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PubMed2000

[Correlation between cardiac autonomic activity and compromise of left ventricular function in dilated cardiomyopathy].

In recent years, evaluation of cardiac autonomic activity by means of heart rate variability (HRV) determination and baroreflex sensitivity (BRS) testing has become readily available. The results of the ATRAMI (Autonomic Tone and Reflexes After Myocardial Infarction) study showed that both diminished HRV and baro-reflex sensitivity are associated with poor outcome in patients after myocardial infarction. In contrast to patients with coronary disease little information is available concerning cardiac autonomic activity in idiopathic dilated cardiomyopathy (IDC). Therefore, HRV and BRS were assessed in 160 patients with IDC and preserved sinus rhythm in order to investigate the relationship between HRV, BRS, and left ventricular ejection fraction. Time domain indices of HRV were computed from 24-hour digital Holter recordings. BRS testing was performed using the noninvasive phenylephrine method. Mean standard deviation of all normal RR intervals (SDNN) of the whole study population was 112 +/- 46 ms. A well preserved HRV (SDNN > 105 ms) was found in 74 patients (46%), a moderately decreased HRV (SDNN 70-105 ms) in 59 patients (37%), and a severely decreased HRV (SDNN < 70 ms) in 27 patients (17%). Mean BRS was 7.5 +/- 5.0 ms/mm Hg. A well preserved BRS (> 6 ms/mm Hg) was present in 78 patients (57%), a moderately decreased BRS (3-6 ms/mm Hg) was present in 38 patients (28%), and a severely decreased BRS (< 3 ms/mm Hg) in 21 patients (15%). There was only a weak correlation between SDNN and BRS (r = 0.19; p < 0.05). A weak correlation was found for SDNN and left ventricular ejection fraction (r = 0.29; p < 0.05). There was no significant correlation between BRS and left ventricular ejection fraction (r = 0.14). In summary, there was only a weak correlation between the HRV, BRS, and left ventricular ejection fraction in patients with IDC suggesting that these 3 variables may be independent predictors of sudden death in IDC. The relative prognostic value of these variables and other potential risk predictors including the presence of arrhythmias on Holter, microvolt T wave alternans, QTc dispersion, and signal-averaged ECG is currently under investigation in a large prospective observational study (Marburg Cardiomyopathy Study (MACAS)) during 5-year follow-up at our institution.

Adolescent↗
PubMed1992

Autonomic nervous function and its relationship to cardiac performance in middle-aged diabetic patients without clinically evident cardiovascular disease.

Autonomic nervous function was evaluated in 36 patients with insulin-dependent diabetes mellitus (IDDM), 39 patients with non-insulin-dependent diabetes mellitus (NIDDM) and 48 control subjects, all without clinically evident cardiovascular disease. Valsalva ratio and heart rate variation during deep breathing were lower in both diabetic groups than in the control group. Autonomic nervous function score (ANFS) was more abnormal in patients with IDDM than in control subjects, but was not significantly increased in patients with NIDDM. There was a negative correlation between ANFS and left ventricular diastolic filling evaluated by echocardiography or peak heart rate during exercise in both diabetic groups. There were no correlations between ANFS and left ventricular systolic function at rest or during exercise in any of the groups. In conclusion, autonomic nervous function was abnormal in middle-aged diabetic patients, and it was associated with impaired left ventricular diastolic filling at rest and decreased heart rate response to exercise, but not with left ventricular systolic function.

Analysis of Variance↗
PubMed1999

[Correlation between intraoperative hemodynamic variability and postoperative arrhythmias in patients with pulmonary surgery].

Multivariate analyses were performed by logistic regression procedure to identify the significant risk factors for postoperative arrhythmias. The 29 variables included in the analyses were as follows: age, sex, hemodynamic variability, preoperative complication (hypertension, myocardial ischemia, and diabetes mellitus et al), surgical staging for lung cancer, anesthetic method, surgical procedure, intraoperative complications (hypoxemia, arrhythmia and myocardial ischemia), and so on. We evaluated intraoperative hemodynamic variability using mean value and coefficient of variation (CV) of heart rate and blood pressure computed from anesthetic records. Supraventricular tachyarrhythmias occurred in 27 (22.3%) of 121 consecutive patients undergoing pulmonary resection. Increases in mean heart rate and CV of heart rate, older patients, intraoperative blood transfusion, and left thoracotomy were associated with arrhythmias (P < 0.05). There was no correlation of arrhythmia with preoperative complications, surgical staging for lung cancer, anesthetic method, or surgical procedure. It is suggested that impairment of cardiac autonomic nervous system function associated with possible injury to the cardiac autonomic nerves during pulmonary resection is one of the risk factors for arrhythmias after thoracotomy.

