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Autonomic Modulation (autonomic + modulation)
Kinds of Autonomic Modulation Selected AbstractsAdrenergic-Cholinergic Interaction that Modulates Repolarization in the Atrium is Altered with AgingJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 4 2002EUGENE A. SOSUNOV Ph.D. Autonomic Modulation of Atrial Repolarization.Introduction: Aging is associated with involution of both limbs of the autonomic nervous system, and the prejunctional and postjunctional effects of adrenergic and cholinergic stimulation are altered with senescence. Hence, postjunctional age-related changes in adrenergic-cholinergic interaction are a likely occurrence and may contribute to an altered substrate for arrhythmias. Methods and Results: Microelectrode techniques were used to record action potentials from epicardial slices of Bachmann's bundles of dogs aged 3 to 5 years (adult) and 8 to 12 years (old) in the absence or presence of acetylcholine and isoproterenol (separately and in combination). In control, action potential duration to 90% repolarization (APD) was longer in old atria. Acetylcholine (10,8 to 10,5 mol/L) in a concentration-dependent manner hyperpolarized and shortened APD in both tissues, with more prominent effects in the old. The effects of isoproterenol (10,9 to 10,6 mol/L) to elevate the plateau and shorten APD were about the same in both adult and old tissues. In adults, low concentrations of isoproterenol (10,9 and 10,8 mol/L) significantly prolonged APD, which had been first shortened by acetylcholine. This effect of isoproterenol was decreased in old atrial tissue, resulting in shorter APD in old than adult atria in the combined presence of beta-adrenergic and muscarinic agonists. Conclusion: In adult Bachmann's bundle, beta-adrenergic stimulation effectively operates as a "brake" to decrease the extent of cholinergic-induced APD shortening. The action of beta-adrenergic stimulation to antagonize acetylcholine-induced acceleration of repolarization declines with age, which may contribute to an altered arrhythmogenic substrate. [source] Independent Autonomic Modulation of Sinus Node and Ventricular Myocardium in Healthy Young Men During SleepJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2000PETER KOWALLIK M.D. Autonomic Modulation of Sinus Node and Ventricle. Introduction. The aim of this study was to investigate whether autonomic modulation of ventricular repolarization may spontaneousiy differ from that of the sinoatrial node. Methods and Results. Onset of P waves. QRS complexes, and the apex and end of T waves were detected heat to heat in high-resolution ECGs from nine healthy young men during the night. There were time-dependent fluctuations in the QT/RR slopes of consecutive 5-minute segments that could not he explained by the mean RR cycle length of the respective segment. Because the variahility found in QT intervals could not be explained hy either possible effects of rate dependence or hysteresis, autonomic effects were obvious. Power speetral analysis was performed for consecutive 5-minute segments of PP and QT techograms. In a given subject. trends in the time course of low-frequency (LF) and high-frequency (HF) power in PP and QT often were similar, but they were quite different at other times. The mean LF/HF ratio for QTend (0.75 ± 0.1) was different from that of PP (1.8 ± 0.2; P = 0.002), indicating differences in sympathovagal balance at the different anatomic sites. Furthermore, at a given mean heart rate, averaged QT intervals were different on a time scale of several minutes to hours. The QT/RR slope of 5-minute segments correlated significantly with the HF power of QT variability but not with that of PP variability, indicating effects of the autonomic nervous system on ventricular action potential restitution. Conclusion. These differences demonstrate that changes in sinus node automaticity are not necessarily indicative of the autonomic control of ventricular myocardium. (J Cardiavasc Electrophysiol, Vol. II, pp. 1063-1070. October 2000) [source] Acute Effects of Moxonidine on Cardiac Autonomic ModulationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010DAYIMI KAYA M.D. Background: Moxonidine, an imidazoline I1 receptor agonist, is a centrally acting antihypertensive agent having sympatholytic effect. However, there are only limited data regarding the effects of this drug on autonomic cardiac functions. Methods and results: In this study we investigated the acute effects of moxonidine on cardiac autonomic modulation by heart rate variability (HRV) analysis. The effects of oral 0.4-mg moxonidine were studied on 11 healthy male volunteers in a randomized, double-blind, placebo controlled, and crossover study. After 15 minutes