Standard Deviation Of The NN Intervals Research Articles

Low dose mercury and heart rate variability among community residents nearby to an industrial complex in Korea

Background The effect of mercury on the cardiovascular system has been recently reported, but the mechanisms and its nature, especially in low dose ranges, still need to be confirmed. In this cross-sectional study, the hair mercury was analyzed in relation to the cardiac autonomic activity among community residents nearby to an industrial complex in Korea. Methods A hair sample was obtained from the occiput and was analyzed using a DMA-80 (Milestone ®, Italy) mercury analyzer. We measured cardiovascular risk factors, including serum total cholesterol, serum triglyceride, HDL cholesterol, systolic and diastolic blood pressure, body mass index (BMI), past history of hypertension, diabetes, and dyslipidemia as potential confounders. As an end point, heart rate variability was assessed for 5 min, in time and frequency domains, using SA-3000P (Medi-core ®, Korea). For the time domain, standard deviation of the NN intervals (SDNN) was measured. For the frequency domains, very low frequency (VLF, ≤0.04 Hz), low frequency (LF, 0.04–0.15 Hz), high frequency (HF, 0.15–0.4 Hz), total power (TP, ≈≤0.4 Hz), LF/HF ratio, LF norm (LF/LF + HF), and HF norm (HF/LF + HF) were measured. The association between hair mercury concentration and heart rate variability was assessed after controlling for covariates, including age, gender, socioeconomic status, and other relevant cardiovascular risk factors. Results In total, 1589 subjects with a mean age of 33 years (range: 5–83) were included in the final analysis. Hair mercury concentration ranged from 0.01 to 13.36 ppm with a geometric mean of 0.83 μg/g. The hair mercury level was elevated for males, adults, and fish (especially sashimi) consumers, and higher household income group. When age was categorized into decades and analyzed separately, mercury significantly reduced HF measure in the second decade of age in Siwha area ( β = −0.193, p = 0.0469) and in the first decade of age in Banwol area ( β = −0.520, p = 0.0129). HF parameter decreased by 8.4% [95% confidence interval: 2.2–15.1%] with an 1 ppm increase in hair mercury concentration after adjusting for other selected variables in the multiple linear regression analysis. Conclusions The results suggest that mercury may affect the cardiac autonomic activity through parasympathetic dysfunction even at low exposure levels.

Exposure to environmental carbon monoxide may have a greater negative effect on cardiac autonomic function in people with metabolic syndrome

Carbon monoxide (CO) has been recognized as a risk factor for adverse cardiovascular outcomes. We investigated the effects of CO on cardiac autonomic function by measuring the heart rate variability (HRV) in patients with and without metabolic syndrome (MetS). We also explored the relationship between CO exposure and specific components of MetS. Data were obtained from air pollution measurements and from health examinations on a total of 986 subjects, from a Korean community. Measurements of the 5-min HRV and examinations for MetS were conducted, and a linear regression model with a time lag was evaluated for any association. The group with MetS showed a significant reduction in the standard deviation of the normal-to-normal intervals (SDNN) and in the high frequency domain of HRV. After adjusting for age, sex, smoking status, day of the week effect, month effect, temperature, and relative humidity, these declines were significantly associated with exposure to CO for 25 to 48 h prior to the HRV measurement. Evidence for effect-modification by two specific MetS components, fasting blood glucose and triglycerides, was also observed in relation to CO exposure. These results suggest that CO exposure may trigger changes in cardiac autonomic function, and that subjects at high risk for heart disease may be more susceptible to CO effects.

