Correlation between glycemic trends assessed by 24 h continuous monitoring and autonomic activity in patients with recent onset type 2 diabetes.

We observe, in patients with type 2 diabetes of recent onset, the activity of the autonomic nervous system and glucose metabolic impairment. The data indicate the hyperactivity of the sympathetic and minimal changes in glucose values. The role played by glycemia appeared to be less important than that represented by insulin resistance.

Autonomic system modification in Zen practitioners.

BACKGROUND: Meditation in its various forms is a traditional exercise with a potential benefit on well-being and health. On a psychosomatic level these exercises seem to improve the salutogenetic potential in man.Especially the cardiorespiratory interaction seems to play an important role since most meditation techniques make use of special low frequency breathing patterns regardless of whether they result from a deliberate guidance of breathing or other mechanisms, for example, the recitation of specific verse. During the different exercises of Zen meditation the depth and the duration of each respiratory cycle is determined only by the process of breathing. Respiratory manoeuvres during Zazen meditation may produce HR variability changes similar to those produces during biofeedback. Recognition that the respiratory sinus arrhythmia (RSA) was mediated by efferent vagal activity acting on the sinus node led investigators to attempt to quantify the fluctuations in R-R intervals that were related to breathing. MATERIALS AND METHODS: Nine Zen practitioners with five years of experience took part in the study. Autonomic nervous system function was evaluated by heart rate variability (HRV) analysis during 24-hours ECG recording during zen meditation and at rest. RESULTS: The data of this small observational study confirm that ZaZen breathing falls within the range of low frequency HR spectral bands. Our data suggest that the modification of HR spectral power remained also in normal day when the subject have a normal breathing. CONCLUSION: We suggest that the changes in the breathing rate might modify the chemoreflex and the continuous practice in slow breathing can reduce chemoreflex. This change in the automonic control of respiration can be permanent with a resetting of endogenous circulatory rhythms.

QTc interval prolongation in HIV-infected patients: a case-control study by 24-hour Holter ECG recording.

BACKGROUND: Aim of the study was to assess QTc interval by a 24-hour ECG recording in a group of HIV-infected individuals with a basal prolonged QTc. The risk factors associated with QTc prolongation and the indices of cardiovascular autonomic control were also evaluated. METHODS: A case-control study was performed using as cases 32 HIV-infected patients with prolonged (>440 msec) QTc interval as assessed by Holter ECG, and as controls 64 HIV-infected subjects with normal QTc interval. Autonomic function was evaluated by heart rate variability analysis during 24-hour recording. RESULTS: Duration of HIV disease was significantly longer among cases than among controls (p=0.04). Waist/hip ratio was also higher among cases than among controls (p=0.05). Frequency domain analysis showed the absence of physiologic decrease of low frequency (LF) in the night period in both cases and controls. The LF night in cases showed a statistically significant reduction when compared with controls (p=0.007). CONCLUSIONS: In our study group, QTc interval prolongation was associated with a longer duration of HIV infection and with a greater waist/hip ratio. HIV patients with QTc interval prolongation and with a longer duration of HIV infection were more likely to have an impairment of parasympathetic and sympathetic cardiac component.

The correlation among QTc interval, hyperglycaemia and the impaired autonomic activity.

BACKGROUND: The QT interval reflects the duration of the intracellular action potential. Little is known on the interval QT duration in non diabetic insulin-resistant subjects. OBJECTIVE: The aims of the current study were to evaluate the QTc interval in three groups of non diabetic insulin-resistant subjects and the possible correlation between QTc and the autonomic nervous system's activity. DESIGN: 90 subjects were divided in subjects with impaired fasting glycaemia (IFG) and, by the results of OGTT, according to the criteria of ADA, in subjects with normal glucose regulation (NGR) and impaired glucose tolerance (IGT). Insulin resistance was evaluated by the homeostasis model assessment-index (HOMA-I). Heart rate variability and Qtc were calculated. RESULTS: QTc interval is correlated with SDNN, LF n.u. and LF/HF. CONCLUSION: We have observed that the QTc interval is prolonged in insulin-resistant subjects with associated impaired glucose metabolism, while no difference was reported between insulin-resistant and non insulin-resistant subjects with normal glucose regulation. We hypothesize that hyperglycaemia could play a major role than hyperinsulinemia on the QTc prolongation.

