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Lorvidhaya P, Addo K, Chodosh A, Iyer V, Lum J, Buxton AE. Sudden cardiac death risk stratification in patients with heart failure. Heart Fail Clin 2011; 7:157-74, vii. [PMID: 21439495 DOI: 10.1016/j.hfc.2010.12.001] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
The multiplicity of mechanisms contributing to arrhythmogenesis in patients with heart failure carries obvious implications for risk stratification. If patients having the propensity to develop arrhythmias by these different mechanisms are to be identified, tests must be devised that reveal the substrates or other factors that relate to each mechanism. In the absence of this, efforts to risk stratify patients are likely to be neither cost-effective nor accurate. This article reviews the current knowledge base of risk stratification for sudden death in patients with heart failure, while acknowledging several limitations in the studies examined.
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Affiliation(s)
- Peem Lorvidhaya
- Division of Cardiology, Rhode Island and Miriam Hospitals, The Warren Alpert Medical School of Brown University, 2 Dudley Street, Suite 360, Providence, RI 02905, USA
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102
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Comparison of the prognostic values of invasive and noninvasive assessments of baroreflex sensitivity in heart failure. J Hypertens 2011; 29:1546-52. [DOI: 10.1097/hjh.0b013e3283487827] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
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103
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Mostarda C, Moraes-Silva IC, Moreira ED, Medeiros A, Piratello AC, Consolim-Colombo FM, Caldini EG, Brum PC, Krieger EM, Irigoyen MC. Baroreflex Sensitivity Impairment Is Associated With Cardiac Diastolic Dysfunction in Rats. J Card Fail 2011; 17:519-25. [DOI: 10.1016/j.cardfail.2011.02.007] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Revised: 02/07/2011] [Accepted: 02/24/2011] [Indexed: 11/17/2022]
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Brack KE, Coote JH, Ng GA. Vagus nerve stimulation protects against ventricular fibrillation independent of muscarinic receptor activation. Cardiovasc Res 2011; 91:437-46. [PMID: 21576131 DOI: 10.1093/cvr/cvr105] [Citation(s) in RCA: 78] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
AIMS The role of the vagus in the ventricle is controversial, although the vagus can protect against ventricular fibrillation (VF) via nitric oxide (NO). This study aims to determine whether the mechanisms involved are dependent on post-ganglionic release and muscarinic receptor activation. For this purpose, NO release and electrophysiological effects of vagus nerve stimulation (VNS) were evaluated in relation to acetylcholine and vasoactive intestinal peptide (VIP). In addition, the role of the coronary endothelium and afferent nerves was tested. METHODS AND RESULTS Using the isolated innervated rabbit heart, we measured ventricular NO release using 4,5-diaminofluorescein (DAF-2) fluorescence and ventricular fibrillation threshold (VFT) during VNS after muscarinic, ganglionic, and VIP inhibition [atropine, hexamethonium, and VIP (6-28), respectively] and after Triton-X endothelial functional dysfunction. The vagal-mediated increases in NO and VFT were not significantly affected (P> 0.05) during (i) atropine perfusion [increase in NO: 196.8 ± 35.2 mV (control) vs. 156.1 ± 20.3 mV (atropine) and VFT 3.1 ± 0.5 mA (control) vs. 2.7 ± 0.4 mA (atropine)], (ii) VIP inhibition-increase in NO: 243.0 ± 42.4 mV (control) vs. 203.9 ± 28.5 mV [VIP(6-28)] and VFT 3.3 ± 0.3 mA (control) vs. 3.9 ± 0.6 mA [VIP(6-28)], or (iii) after endothelial functional dysfunction [increase in NO: 127.7 ± 31.7 mV (control) vs. 172.1 ± 31.5 mV (Triton-X) and VFT 2.6 ± 0.4 mA (control) vs. 2.5 ± 0.5 mA (Triton-X)]. However, the vagal effects were inhibited during ganglionic blockade [increase in NO: 175.1 ± 38.1 mV (control) vs. 0.6 ± 25.3 mV (hexamethonium) and VFT 3.3 ± 0.5 mA (control) vs. -0.3 ± 0.3 mA (hexamethonium)]. CONCLUSIONS We show that the vagal anti-fibrillatory action in the rabbit ventricle occurs via post-ganglionic efferent nerve fibres, independent of muscarinic receptor activation, VIP, and the endothelium. Together with our previous publications, our data support the possibility of a novel ventricular nitrergic parasympathetic innervation and highlight potential for new therapeutic targets to treat ventricular dysrhythmias.