rest, time and frequency domain parameters of HRV were calculated from 5-minute continue electrocardiography recordings in supine position, during controlled respiration (15 breath/min) and during handgrip exercise before and 1 hour after taking placebo or moxonidine. Baseline parameters before taking placebo and moxonidine were similar (P > 0.05). Moxonidine, but not placebo, caused an increase in heart failure (HF) (119 ± 21 vs 156 ± 23, P = 0.029) and HFnu (39 ± 4 vs 47 ± 4, P = 0.033) and decrease in LFnu (61 ± 4 vs 53 ± 4, P = 0.033) and LF/HF ratio (1.96 ± 0.36 vs 1.12 ± 0.35, P = 0.010) in supine position compared with baseline parameters. However, there was no difference in other time or frequency domain parameters during controlled breathing and handgrip exercise either with moxonidine or placebo administration (P > 0.05). Single dose of moxonidine administration increases cardiovagal tone but parasympathetic and sympathetic autonomic maneuvers attenuated its short term effects on HRV in healthy male subjects. (PACE 2010; 929,933) [source] The Full Stomach Test as a Novel Diagnostic Technique for Identifying Patients at Risk of Brugada SyndromeJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 6 2006F.A.C.C., Ph.D., TAKANORI IKEDA M.D. Introduction: Autonomic modulation, particularly high vagal tone, plays an important role in the occurrence of ventricular tachyarrhythmias in the Brugada syndrome. Food intake modulates vagal activity. We assessed the usefulness of a novel diagnostic technique, the "full stomach test," for identifying a high-risk group in patients with a Brugada-type electrocardiogram (ECG). Methods and Results: In 35 patients with a Brugada-type ECG, we assessed 12-lead ECGs before and after a large meal, a pilsicainide pharmacological test, spontaneous ST-segment change, late potentials by signal-averaged ECG, microvolt T-wave alternans, and four other ECG parameters. These patients were divided into two groups (i.e., high-risk group [n = 17] and indeterminate risk group [n = 18]). The full stomach test was defined as positive when augmentation of characteristic ECG abnormalities was observed after meals. Thirteen patients had a prior history of life-threatening events such as aborted sudden death and syncope, with a total of 30 episodes. These episodes had a circadian pattern, at night and after meals. The full stomach test was positive in 17 of the study patients (49%). A positive test outcome was characterized by a higher incidence of a history of life-threatening events than a negative test outcome (P = 0.015, odds ratio = 7.1). In comparison between the two groups, the incidence (82%) of positive outcomes in the high-risk group was significantly higher than that (17%) in the indeterminate risk group (P = 0.0002). Conclusions: Characteristic ECG changes diagnostic of Brugada syndrome are augmented by a large meal. These data are associated with a history of life-threatening events in Brugada syndrome. [source] Cardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertensionACTA PHYSIOLOGICA, Issue 3 2009S. R. Collier Abstract Aim:, Cardiac autonomic modulation and baroreflex sensitivity (BRS) are altered in individuals with hypertension. Aerobic exercise (AE) training has been shown to improve both measures, yet little is known about the effects of resistance exercise (RE). The purpose of this study was to examine the heart rate variability (HRV) and BRS following 4 weeks of resistance or aerobic training in a population with borderline high blood pressure (BP). Methods:, Twenty-nine mild hypertensives were recruited and randomly assigned to 4 weeks of RE or AE training. Before and after training, resting measures of HRV frequencies and BRS were obtained. Results:, There was a significant decrease in resting systolic BP for both exercise training modes (RE 136 ± 3.0 pre- to 132 ± 3.4 post-training vs. AE 142 ± 4.0 pre- to 137 ± 3.6 mmHg post-training, P = 0.019). Diastolic BP decreased significantly following both exercise training modes (RE 78 ± 1.31 pre to 74 ± 1.1 post vs. AE 80 ± 1.7 pre to 77 ± 1.6 mmHg post, P = 0.002). A significant time by training mode interaction for low frequency : high frequency (HF) ratio (P = 0.017) with AE decreasing the ratio (275.21 ± 67.28 to 161.26 ± 61.49) and RE increasing this ratio (143.73 ± 65.00 to 227.83 ± 59.41). Natural log-transformed (ln) HRV values showed a time-by-training mode interaction for ln HF (P = 0.05) as ln HF increased (4.7 ± 0.38 to 5.4 ± 0.35 ms2) following AE and decreased (5.98 ± 0.37 to 5.76 ± 0.42 ms2) following RE. BRS increased following aerobic training and decreased after resistance training (6.74 ± 1.2 to 7.94 ± 1.3 and 10.44 ± 1.2 to 9.1 ± 1.2 ms mmHg,1 respectively, P = 0.021). Conclusions:, Aerobic