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Keur-Huizinga L, Kramer SE, de Geus EJC, Zekveld AA. A Multimodal Approach to Measuring Listening Effort: A Systematic Review on the Effects of Auditory Task Demand on Physiological Measures and Their Relationship. Ear Hear 2024; 45:1089-1106. [PMID: 38880960 PMCID: PMC11325958 DOI: 10.1097/aud.0000000000001508] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2023] [Accepted: 03/18/2024] [Indexed: 06/18/2024]
Abstract
OBJECTIVES Listening effort involves the mental effort required to perceive an auditory stimulus, for example in noisy environments. Prolonged increased listening effort, for example due to impaired hearing ability, may increase risk of health complications. It is therefore important to identify valid and sensitive measures of listening effort. Physiological measures have been shown to be sensitive to auditory task demand manipulations and are considered to reflect changes in listening effort. Such measures include pupil dilation, alpha power, skin conductance level, and heart rate variability. The aim of the current systematic review was to provide an overview of studies to listening effort that used multiple physiological measures. The two main questions were: (1) what is the effect of changes in auditory task demand on simultaneously acquired physiological measures from various modalities? and (2) what is the relationship between the responses in these physiological measures? DESIGN Following Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, relevant articles were sought in PubMed, PsycInfo, and Web of Science and by examining the references of included articles. Search iterations with different combinations of psychophysiological measures were performed in conjunction with listening effort-related search terms. Quality was assessed using the Appraisal Tool for Cross-Sectional Studies. RESULTS A total of 297 articles were identified from three databases, of which 27 were included. One additional article was identified from reference lists. Of the total 28 included articles, 16 included an analysis regarding the relationship between the physiological measures. The overall quality of the included studies was reasonable. CONCLUSIONS The included studies showed that most of the physiological measures either show no effect to auditory task demand manipulations or a consistent effect in the expected direction. For example, pupil dilation increased, pre-ejection period decreased, and skin conductance level increased with increasing auditory task demand. Most of the relationships between the responses of these physiological measures were nonsignificant or weak. The physiological measures varied in their sensitivity to auditory task demand manipulations. One of the identified knowledge gaps was that the included studies mostly used tasks with high-performance levels, resulting in an underrepresentation of the physiological changes at lower performance levels. This makes it difficult to capture how the physiological responses behave across the full psychometric curve. Our results support the Framework for Understanding Effortful Listening and the need for a multimodal approach to listening effort. We furthermore discuss focus points for future studies.
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Affiliation(s)
- Laura Keur-Huizinga
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology—Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands
- Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Sophia E. Kramer
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology—Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands
| | - Eco J. C. de Geus
- Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
| | - Adriana A. Zekveld
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology—Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, Amsterdam, The Netherlands
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2
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Keur-Huizinga L, Huizinga NA, Zekveld AA, Versfeld NJ, van de Ven SRB, van Dijk WAJ, de Geus EJC, Kramer SE. Effects of hearing acuity on psychophysiological responses to effortful speech perception. Hear Res 2024; 448:109031. [PMID: 38761554 DOI: 10.1016/j.heares.2024.109031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/23/2024] [Revised: 05/02/2024] [Accepted: 05/13/2024] [Indexed: 05/20/2024]
Abstract
In recent studies, psychophysiological measures have been used as markers of listening effort, but there is limited research on the effect of hearing loss on such measures. The aim of the current study was to investigate the effect of hearing acuity on physiological responses and subjective measures acquired during different levels of listening demand, and to investigate the relationship between these measures. A total of 125 participants (37 males and 88 females, age range 37-72 years, pure-tone average hearing thresholds at the best ear between -5.0 to 68.8 dB HL and asymmetry between ears between 0.0 and 87.5 dB) completed a listening task. A speech reception threshold (SRT) test was used with target sentences spoken by a female voice masked by male speech. Listening demand was manipulated using three levels of intelligibility: 20 % correct speech recognition, 50 %, and 80 % (IL20 %/IL50 %/IL80 %, respectively). During the task, peak pupil dilation (PPD), heart rate (HR), pre-ejection period (PEP), respiratory sinus arrhythmia (RSA), and skin conductance level (SCL) were measured. For each condition, subjective ratings of effort, performance, difficulty, and tendency to give up were also collected. Linear mixed effects models tested the effect of intelligibility level, hearing acuity, hearing asymmetry, and tinnitus complaints on the physiological reactivity (compared to baseline) and subjective measures. PPD and PEP reactivity showed a non-monotonic relationship with intelligibility level, but no such effects were found for HR, RSA, or SCL reactivity. Participants with worse hearing acuity had lower PPD at all intelligibility levels and showed lower PEP baseline levels. Additionally, PPD and SCL reactivity were lower for participants who reported suffering from tinnitus complaints. For IL80 %, but not IL50 % or IL20 %, participants with worse hearing acuity rated their listening effort to be relatively high compared to participants with better hearing. The reactivity of the different physiological measures were not or only weakly correlated with each other. Together, the results suggest that hearing acuity may be associated with altered sympathetic nervous system (re)activity. Research using psychophysiological measures as markers of listening effort to study the effect of hearing acuity on such measures are best served by the use of the PPD and PEP.
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Affiliation(s)
- Laura Keur-Huizinga
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands; Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands.
| | - Nicole A Huizinga
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands; Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Adriana A Zekveld
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands
| | - Niek J Versfeld
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands
| | - Sjors R B van de Ven
- Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Wieke A J van Dijk
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands
| | - Eco J C de Geus
- Department of Biological Psychology, Vrije Universiteit Amsterdam, Amsterdam, the Netherlands
| | - Sophia E Kramer
- Amsterdam UMC location Vrije Universiteit Amsterdam, Otolaryngology - Head and Neck Surgery, Ear & Hearing, Amsterdam Public Health Research Institute, De Boelelaan 1117, Amsterdam, the Netherlands
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3
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O'Leary DS, Mannozzi J, Augustyniak RA, Ichinose M, Spranger MD. Hypertension depresses arterial baroreflex control of both heart rate and cardiac output during rest, exercise, and metaboreflex activation. Am J Physiol Regul Integr Comp Physiol 2022; 323:R720-R727. [PMID: 36121147 PMCID: PMC9602692 DOI: 10.1152/ajpregu.00093.2022] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 08/24/2022] [Accepted: 09/08/2022] [Indexed: 01/19/2023]
Abstract
Rapid regulation of arterial blood pressure on a beat-by-beat basis occurs primarily via arterial baroreflex control of cardiac output (CO) via rapid changes in heart rate (HR). Previous studies have shown that changes in HR do not always cause changes in CO, because stroke volume may vary. Whether these relationships are altered in hypertension is unknown. Using the spontaneous baroreflex sensitivity (SBRS) approach, we investigated whether baroreflex control of HR and CO were impaired after the induction of hypertension in conscious, chronically instrumented canines at rest, during mild exercise, and during exercise with metaboreflex activation (induced via reductions in hindlimb blood flow) both before and after induction of hypertension (induced via a modified Goldblatt approach-unilateral reduction in renal blood flow to ∼30% of control values until systolic pressure ≥ 140 mmHg and a diastolic pressure ≥ 90 mmHg for >30 days). After induction of hypertension, SBRS control of both HR and CO was reduced in all settings. In control, only about 50% of SBRS changes in HR caused changes in CO. This pattern was sustained in hypertension. Thus, in hypertension, the reduced SBRS in the control of HR caused reduced SBRS control of CO and this likely contributes to the increased incidence of orthostatic hypotension seen in hypertensive patients.
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Affiliation(s)
- Donal S O'Leary
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Joseph Mannozzi
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Robert A Augustyniak
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
| | - Masashi Ichinose
- Human Integrative Physiology Laboratory, School of Business Administration, Meiji University, Tokyo, Japan
| | - Marty D Spranger
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan
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Becker BK, Johnston JG, Young CM, Torres Rodriguez AA, Jin C, Pollock DM. Endothelin B receptors impair baroreflex function and increase blood pressure variability during high salt diet. Auton Neurosci 2021; 232:102796. [PMID: 33798837 PMCID: PMC8040376 DOI: 10.1016/j.autneu.2021.102796] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/16/2020] [Revised: 03/01/2021] [Accepted: 03/04/2021] [Indexed: 10/21/2022]
Abstract
Baroreflex function is an integral component maintaining consistent blood pressure. Hypertension is often associated with baroreflex dysfunction, and environmental risk factors such as high salt diet exacerbate hypertension in subjects with baroreflex dysfunction. However, the interactions between high salt diet, baroreflex dysfunction, and hypertension are incompletely understood. The endothelin system is another potent mediator of blood pressure control especially in response to a high salt diet. We hypothesized that the endothelin B (ETB) receptor activation on adrenergic nerves decreases baroreflex sensitivity. We utilized male ETB receptor deficient (ETB-def) rats that express functional ETB receptors only on adrenergic nerves and transgenic (TG) controls to evaluate baroreflex function during normal (0.49% NaCl) and high (4.0% NaCl) salt diets. In conscious rats equipped with telemetry, ETB-def rats had an increased lability of systolic blood pressure (SBP) compared to TG controls as indicated by higher standard deviation (SD) of SBP under both normal (10.2 ± 0.6 vs. 12.4 ± 0.9 mmHg, respectively, p = 0.0001) and high (11.7 ± 0.6 vs. 16.1 ± 1.0 mmHg, p = 0.0001) salt diets. In anesthetized preparations, ETB-def rats displayed reduced heart rate (p genotype = 0.0167) and renal sympathetic nerve (p genotype = 0.0022) baroreflex sensitivity. We then gave male Sprague-Dawley rats the selective ETB receptor antagonist, A-192621 (10 mg/kg/day), to block ETB receptors. Following ETB receptor antagonism, even though SBP increased (131 ± 7 before vs. 152 ± 8 mmHg after, p < 0.0001), the lability (standard deviation) of SBP decreased (9.3 ± 2.0 vs. 7.1 ± 1.1 mmHg, p = 0.0155). These data support our hypothesis that ETB receptors on adrenergic nerves contribute to baroreflex dysfunction.