Association between Anxiety Disorders and Heart Rate Variability in The Netherlands Study of Depression and Anxiety (NESDA)

To determine whether patients with different types of anxiety disorder (panic disorder, social phobia, generalized anxiety disorder) have higher heart rate and lower heart rate variability compared with healthy controls in a sample that was sufficiently powered to examine the confounding effects of lifestyle and antidepressants. The standard deviation of the normal-to-normal intervals (SDNN), heart rate (HR), and respiratory sinus arrhythmia (RSA) were measured in 2059 subjects (mean age = 41.7 years, 66.8% female) participating in The Netherlands Study of Depression and Anxiety (NESDA). Based on the Diagnostic and Statistical Manual of Mental Disorders, 4th Edition (DSM-IV) and Composite International Diagnostic Interview (CIDI), NESDA participants were classified as healthy controls (n = 616), subjects with an anxiety diagnosis earlier in life (n = 420), and subjects with current anxiety diagnosis (n = 1059). Current anxious subjects had a significantly lower SDNN and RSA compared with controls. RSA was also significantly lower in remitted anxious subjects compared with controls. These associations were similar across the three different types of anxiety disorders. Adjustment for lifestyle had little impact. However, additional adjustment for antidepressant use reduced all significant associations between anxiety and HRV to nonsignificant. Anxious subjects who used a tricyclic antidepressant, a selective serotonin reuptake inhibitor, or another antidepressant showed significantly lower mean SDNN and RSA compared with controls (effect sizes = 0.20-0.80 for SDNN and 0.42-0.79 for RSA). Nonmedicated anxious subjects did not differ from controls in mean SDNN and RSA. This study shows that anxiety disorders are associated with significantly lower HR variability, but the association seems to be driven by the effects of antidepressants.

Relationship between Autonomic Nervous System Activity and Lower Urinary Tract Symptoms: An Analysis of Heart Rate Variability in Men with Lower Urinary Tract Symptoms

Objectives: Lower urinary tract symptoms (LUTS) are common, but their etiology and mechanism remain unclear. We believe that changes in autonomic nervous system (ANS) activity may be contributory because the lower urinary tract is regulated through the sympathetic and parasympathetic nervous systems. Heart rate variability (HRV) is a tool by which autonomic nervous function can be measured; therefore, we measured and compared parameters of heart rate variability between men with LUTS and asymptomatic subjects.Methods: We studied 35 men with LUTS (mean age 50.5 ± 14.9 years) and 110 asymptomatic male volunteers who had requested a health check up (mean age 49.5 ± 5.19 years) from July 2006 to June 2008. HRV is known to be a useful tool for evaluating ANS activity, and we measured and compared HRV in the resting state.Results: The standard deviation of the N‐N interval (SDNN) and total power (TP) for patients with LUTS revealed no significant differences from those in the control group. On frequency domain analysis, there was evidence of decreased high frequency (HF) in patients with LUTS (P < 0.05), but there were no significant differences in other parameters, such as heart rate, square root of the mean squared differences of successive N‐N intervals (RMSSD), very low frequency (VLF), low frequency (LF), or LF/HF ratio.Conclusion: Patients with LUTS exhibited different HRV parameters compared with asymptomatic controls. Their decreased HF indicated that they may have had an imbalance in the autonomic nervous system.

Impact of pulmonary vein isolation on the autonomic modulation in patients with paroxysmal atrial fibrillation and prolonged sinus pauses

The efficacy of catheter-based pulmonary vein isolation (PVI) for paroxysmal atrial fibrillation (AF) and prolonged sinus pauses [bradycardia-tachycardia syndrome (BTS)] has been already described. However, the effects of PVI on autonomic modulation in BTS patients remain to be determined. We, therefore, examined the alteration in the autonomic modulation through the PVI procedure by using a heart rate variability (HRV) analysis of 24 h ambulatory monitoring. This study consisted of 26 symptomatic paroxysmal AF patients either with prolonged sinus pauses on termination of AF (>3.0 s, BTS group, n = 11) or without any evidence of sinus node dysfunction (control group, matched for sex and age, n = 15) who underwent PVI. All 11 BTS patients became free from both AF and prolonged sinus pauses without pacemaker implantation (23 +/- 14 months of observation). The mean heart rate significantly increased in the control group (P < 0.05), but not in the BTS group after the PVI procedure, although the HRV parameters of root-mean-square successive differences in the adjacent NN intervals, standard deviation of the NN intervals, and high frequency did significantly decrease in both groups (P < 0.05). Although the parasympathetic modulation was significantly attenuated after the PVI procedure, the mean heart rate did not increase in the BTS patients, probably due to the pre-existing sinus node dysfunction.