exercise improved the autonomic nervous system (increasing vagal tone, reducing sympathovagal balance while increasing BRS) while RE showed no improvements in cardiac autonomic tone and decreased BRS. [source] The Ictal Bradycardia Syndrome: Localization and LateralizationEPILEPSIA, Issue 4 2006Jeffrey W. Britton Summary:,Purpose: Previous studies have established the importance of the insular cortex and temporal lobe in cardiovascular autonomic modulation. Some investigators, based on the results of cortical stimulation response, functional imaging, EEG recordings of seizures, and lesional studies, have suggested that cardiac sympathetic and parasympathetic function may be lateralized, with sympathetic representation lateralized to the right insula, and parasympathetic, to the left. These studies have suggested that ictal bradycardia is most commonly a manifestation of activation of the left temporal and insular cortex. However, the evidence for this is inconsistent. We sought to assess critically the predictable value of ictal bradycardia for seizure localization and lateralization. Methods: In this study, we reviewed the localization of seizure activity in 13 consecutive patients with ictal bradycardia diagnosed during prolonged video-EEG monitoring at Mayo Clinic Rochester. The localization of electrographic seizure activity at seizure onset and bradycardia onset was identified in all patients. In addition, we performed a comprehensive review of the ictal bradycardia literature focusing on localization of seizure activity in ictal bradycardia cases. Results: All occurrences of ictal bradycardia in the 13 identified patients were associated with temporal lobe,onset seizures. However, no consistent lateralization of seizure activity was found at onset of seizure activity or at onset of bradycardia in this population. Seizure activity was bilateral at bradycardia onset in nine of 13 patients. The results from the literature review also showed that a predominance of patients had bilateral activity at bradycardia onset; however, more of the ictal bradycardia cases from the literature had left hemispheric localization of seizure onset. Conclusions: Ictal bradycardia most often occurs in association with bilateral hemispheric seizure activity and is not a consistent lateralizing sign in localizing seizure onset. Our data do not support the existence of a strictly unilateral parasympathetic cardiomotor representation in the left hemisphere, as has been suggested. [source] Independent Autonomic Modulation of Sinus Node and Ventricular Myocardium in Healthy Young Men During SleepJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 10 2000PETER KOWALLIK M.D. Autonomic Modulation of Sinus Node and Ventricle. Introduction. The aim of this study was to investigate whether autonomic modulation of ventricular repolarization may spontaneousiy differ from that of the sinoatrial node. Methods and Results. Onset of P waves. QRS complexes, and the apex and end of T waves were detected heat to heat in high-resolution ECGs from nine healthy young men during the night. There were time-dependent fluctuations in the QT/RR slopes of consecutive 5-minute segments that could not he explained by the mean RR cycle length of the respective segment. Because the variahility found in QT intervals could not be explained hy either possible effects of rate dependence or hysteresis, autonomic effects were obvious. Power speetral analysis was performed for consecutive 5-minute segments of PP and QT techograms. In a given subject. trends in the time course of low-frequency (LF) and high-frequency (HF) power in PP and QT often were similar, but they were quite different at other times. The mean LF/HF ratio for QTend (0.75 ± 0.1) was different from that of PP (1.8 ± 0.2; P = 0.002), indicating differences in sympathovagal balance at the different anatomic sites. Furthermore, at a given mean heart rate, averaged QT intervals were different on a time scale of several minutes to hours. The QT/RR slope of 5-minute segments correlated significantly with the HF power of QT variability but not with that of PP variability, indicating effects of the autonomic nervous system on ventricular action potential restitution. Conclusion. These differences demonstrate that changes in sinus node automaticity are not necessarily indicative of the autonomic control of ventricular myocardium. (J Cardiavasc Electrophysiol, Vol. II, pp. 1063-1070. October 2000) [source] Acute Effects of Moxonidine on Cardiac Autonomic ModulationPACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010DAYIMI KAYA M.D. Background: Moxonidine, an imidazoline I1 receptor agonist, is a centrally acting antihypertensive agent having sympatholytic effect. However, there are only limited data