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Affiliation(s)
- Bryan K Becker
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America.
| | - Jermaine G Johnston
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
| | - Carolyn M Young
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
| | - Alfredo A Torres Rodriguez
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
| | - Chunhua Jin
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
| | - David M Pollock
- Cardio-Renal Physiology and Medicine, Department of Medicine, Division of Nephrology, University of Alabama at Birmingham, Birmingham, AL 35294, United States of America
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5
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Bates ME, Mun EY, Buckman JF, Vaschillo E, Vaschillo B, Lehrer P, Udo T, Lesnewich LM. Getting to the Heart of Low Sensitivity to Alcohol: Context Moderates Low Cardiovascular Response to Alcohol in Persons With a Family History of Alcohol Use Disorder. Alcohol Clin Exp Res 2020; 44:589-599. [PMID: 31984514 PMCID: PMC7079052 DOI: 10.1111/acer.14293] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2019] [Accepted: 01/16/2020] [Indexed: 01/16/2023]
Abstract
Background Low sensitivity to alcohol in persons with a family history of alcoholism (FH+), compared to those without (FH−), contributes to risk for alcohol use disorder (AUD). However, sensitivity of FH+ cardiovascular response to alcohol is not well understood. This gap is significant because cardiovascular processes contribute to emotional regulation and stress response problems theorized to be central to the development and persistence of AUD. This study compared changes in heart rate (HR) and HR variability (HRV) between FH groups after consuming alcohol and control beverages and examined how these changes were moderated by emotional and alcohol‐related contexts. Methods Young adults (N = 165) with FH+ (n = 110) or FH− (n = 55) each completed 2 sessions, separated by 1 week. They received one of 3 different beverages (alcohol, placebo, and told‐no‐alcohol) in each session. Electrocardiogram data were recorded during pre–beverage consumption and post–beverage consumption baselines, and then during 4 picture cue tasks (neutral, positive, negative, and alcohol‐related). Generalized estimating equations were used to examine differences in cardiovascular reactivity (changes in HR and HRV power at ~ 0.1 Hz) across FH groups, beverage conditions, and picture cue tasks. Results A significant beverage condition × cue task × FH interaction effect on HRV was observed. The FH+ group, compared to the FH− group, showed (a) significantly less HRV suppression in specific cue contexts following alcohol, (b) a mixed pattern of more and less HRV suppression across cue contexts following placebo, and (c) a similar HRV reactivity pattern in the told‐no‐alcohol condition across cue tasks. For HR, there were no significant effects involving FH. Conclusions Diminished cardiovascular sensitivity to oral alcohol in FH+ persons varied within a given drinking episode depending on emotional and alcohol‐related features of the context, suggesting that environmental characteristics play a role in the expression of low sensitivity to alcohol among FH+ individuals.
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Affiliation(s)
- Marsha E Bates
- From the, Division of Life Sciences, (MEB, JFB, EV, BV), Department of Kinesiology and Health, School of Arts and Sciences, Rutgers University - New Brunswick, New Brunswick, New Jersey.,Center of Alcohol and Substance Use Studies, (MEB, JFB, EV, BV, LML), Graduate School of Applied and Professional Psychology, Rutgers University - New Brunswick, Piscataway, New Jersey
| | - Eun-Young Mun
- Department of Health Behavior and Health Systems, (E-YM), School of Public Health, University of North Texas Health Science Center, Fort Worth, Texas
| | - Jennifer F Buckman
- From the, Division of Life Sciences, (MEB, JFB, EV, BV), Department of Kinesiology and Health, School of Arts and Sciences, Rutgers University - New Brunswick, New Brunswick, New Jersey.,Center of Alcohol and Substance Use Studies, (MEB, JFB, EV, BV, LML), Graduate School of Applied and Professional Psychology, Rutgers University - New Brunswick, Piscataway, New Jersey
| | - Evgeny Vaschillo
- From the, Division of Life Sciences, (MEB, JFB, EV, BV), Department of Kinesiology and Health, School of Arts and Sciences, Rutgers University - New Brunswick, New Brunswick, New Jersey.,Center of Alcohol and Substance Use Studies, (MEB, JFB, EV, BV, LML), Graduate School of Applied and Professional Psychology, Rutgers University - New Brunswick, Piscataway, New Jersey
| | - Bronya Vaschillo
- From the, Division of Life Sciences, (MEB, JFB, EV, BV), Department of Kinesiology and Health, School of Arts and Sciences, Rutgers University - New Brunswick, New Brunswick, New Jersey.,Center of Alcohol and Substance Use Studies, (MEB, JFB, EV, BV, LML), Graduate School of Applied and Professional Psychology, Rutgers University - New Brunswick, Piscataway, New Jersey
| | - Paul Lehrer
- Department of Psychiatry, (PL), Robert Wood Johnson Medical School, Rutgers University - New Brunswick, Piscataway, New Jersey
| | - Tomoko Udo
- Department of Health Policy, Management, and Behavior, (TU), School of Public Health, University at Albany- SUNY, Rensselaer, New York
| | - Laura M Lesnewich
- Center of Alcohol and Substance Use Studies, (MEB, JFB, EV, BV, LML), Graduate School of Applied and Professional Psychology, Rutgers University - New Brunswick, Piscataway, New Jersey.,Department of Psychology, (LML), School of Arts and Sciences, Rutgers University - New Brunswick, Piscataway, New Jersey
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6
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Bringard A, Adami A, Fagoni N, Fontolliet T, Lador F, Moia C, Tam E, Ferretti G. Dynamics of the RR-interval versus blood pressure relationship at exercise onset in humans. Eur J Appl Physiol 2017; 117:619-630. [PMID: 28238048 DOI: 10.1007/s00421-017-3564-6] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2016] [Accepted: 02/07/2017] [Indexed: 10/20/2022]
Abstract
PURPOSE The dynamics of the postulated phenomenon of exercise baroreflex resetting is poorly understood, but can be investigated using closed-loop procedures. To shed light on some mechanisms and temporal relationships participating in the resetting process, we studied the time course of the relationship between the R-R interval (RRi) and arterial pressure with a closed-loop approach. METHODS On ten young volunteers at rest and during light exercise in supine and upright position, we continuously determined, on single-beat basis, RRi (electrocardiography), and arterial pressure (non-invasive finger pressure cuff). From pulse pressure profiles, we determined cardiac output (CO) by Modelflow, computed mean arterial pressure (MAP), and calculated total peripheral resistance (TPR). RESULTS At exercise start, RRi was lower than in quiet rest. As exercise started, MAP fell to a minimum (MAPm) of 72.8 ± 9.6 mmHg upright and 73.9 ± 6.2 supine, while RRi dropped. The initial RRi versus MAP relationship was linear, with flatter slope than resting baroreflex sensitivity, in both postures. TPR fell and CO increased. After MAPm, RRi and MAP varied in opposite direction toward exercise steady state, with further CO increase. CONCLUSION These results suggest that, initially, the MAP fall was corrected by a RRi reduction along a baroreflex curve, with lower sensitivity than at rest, but eventually in the same pressure range as at rest. After attainment of MAPm, a second phase started, where the postulated baroreflex resetting might have occurred. In conclusion, the change in baroreflex sensitivity and the resetting process are distinct phenomena, under different control systems.
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Affiliation(s)
- Aurélien Bringard
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Alessandra Adami
- Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland.,Division of Respiratory and Critical Care Physiology and Medicine, Rehabilitation Clinical Trials Center, Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, 1124 W Carson St, Torrance, CA, 90502, USA
| | - Nazzareno Fagoni
- Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy
| | - Timothée Fontolliet
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Frédéric Lador
- Service de Pneumologie, Programme Hypertension Pulmonaire, Département des Spécialités de Médecine, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève, Switzerland
| | - Christian Moia
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland.,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland
| | - Enrico Tam
- Dipartimento di Scienze Neurologiche, Biomediche e del Movimento, Università di Verona, Via Felice Casorati 43, 37131, Verona, Italy
| | - Guido Ferretti
- Département d'Anesthésiologie, Pharmacologie et Soins Intensifs, Hôpitaux Universitaires de Genève, 4 rue Gabrielle-Perret-Gentil, CH-1211, Genève 4, Switzerland. .,Département des Neurosciences Fondamentales, Université de Genève, 1 rue Michel Servet, CH-1211, Genève 4, Switzerland. .,Dipartimento di Medicina Molecolare e Traslazionale, Università di Brescia, Viale Europa 11, 25123, Brescia, Italy.