Circadian rhythm of the autonomic nervous system in insulin resistant subjects with normoglycemia, impaired fasting glycemia, impaired glucose tolerance, type 2 diabetes mellitus.

BACKGROUND: In type 2 diabetes mellitus both insulin resistance and hyperglycemia are considered responsible for autonomic dysfunction. The relation between the autonomic activity, impaired fasting glycemia and impaired glucose tolerance is, however, unclear. The purpose of this study was to evaluate and compare the circadian autonomic activity expressed as heart rate variability (HRV) measured by 24-hours ECG recording in insulin resistant subjects (IR) with characteristics as follow: IR subjects with normal oral glucose tolerance test results, IR subjects with impaired fasting glucose, IR subjects with impaired glucose tolerance and subjects with type 2 diabetes mellitus. METHODS: Eighty Caucasian insulin resistant subjects (IR) and twenty five control subjects were recruited for the study. IR subjects were divided into four groups according to the outcoming results of oral glucose tests (OGTTs): IR subjects with normal glucose regulation (NGR), IR subjects with impaired fasting glycemia (IFG), IR subjects with impaired glucose tolerance (IGT) and subjects with type 2 diabetes mellitus (DM). Autonomic nervous activity was studied by 24-hours ECG recording. Heart rate variability analysis was performed in time and frequency domains: SDNN, RMS-SD, low frequency (LF) and high frequency (HF) were calculated. RESULTS: The total SDNN showed statistically significant reduction in all four groups with insulin resistant subjects (IR) when compared to the control group (p <0,001). During night LF normalized units (n.u.) were found to be higher in all four groups including IR subjects than in the control group (all p < 0,001) and subjects with normal glucose regulation (NGR), with impaired fasting glycemia (IFG) and with impaired glucose tolerance (IGT) were found to have higher LF n.u. than those in the type 2 diabetes mellitus group. The linear regression model demonstrated direct association between LF values and the homeostasis model assessment-index (HOMA-I), in the insulin resistant group (r = 0,715, p <0,0001). CONCLUSION: The results of our study suggest that insulin resistance might cause global autonomic dysfunction which increases along with worsening glucose metabolic impairment. The analysis of sympathetic and parasympathetic components and the sympathovagal balance demonstrated an association between insulin resistance and sympathetic over-activity, especially during night. The results indicated that the sympathetic over-activity is directly correlated to the grade of insulin resistance calculated according to the HOMA-I. Since increased sympathetic activity is related to major cardiovascular accidents, early diagnosis of all insulin resistant patients should be contemplated.

Alterations of the sympathovagal balance evaluated by heart rate variability in a rare case of adult Still's disease.

We present a rare case of adult Still's disease with cardiac involvement (myocarditis and coronary arteritis). The autonomic nervous system function was evaluated by heart rate variability (HRV) analysis performed by 24-hour electrocardiographic recording during the acute phase of the disease and the remission (after 1 month and 1 year). The HRV parameters were studied in the time (standard deviation of all NN intervals-total power - SDNN, square root of the mean of the sum of the squares of the differences between adjacent NN - RMS-SD and HRV index) and frequency domains (low frequency, high frequency, and low frequency/high frequency). The results of the analysis of the HRV highlight that in the acute phase of the disease with cardiac involvement the autonomic nervous system is globally altered, with modifications of the sympathovagal balance, due to impairment of the parasympathetic component. This trend tends to persist in the short period (1 month), but seems to resolve completely within 1 year. An altered sympathovagal balance should be considered as a possible marker of vasculitis-related ischemia.