regarding the effects of this drug on autonomic cardiac functions. Methods and results: In this study we investigated the acute effects of moxonidine on cardiac autonomic modulation by heart rate variability (HRV) analysis. The effects of oral 0.4-mg moxonidine were studied on 11 healthy male volunteers in a randomized, double-blind, placebo controlled, and crossover study. After 15 minutes rest, time and frequency domain parameters of HRV were calculated from 5-minute continue electrocardiography recordings in supine position, during controlled respiration (15 breath/min) and during handgrip exercise before and 1 hour after taking placebo or moxonidine. Baseline parameters before taking placebo and moxonidine were similar (P > 0.05). Moxonidine, but not placebo, caused an increase in heart failure (HF) (119 ± 21 vs 156 ± 23, P = 0.029) and HFnu (39 ± 4 vs 47 ± 4, P = 0.033) and decrease in LFnu (61 ± 4 vs 53 ± 4, P = 0.033) and LF/HF ratio (1.96 ± 0.36 vs 1.12 ± 0.35, P = 0.010) in supine position compared with baseline parameters. However, there was no difference in other time or frequency domain parameters during controlled breathing and handgrip exercise either with moxonidine or placebo administration (P > 0.05). Single dose of moxonidine administration increases cardiovagal tone but parasympathetic and sympathetic autonomic maneuvers attenuated its short term effects on HRV in healthy male subjects. (PACE 2010; 929,933) [source] Engineering physiologically controlled pacemaker cells with lentiviral HCN4 gene transferTHE JOURNAL OF GENE MEDICINE, Issue 5 2008Gerard J. J. Boink Abstract Background Research on biological pacemakers for the heart has so far mainly focused on short-term gene and cell therapies. To develop a clinically relevant biological pacemaker, long-term function and incorporation of autonomic modulation are crucial. Lentiviral vectors can mediate long-term gene expression, while isoform 4 of the Hyperpolarization-activated Cyclic Nucleotide-gated channel (encoded by HCN4) contributes to pacemaker function and responds maximally to cAMP, the second messenger in autonomic modulation. Material and Methods Action potential (AP) properties and pacemaker current (If) were studied in single neonatal rat ventricular myocytes that overexpressed HCN4 after lentiviral gene transduction. Autonomic responsiveness and cycle length stability were studied using extracellular electrograms of confluent cultured monolayers. Results Perforated patch-clamp experiments demonstrated that HCN4-transduced single cardiac myocytes exhibited a 10-fold higher If than non-transduced single myocytes, along with slow diastolic depolarization, comparable to pacemaker cells of the sinoatrial node, the dominant native pacemaker. HCN4-transduced monolayers exhibited a 47% increase in beating rate, compared to controls. Upon addition of DBcAMP, HCN4-transduced monolayers had beating rates which were 54% faster than baseline and significantly more regular than controls. Conclusions Lentiviral vectors efficiently transduce cardiac myocytes and mediate functional gene expression. Because HCN4-transduced myocytes demonstrate an increase in spontaneous beating rate and responsiveness to autonomic modulation, this approach may be useful to create a biological pacemaker. Copyright © 2008 John Wiley & Sons, Ltd. [source] Influence of Age on Linear and Nonlinear Measures of Autonomic Cardiovascular ModulationANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 2 2010Michael K. Boettger M.D. Background: Age has been identified as an independent risk factor for cardiovascular diseases. In addition, autonomic imbalance toward sympathetic preponderance has been shown to facilitate the occurrence of heart disease. Here, we aimed to assess autonomic modulation of cardiovascular parameters during normal ageing applying well-established linear and novel nonlinear parameters. Methods: Linear and nonlinear measures of heart rate variability and complexity as well as measures of QT interval variability and baroreflex sensitivity were obtained from a total of 131 healthy, medication-free participants from a continuous age range between 20 and 90 years, who were allocated to three different age groups. Results: Heart rate variability and complexity significantly decreased with age, while regularity of heart rate time series increased. In addition, QT interval variability linearly increased with age, while baroreflex sensitivity showed a pronounced decrease. Overall, concerning effects of ageing, linear and nonlinear parameters showed equal differentiation between groups. Conclusion: These data indicate a shift of autonomic balance toward sympathetic predominance in higher age groups, limiting the reactiveness of the cardiovascular system