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7
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Gee AH, Barbieri R, Paydarfar D, Indic P. Predicting Bradycardia in Preterm Infants Using Point Process Analysis of Heart Rate. IEEE Trans Biomed Eng 2016; 64:2300-2308. [PMID: 27898379 DOI: 10.1109/tbme.2016.2632746] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Episodes of bradycardia are common and recur sporadically in preterm infants, posing a threat to the developing brain and other vital organs. We hypothesize that bradycardias are a result of transient temporal destabilization of the cardiac autonomic control system and that fluctuations in the heart rate signal might contain information that precedes bradycardia. We investigate infant heart rate fluctuations with a novel application of point process theory. METHODS In ten preterm infants, we estimate instantaneous linear measures of the heart rate signal, use these measures to extract statistical features of bradycardia, and propose a simplistic framework for prediction of bradycardia. RESULTS We present the performance of a prediction algorithm using instantaneous linear measures (mean area under the curve = 0.79 ± 0.018) for over 440 bradycardia events. The algorithm achieves an average forecast time of 116 s prior to bradycardia onset (FPR = 0.15). Our analysis reveals that increased variance in the heart rate signal is a precursor of severe bradycardia. This increase in variance is associated with an increase in power from low content dynamics in the LF band (0.04-0.2 Hz) and lower multiscale entropy values prior to bradycardia. CONCLUSION Point process analysis of the heartbeat time series reveals instantaneous measures that can be used to predict infant bradycardia prior to onset. SIGNIFICANCE Our findings are relevant to risk stratification, predictive monitoring, and implementation of preventative strategies for reducing morbidity and mortality associated with bradycardia in neonatal intensive care units.
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8
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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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9
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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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Horwitz BA, Chau SM, Hamilton JS, Song C, Gorgone J, Saenz M, Horowitz JM, Chen CY. Temporal relationships of blood pressure, heart rate, baroreflex function, and body temperature change over a hibernation bout in Syrian hamsters. Am J Physiol Regul Integr Comp Physiol 2013; 305:R759-68. [PMID: 23904107 DOI: 10.1152/ajpregu.00450.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Hibernating mammals undergo torpor during which blood pressure (BP), heart rate (HR), metabolic rate, and core temperature (TC) dramatically decrease, conserving energy. While the cardiovascular system remains functional, temporal changes in BP, HR, and baroreceptor-HR reflex sensitivity (BRS) over complete hibernation bouts and their relation to TC are unknown. We implanted BP/temperature telemetry transmitters into Syrian hamsters to test three hypotheses: H-1) BP, HR, and BRS decrease concurrently during entry into hibernation and increase concurrently during arousal; H-2) these changes occur before changes in TC; and H-3) the pattern of changes is consistent over successive bouts. We found: 1) upon hibernation entry, BP and HR declined before TC and BRS, suggesting baroreflex control of HR continues to regulate BP as the BP set point decreases; 2) during the later phase of entry, BRS decreased rapidly whereas BP and TC fell gradually, suggesting the importance of TC in further BP declines; 3) during torpor, BP slowly increased (but remained relatively low) without changes in HR or BRS or increased TC, suggesting minimal baroreflex or temperature influence; 4) during arousal, increased TC and BRS significantly lagged increases in BP and HR, consistent with establishment of tissue perfusion before increased TC/metabolism; and 5) the temporal pattern of these changes was similar over successive bouts in all hamsters. These results negate H-1, support H-2 with respect to BP and HR, support H-3, and indicate that the baroreflex contributes to cardiovascular regulation over a hibernation bout, albeit operating in a fundamentally different manner during entry vs. arousal.
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Affiliation(s)
- Barbara A Horwitz
- Department of Neurobiology, Physiology, & Behavior, University of California, Davis, Davis, California
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11
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Rubinger D, Backenroth R, Sapoznikov D. Sympathetic Nervous System Function and Dysfunction in Chronic Hemodialysis Patients. Semin Dial 2013; 26:333-43. [DOI: 10.1111/sdi.12093] [Citation(s) in RCA: 62] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Affiliation(s)
- Dvora Rubinger
- Nephrology and Hypertension Services; Hadassah University; Medical Center; Jerusalem; Israel
| | - Rebecca Backenroth
- Nephrology and Hypertension Services; Hadassah University; Medical Center; Jerusalem; Israel
| | - Dan Sapoznikov
- Nephrology and Hypertension Services; Hadassah University; Medical Center; Jerusalem; Israel
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12
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Narayan J, Amatoury J, Verma M, Kairaitis K, Wheatley JR, Amis TC. Resetting the baroreflex during snoring: role of resistive loading and intra-thoracic pressure. Respir Physiol Neurobiol 2013; 185:489-96. [PMID: 23219813 DOI: 10.1016/j.resp.2012.11.011] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 11/15/2012] [Accepted: 11/19/2012] [Indexed: 12/20/2022]
Abstract
Baroreflex sensitivity (BRS) is reduced during snoring in humans and animal models. We utilised our rabbit model to examine the contribution of increased upper airway resistance to baroreflex resetting during snoring, by comparing BRS and baroreflex operating point (OP) values during IS to those obtained during tracheostomised breathing through an external resistive load (RL) titrated to match IS levels of peak inspiratory pleural pressure (Ppl). During both IS and RL, BRS decreased by 45% and 49%. There was a linear relationship between the change in Ppl and the decrease in BRS, which was similar for IS and RL. During both RL and IS, there was a shift in OP driven by ~16% increase in HR and no change in arterial pressure. Snoring related depression of BRS is likely mediated via a HR driven change in OP, which itself may be the outcome of negative intra-thoracic pressure mediated effects on right atrial wall stretch reflex control of heart rate.
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Affiliation(s)
- Jyotishna Narayan
- Ludwig Engel Centre for Respiratory Research, Department of Respiratory and Sleep Medicine, Sydney, NSW, Australia.
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13
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Rubinger D, Backenroth R, Sapoznikov D. Sympathetic activation and baroreflex function during intradialytic hypertensive episodes. PLoS One 2012; 7:e36943. [PMID: 22629345 PMCID: PMC3358286 DOI: 10.1371/journal.pone.0036943] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 04/16/2012] [Indexed: 02/07/2023] Open
Abstract
Background The mechanisms of intradialytic increases in blood pressure are not well defined. The present study was undertaken to assess the role of autonomic nervous system activation during intradialytic hypertensive episodes. Methodology/Principal Findings Continuous interbeat intervals (IBI) and systolic blood pressure (SBP) were monitored during hemodialysis in 108 chronic patients. Intradialytic hypertensive episodes defined as a period of at least 10 mmHg increase in SBP between the beginning and the end of a dialysis session or hypertension resistant to ultrafiltration occurring during or immediately after the dialysis procedure, were detected in 62 out of 113 hemodialysis sessions. SBP variability, IBI variability and baroreceptor sensitivity (BRS) in the low (LF) and high (HF) frequency ranges were assessed using the complex demodulation technique (CDM). Intradialytic hypertensive episodes were associated with an increased (n = 45) or decreased (n = 17) heart rate. The maximal blood pressure was similar in both groups. In patients with increased heart rate the increase in blood pressure was associated with marked increases in SBP and IBI variability, with suppressed BRS indices and enhanced sympatho-vagal balance. In contrast, in those with decreased heart rate, there were no significant changes in the above parameters. End-of- dialysis blood pressure in all sessions associated with hypertensive episode was significantly higher than in those without such episodes. In logistic regression analysis, predialysis BRS in the low frequency range was found to be the main predictor of intradialytic hypertension. Conclusion/Significance Our data point to sympathetic overactivity with feed-forward blood pressure enhancement as an important mechanism of intradialytic hypertension in a significant proportion of patients. The triggers of increased sympathetic activity during hemodialysis remain to be determined. Intradialytic hypertensive episodes are associated with higher end-of- dialysis blood pressure, suggesting that intradialytic hypertension may play a role in generation of interdialytic hypertension.
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Affiliation(s)
- Dvora Rubinger
- Nephrology and Hypertension Services, Department of Medicine, Hadassah University Medical Center, Jerusalem, Israel.
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14
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Narayan J, Amatoury J, Cho JG, Verma M, Kairaitis K, Wheatley J, Amis T. Snoring effects on the baroreflex: an animal model. Respir Physiol Neurobiol 2012; 180:342-51. [PMID: 22244879 DOI: 10.1016/j.resp.2011.12.012] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2011] [Revised: 12/21/2011] [Accepted: 12/22/2011] [Indexed: 10/14/2022]
Abstract
Baroreflex sensitivity (BRS) is reduced in humans during snoring, however the mechanisms are unknown. We used an anaesthetised rabbit induced snoring (IS) model, to test: (1) whether IS was associated with reduced BRS; and (2) if snoring related vibration transmission to peri-carotid tissues influenced BRS levels. BRS was quantified using the spontaneous sequence technique. During IS, BRS fell by 40%, without any associated change in blood pressure (BP) but accompanied by an increase in heart rate (HR). Direct application of a snore frequency and intensity matched vibratory stimulus to the peri-carotid tissues of non-snoring tracheostomised rabbits had no effect on BRS, HR or BP. In conclusion, IS induced depression of BRS is likely mediated via a HR driven change in BRS operating point that is unrelated to snoring-related vibration transmission to carotid baroreceptors. The anaesthetised IS rabbit provides a model in which mechanistic interactions between snoring and BRS can be further explored.
