Changes In Autonomic Nervous Function Research Articles

Changes in autonomic nervous function and influencing factors in a rat insular cortex electrical kindling model

In mammals, the insular cortex plays an important role in autonomic regulation. In patients with insular epilepsy, seizures are always accompanied by autonomic changes. Accordingly, we aimed to establish an electrical kindling model in autonomic-mediating areas of the insular cortex, and to conduct a long-term observation of epileptic genesis in these animals until sudden unexpected death. To establish this model in adult rats, we implanted stimulation electrodes in the granular cell layer of the insular cortex, which controls the heart rate (HR) and respiratory rate (RR). Subsequently, seizure was induced successfully in 92.3 % of the rats, and typical autonomic changes were observed during these seizures. Interestingly, the model was established more easily in older rats, and the rats in which electrical stimulation led to a greater reduction in the HR. Moreover, death occurred in 25 % of the kindled rats. In conclusion, our kindling model demonstrates the ability of insular cortex stimulation to generate epilepsy. Our model thus offers a practical tool for studies of the role of the insular cortex in sudden unexpected death in epilepsy.

Retrospective cohort analysis of heart rate variability in patients with high altitude pulmonary hypertension in Tibet.

BackgroundStudies from both humans and animals experiments have offered abundant evidence supporting that mountain sickness is associated with changes in autonomic nervous function (ANF), which can be measured by heart rate variability (HRV).HypothesisWe aimed to assess changes of ANF in chronic mountain disease by measuring HRV in patients with high altitude pulmonary hypertension (HAPH).MethodsFrom November 2018 to March 2019, 120 patients in the cardiac care unit of the People's Hospital of Tibet Autonomous Region were selected as the observation group, and 50 patients without organic heart disease served as the control group. Pulmonary artery systolic pressure was evaluated by echocardiography in patients with HAPH, divided into three groups: mild (30‐49 mm Hg), moderate (50‐69 mm Hg) and severity (≥70 mm Hg) groups. A 24‐hour dynamic electrocardiogram (DCG) was obtained for each patient. HRV (SDNN, SDANN, RMSSD, PNN50, and HRVTI for time domain; TP, VLF, LF, HF, and LF/HF for frequency domain) indexes were measured and compared.ResultsCompared with the control group, time domain parameters including SDNN, SDANN, RMSSD, PNN50, and HRVTI were reduced, as well as frequency domain indexes such as TP, VLF, LF, and HF. LF/HF was highest in mild HAPH group and lowest in the moderate HAPH group, and the difference between the two groups was statistically significant.ConclusionsThe HRV of patients with chronic HAPH in high altitude areas in Tibet is significantly reduced relative to healthy controls, and significantly negatively correlated with the severity of pulmonary artery hypertension.

Effect of changes in sympathovagal balance on the accuracy of heart rate variability obtained from photoplethysmography.

Heart rate variability (HRV) obtained using photoplethysmography (PPG), which is also known as pulse rate variability (PRV), has already been used in clinical practice. However, it is uncertain whether PRV reflects changes in autonomic nervous function accurately. The aim of the present study was to evaluate quantitatively the effect of alterations in the sympathovagal balance on the agreement between PRV and HRV from electrocardiographs (ECG). Healthy subjects (male, 26; female, 7; age, 22-25 years old) participated in the present study. Paced respiration with 15 breathes/min and breath holding (apnea) were performed to alter the autonomic nervous states of patients. The changes in the low-to-high frequency power ratio (LF/HF) of HRV indicated that there was a sympathovagal balance shift toward vagal predominance during paced respiration, but toward sympathetic predominance during apnea. The results demonstrated that, during paced respiration, all indices had an acceptable agreement [Bland-Altman ratio (BAr)<0.2] between PRV and HRV, with the exception of LF/HF that had an insufficient agreement (BAr=0.25). All indices had very strong correlations [Pearson's correlation coefficients (CC)>0.99] and PRV had a minor but highly significant (P<0.001) increase for the majority of the variability indices, when compared with HRV. During apnea, the discrepancy of the short-term variability indices between PRV and HRV became sizeable with a BAr>0.3 and a minimum CC of 0.96. In conclusion, a decrease of LF/HF caused a marginal inaccuracy of PRV in the indication of sympathovagal balance, while sympathetic activation increased differences in short-term variability between PRV and HRV.

