequate control of blood pressure and one possible explanation for this could be prolonged latency of the baroreflex. We studied 14 patients with histories of syncope and poor orthostatic tolerance (assessed by a progressive orthostatic stress test) and 16 healthy controls. We performed spontaneous sequence analysis of the fluctuations of R-R period (ECG) and systolic arterial pressure (SAP, Finapres) recorded during a 20 min supine period and during 20 min 60 deg head-up tilt (HUT). The baroreflex latency was determined by identifying the lag between the changes in SAP and in R-R interval from which the highest correlation coefficient was obtained. During the supine period, 74% of sequences in control subjects and 54% in patients occurred with zero beats of delay (i.e. R-R interval changed within the same R-R interval). The remaining sequences occurred with delays of up to four beats. HUT shifted the baroreflex delay to be approximately one heartbeat slower and again patients showed more sequences with prolonged response. The delay in heartbeats was transformed into delay in time. In control subjects, 75% of baroreflex responses occurred within 1 s. In patients, 75% of baroreflex responses took more than 2 s to occur. The results showed that syncopal patients with poor orthostatic tolerance have increased baroreflex latency. This may lead to instability and inadequate blood pressure control and may predispose to vasovagal syncope.
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Affiliation(s)
- Giosuè Gulli
- Institute for Cardiovascular Research, University of Leeds, Leeds LS2 9JT.
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Nollo G, Faes L, Porta A, Antolini R, Ravelli F. Exploring directionality in spontaneous heart period and systolic pressure variability interactions in humans: implications in the evaluation of baroreflex gain. Am J Physiol Heart Circ Physiol 2004; 288:H1777-85. [PMID: 15604132 DOI: 10.1152/ajpheart.00594.2004] [Citation(s) in RCA: 83] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although in physiological conditions RR interval and systolic arterial pressure (SAP) are likely to interact in a closed loop, the traditional cross-spectral analysis cannot distinguish feedback (FB) from feedforward (FF) influences. In this study, a causal approach was applied for calculating the coherence from SAP to RR (K(s-r)) and from RR to SAP (K(r-s)) and the gain and phase of the baroreflex transfer function. The method was applied, compared with the noncausal one, to RR and SAP series taken from 15 healthy young subjects in the supine position and after passive head-up tilt. For the low frequency (0.04-0.15 Hz) spectral component, the enhanced FF coupling (K(r-s) = 0.59 +/- 0.21, significant in 14 subjects) and the blunted FB coupling (K(s-r) = 0.17 +/- 0.17, significant in 4 subjects) found at rest indicated the prevalence of nonbaroreflex mechanisms. The tilt maneuver recovered FB influences (K(s-r) = 0.47 +/- 0.16, significant in 14 subjects), which were stronger than FF interactions (K(s-r) = 0.34 +/- 0.19, significant in 9 subjects). At the respiratory frequency, the RR-SAP regulation was balanced at rest (K(s-r) = 0.30 +/- 0.18 and K(r-s) = 0.29 +/- 0.20, significant in 11 and 8 subjects) and shifted toward FB mechanisms after tilt (K(s-r) = 0.35 +/- 0.19 and K(r-s) = 0.19 +/- 0.11, significant in 14 and 8 subjects). The causal baroreflex gain estimates were always lower than the corresponding noncausal values and decreased significantly from rest to tilt in both frequency bands. The tilt-induced increase of the phase lag from SAP to RR suggested a shift from vagal to sympathetic modulation. Thus the importance of nonbaroreflex interactions pointed out the necessity of accounting for causality in the cross-spectral analysis of the interactions between cardiovascular variables in healthy humans.
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Affiliation(s)
- Giandomenico Nollo
- Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38050 Povo, Trento, Italy.
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Faes L, Porta A, Cucino R, Cerutti S, Antolini R, Nollo G. Causal transfer function analysis to describe closed loop interactions between cardiovascular and cardiorespiratory variability signals. BIOLOGICAL CYBERNETICS 2004; 90:390-399. [PMID: 15278463 DOI: 10.1007/s00422-004-0488-0] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2003] [Accepted: 04/28/2004] [Indexed: 05/24/2023]
Abstract
Although the concept of transfer function is intrinsically related to an input-output relationship, the traditional and widely used estimation method merges both feedback and feedforward interactions between the two analyzed signals. This limitation may endanger the reliability of transfer function analysis in biological systems characterized by closed loop interactions. In this study, a method for estimating the transfer function between closed loop interacting signals was proposed and validated in the field of cardiovascular and cardiorespiratory variability. The two analyzed signals x and y were described by a bivariate autoregressive model, and the causal transfer function from x to y was estimated after imposing causality by setting to zero the model coefficients representative of the reverse effects from y to x. The method was tested in simulations reproducing linear open and closed loop interactions, showing a better adherence of the causal transfer function to the theoretical curves with respect to the traditional approach in presence of non-negligible reverse effects. It was then applied in ten healthy young subjects to characterize the transfer functions from respiration to heart period (RR interval) and to systolic arterial pressure (SAP), and from SAP to RR interval. In the first two cases, the causal and non-causal transfer function estimates were comparable, indicating that respiration, acting as exogenous signal, sets an open loop relationship upon SAP and RR interval. On the contrary, causal and traditional transfer functions from SAP to RR were significantly different, suggesting the presence of a considerable influence on the opposite causal direction. Thus, the proposed causal approach seems to be appropriate for the estimation of parameters, like the gain and the phase lag from SAP to RR interval, which have a large clinical and physiological relevance.