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Affiliation(s)
- Jyotishna Narayan
- Ludwig Engel Centre for Respiratory Research, Sydney, NSW, Australia.
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15
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Delayed effect of blood pressure fluctuations on heart rate in patients with end-stage kidney disease. Med Biol Eng Comput 2011; 49:1045-55. [PMID: 21755317 DOI: 10.1007/s11517-011-0806-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2011] [Accepted: 07/02/2011] [Indexed: 12/28/2022]
Abstract
The time delay of the baroreflex may be affected by decreased autonomic activity in uremia. To assess the magnitude and the time delay of heart rate response in patients with end-stage renal disease, continuous beat-to-beat intervals (IBI) and systolic blood pressure (SBP) recordings were monitored in hemodialysis (HD) patients (n = 72), in patients after renal transplantation (TX) (n = 41) and in age-matched controls (C) (n = 34). A 2-term prediction model was computed, in which each IBI change was represented as a function of SBP difference values of two immediately preceding beats. Baroreflex slope and the frequency domain variables low frequency (LF) α index, phase shift, and lag time were also calculated. b₁ coefficient, representing the dependence of IBI difference with the first previous SBP difference was lower in HD than in Cs, but increased after TX. b₁ correlated with age, baroreflex slope, and LF α, and b₂ (the 2nd term), with both the phase shift between SBP and IBI and lag time. The latter was lower in Cs than in HD or transplanted patients. These findings show that the time delay of the heart rate response to SBP variations is increased in renal insufficiency. The prolonged delay may contribute to the circulatory instability in uremic patients.
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16
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Hollow MR, Clutton-Brock TH, Parkes MJ. Can baroreflex measurements with spontaneous sequence analysis be improved by also measuring breathing and by standardization of filtering strategies? Physiol Meas 2011; 32:1193-212. [PMID: 21725145 DOI: 10.1088/0967-3334/32/8/013] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Baroreflex sensitivity (BRS) is known to be attenuated by inspiration and all the original BRS methodologies took this into account by measuring only in expiration. Spontaneous sequence analysis (SSA) is a non-invasive clinical tool widely used to estimate BRS in Man but does not take breathing into account. We have therefore modified it to test whether it too can detect inspiratory attenuation. Traditional SSA is also entangled with issues of distinguishing causal from random relationships between blood pressure and heart period and of the optimum choice of data filter settings. We have also tested whether the sequences our modified SSA rejects do behave as random relationships and show the limitations of the absence of filter standardization. SSA was performed on eupneic data from 1 h periods in 20 healthy subjects. Applying SSA traditionally produced a mean BRS of 23 ± 3 ms mmHg(-1). After modification to measure breathing, SSA detected significant inspiratory attenuation (11 ± 1 ms mmHg(-1)), and the mean expiratory BRS was significantly higher (26 ± 5 ms mmHg(-1)). Traditional SSA therefore underestimates BRS by an amount (3 ms mmHg(-1)) as big as the major physiological and clinical factors known to alter BRS. We show that the sequences rejected by SSA do behave like random associations between pressure and period. We also show the minimal effect of the r(2) filter and the biases that some pressure and heart period filters can introduce. We discuss whether SSA might be improved by standardization of filter settings and by also measuring breathing.
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Affiliation(s)
- M R Hollow
- Wellcome Trust Clinical Research Facility
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17
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Low-frequency fluctuations in heart rate, cardiac output and mean arterial pressure in humans: what are the physiological relationships? J Hypertens 2011; 29:1327-36. [DOI: 10.1097/hjh.0b013e328347a17a] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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18
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Abstract
The methods used to assess cardiac parasympathetic (cardiovagal) activity and its effects on the heart in both humans and animal models are reviewed. Heart rate (HR)-based methods include measurements of the HR response to blockade of muscarinic cholinergic receptors (parasympathetic tone), beat-to-beat HR variability (HRV) (parasympathetic modulation), rate of post-exercise HR recovery (parasympathetic reactivation), and reflex-mediated changes in HR evoked by activation or inhibition of sensory (afferent) nerves. Sources of excitatory afferent input that increase cardiovagal activity and decrease HR include baroreceptors, chemoreceptors, trigeminal receptors, and subsets of cardiopulmonary receptors with vagal afferents. Sources of inhibitory afferent input include pulmonary stretch receptors with vagal afferents and subsets of visceral and somatic receptors with spinal afferents. The different methods used to assess cardiovagal control of the heart engage different mechanisms, and therefore provide unique and complementary insights into underlying physiology and pathophysiology. In addition, techniques for direct recording of cardiovagal nerve activity in animals; the use of decerebrate and in vitro preparations that avoid confounding effects of anesthesia; cardiovagal control of cardiac conduction, contractility, and refractoriness; and noncholinergic mechanisms are described. Advantages and limitations of the various methods are addressed, and future directions are proposed.
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Affiliation(s)
- Mark W Chapleau
- The Cardiovascular Center and Department of Internal Medicine, The University of Iowa Carver College of Medicine, 200 Hawkins Drive, Iowa City, IA 52242, USA.
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19
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Di Rienzo M, Castiglioni P, Parati G. The sequence technique revised: additional concepts on the assessment of spontaneous baroreflex function. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2010:1703-5. [PMID: 21096401 DOI: 10.1109/iembs.2010.5626844] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The sequence technique is commonly employed to estimate the baroreflex sensitivity from the analysis of systolic blood pressure (SBP) and RR Interval (RRI) recordings. Traditionally, the RRI+/SBP- and RRI-/SBP+ sequences are excluded from this analysis.
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Affiliation(s)
- M Di Rienzo
- Dept. of Biomedical Technology, Fondazione Don Carlo Gnocchi ONLUS, 20148 Milano, Italy.
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20
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Kisilevsky BS, Hains SMJ. Exploring the relationship between fetal heart rate and cognition. INFANT AND CHILD DEVELOPMENT 2010. [DOI: 10.1002/icd.655] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
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21
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Hart EC, Joyner MJ, Wallin BG, Karlsson T, Curry TB, Charkoudian N. Baroreflex control of muscle sympathetic nerve activity: a nonpharmacological measure of baroreflex sensitivity. Am J Physiol Heart Circ Physiol 2009; 298:H816-22. [PMID: 20008270 DOI: 10.1152/ajpheart.00924.2009] [Citation(s) in RCA: 78] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The sensitivity of baroreflex control of sympathetic nerve activity (SNA) represents the responsiveness of SNA to changes in blood pressure. In a slightly different analysis, the baroreflex threshold measures the probability of whether a sympathetic burst will occur at a given diastolic blood pressure. We hypothesized that baroreflex threshold analysis could be used to estimate the sensitivity of the sympathetic baroreflex measured by the pharmacological modified Oxford test. We compared four measures of sympathetic baroreflex sensitivity in 25 young healthy participants: the "gold standard" modified Oxford analysis (nitroprusside and phenylephrine), nonbinned spontaneous baroreflex analysis, binned spontaneous baroreflex analysis, and threshold analysis. The latter three were performed during a quiet baseline period before pharmacological intervention. The modified Oxford baroreflex sensitivity was significantly related to the threshold slope (r = 0.71, P < 0.05) but not to the binned (1 mmHg bins) and the nonbinned spontaneous baroreflex sensitivity (r = 0.22 and 0.36, respectively, P > 0.05), which included burst area. The threshold analysis was also performed during the modified Oxford manipulation. Interestingly, we found that the threshold analysis results were not altered by the vasoactive drugs infused for the modified Oxford. We conclude that the noninvasive threshold analysis technique can be used as an indicator of muscle SNA baroreflex sensitivity as assessed by the modified Oxford technique. Furthermore, the modified Oxford method does not appear to alter the properties of the baroreflex.
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Affiliation(s)
- Emma C Hart
- Dept. of Anesthesiology, Mayo Clinic, Rochester, MN 59906, USA.