Analysis of Autonomic, Respiratory and Motor Function of Infants in Pre- and Post-Liver Transplantation

Purpose: Children with liver impairment are likely to develop changes in autonomic nervous function and delay in motor development. The assessment and identification of these dysfunctions may allow an appropriate physiotherapeutic care. Method: Cross sectional study of 18 infants, 11 controls and 7 infants (post-liver transplantation) with an average age of 10 ± 4.5 months, was evaluated in pre- and post-liver transplant. All infants underwent to assessments of motor skills, body composition, chest and abdominal motion, and cardiac autonomic modulation was measured by heart rate variability. Results: Motor delay and malnutrition were found in all infants. The gravity index (PELD)—pediatric end-stage liver disease—showed a negative correlation with the Alberta Infant Motor Scale (r = 0.83, p = 0.01). In addition, reduced parasympathetic modulation was demonstrated by the rMSSD, SD1 and ApEn, pre- and post-transplant. Conclusion: Infants with liver disease, even after transplantation, have delay in motor development, as well as changes in their nutritional and autonomic dysfunction.

Cardiovascular autonomic responses to head-up tilt in gestational hypertension and normal pregnancy

Aims. The aim of the present study was to evaluate the influence of gestational hypertension on hemodynamics and cardiovascular autonomic regulation at rest and their responses to head-up tilt (HUT). We prospectively studied 56 pregnant women (28 with gestational hypertension and 28 healthy pregnant women) during the third trimester of pregnancy and 3 months after pregnancy. Major findings. In women with pregnancy-induced hypertension, compared with control women, there were significant differences in hemodynamics and in markers of cardiovascular regulation (p < 0.05 to p < 0.001). Postural change from the supine to the upright position was associated with significant changes in hemodynamic responses in both groups during pregnancy (from p < 0.05 to p < 0.001). Regulatory response to HUT in both groups was characterized with a decrease in HF power and increase in LF/HF ratio (from p < 0.01 to p < 0.001). Responses to HUT in total power and VLF power were attenuated in hypertensive pregnancies (p < 0.001 to p < 0.01, respectively, vs control group). Conclusions. Our results suggest that autonomic cardiovascular regulation may not play a major role in women with gestational hypertension . The lack of irreversible changes in autonomic nervous function in hypertensive women appeared to be a feature of gestational-induced hypertension.

HERZFREQUENZVARIABILITÄT IM SCHLAF UNTERSUCHT MIT DER TRENDBEREINIGENDEN FLUKTUATIONS-ANALYSE UND DER SPEKTRALANALYSE

Heart rate variability during sleep reflects the changes of autonomic nervous function which accompany the different underlying regulations. Sleep related breathing disorders affect heart rate variability during sleep in a characteristic way which is called cyclical variation of heart rate. In this study we tested two methods in order to separate the effect of sleep stages and the effect of sleep apnea on heart rate variability. We used spectral analysis based on 5-minute windows and detrended fluctuation analysis and derived parameters for sleep stages (wake, light sleep, deep sleep, REM sleep) and apnea severity (no apnea, moderate apnea, severe apnea). Detrended fluctuation analysis yielded a better separation of sleep stages (74.4% correct assignments) and apnea severity (85.0% correct assignments) than spectral analysis.

Effects of Qi-Training on Heart Rate Variability

This study investigates changes in autonomic nervous function through Qi-training. The power spectrum of heart rate variability (HRV) was examined in 20 sedentary healthy subjects and 20 Qi-trainees. It was found that Qi-training in healthy young subjects during controlled respiration increases the high frequency (HF) power and decreases the low frequency/high frequency (LF/HF) power ratio of HRV. These results support the hypothesis that Qi-training increases cardiac parasympathetic tone. In addition, Qi-trainees were found to have higher parasympathetic heart modulation compared with their age-matched, sedentary counterparts. This augmented HRV in Qi-trainees provides further support for long-term Qi-training as a possible non-pharmacological cardio-protective maneuver. In conclusion, Qi-training may stabilize the autonomic nervous system by modulating the parasympathetic nervous system.

Changes in autonomic nervous function during the 4-year follow-up in middle-aged diabetic and nondiabetic subjects initially free of coronary heart disease.