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Affiliation(s)
- Kieran E Brack
- Department of Cardiovascular Sciences, Cardiology Group, University of Leicester, Glenfield Hospital, Leicester, UK
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105
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Sympathetic-parasympathetic interaction in health and disease: abnormalities and relevance in heart failure. Heart Fail Rev 2011; 16:101-7. [PMID: 20577900 DOI: 10.1007/s10741-010-9179-1] [Citation(s) in RCA: 109] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
Sympathetic-parasympathetic interaction plays a major role in the evolution and outcome of many cardiovascular disorders. Nonetheless, a thorough understanding of this relationship and of its potential implications for prognosis and management still escapes many cardiologists. This article reviews the background of sympathetic-parasympathetic interactions focusing on the best direct evidence available, namely direct neural recordings of the activity of single vagal and sympathetic fibers directed to the heart. It examines indirect but highly reliable markers of this interaction as they can be studied in the clinical setting of ischemic heart disease and of heart failure, focusing primarily on the experimental and clinical studies of baroreflex sensitivity. It concludes by drawing inferences likely to lead to a novel approach to the management of heart failure, resulting from the knowledge gained about the vagal control of the heart and based on electrical vagal stimulation.
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Baroreflex sensitivity is higher during acute psychological stress in healthy subjects under β-adrenergic blockade. Clin Sci (Lond) 2011; 120:161-7. [PMID: 20828371 PMCID: PMC2973234 DOI: 10.1042/cs20100137] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Acute psychological stress challenges the cardiovascular system with an increase in BP (blood pressure), HR (heart rate) and reduced BRS (baroreflex sensitivity). β-adrenergic blockade enhances BRS during rest, but its effect on BRS during acute psychological stress is unknown. This study tested the hypothesis that BRS is higher during acute psychological stress in healthy subjects under β-adrenergic blockade. Twenty healthy novice male bungee jumpers were randomized and studied with (PROP, n=10) or without (CTRL, n=10) propranolol. BP and HR responses and BRS [cross-correlation time-domain (BRSTD) and cross-spectral frequency-domain (BRSFD) analysis] were evaluated from 30 min prior up to 2 h after the jump. HR, cardiac output and pulse pressure were lower in the PROP group throughout the study. Prior to the bungee jump, BRS was higher in the PROP group compared with the CTRL group [BRSTD: 28 (24-42) compared with 17 (16-28) ms·mmHg-1, P<0.05; BRSFD: 27 (20-34) compared with 14 (9-19) ms·mmHg-1, P<0.05; values are medians (interquartile range)]. BP declined after the jump in both groups, and post-jump BRS did not differ between the groups. In conclusion, during acute psychological stress, BRS is higher in healthy subjects treated with non-selective β-adrenergic blockade with significantly lower HR but comparable BP.