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22
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Sala-Mercado JA, Ichinose M, Coutsos M, Li Z, Fano D, Ichinose T, Dawe EJ, O'Leary DS. Progressive muscle metaboreflex activation gradually decreases spontaneous heart rate baroreflex sensitivity during dynamic exercise. Am J Physiol Heart Circ Physiol 2009; 298:H594-600. [PMID: 19966049 DOI: 10.1152/ajpheart.00908.2009] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Ischemia of active skeletal muscle elicits a pressor response termed the muscle metaboreflex. We tested the hypothesis that in normal dogs during dynamic exercise, graded muscle metaboreflex activation (MMA) would progressively attenuate spontaneous heart rate baroreflex sensitivity (SBRS). The animals were chronically instrumented to measure heart rate (HR), cardiac output (CO), mean and systolic arterial pressure (MAP and SAP), and left ventricular systolic pressures (LVSP) at rest and during mild or moderate treadmill exercise before and during progressive MMA [via graded reductions of hindlimb blood flow (HLBF)]. SBRS [slopes of the linear relationships (LRs) between HR and LVSP or SAP during spontaneous sequences of > or =3 consecutive beats when HR changed inversely vs. pressure] decreased during mild exercise from the resting values (-5.56 +/- 0.86 vs. -2.67 +/- 0.50 beats.min(-1).mmHg(-1), P <0.05), and in addition, these LRs were shifted upward. Progressive MMA gradually and linearly increased MAP, CO, and HR; linearly decreased SBRS; and shifted LRs upward and rightward to higher HR and pressures denoting baroreflex resetting. Moderate exercise caused a substantial reduction in SBRS (-1.57 +/- 0.38 beats.min(-1).mmHg(-1), P <0.05) and both an upward and rightward resetting. Gradual MMA at this higher workload also caused significant progressive increases in MAP, CO, and HR and progressive decreases in SBRS, and the LRs were shifted to higher MAP and HR. Our results demonstrate that gradual MMA during mild and moderate dynamic exercise progressively decreases SBRS. In addition, baroreflex control of HR is progressively reset to higher blood pressure and HR in proportion to the extent of MMA.
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Affiliation(s)
- Javier A Sala-Mercado
- Department of Physiology, Wayne State University School of Medicine, Detroit, Michigan, USA
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23
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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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24
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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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25
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EVAluation of the prognostic value of BARoreflex sensitivity in hypertensive patients: the EVABAR study. J Hypertens 2008; 26:1373-8. [PMID: 18551013 DOI: 10.1097/hjh.0b013e3283015e5a] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
Abstract
AIMS The prognostic value of baroreflex sensitivity in hypertensive patients has not much been studied. METHOD A cohort of 451 hypertensive patients without cardiovascular history was studied for an average of 6.2 +/- 2.8 years follow-up. Each patient had a baroreflex sensitivity measurement by the sequence method, which is represented by the slope of up-sequences (systolic blood pressure+/pulse interval+) and down-sequences (systolic blood pressure-/pulse interval-) of spontaneous fluctuations in systolic blood pressure and pulse interval. RESULTS During the follow-up, there were 20 deaths from any cause and 30 patients presented a major adverse cardiovascular event. Deaths and major adverse cardiovascular events were associated with a reduction in baroreflex sensitivity (systolic blood pressure+/pulse interval+ and systolic blood pressure-/pulse interval-). In multivariate analysis, the reduction in baroreflex sensitivity systolic blood pressure+/pulse interval+ was associated with an increased risk of deaths from any cause (Odds ratio 1.23; 95% confidence interval 1.02-1.67, P = 0.04). A baroreflex sensitivity systolic blood pressure+/pulse interval+ under 4.5 ms/mmHg was associated with a 2.5-increased relative risk of major adverse cardiovascular event (95% confidence interval 1.11-5.93, P = 0.03). However, multivariate analysis showed that baroreflex sensitivity systolic blood pressure-/pulse interval- was not associated either with death or major adverse cardiovascular events. CONCLUSIONS Reduction in baroreflex sensitivity marked by a reduction in vagal reflexes is an independent marker of the risk of mortality and major adverse cardiovascular events in hypertensive patients.
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26
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Montano N, Porta A, Cogliati C, Costantino G, Tobaldini E, Casali KR, Iellamo F. Heart rate variability explored in the frequency domain: a tool to investigate the link between heart and behavior. Neurosci Biobehav Rev 2008; 33:71-80. [PMID: 18706440 DOI: 10.1016/j.neubiorev.2008.07.006] [Citation(s) in RCA: 275] [Impact Index Per Article: 17.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2008] [Revised: 07/17/2008] [Accepted: 07/22/2008] [Indexed: 11/28/2022]
Abstract
The neural regulation of circulatory function is mainly effected through the interplay of the sympathetic and vagal outflows. This interaction can be explored by assessing cardiovascular rhythmicity with appropriate spectral methodologies. Spectral analysis of cardiovascular signal variability, and in particular of RR period (heart rate variability, HRV), is a widely used procedure to investigate autonomic cardiovascular control and/or target function impairment. The oscillatory pattern which characterizes the spectral profile of heart rate and arterial pressure short-term variability consists of two major components, at low (LF, 0.04-0.15Hz) and high (HF, synchronous with respiratory rate) frequency, respectively, related to vasomotor and respiratory activity. With this procedure the state of sympathovagal balance modulating sinus node pacemaker activity can be quantified in a variety of physiological and pathophysiological conditions. Changes in sympathovagal balance can be often detected in basal conditions, however a reduced responsiveness to an excitatory stimulus is the most common feature that characterizes numerous pathophysiological states. Moreover the attenuation of an oscillatory pattern or its impaired responsiveness to a given stimulus can also reflect an altered target function and thus can furnish interesting prognostic markers. The dynamic assessment of these autonomic changes may provide crucial diagnostic, therapeutic and prognostic information, not only in relation to cardiovascular, but also non-cardiovascular disease. As linear methodologies fail to provide significant information in conditions of extremely reduced variability (e.g. strenuous exercise, heart failure) and in presence of rapid and transients changes or coactivation of the two branches of autonomic nervous system, the development of new non-linear approaches seems to provide a new perspective in investigating neural control of cardiovascular system.
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Affiliation(s)
- Nicola Montano
- Department of Clinical Science, Luigi Sacco Hospital, University of Milan, Milan, Italy.
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27
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Vaschillo EG, Bates ME, Vaschillo B, Lehrer P, Udo T, Mun EY, Ray S. Heart rate variability response to alcohol, placebo, and emotional picture cue challenges: effects of 0.1-Hz stimulation. Psychophysiology 2008; 45:847-58. [PMID: 18513359 DOI: 10.1111/j.1469-8986.2008.00673.x] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
Abstract
Heart rate variability (HRV) supports emotion regulation and is reduced by alcohol. Based on the resonance properties of the cardiovascular system, a new 0.1-Hz methodology was developed to present emotional stimuli and assess HRV reaction in participants (N=36) randomly assigned to an alcohol, placebo, or control condition. Blocked picture cues (negative, positive, neutral) were presented at a rate of 5 s on, 5 s off (i.e., 0.1-Hz frequency). SDNN, pNN50, and HF HRV were reduced by alcohol, compared to the placebo and control. The 0.1-Hz HRV index was diminished by alcohol and placebo, suggesting that autonomic regulation can be affected by cognitive expectancy. The 0.1-Hz HRV index and pNN50 detected changes in arousal during emotional compared to neutral cues, and the 0.1-Hz HRV index was most sensitive to negative valence. The 0.1-Hz HRV methodology may be useful for studying the intersection of cognition, emotion, and autonomic regulation.
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Affiliation(s)
- Evgeny G Vaschillo
- Center of Alcohol Studies, Rutgers, The State University of New Jersey, Piscataway, New Jersey 08854, USA.
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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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Sala-Mercado JA, Ichinose M, Hammond RL, Coutsos M, Ichinose T, Pallante M, Iellamo F, O'Leary DS. Spontaneous baroreflex control of heart rate versus cardiac output: altered coupling in heart failure. Am J Physiol Heart Circ Physiol 2008; 294:H1304-9. [PMID: 18192213 DOI: 10.1152/ajpheart.01186.2007] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Dynamic cardiac baroreflex responses are frequently investigated by analyzing the spontaneous reciprocal changes in arterial pressure and heart rate (HR). However, whether the spontaneous baroreflex-induced changes in HR translate into changes in cardiac output (CO) is unknown. In addition, this linkage between changes in HR and changes in CO may be different in subjects with heart failure (HF). We examined these questions using conscious dogs before and after pacing-induced HF. Spontaneous baroreflex sensitivity in the control of HR and CO was evaluated as the slopes of the linear relationships between HR or CO and left ventricular systolic pressure (LVSP) during spontaneous sequences of greater or equal to three consecutive beats when HR or CO changed inversely versus pressure. Furthermore, the translation of baroreflex HR responses into CO responses (HR-CO translation) was examined by computing the overlap between HR and CO sequences. In normal resting conditions, 44.0 +/- 4.4% of HR sequences overlapped with CO sequences, suggesting that only around half of the baroreflex HR responses cause CO responses. In HF, HR-LVSP, CO-LVSP, and the HR-CO translation significantly decreased compared with the normal condition (-2.29 +/- 0.5 vs. -5.78 +/- 0.7 beats.min(-1).mmHg(-1); -70.95 +/- 11.8 vs. -229.89 +/- 29.6 ml.min(-1).mmHg(-1); and 19.66 +/- 4.9 vs. 44.0 +/- 4.4%, respectively). We conclude that spontaneous baroreflex HR responses do not always cause changes in CO. In addition, HF significantly decreases HR-LVSP, CO-LVSP, and HR-CO translation.