Aged↗
PubMed2000

Early exclusion of hand1-deficient cells from distinct regions of the left ventricular myocardium in chimeric mouse embryos.

The basic helix-loop-helix transcription factor gene Hand1 has been implicated in development of the heart. However, the early lethality of Hand1-null mutant mouse embryos has precluded a precise understanding of its function. In this study, we have generated Hand1 homozygous mutant ES cells and performed in vitro differentiation experiments and chimeric analysis to study the role of Hand1 function during cardiac development. Hand1-null ES cells were able to differentiate into beating cardiomyocytes in vitro that expressed cardiac myosin and several cardiac-specific transcripts including Nkx2-5, alpha-cardiac actin, and the myofilament genes myosin light chain 2a and 2v. In chimeras derived from Hand1-null ES cells and ROSA26 embryos, mutant cells were underrepresented in the left caudal region of the linear heart tube at E8.0. By E9.5, after cardiac looping, mutant cells were underrepresented in the anterior region of the outer curvature of the left ventricular myocardium, but did contribute to other parts of the left ventricle and to other cardiac chambers. These results imply that Hand1 is not essential for differentiation of ventricular cardiomyocytes. Hand1-null cells were also underrepresented in several other regions of later embryos, including the rhombencephalic neural tube that was associated with a deficiency of mutant cells in the neural crest cell-derived cardiac outflow tract and first branchial arch. In summary, Hand1 has cell-autonomous functions during cardiac morphogenesis in both mesodermal and neural crest derivatives.

Animals↗
PubMed2003

[Cardiac sympathetic dysfunction in Parkinson's disease--relationship between results of 123I-MIBG scintigraphy and autonomic nervous function evaluated by the Valsalva maneuver].

We examined whether the results of 123I-MIBG scintigraphy reflect cardiac sympathetic nerve function in patients with Parkinson's disease (PD). The subjects were 62 patients with Parkinson's disease (age, 65.4 +/- 6.3 years) and 53 controls (65.2 +/- 7.1 years). All subjects underwent 123I-MIBG scintigraphy and QTc interval measurement on ECG. Hemodynamic autonomic function was estimated by the Valsalva maneuver in 37 subjects (63.9 +/- 5.2 years) randomly selected from the patients with PD. As control, the Valsalva maneuver was also done in 20 randomly selected controls (64.1 +/- 5.0 years), and 123I-MIBG scintigraphy was performed in 21 controls (67.7 +/- 5.3 years old). The subjects rested in a supine position for 20 min and were given an intravenous injection of 111 MBq 123I-MIBG. Relative organ uptake was determined by the region of interest (ROI) in the anterior view and the ratio of average pixel count in the heart (H) to that in the mediastinum (M) was calculated (H/M ratio) for early (after 15 min) and delayed (after 3 hrs) periods. The Valsalva maneuver was done by having the subjects exhale into a mouthpiece at an expiratory pressure of 40 mmHg for 15 seconds. Blood pressure and RR intervals were measured during the Valsalva maneuver by tonometry, using a noninvasive blood pressure monitoring system (ANS 508, Nihon Colin Co., Ltd.). Baroreceptor reflex sensitivities (BRS) of the second phase (BRS II) and fourth phase (BRS IV) of the Valsalva maneuver were calculated, and blood pressure elevations during the late second phase (IIp) and fourth phase (IVp) were measured. QTc was greater in the patients with PD (417 ms) than in the control subjects (409 ms). The H/M ratios of the early and delayed images in the patients with PD (1.76, 1.61) were significantly lower than those in the control subjects (2.56, 2.45). The early and delayed H/M ratios significantly correlated with the severity of disease according to Hoehn-Yahr stage. QTc interval and IVp significantly correlated with early and delayed H/M ratios. No other significant correlations were detected. The early H/M ratio in the patients with PD who had IVp within the normal range was lower than the early H/M ratio in control subjects. Our results show that early and delayed H/M ratio correlates with cardiac autonomic function, evaluated on the basis of QTc interval and the Valsalva maneuver, but not with baroreceptor reflex sensitivity or vasomotor autonomic function. Our findings suggest that silent cardiac autonomic dysfunction may be evaluated by 123I-MIBG scintigraphy, because early and delayed H/M ratios were lower in the patients with PD who had normal IVp than in the control subjects.