복싱에어로빅 운동이 안정 시 심박수변이도에 미치는 영향

본 연구는 여자대학생에게 복싱에어로빅 운동 후, 그 운동이 심박수변이도에 미치는 영향을 알아보기 위하여 시도되었다. 운동전 측정과 3개월 복싱에어로빅 운동 후 측정, 두 차례에 의하여 검사한 결과 다음과 같은 결론을 얻었다. (1) 심박수변이도의 결과 Mean HRT는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (2) 심박수변이도의 결과 SDNN은 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (3) 심박수변이도의 결과 RMSSD는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (4) 심박수변이도의 결과 TP는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (5) 심박수변이도의 결과 LF는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (6) 심박수변이도의 결과 HF는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (7) 심박수변이도의 결과 LF/HF는 집단 및 시간, 집단과 시간간의 교호작용이 유의한 차이가 나타나지 않았다. (8) 심박수변이도의 결과 VLF는 집단 및 시간, 집단과 시 간간의 교호작용이 유의한 차이가 나타나지 않았다. 이상을 종합할 때 심박수변이도는 환경적인 영향을 받는 것으로 생각되어지며, 심박수변이도가 운동에 미치는 영향을 자세하기 규명하기 위해서는 비교적 동일한 집단을 더욱 세분화시키고 연령대와 성별, 운동형태 등에 따른 보다 장기적인 연구가 필요한 것으로 생각된다. The Purpose of this study was to examine the effects of boxing aerobic training on resting heart rate variability (HRV) in females. The subjects for this study were performed 16 female college students that aged 19-23. The subjects were divided into two groups; boxing aerobic exercise group (9 students) and control group (7 students). Boxing aerobic training program was performed three times a week for twelve weeks with <TEX>$VO_{2max}$</TEX> 60-80% exercise intensity. The results of this study were following; 1. Mean HRT (mean heart rate) had no signigicant difference among the groups and exercise time. 2. SDNN (standard deviation of the normal to normal interval) had no significant difference among the group and exercise time. 3. RMS-SD (square root of the mean squared differences of successive normal to normal interval) had no significant difference among the groups and exercise time. 4. TP (total power) had no significant difference among the groups and exercise time. 5. LF (low frequency) had no significant difference among the groups and exercise time. 6. HF (high frequency) had no significant difference among the groups and exercise time. 7. LF/HF (low frequence/high frequency ratio) had no significant difference among the groups and exercise time. 8. VLF (very low frequency) had no significant difference among the groups and exercise time.

Does a low sodium diet modify heart rate variability? A randomised placebo-controlled double-blind trial

Background Increased heart rate variability (HRV) is associated with a low risk of mortality, as is consuming a low sodium diet. As the survival benefits of a low sodium diet may be mediated partly by an increase in HRV, we have tested the hypothesis that adopting a low sodium diet increases HRV. Methods We used a randomised double-blind placebo-controlled trial design. Participants were aged 18–65 years old, had a physician diagnosis of asthma. All adopted a low sodium diet and they were randomised to receive either 80 mmol/day of oral sodium supplements (normal sodium intake — NSI) or matched placebo (low sodium intake—LSI) for 6 weeks. The primary outcome was change in SDNN (standard deviation of the N– N intervals); secondary outcomes were changes in other time domain and frequency domain measures of HRV. Results In those allocated to the LSI, mean daily urinary sodium excretion decreased by 22 mmol; and in those allocated to the NSI mean daily urinary sodium excretion increased by 31 mmol. There were no differences between the two groups for either the primary or secondary outcome measures. The mean difference in change in SDNN between those who received the LSI compared to the NSI was − 2.7 ms (95% Confidence Intervals CI; − 18.0 to + 12.6). Conclusions Adopting a low sodium diet does not have an impact on SDNN over a 6 weeks period. Future studies should aim to achieve a larger change in dietary sodium intake for a longer duration than 6 weeks.