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Affiliation(s)
- Javier A Sala-Mercado
- Department of Physiology, Wayne State University School of Medicine, Detroit, MI 48201, USA
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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. 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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Cividjian A, Martinez JY, Combourieu E, Precloux P, Beraud AM, Rochette Y, Cler M, Bourdon L, Escarment J, Quintin L. Beat-by-beat cardiovascular index to predict unexpected intraoperative movement in anesthetized unparalyzed patients: a retrospective analysis. J Clin Monit Comput 2006; 21:91-101. [PMID: 17186401 DOI: 10.1007/s10877-006-9061-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2006] [Accepted: 10/31/2006] [Indexed: 10/23/2022]
Abstract
OBJECTIVE Unexpected intraoperative movement may be detrimental during delicate surgery. This study tested retrospectively an algorithm based on beat-by-beat circulatory variables (incorporated into a Cardiovascular depth of anesthesia index: CARDEAN in relationship to unexpected movement, and compared its performance to that of the electroencephalogram (EEG)-derived index: BIS-XP 4.0. METHODS 40 ASA I or II patients presenting for knee surgery had EEG (BIS XP 4.0), beat-by-beat (Finapres) finger non-invasive blood pressure (BP), conventional brachial BP and electrocardiogram (EKG) monitors attached. Anesthesia was induced and maintained with propofol and remifentanil. Before incision, the propofol concentration was set to maintain BIS < 60. From incision to emergence, the anesthesiologist was denied access to BIS or Finapres. Anesthesia adjustment was titrated at the discretion of the anesthesiologist according to conventional signs only: brachial BP, EKG, eyelash reflex, movement. Occurrences of movement and eye signs (divergence of eyeballs, tears, corneal reflex, eyelash reflex) were observed. The CARDEAN algorithm was written retrospectively and tested vs. BIS. RESULTS 11 movements occurred in 8 patients. CARDEAN > 60 predicted movement in 30% of the cases, 15 to 274 s before movement (sensitivity: 100%, specificity: 95%; relative operating curve ROC = 0.98; prediction probability pk = 0.98). BIS > 60 predicted movement in 19% of cases (sensitivity: 64%; specificity: 94%, ROC: 0.85, pk: 0.85). CONCLUSION Retrospectively, a cardiovascular index predicted unexpected intraoperative movements. Prospective validation is needed.
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Vaschillo EG, Vaschillo B, Lehrer PM. Characteristics of resonance in heart rate variability stimulated by biofeedback. Appl Psychophysiol Biofeedback 2006; 31:129-42. [PMID: 16838124 DOI: 10.1007/s10484-006-9009-3] [Citation(s) in RCA: 208] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
As we previously reported, resonant frequency heart rate variability biofeedback increases baroreflex gain and peak expiratory flow in healthy individuals and has positive effects in treatment of asthma patients. Biofeedback readily produces large oscillations in heart rate, blood pressure, vascular tone, and pulse amplitude via paced breathing at the specific natural resonant frequency of the cardiovascular system for each individual. This paper describes how resonance properties of the cardiovascular system mediate the effects of heart rate variability biofeedback. There is evidence that resonant oscillations can train autonomic reflexes to provide therapeutic effect. The paper is based on studies described in previous papers. Here, we discuss the origin of the resonance phenomenon, describe our procedure for determining an individual's resonant frequency, and report data from 32 adult asthma patients and 24 healthy adult subjects, showing a negative relationship between resonant frequency and height, and a lower resonant frequency in men than women, but no relationship between resonant frequency and age, weight, or presence of asthma. Resonant frequency remains constant across 10 sessions of biofeedback training. It appears to be related to blood volume.
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Affiliation(s)
- Evgeny G Vaschillo
- Center of Alcohol Studies, The State University of New Jersey-Rutgers, 607 Allison Road, Piscataway, NJ 08854, USA.
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Beckers F, Verheyden B, Ramaekers D, Swynghedauw B, Aubert AE. EFFECTS OF AUTONOMIC BLOCKADE ON NON-LINEAR CARDIOVASCULAR VARIABILITY INDICES IN RATS. Clin Exp Pharmacol Physiol 2006; 33:431-9. [PMID: 16700875 DOI: 10.1111/j.1440-1681.2006.04384.x] [Citation(s) in RCA: 53] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
1. The present study assesses the effects of autonomic blockade (alpha- and beta-adrenoceptor and cholinergic) on cardiovascular function studied by heart rate variability (HRV), blood pressure variability (BPV) and baroreflex sensitivity in rats using non-linear dynamics. Little is known about the influence of pharmacological autonomic nervous system interventions on non-linear cardiovascular regulatory indices. 2. In 13 conscious rats, heart rate and aortic blood pressure were measured continuously before, during and after autonomic blockade with atropine, phentolamine and propranolol. Non-linear scaling properties were studied using 1/f slope, fractal dimension and long- and short-term correlation. Non-linear complexity was described with correlation dimension, Lyapunov exponent and approximate entropy. Non-linear indices were compared with linear time and frequency domain indices. 3. Beta-adrenoceptor blockade did not alter the non-linear characteristics of HRV and BPV, although low-frequency power of HRV was depressed. Alpha-adrenoceptor blockade decreased the scaling behaviour of HRV, whereas cholinergic blockade decreased the complexity of the non-linear system of HRV. For BPV, the scaling behaviour was increased during alpha-adrenoceptor blockade and the complexity was increased during cholinergic blockade. The linear indices of HRV and BPV were decreased. 4. The present results indicate that the beta-adrenoceptor system has little involvement in the generation of non-linear HRV and BPV in rats. 5. Alpha-adrenoceptor blockade mostly influenced the scaling properties of the time series, whereas cholinergic blockade induced changes in the complexity measures. 6. The absence of the baroreflex mechanism can trigger a compensatory feed-forward system increasing the complexity of BPV.
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Affiliation(s)
- Frank Beckers
- Laboratory of Experimental Cardiology, School of Medicine, Gasthuisberg University Hospital, KU Leuven, Leuven, Belgium.
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Ormezzano O, Poirier O, Mallion JM, Nicaud V, Amar J, Chamontin B, Mounier-Véhier C, François P, Cambien F, Baguet JP. A polymorphism in the endothelin-A receptor gene is linked to baroreflex sensitivity. J Hypertens 2005; 23:2019-26. [PMID: 16208144 DOI: 10.1097/01.hjh.0000184748.49189.36] [Citation(s) in RCA: 18] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
BACKGROUND The baroreflex plays an essential role in regulating the cardiovascular system. However, very few studies have focused on the links between genetic polymorphisms and baroreflex sensitivity (BRS). METHODS A total of 146 hypertensive individuals who had never been treated, and 105 healthy individuals (controls) were included in the study. The genotypes of 17 polymorphisms of 11 genes involved in the regulation of the cardiovascular system were studied. BRS was measured using a sequence method: BRS was evaluated as the slope of spontaneous increases [systolic blood pressure (SBP)+/reflex response (RR)+] or decreases (SBP-/RR-) in SBP and pulse interval by recording blood pressure (BP) continuously for 20 min. RESULTS Following univariate analysis, the genetic polymorphism of endothelin receptor A EDNRA/C+1222T was found to be significantly correlated with the BRS (SBP-/RR-) level in both populations. In normotensive subjects, mean BRS values (SBP-/RR-) were 11.93 +/- 3.69 ms/mmHg in EDNRA CC homozygotes, 9.94 +/- 2.97 ms/mmHg in CT heterozygotes and 9.51 +/- 3.16 ms/mmHg in TT homozygotes (P = 0.01). In hypertensive subjects, mean BRS values (SBP-/RR-) were 9.26 +/- 3.59 ms/mmHg in EDNRA CC homozygotes, 9.03 +/- 4.14 ms/mmHg in CT heterozygotes and 6.60 +/- 2.42 ms/mmHg in TT homozygotes (P = 0.01). After adjustment for age, sex, SBP and diastolic blood pressure and body mass index, the EDNRA/C+1222T polymorphism remained significantly correlated with BRS in both normotensive (P = 0.01) and hypertensive (P = 0.01) subjects. CONCLUSIONS These results suggest that the endothelin system may be involved in the regulation of BRS in humans. In particular, the T allele of the EDNRA/C+1222T polymorphism is associated with a reduction in BRS in both healthy and hypertensive subjects.
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Affiliation(s)
- Olivier Ormezzano
- Service de Cardiologie et Hypertension Artérielle, Grenoble, France.
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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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Malliani A. Heart rate variability: from bench to bedside. Eur J Intern Med 2005; 16:12-20. [PMID: 15733815 DOI: 10.1016/j.ejim.2004.06.016] [Citation(s) in RCA: 116] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2004] [Revised: 05/25/2004] [Accepted: 06/17/2004] [Indexed: 11/30/2022]
Abstract
Power spectrum analysis of cardiovascular signal variability, and in particular of the RR period (heart rate variability, HRV), is a widely used methodology for investigating autonomic neural regulation in health and disease that can quantify the sympathovagal balance modulating the sinus node pacemaker. In some cases, it can also quantify the neural regulation of other organs or apparatuses. However, use of the correct methodology is crucial to extract the information embedded in the frequency domain. In numerous abnormal conditions, such as essential arterial hypertension, acute myocardial infarction and heart failure, the sympathovagal balance may be altered in basal conditions. However, a reduced responsiveness to an excitatory stimulus is the most common feature that characterizes numerous pathophysiological states. The attenuation of an oscillatory pattern can also reflect an altered target function, thus providing important prognostic markers. The general features of this approach correspond well to the needs of an internist attempting to envisage the involvement of the whole organism in a disease process.