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107
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108
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Schwartz PJ. Vagal Stimulation for Heart Diseases: From Animals to Men - An Example of Translational Cardiology -. Circ J 2011; 75:20-7. [DOI: 10.1253/circj.cj-10-1019] [Citation(s) in RCA: 47] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Peter J. Schwartz
- Department of Lung, Blood and Heart, University of Pavia
- Department of Cardiology, Fondazione IRCCS Policlinico S. Matteo
- Laboratory of Cardiovascular Genetics, IRCCS Istituto Auxologico Italiano
- Cardiovascular Genetics Laboratory, Hatter Institute for Cardiovascular Research, Department of Medicine, University of Cape Town
- Chair of Sudden Death, Department of Family and Community Medicine, College of Medicine, King Saud University
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109
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Bivariate phase-rectified signal averaging for assessment of spontaneous baroreflex sensitivity: pilot study of the technology. J Electrocardiol 2010; 43:649-53. [DOI: 10.1016/j.jelectrocard.2010.05.012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2010] [Indexed: 11/19/2022]
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Bhatia V, Rarick KR, Stauss HM. Effect of the data sampling rate on accuracy of indices for heart rate and blood pressure variability and baroreflex function in resting rats and mice. Physiol Meas 2010; 31:1185-201. [PMID: 20664161 DOI: 10.1088/0967-3334/31/9/009] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
The aim of this study was to determine the minimal sampling rate (SR) required for blood pressure (BP) waveform recordings to accurately determine BP and heart rate (HR) variability indices and baroreceptor reflex sensitivity in rats and mice. We also determined if an 8-bit (versus 12-bit) analog-to-digital converter (ADC) resolution is sufficient to accurately determine these hemodynamic parameters and if spline interpolation to 1000 Hz of BP waveforms sampled at lower SRs can improve accuracy. BP and ECG recordings (1000 Hz SR, 12-bit ADC resolution) from two strains of rats and BP recordings (1000 Hz SR, 12-bit ADC resolution) from two strains of mice were mathematically converted to lower SRs and/or 8-bit ADC resolution. Time-domain HR variability and frequency-domain HR and BP variability indices and baroreflex sensitivity (using the sequence technique) were determined and the results obtained from the original files were compared to the results obtained from the mathematically altered files. Our results demonstrate that an ADC resolution of 8 bit is not sufficient to determine HR and BP variability in rats and mice and baroreceptor reflex sensitivity in mice. Average values for systolic, mean and diastolic BP and HR can be accurately derived from BP waveforms recorded at a minimal SR of 200 Hz in rats and mice. Spline interpolation of BP waveforms to 1000 Hz prior to extracting derived parameters reduces this minimal SR to 50 Hz in rats but still requires 200 Hz in mice. Frequency-domain BP variability (very low and low frequency spectral powers) can be estimated accurately at a minimum SR of 100 Hz in rats and mice and spline interpolation of BP waveforms to 1000 Hz reduces this minimal SR to 50 Hz in rats but does not reduce the minimal SR in mice. Time- and frequency-domain HR variability parameters require at least a SR of 1000 Hz in rats and mice. Spline interpolation of BP waveforms to 1000 Hz reduces this minimal SR to 100 Hz in rats and to 200 Hz in mice. Estimation of baroreflex sensitivity using the sequence technique requires a SR of at least 1000 Hz in rats and mice. Spline interpolation of BP waveforms to 1000 Hz reduces this minimal SR to 100 Hz in rats but does not reduce the minimum SR in mice. Finally, our results indicate that HR time series derived from BP waveforms are not totally consistent with HR time series derived from the ECG in rats. In conclusion, accurate assessment of HR variability and baroreflex sensitivity from BP waveform recordings requires a SR of at least 1000 Hz in rats and mice. If lower SRs are used for BP waveform recordings, a cubic spline interpolation to 1000 Hz (or an even higher SR) prior to extracting derived parameters significantly improves accuracy.
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Affiliation(s)
- Vivek Bhatia
- Department of Internal Medicine, Albert Einstein College of Medicine, Bronx, New York, NY 10467, USA.
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111
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Abstract
PURPOSE OF REVIEW Chronic heart failure (CHF) is a common condition with significant morbidity despite optimal medical therapy. Standard therapy involves inhibiting the maladaptive changes of metabolism and neuro-hormones that characterize the syndrome of CHF. Anabolic deficiency is a major component of the CHF syndrome and testosterone replacement therapy has been subject to recent trials. RECENT FINDINGS The recent literature shows that physiological testosterone replacement therapy leads to modest improvements in voluntary muscle strength, lean muscle mass, endurance and positive effects on neuro-muscular and baro-receptor reflexes. Long-term efficacy and safety remain unstudied at present. SUMMARY Testosterone replacement therapy appears to improve metabolism and endurance in patients with CHF; further trials will be necessary before widespread use. Physicians who regularly treat patients with CHF may consider testosterone therapy but it is likely that they will require the advice and support from endocrine specialists.