to adjust to different demands and increasing the risk for developing tachyarrhythmias. Ann Noninvasive Electrocardiol 2010;15(2):165,174 [source] Beat-to-Beat QT Interval Variability Is Primarily Affected by the Autonomic Nervous SystemANNALS OF NONINVASIVE ELECTROCARDIOLOGY, Issue 3 2008Ph.D., Takanao Mine M.D. Background: Beat-to-beat QT interval variability is associated with life-threatening arrhythmias and sudden death, however, its precious mechanism and the autonomic modulation on it remains unclear. The purpose of this study was to determine the effect of drugs that modulate the autonomic nervous system on beat-to-beat QT interval. Method: RR and QT intervals were determined for 512 consecutive beats during fixed atrial pacing with and without propranolol and automatic blockade (propranolol plus atropine) in 11 patients without structural heart disease. Studied parameters included: RR, QTpeak (QRS onset to the peak of T wave), QTend (QRS onset to the end of T wave) interval, standard deviation (SD) of the RR, QTpeak, and QTend (RR-SD, QTpeak-SD, and QTend-SD), coefficients of variation (RR- CV, QTpeak-CV, and QTend-CV) from time domain analysis, total power (TP; RR-TP, QTpeak-TP, and QTend-TP), and power spectral density of the low-frequency band (LF; RR-LF, QTpeak-LF, and QTend-LF) and the high-frequency band (HF; RR-HF, QTpeak-HF and QTend-HF). Results: Administration of propranolol and infusion of atropine resulted in the reduction of SD, CV, TP, and HF of the QTend interval when compared to controlled atrial pacing (3.7 ± 0.6 and 3.5 ± 0.5 vs 4.8 ± 1.4 ms, 0.9 ± 0.1 and 0.9 ± 0.1 vs 1.2 ± 0.3%, 7.0 ± 2.2 and 7.0 ± 2.2 vs 13.4 ± 8.1 ms2, 4.2 ± 1.4 and 4.2 ± 1.2 vs 8.4 ± 4.9 ms2, respectively). Administration of propranolol and atropine did not affect RR interval or QTpeak interval indices during controlled atrial pacing. Conclusions: Beat-to-beat QT interval variability is affected by drugs that modulate the autonomic nervous system. [source] Spinal tumor necrosis factor , neutralization reduces peripheral inflammation and hyperalgesia and suppresses autonomic responses in experimental arthritis: A role for spinal tumor necrosis factor , during induction and maintenance of peripheral inflammationARTHRITIS & RHEUMATISM, Issue 5 2010Michael Karl Boettger Objective In addition to the sensitization of pain fibers in inflamed tissues, the increased excitability of the spinal cord is an important mechanism of inflammatory pain. Furthermore, spinal neuronal excitability has been suggested to play a role in modulating peripheral inflammation. This study was undertaken to test the hypothesis that spinal actions of the proinflammatory cytokine tumor necrosis factor , (TNF,) add significantly to both hyperalgesia and maintenance of peripheral inflammation. Methods Rats with antigen-induced arthritis (AIA) were treated intrathecally with the TNF,-neutralizing compound etanercept continuously during the complete time course of AIA, which was 3 days for the acute phase and 21 days for the chronic phase. During this time, inflammation and pain-related behavior were monitored. Since a role for autonomic control of inflammation was proposed, measures from heart rate time series were obtained in the acute phase. Findings were compared with those in vehicle-treated animals and in animals receiving etanercept intraperitoneally. Results Spinally administered etanercept acutely reduced pain-related behavior, attenuated both the development and the maintenance of inflammation, and was superior to systemic administration. Parameters indicating autonomic modulation showed a shift toward a sympathetically dominated state in vehicle-treated animals, which was prevented by intrathecal etanercept. Conclusion Our findings indicate that spinal TNF, plays an important role in both pain signaling and modulation of peripheral inflammation. Thus, neutralizing this cytokine at the spinal site not only represents a putative therapeutic option for different pain syndromes, but may be directly used to attenuate peripheral inflammation. [source] Ketamine and its preservative, benzethonium chloride, both inhibit human recombinant ,7 and ,4,2 neuronal nicotinic acetylcholine receptors in Xenopus oocytesBRITISH JOURNAL OF PHARMACOLOGY, Issue 4 2001Kristen M Coates Ketamine is a dissociative anaesthetic that is formulated as Ketalar, which contains the preservative benzethonium chloride (BCl). We have studied the effects of pure racemic ketamine, the preservative BCl and the Ketalar mixture on human neuronal nicotinic acetylcholine receptors (nAChRs) composed of the ,7 subunit or ,4 and ,2 subunits expressed in Xenopus laevis oocytes. Ketamine inhibited responses to 1 mM acetylcholine (ACh) in both the human ,7 and ,4,2 nAChRs, with IC50 