3-Iodobenzylguanidine↗
PubMed2000

Left ventricular function and autonomic nervous system balance during two different stages of the menstrual cycle.

We studied the left ventricular function and cardiac autonomic nervous system balance variations during two different stages of the menstrual cycle. These two variables, as well as plasmatic estradiol and progesterone concentrations, were measured in a drug-free state in 20 women (29+/-6 year-old) with regular menstrual periods. A clinical evaluation, an echo-Doppler and a Valsalva manoeuvre were performed in all the patients on the third day of their menstrual cycle (follicular phase) and three days prior to their next menstrual cycle (luteinizing phase). When comparing the results obtained in these two phases, a statistically significant increase was put forward in plasmatic estradiol (50.6+/-24 vs. 127.3+/-52.8 pg/ml) and progesterone (0.37+/-0.42 vs. 11.92+/-10.8 ng/ml) concentrations, Valsalva index (1.55+/-0.22 vs. 1.67+/-0.33; P=0.044) and E/A mitral wave ratio (1.63+/-0.36 vs. 1.75+/-0.35, P=0.02). The right and left atrial volumes, left ventricular volumes and ejection fraction were similar in the two menstrual phases studied. We conclude that the autonomic nervous system balance and the left ventricular diastolic function suffer significant changes during the luteinizing phase of the menstrual cycle in normal women.

Adult↗
PubMed1983

Cardiac neural discharge and epileptogenic activity in the cat: an animal model for unexplained death.

This study developed an animal model to explore the hypothesis that altered autonomic function may be one cause for unexplained sudden epileptic deaths. After alpha-chloralose anesthesia, 9 cats received a tracheostomy and a thoracotomy. Intravenous gallamine was used to paralyze the cats. Blood pressure, arterial blood gases, electrocardiogram, and rectal temperature were monitored. Simultaneous monitoring of the neural discharge in postganglionic cardiac sympathetic branches and the vagus nerve was combined with a bilateral craniectomy and electrocorticography. Pentylenetetrazol was given intravenously at 10 min intervals in 10, 20, 50, 100, 200, and 2000 mg/kg doses. Epileptiform discharges were categorized as a prolonged ictal (duration of 10 sec or more), brief ictal (duration of less than 10 sec mixed with suppression), and interictal spike activity. The two types of ictal activity were quantified by duration in seconds for the 10 min interval after each dose of pentylenetetrazol; the number of interictal spikes/min was determined for each minute of the entire experiment. This study developed a model which quantified the degree of epileptiform activity and correlated it with changes in cardiovascular function and autonomic cardiac neural discharge. An imbalance within and between sympathetic and parasympathetic cardiac neural discharges was found, as was a significant disruption of the physiological relationships between heart rate and blood pressure. Frequent and varied electrocardiogram abnormalities occurred. All of the above changes occurred during minimal (interictal) subconvulsant as well as during maximal (ictal) convulsant epileptogenic activity.

Animals↗
PubMedDate not supplied

Heart rate and systolic blood pressure variability: the impact of thinness and aging in human male subjects.