Combined effect of cigarette smoking and sulfur dioxide on heart rate variability

Cigarette smoking (CS) and air pollution can both alter autonomic cardiac function, yet little has been reported on their combined effect on cardiovascular dysfunction. Therefore, we assessed the potential effect of smoking on the association between sulfur dioxide (SO 2) and heart rate variability (HRV) in community residents. We found evidence that SO 2 induced short but dramatic decreases in HRV indices, the standard deviation of the NN interval (SDNN), low frequency (LF), and high frequency (HF), in smokers compared with non-smokers. We suggest that CS influences the decrease in HRV directly caused by SO 2, and the effect in susceptible groups may be more serious.

The Health Effects of Mercury on the Cardiac Autonomic Activity According to the Heart Rate Variability

Objectives: The effect of mercury on the cardiovascular system has recently been reported on, but the mechanisms as well as its nature of this effect still need to be confirmed. In this study, the mercury in the hair of a community population was analyzed in relation to the cardiac autonomic activity. Methods: A hair sample was obtained from the occiput area and the mercury in the hair was analyzed by using a Direct Mercury Analyzer. We measured the cardiovascular risk factors, including total cholesterol, triglyceride, blood pressure, and the body mass index (BMI). Heart rate variability was assessed for 5 minutes, in the time and frequency domain, by using SA-3000P from the Medi-core ® company. The association between the mercury in the hair and heart rate variability was assessed after controlling for the other cardiovascular risk factors. Results: The mean age of the 671 total subjects was 36 years. The geometric mean of the hair mercury was 0.90 ppm. The hair mercury level was elevated in males, adults, smokers and drinkers. Hair mercury and age, the systolic and diastolic blood pressure, total cholesterol, triglyceride, LDL cholesterol and BMI were all positively correlated. However, hair mercury and heart rate, HDL cholesterol, standard deviation of the NN intervals (SDNN), total power (TP), low-frequency (LF), high- frequency (HF) were negatively correlated. In the higher mercury group, heart rate, SDNN, LF and HF indices were significantly lower compared with those of the lower mercury group. Heart rate was decreased 2.6 beats/min, Ln (HF) was decreased 0.131 msec2 and HF norm was decreased 2.550 with a 1 ppm increase of Ln (Hg), according to multiple linear regression analysis after controlling for age, gender and other cardiovascular risk factors. Conclusion: This cross-sectional study showed that mercury may affect the cardiac autonomic activity through parasympathetic dysfunction.

Different trends of changes in heart rate variability in patients with anterior and inferior acute myocardial infarction.

Modifications in heart rate variability (HRV) parameters occur after acute myocardial infarction. The aim of this study was to evaluate the trend of HRV change during the acute phase and the first month after myocardial infarction, and establish whether they were affected by the anterior or inferior location of the infarction. The time-domain HRV measures of 59 patients with a first uncomplicated acute myocardial infarction were computed from 24-hour ECG recordings made on days 1, 2, 10, and 28 after hospital admission. At day 1, the mean RR cycle length (NN), the standard deviation of the NN intervals (SDNN), and the root mean square successive difference of NN intervals (RMSSD) were lower in the patients with anterior myocardial infarction. Although the parameters were similar in all of the patients at day 28, their behavior over time was different (P = 0.01): the SDNN in the patients with inferior myocardial infarction had decreased to the values found in anterior myocardial infarction patients by day 2 but, at day 10, both NN and SDNN tended to recover in both groups; RMSSD had diminished in both groups by day 2, but at day 10, had increased in the patients with anterior, but not in those with inferior myocardial infarction. These findings suggest that (1) in the very early phase of myocardial infarction, HRV is different in the two locations, (2) during the first hours of myocardial infarction patients with inferior location showed a greater vagal activity than patients with anterior location that became lower at day 10, and (3) the recovery of HRV is an early phenomenon in both groups, being already evident by the second week after myocardial infarction.