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Affiliation(s)
- L Faes
- Lab. Biosegnali, Dipartimento di Fisica, Universitá di Trento, via Sommarive 14, 38050 Trento, Povo, Italy.
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40
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Nollo G, Faes L, Porta A, Pellegrini B, Ravelli F, Del Greco M, Disertori M, Antolini R. Evidence of unbalanced regulatory mechanism of heart rate and systolic pressure after acute myocardial infarction. Am J Physiol Heart Circ Physiol 2002; 283:H1200-7. [PMID: 12181151 DOI: 10.1152/ajpheart.00882.2001] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The interactions between systolic arterial pressure (SAP) and R-R interval (RR) fluctuations after acute myocardial infarction (AMI) were investigated by measures of synchronization separating the feedback from the feedforward control and capturing both linear and nonlinear contributions. The causal synchronization, evaluating the ability of RR to predict SAP (chi(s/t)) or vice versa (chi(t/s)), and the global synchronization (chi) were estimated at rest and after head-up tilt in 35 post-AMI patients, 20 young and 12 old. Significance and nonlinearity of the coupling were assessed by surrogate data analysis. Tilting increased the number of young subjects in which RR-SAP link was significant (from 17 to 19) and linear (from 11 to 18). In AMI, both significance and linearity of the coupling were low at rest (26 significant and 24 nonlinear) and further reduced after tilt (17 significant and 16 nonlinear). Old subjects showed a partial recovery of linearity after tilt (rest: 1 linear of 7 significant; tilt: 5 linear of 8 significant). In young subjects, the causal synchronization indexes were balanced and increased from rest (chi(t/s) = 0.072 +/- 0.037 and chi(s/t) = 0.054 +/- 0.028) to tilt (chi(t/s) = 0.125 +/- 0.071 and chi(s/t) = 0.108 +/- 0.053). On the contrary, in old subjects and AMI patients, the feedforward was prevalent to the feedback coupling at rest (old: chi(t/s) = 0.041 +/- 0.023 and chi(s/t) = 0.069 +/- 0.042; AMI: chi(t/s) = 0.050 +/- 0.030 and chi(s/t) = 0.089 +/- 0.053). Tilting blunted the unbalance in old subjects (chi(t/s) = 0.065 +/- 0.052 and chi(s/t) = 0.069 +/- 0.044) but not in AMI patients (chi(t/s) = 0.040 +/- 0.019 and chi(s/t) = 0.060 +/- 0.040). Thus, after AMI, nonlinear mechanisms are elicited in RR-SAP interactions. Furthermore, the neural regulation of the cardiovascular system resulted in imbalance as a consequence of impaired feedback and enhanced feedforward control mechanisms.
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Affiliation(s)
- Giandomenico Nollo
- Dipartimento di Fisica, Università di Trento, and Istituto Trentino di Cultura-ist, 38050 Povo, Trento, Italy.
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Legramante JM, Galante A, Massaro M, Attanasio A, Raimondi G, Pigozzi F, Iellamo F. Hemodynamic and autonomic correlates of postexercise hypotension in patients with mild hypertension. Am J Physiol Regul Integr Comp Physiol 2002; 282:R1037-43. [PMID: 11893607 DOI: 10.1152/ajpregu.00603.2001] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We investigated the interplay of neural and hemodynamic mechanisms in postexercise hypotension (PEH) in hypertension. In 15 middle-aged patients with mild essential hypertension, we evaluated blood pressure (BP), cardiac output (CO), total peripheral resistance (TPR), forearm (FVR) and calf vascular resistance (CVR), and autonomic function [by spectral analysis of R-R interval and BP variabilities and spontaneous baroreflex sensitivity (BRS)] before and after maximal exercise. Systolic and diastolic BP, TPR, and CVR were significantly reduced from baseline 60-90 min after exercise. CO, FVR, and HR were unchanged. The low-frequency (LF) component of BP variability increased significantly after exercise, whereas the LF component of R-R interval variability was unchanged. The overall change in BRS was not significant after exercise vs. baseline, although a significant, albeit small, BRS increase occurred in response to hypotensive stimuli. These findings indicate that in hypertensive patients, PEH is mediated mainly by a peripheral vasodilation, which may involve metabolic factors linked to postexercise hyperemia in the active limbs. The vasodilator effect appears to override a concomitant, reflex sympathetic activation selectively directed to the vasculature, possibly aimed to counter excessive BP decreases. The cardiac component of arterial baroreflex is reset during PEH, although the baroreflex mechanisms controlling heart period appear to retain the potential for greater opposition to hypotensive stimuli.
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Affiliation(s)
- Jacopo M Legramante
- Dipartimento di Medicina Interna, Centro di Riabilitazione Cardiologica San Raffaele and Università di Roma Tor Vergata, 00173 Rome, Italy
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