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Affiliation(s)
- Alberto Malliani
- Dipartimento di Scienze Cliniche “Luigi Sacco,” Università degli Studi di Milano, Medicina Interna II, Ospedale L. Sacco, Via G.B. Grassi 74, 20157, Milan, Italy
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Lucini D, Cerchiello M, Pagani M. Selective reductions of cardiac autonomic responses to light bicycle exercise with aging in healthy humans. Auton Neurosci 2004; 110:55-63. [PMID: 14766326 DOI: 10.1016/j.autneu.2003.10.002] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2003] [Revised: 10/13/2003] [Accepted: 10/21/2003] [Indexed: 10/26/2022]
Abstract
We examined on 56 (age 38+/-2 [range: 16-60] years) healthy subjects the effects of aging on cardiovascular autonomic responses to progressive supine bicycle exercise of light intensity. Autoregressive spectral analysis of RR interval and systolic arterial pressure (SAP) variabilities provided measures of the exercise-induced changes in baroreflex gain (by index alpha) and in sympathetic and vagal modulation of the SA node (by the normalized low [LF] and high frequency [HF] component of RR interval variability, respectively), as well as of changes in sympathetic vasomotor control (LF(SAP)). For each hemodynamic and autonomic variable, the gain of the response was expressed both as individual step increments, and as the slope of the linear regression of the sequential data points from rest and during the three steps of exercise. Age resulted significantly correlated to changes in spectral derived markers of SA modulation (LF(RR), HF(RR) and index alpha). Conversely, no significant relationships were found with changes in RR interval, in SAP and indices of vascular regulation (LF(SAP)). In addition, exercise-induced changes in indices of SA node regulation were more evident in the youngest tertile (age 25+/-1 years), compared to the oldest tertile (age 52+/-1 years). In conclusion, we have observed that aging progressively and selectively reduces the cardiac autonomic excitatory response to light exercise, while hemodynamic and vascular responsiveness are maintained.
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Affiliation(s)
- Daniela Lucini
- Centro Ricerca Terapia Neurovegetativa, Dipartimento Scienze Cliniche "L Sacco", University of Milano, Via G.B. Grassi, 74 20157 Milan, Italy
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Richard CA, Rector DM, Macey PM, Ali N, Harper RM. Late-developing rostral ventrolateral medullary surface responses to cardiovascular challenges during sleep. Brain Res 2003; 985:65-77. [PMID: 12957369 DOI: 10.1016/s0006-8993(03)03159-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Pressor and depressor manipulations are usually followed by compensatory autonomic, respiratory, somatomotor or arousal responses that limit the extent of blood pressure change. Of neural sites participating in blood pressure control, the rostral ventrolateral medullary surface (RVLMS) contributes significantly, and exhibits rapid-onset overall activity declines and increases to pressor and depressor challenges, respectively. In addition, longer-latency physiological responses develop that further compensate for the homeostatic challenge; some of these later influences are associated with arousal. Late-developing RVLMS activity changes accompanying physiologic responses that normalize a cardiovascular manipulation may provide insights into compensatory neural mechanisms during sleep following sustained or extreme blood pressure changes. We used intrinsic optical imaging procedures in seven unanesthetized adult cats to examine RVLMS and control site responses to pressor and depressor challenges during sleep that resulted in somatomotor, respiratory, heart rate or electroencephalographic indications of late-developing (post-baroreflex) compensatory responses. Although initial RVLMS responses differed in direction between pressor and depressor challenges, neural activity increased later in both manipulations, coincident with overt physiological manifestations indicative of compensatory responses, including arousal. Arousal occurred in 44% of blood pressure challenges. Comparable late-developing neural activity increases were not apparent in control sites. Latencies of late RVLMS responses during rapid eye movement sleep were significantly longer than in quiet sleep for pressor challenges. The pattern of the late RVLMS responses was not dependent on arousal, and suggests that the RVLMS participates in both the early baroreflex response and the late-developing compensatory actions.
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Affiliation(s)
- Christopher A Richard
- Department of Neurobiology, UCLA School of Medicine, 10833 LeConte Avenue, Los Angeles, CA 90095-1763, USA
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Lanfranchi PA, Somers VK. Arterial baroreflex function and cardiovascular variability: interactions and implications. Am J Physiol Regul Integr Comp Physiol 2002; 283:R815-26. [PMID: 12228049 DOI: 10.1152/ajpregu.00051.2002] [Citation(s) in RCA: 192] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The arterial baroreflex contributes importantly to the short-term regulation of blood pressure and cardiovascular variability. A number of factors (including reflex, humoral, behavioral, and environmental) may influence gain and effectiveness of the baroreflex, as well as cardiovascular variability. Many central neural structures are also involved in the regulation of the cardiovascular system and contribute to the integrity of the baroreflex. Consequently, brain injuries or ischemia may induce baroreflex impairment and deranged cardiovascular variability. Baroreflex dysfunction and deranged cardiovascular variability are also common findings in cardiovascular disease. A blunted baroreflex gain and impaired heart rate variability are predictive of poor outcome in patients with heart failure and myocardial infarction and may represent an early index of autonomic activation in left ventricular dysfunction. The mechanisms mediating these relationships are not well understood and may in part be the result of cardiac structural changes and/or altered central neural processing of baroreflex signals.
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Lucini D, Milani RV, Costantino G, Lavie CJ, Porta A, Pagani M. Effects of cardiac rehabilitation and exercise training on autonomic regulation in patients with coronary artery disease. Am Heart J 2002; 143:977-83. [PMID: 12075252 DOI: 10.1067/mhj.2002.123117] [Citation(s) in RCA: 110] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
BACKGROUND Although cardiovascular rehabilitation and exercise training have substantial benefits in various ischemic heart disease (IHD) risk factors and subsequent prognosis after major IHD events, there is a paucity of information about its effects on autonomic regulation (such as heart rate variability [HRV] and baroreflex gain), particularly considering its arterial and cardiopulmonary components. METHODS We studied 40 patients (aged 60 +/- 6 y) after major IHD events, including 29 who underwent a comprehensive phase II cardiac rehabilitation and exercise training program and 11 controls who did not attend cardiac rehabilitation. Specifically, we determined whether active training improves prognostic indices of autonomic regulation of the SA node and whether changes in baroreflex gain could be ascribed to the arterial or to the cardiopulmonary component of the overall arterial pressure/heart period baroreflex. RESULTS Only patients with IHD undergoing active rehabilitation demonstrated a significant increase in R-R interval, in its variance, in overall gain of arterial pressure/heart period baroreflex (7.44 +/- 1.20 ms/mm Hg to 12.12 +/- 1.48 ms/mm Hg, P <.001) and in peak oxygen consumption (Delta = 2.45 mL/kg/min, P <.001). Separate examination of the selective arterial and cardiopulmonary components showed that only the latter increased significantly (6.17 +/- 1.09 ms/mm Hg to 10.62 +/- 1.56 ms/mm Hg; P <.01). CONCLUSIONS Cardiac rehabilitation is associated with significant improvements in autonomic markers of neural regulation of the SA node, such as increases in R-R variance and the gain of the overall spontaneous baroreflex, with specific improvements in the cardiopulmonary component as opposed to the arterial baroreflex component of this system. These improvements may further explain the reduction in morbidity and mortality noted after formal cardiac rehabilitation and exercise training programs.
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Affiliation(s)
- Daniela Lucini
- Centro di Ricerca sulla Terapia Neurovegetativa, Medicina Interna I, Ospedale L. Sacco, DiSP LITA Vialba, Centro Ricerche Cardiovascolari, CNR, Università di Milano, Milano, 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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Penttilä J, Vesalainen R, Helminen A, Kuusela T, Hinkka S, Rahi K, Kaila T, Scheinin H. Spontaneous baroreflex sensitivity as a dynamic measure of cardiac anticholinergic drug effect. JOURNAL OF AUTONOMIC PHARMACOLOGY 2001; 21:71-8. [PMID: 11679015 DOI: 10.1046/j.1365-2680.2001.00210.x] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
1. In this study, the analysis of spontaneous baroreflex sensitivity (BRS) was applied to the dynamic assessment of cardiac anticholinergic drug effect in healthy male volunteers. 2. The anticholinergic effects of single intravenous (i.v.) injections of atropine (10 microg kg(-1)), glycopyrrolate (5 microg kg(-1)) and scopolamine (5 microg kg(-1)), as well as a 2-h infusion of glycopyrrolate (5 microg kg(-1) h(-1)) were investigated. Baroreflex sensitivity, a validated measure of cardiac parasympathetic reflex regulation, was repeatedly measured from 5-min recordings of electrocardiogram (ECG) and continuous blood pressure by using the sequence technique, a method based on detection of spontaneous fluctuations in blood pressure and heart rate. 3. Single injections of atropine, glycopyrrolate and scopolamine decreased the mean BRS by 71 +/- 32, 68 +/- 23 and 27 +/- 45%, respectively, whereas the slow glycopyrrolate infusion gradually decreased BRS (up to 83 +/- 11% reduction) and increased both systolic (SAP) and diastolic arterial pressures (DAP) (on an average, by 9 mmHg). 4. During the withdrawal of the parasympathetic blockade (indicated by increasing BRS), the proportion of baroreflex sequences in the recordings increased transiently from 10 up to 20-25%, probably reflecting the restoration of the baroreflex integrity and the baroreflex-induced attempt to counteract the blood pressure increase. 5. The sequence method to study BRS seems to be feasible in the assessment of cardiac anticholinergic drug effects, and it also provides good time resolution for the dynamic measurements.