values of 20 and 50 ,M respectively. Inhibition of the ,7 nAChRs occurred within a clinically relevant concentration range, while inhibition of the ,4,2 nAChR was observed only at higher concentrations. The Ketalar formulation inhibited nAChR function more effectively than was expected given its ketamine concentration. The surprising increased inhibitory potency of Ketalar compared with pure ketamine appeared to be due to the activity of BCl, which inhibited both ,7 (IC50 value of 122 nM) and ,4,2 (IC50 value of 49 nM) nAChRs at concentrations present in the clinical formulation of Ketalar. Ketamine is a noncompetitive inhibitor at both the ,7 and ,4,2 nAChR. In contrast, BCl causes a parallel shift in the ACh dose-response curve at the ,7 nAChR suggesting competitive inhibition. Ketamine causes both voltage-dependent and use-dependent inhibition, only in the ,4,2 nAChR. Since ,7 nAChRs are likely to be inhibited during clinical use of Ketalar, the actions of ketamine and BCl on this receptor subtype may play a role in the profound analgesia, amnesia, immobility and/or autonomic modulation produced by this anaesthetic. British Journal of Pharmacology (2001) 134, 871,879; doi:10.1038/sj.bjp.0704315 [source] Hyperthyroidism is characterized by both increased sympathetic and decreased vagal modulation of heart rate: evidence from spectral analysis of heart rate variabilityCLINICAL ENDOCRINOLOGY, Issue 6 2006Jin-Long Chen Summary Objective, The clinical manifestations of hyperthyroidism resemble those of the hyperadrenergic state. This study was designed to evaluate the impact of hyperthyroidism on the autonomic nervous system (ANS) and to investigate the relationship between serum thyroid hormone concentrations and parameters of spectral heart rate variability (HRV) analysis in hyperthyroidism. Design and patients, Thirty-two hyperthyroid Graves' disease patients (mean age 31 years) and 32 sex-, age-, and body mass index (BMI)-matched normal control subjects were recruited to receive one-channel electrocardiogram (ECG) recording. Measurements, The cardiac autonomic nervous function was evaluated by the spectral analysis of HRV, which indicates the autonomic modulation of the sinus node. The correlation coefficients between serum thyroid hormone concentrations and parameters of the spectral HRV analysis were also computed. Results, The hyperthyroid patients revealed significant differences (P < 0·001) compared with the controls in the following HRV parameters: a decrease in total power (TP), very low frequency power (VLF), low frequency power (LF), high frequency power (HF), and HF in normalized units (HF%); and an increase in LF in normalized units (LF%) and in the ratio of LF to HF (LF/HF). After correction of hyperthyroidism in 28 patients, all of the above parameters were restored to levels comparable to those of the controls. In addition, serum thyroid hormone concentrations showed significant correlations with spectral HRV parameters. Conclusions, Hyperthyroidism is in a sympathovagal imbalanced state, characterized by both increased sympathetic and decreased vagal modulation of the heart rate. These autonomic dysfunctions can be detected simultaneously by spectral analysis of HRV, and the spectral HRV parameters could reflect the disease severity in hyperthyroid patients. [source] Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variabilityCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2009Urban Wiklund Summary Background:, Media have anecdotally reported that drinking energy drinks in combination with alcohol and exercise could cause sudden cardiac death. This study investigated changes in the electrocardiogram (ECG) and heart rate variability after intake of an energy drink, taken in combination with alcohol and exercise. Methods:, Ten healthy volunteers (five men and five women aged 19,30) performed maximal bicycle ergometer exercise for 30 min after: (i) intake of 0·75 l of an energy drink mixed with alcohol; (ii) intake of energy drink; and, (iii) no intake of any drink. ECG was continuously recorded for analysis of heart rate variability and heart rate recovery. Results:, No subject developed any clinically significant arrhythmias. Post-exercise recovery in heart rate and heart rate variability was slower after the subjects consumed energy drink and alcohol before exercise, than after exercise alone. Conclusion:, The healthy subjects developed blunted cardiac autonomic modulation after exercising when they had consumed energy drinks mixed with alcohol. Although they did not develop any significant arrhythmia, individuals predisposed to arrhythmia by congenital or other rhythm disorders could have an increased risk for malignant cardiac arrhythmia in similar situations. [source] | |||||||||||||