To study the changes in autonomic nervous function during the 4-year follow-up period in diabetic patients and to investigate factors predicting autonomic nervous dysfunction. A 4-year follow-up study. At baseline the study subjects without known cardiovascular disease were recruited from a large group of diabetic and nondiabetic subjects selected randomly from a baseline population. Middle-aged control subjects (n = 44), patients with insulin-dependent diabetes mellitus (n = 32) and patients with non-insulin-dependent diabetes mellitus (n = 32) were studied at baseline and after the 4-year follow-up. Autonomic nervous function tests and exercise test at baseline and after the 4-year follow-up. At the baseline, heart rate variation during deep breathing was significantly lower in patients with insulin-dependent diabetes (13.0 +/- 1.2 beats min-1; P < 0.05) and in patients with non-insulin-dependent diabetes (12.9 +/- 1.5 beats min-1; P < 0.05) than in control subjects (16.6 +/- 1.1 beats min-1). At baseline, autonomic nervous function score was significantly higher indicating disturbed autonomic nervous function in patients with insulin-dependent diabetes (1.74 +/- 0.19; P < 0.01) than in control subjects (1.24 +/- 0.14), but the difference was not significant between control subjects and patients with non-insulin-dependent diabetes (1.47 +/- 0.12). During the follow-up, autonomic nervous function score increased in patients with non-insulin-dependent diabetes to 2.00 +/- 0.21 (P < 0.001, as compared to baseline), but did not change in patients with insulin-dependent diabetes (1.77 +/- 0.18) or control subjects (1.22 +/- 0.12). In both diabetic groups, the deterioration of autonomic nervous function score during the 4-year follow-up was associated with poor glycaemic control at baseline. Clinical manifestation of coronary heart disease was found in three (7%) control subjects, 12 (37%; P < 0.001) patients with insulin-dependent diabetes and 11 (34%; P < 0.01) patients with non-insulin-dependent diabetes mellitus at follow-up examination. Autonomic nervous function was more abnormal in those insulin-dependent diabetic patients with coronary heart disease than those without. During the 4-year follow-up the impairment in autonomic nervous function occurred mainly in patients with noninsulin-dependent diabetes. Poor glycaemic control appears to be an important determinant of the progression of autonomic nervous dysfunction in diabetes.

Changes in Autonomic Nervous Function Over a Five‐year Period in Diabetic Patients

Changes in Autonomic Nervous Function Over a Five‐year Period in Diabetic Patients

Autonomic cardiovascular reflexes in pregnancy. A longitudinal study.

Cardiovascular reflexes were studied in 22 healthy women before they were pregnant, once during each pregnancy trimester and after delivery to evaluate the effect of pregnancy on autonomic control of haemodynamics. The Valsalva manoeuvre, the deep breathing test, the orthostatic test and the isometric handgrip test were used to assess changes in autonomic nervous function. We found that pregnancy altered the heart rate response in the Valsalva manoeuvre, the deep breathing test and the orthostatic tests. The deep breathing difference (p = 0.03) and max/min ratio (p = 0.03) decreased in pregnancy, whereas standing heart rate increased (p < 0.0001). Both the systolic and diastolic blood pressure increased after standing up during pregnancy. The circulatory responses to isometric exercise were not affected by pregnancy. The results show that parasympathetic responsiveness is decreased in pregnancy and that it returns to normal after delivery.

Acute, reversible autonomic nervous system abnormalities in juvenile insulin-dependent diabetes. A pupillographic study.

Autonomic nervous function was studied by infrared TV-pupillography in nine insulin-dependent diabetic subjects with 0 to 3 years duration of diabetes, during poor and good metabolic control. During poor control there was no change in the latency time, the maximal contraction velocity or the amplitude of the light response, whereas the redilatation time was prolonged by 28%, from 2.26 +/- 0.27 to 2.90 +/- 0.58 s (mean +/- SD) (2p = 0.012). The pupil size after adaptation to darkness was unchanged, but the light induced pupillary unrest was reduced by 35% from 1.68 +/- 0.62 to 1.10 +/- 0.36 mm2 (2p = 0.0037), and the degree of miosis in continuous illumination was reduced by 47% from 0.32 +/- 0.13 to 0.17 +/- 0.08 (2p = 0.0011), during metabolic derangement. The study has thus demonstrated reversible changes in autonomic nervous function, which are related to the diabetic metabolic state and thereby analogous to the previously well established reversible functional changes in the somatic nervous system in early diabetes.