Cardiac Autonomic Modulation (cardiac + autonomic_modulation)

Distribution by Scientific Domains
Medical Sciences75%

Selected Abstracts

Acute Effects of Moxonidine on Cardiac Autonomic Modulation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010
DAYIMI 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]

Cardiac autonomic function and baroreflex changes following 4 weeks of resistance versus aerobic training in individuals with pre-hypertension

ACTA PHYSIOLOGICA, Issue 3 2009
S. 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]

Acute Effects of Moxonidine on Cardiac Autonomic Modulation

PACING AND CLINICAL ELECTROPHYSIOLOGY, Issue 8 2010
DAYIMI 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]

Influence of energy drinks and alcohol on post-exercise heart rate recovery and heart rate variability

CLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 1 2009
Urban 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]