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Affiliation(s)
- J Penttilä
- Department of Pharmacology and Clinical Pharmacology, University of Turku, Turku, Finland
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Head GA, Lukoshkova EV, Burke SL, Malpas SC, Lambert EA, Janssen BJ. Comparing spectral and invasive estimates of baroreflex gain. IEEE ENGINEERING IN MEDICINE AND BIOLOGY MAGAZINE : THE QUARTERLY MAGAZINE OF THE ENGINEERING IN MEDICINE & BIOLOGY SOCIETY 2001; 20:43-52. [PMID: 11321719 DOI: 10.1109/51.917723] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Affiliation(s)
- G A Head
- Neuropharmacology Laboratory, Baker Medical Research Institute, Prahran.
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Di Rienzo M, Parati G, Castiglioni P, Tordi R, Mancia G, Pedotti A. Baroreflex effectiveness index: an additional measure of baroreflex control of heart rate in daily life. Am J Physiol Regul Integr Comp Physiol 2001; 280:R744-51. [PMID: 11171653 DOI: 10.1152/ajpregu.2001.280.3.r744] [Citation(s) in RCA: 184] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
In healthy subjects, progressive beat-to-beat increases or decreases in systolic blood pressure (SBP) ramps are not always accompanied by baroreflex-driven lengthening or shortening in pulse interval (PI) ramps, respectively. This phenomenon has been quantified by a new index, the baroreflex effectiveness index (BEI), defined as the ratio between the number of SBP ramps followed by the respective reflex PI ramps and the total number of SBP ramps observed in a given time window. Specificity of BEI was shown in eight cats by a -89% reduction of BEI after sinoaortic denervation. In 14 healthy humans, the 24-h average BEI value was 0.21, with a marked day-night modulation ( approximately 0.25 day, approximately 0.15 night) in counterphase with modulation of baroreflex sensitivity (BRS). Our analysis indicates that 1) in normal subjects, arterial baroreflex can induce beat-by-beat PI changes in response to only 21% of all SBP ramps, possibly because of central inhibitory influences or of interferences at sinus node level by nonbaroreflex mechanisms and 2) BEI provides information on the baroreflex function that is complementary to BRS.
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Affiliation(s)
- M Di Rienzo
- LaRC-Centro di Bioingegneria, Fondazione Don Carlo Gnocchi ONLUS and Politecnico di Milano, 20148 Milano, Italy.
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Porta A, Baselli G, Rimoldi O, Malliani A, Pagani M. Assessing baroreflex gain from spontaneous variability in conscious dogs: role of causality and respiration. Am J Physiol Heart Circ Physiol 2000; 279:H2558-67. [PMID: 11045994 DOI: 10.1152/ajpheart.2000.279.5.h2558] [Citation(s) in RCA: 121] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
A double exogenous autoregressive (XXAR) causal parametric model was used to estimate the baroreflex gain (alpha(XXAR)) from spontaneous R-R interval and systolic arterial pressure (SAP) variabilities in conscious dogs. This model takes into account 1) effects of current and past SAP variations on the R-R interval (i.e., baroreflex-mediated influences), 2) specific perturbations affecting R-R interval independently of baroreflex circuit (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at frequencies slower than respiration), and 3) influences of respiration-related sources acting independently of baroreflex pathway (e.g., rhythmic neural inputs modulating R-R interval independently of SAP at respiratory rate, including the effect of stimulation of low-pressure receptors). Under control conditions, alpha(XXAR) = 14.7 +/- 7.2 ms/mmHg. It decreases after nitroglycerine infusion and coronary artery occlusion, even though the decrease is significant only after nitroglycerine, and it is completely abolished by total arterial baroreceptor denervation. Moreover, alpha(XXAR) is comparable to or significantly smaller than (depending on the experimental condition) the baroreflex gains derived from sequence, power spectrum [at low frequency (LF) and high frequency (HF)], and cross-spectrum (at LF and HF) analyses and from less complex causal parametric models, thus demonstrating that simpler estimates may be biased by the contemporaneous presence of regulatory mechanisms other than baroreflex mechanisms.
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Affiliation(s)
- A Porta
- Dipartimento di Scienze Precliniche, Laboratorio Interdisciplinare Tecnologie Avanzate di Vialba, Universitá degli Studi di Milano, 20157 Milan, Italy.
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Pitzalis MV, Massari F, Mastropasqua F, Fioretti A, Guida P, Colombo R, Balducci C, Rizzon P. Age effect on phase relations between respiratory oscillations of the RR interval and systolic pressure. Pacing Clin Electrophysiol 2000; 23:847-53. [PMID: 10833705 DOI: 10.1111/j.1540-8159.2000.tb00854.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Spectral analysis may allow the evaluation of (baroreflex) gain and phase between the RR interval and systolic pressure oscillations synchronous with respiration but, unlike baroreflex gain, the determinants of phase are not completely understood. We evaluated the correlates of spectral phase in 92 healthy subjects (44 men) aged 10-80 years. To do so, the cardiorespiratory signals during paced breathing at 16 breaths/min were continuously recorded and analyzed. In addition, respiratory sinus arrhythmia and baroreflex gain (two indices of cardiac vagal activity) and phase were calculated by using an autoregressive spectral technique. At univariate analysis, the phase correlated with age (r = 0.48, P < 0.001), the RR interval (r = 0.32, P < 0.01), respiratory sinus arrhythmia (r = -0.3, P < 0.01), baroreflex gain (r = -0.29, P < 0.01), and body mass index (r = 0.25, P < 0.05). At multivariate analysis, age was the most important physiological correlate of phase, accounting for 23% of interindividual phase variation. Cardiac vagal activity measures (which were higher in women than men) and the RR interval were also significant independent correlates of phase. We conclude that in addition to the RR interval and cardiac vagal activity, age has a significant impact on the phase relationship between respiratory related oscillations of the RR interval and systolic blood pressure. This spectral measure may contain additional information concerning the mechanisms that influence cardiovascular rhythms.
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Affiliation(s)
- M V Pitzalis
- Institute of Cardiology, University of Bari, Italy.
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Lucini D, Porta A, Milani O, Baselli G, Pagani M. Assessment of arterial and cardiopulmonary baroreflex gains from simultaneous recordings of spontaneous cardiovascular and respiratory variability. J Hypertens 2000; 18:281-6. [PMID: 10726714 DOI: 10.1097/00004872-200018030-00007] [Citation(s) in RCA: 39] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES In usual models of cardiovascular regulation, arterial pressure drives RR interval through a simple baroreflex, and the influence of respiration is dismissed. We examined the applicability of a trivariate autoregressive model to obtain separate values of the gain of the arterial and non-arterial, i.e. cardiopulmonary, components of the lumped baroreflex, employing spontaneous RR interval, systolic arterial pressure and respiration variability. DESIGN We studied 30 normal subjects (age 37 +/- 1 years), both at rest and during standing, a condition known to enhance sympathetic activity while reducing venous return. Electrocardiogram was obtained by telemetry, arterial pressure by Finapres and respiration with a piezoelectric respiratory belt Data were acquired with a PC and processed with an ad hoc Windows program. METHODS We employed an additive and a linear multivariate approach to approximate overall gain of the arterial pressure-heart beat period baroreflex (alphalumped) and of its arterial (alphaart) and non-arterial, i.e. cardiopulmonary (alphacp), components, from continuous beat-by-beat series of RR interval, systolic arterial pressure variability and respiration, without using any non-physiological intervention. RESULTS The overall baroreflex gain at rest (alphalumped = 23.7 +/- 3.4 ms/mmHg) was subdivided into arterial (alphaart = 5.2 +/- 1.0 ms/mmHg) and cardiopulmonary (alphacp = 18.5 +/- 3.2ms/mmHg) components. During active orthostatism, alphaluumped was diminished to 10.0 +/- 2.2 ms/ mmHg. In addition, standing selectively reduced alphacp to 4.8 +/- 1.3 ms/mmHg, while alphaart was not significantly changed. CONCLUSIONS A trivariate autoregressive model, that considers explicitly the influence of respiration, can subdivide overall, lumped, arterial pressure-heart period baroreflex gain, into two separate components, alphaart and alphacp. Only the latter is reduced by active orthostatism.
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Affiliation(s)
- D Lucini
- Centro di Ricerca sulla Terapia Neurovegetative, Medicine Interna I, Ospedale L. Sacco, CNR, Università di Milano, Milan, Italy
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