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Affiliation(s)
- Chris J Malkin
- Department of Cardiology Sheffield Teaching Hospitals NHS Foundation Trust, Sheffield, UK
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Taçoy G, Açikgöz K, Kocaman SA, Özdemir M, Çengel A. Is there a relationship between obesity, heart rate variability and inflammatory parameters in heart failure? J Cardiovasc Med (Hagerstown) 2010; 11:118-24. [DOI: 10.2459/jcm.0b013e328332e730] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
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Harrison JL, Hildreth CM, Callahan SM, Goodchild AK, Phillips JK. Cardiovascular autonomic dysfunction in a novel rodent model of polycystic kidney disease. Auton Neurosci 2010; 152:60-6. [DOI: 10.1016/j.autneu.2009.09.019] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2009] [Revised: 09/14/2009] [Accepted: 09/25/2009] [Indexed: 11/16/2022]
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Despas F, Trouillet C, Franchitto N, Labrunee M, Galinier M, Senard JM, Pathak A. Levosimedan improves hemodynamics functions without sympathetic activation in severe heart failure patients: Direct evidence from sympathetic neural recording. ACTA ACUST UNITED AC 2009; 12:25-30. [DOI: 10.3109/17482940903434077] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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115
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Schwartz PJ, De Ferrari GM. Vagal stimulation for heart failure: Background and first in-man study. Heart Rhythm 2009; 6:S76-81. [DOI: 10.1016/j.hrthm.2009.08.012] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/15/2009] [Indexed: 11/29/2022]
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116
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Floras JS. Sympathetic nervous system activation in human heart failure: clinical implications of an updated model. J Am Coll Cardiol 2009; 54:375-85. [PMID: 19628111 DOI: 10.1016/j.jacc.2009.03.061] [Citation(s) in RCA: 379] [Impact Index Per Article: 25.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/11/2009] [Revised: 03/16/2009] [Accepted: 03/23/2009] [Indexed: 11/28/2022]
Abstract
Disturbances in cardiovascular neural regulation, influencing both disease course and survival, progress as heart failure worsens. Heart failure due to left ventricular systolic dysfunction has long been considered a state of generalized sympathetic activation, itself a reflex response to alterations in cardiac and peripheral hemodynamics that is initially appropriate, but ultimately pathological. Because arterial baroreceptor reflex vagal control of heart rate is impaired early in heart failure, a parallel reduction in its reflex buffering of sympathetic outflow has been assumed. However, it is now recognized that: 1) the time course and magnitude of sympathetic activation are target organ-specific, not generalized, and independent of ventricular systolic function; and 2) human heart failure is characterized by rapidly responsive arterial baroreflex regulation of muscle sympathetic nerve activity (MSNA), attenuated cardiopulmonary reflex modulation of MSNA, a cardiac sympathoexcitatory reflex related to increased cardiopulmonary filling pressure, and by individual variation in nonbaroreflex-mediated sympathoexcitatory mechanisms, including coexisting sleep apnea, myocardial ischemia, obesity, and reflexes from exercising muscle. Thus, sympathetic activation in the setting of impaired systolic function reflects the net balance and interaction between appropriate reflex compensatory responses to impaired systolic function and excitatory stimuli that elicit adrenergic responses in excess of homeostatic requirements. Recent observations have been incorporated into an updated model of cardiovascular neural regulation in chronic heart failure due to ventricular systolic dysfunction, with implications for the clinical evaluation of patients, application of current treatment, and development of new therapies.
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Affiliation(s)
- John S Floras
- Mount Sinai Hospital and University Health Network Division of Cardiology, and the University of Toronto, Toronto, Ontario, Canada.
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Aukrust P, Ueland T, Gullestad L, Yndestad A. Testosterone: A Novel Therapeutic Approach in Chronic Heart Failure?⁎⁎Editorials published in the Journal of the American College of Cardiologyreflect the views of the authors and do not necessarily represent the views of JACCor the American College of Cardiology. J Am Coll Cardiol 2009; 54:928-9. [DOI: 10.1016/j.jacc.2009.05.039] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2009] [Accepted: 05/19/2009] [Indexed: 10/20/2022]
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