BACKGROUND: Life spans are steadily increasing in developing countries where 'thinness' is widely prevalent. However, the interaction of aging and thinness has been poorly studied in terms of its physiological consequences. OBJECTIVE: To determine the impact of aging and 'thinness' (body mass index (BMI) < 18.5 kg/m2) on resting heart rate and systolic blood pressure (SBP) variability indices in the frequency domain. SUBJECTS: Ninety seven healthy male subjects were divided into two age categories; young; 18-30 yrs and old superior 60 yrs. The subjects were further divided on the basis of BMI into young, thin (n=32), young, normal BMI (BMI 18.5-25, n = 27), old, thin (n = 15) and old, normal BMI (n = 23) groups. METHODS: Cardiac autonomic nerve function was determined using heart rate variability indices in the frequency domain (low frequency, cardiac sympathetic 0.04- 0.15 Hz; high frequency, cardiac parasympathetic 0.15-0.4 Hz). Vasomotor sympathetic activity was determined from the low frequency component of SBP variability. Baroreflex sensitivity was determined from the spectral power of both RR variability and SBP variability between 0.07 to 0.14 Hz. RESULTS: Thinness was associated with a reduction in the absolute total, low and high frequency heart rate power spectrum as compared to individuals of normal BMI, but this difference was only apparent in young adults (P < 0.05) and not in older subjects. The age related decline in heart rate variability (absolute units) was apparent for subjects of both low and normal BMI (P < 0.05). There were no differences in SBP variability either with age or BMI. CONCLUSIONS: The data suggest that aging has a pronounced effect on heart rate variability, which may mask differences in heart rate variability related to thinness.

Adolescent↗
PubMed2002

Relationship between autonomic cardiac activity, beta-cell function, anthropometrics and metabolic indices in type II diabetics.

OBJECTIVE: Recent studies have demonstrated that C-peptide exerts beneficial effects on the diabetic state, including improvements in kidney and nerve function. Thus, we investigated the effect of residual pancreatic C-peptide secretion on the cardiac autonomic nervous system in well- and poorly controlled type II diabetic patients. DESIGN: Randomised cross-sectional study. PATIENTS: Forty type II diabetic patients free from diabetic neuropathy, with similar anthropometric parameters, volunteered for our study. MEASUREMENTS: Insulin action, residual pancreatic C-peptide secretion and the cardiac autonomic nervous system were investigated by euglycaemic hyperinsulinaemic clamp, glucagon bolus test and heart rate variability, respectively. M-values were used as an index of insulin sensitivity. High frequency (HF) and low frequency (LF) oscillations in heart rate were analysed. RESULTS: The patients were categorized into those with good (HbA1c < or = 7.0) and poor (HbA1c > or = 8.0) metabolic control. The patients with good metabolic control had fasting plasma glucose and C-peptide levels, plasma area under the curve (auc) insulin and C-peptide levels, M-values, LF values and LF/HF ratio significantly lower than patients with poor metabolic control. In contrast, RR interval, total power and HF values had an opposite trend. Basal plasma C-peptide correlated with LF/HF in patients with good (r = -0.42; P < 0.05) and poor metabolic control (r = -0.45; P < 0.05). An even stronger correlation between auc C-peptide and LF/HF in patients with good (r = -0.53, P < 0.002) and poor metabolic control (r = -0.49; P < 0.03), as well as in the whole group (r = -0.83; P < 0.001) was found. By multiple regression analyses performed in all patients, LF/HF were independently associated with auc C-peptide (t = -8.618; P < 0.001) but not basal C-peptide levels (t = -0.137; P < 0.88). CONCLUSION: Our study demonstrated that preserved C-peptide secretion is associated with a well balanced cardiac autonomic activity in type II diabetic patients.

Area Under Curve↗
PubMed2004

Circadian variation of QTc dispersion in children with vasovagal syncope.

AIMS: To assess the validity of QTc dispersion to cardiac autonomic nervous function status. METHOD AND RESULTS: Prospective comparisons of QTc dispersion measurements in 77 neurally mediated cardiac syncope (NMCS) patients (29 boys, 48 girls, mean age 13.4+/-0.78) were evaluated. Head-up tilt test (HUT) was positive in 38 patients and negative in 39 patients. QTc dispersion was significantly higher early morning and late night in HUT-positive group compared with HUT-negative group (p<0.001). Although there was a circadian rhythm in HUT-positive group, there was no change on the QTc dispersion within a day in the HUT-negative group. QTc dispersion in the HUT-positive group was high in accordance with their high sympathetic nervous stimulation. Moreover, QTc dispersion was higher during late night and early morning than the rest of the day. CONCLUSION: These results may explain why the HUT-positive patients usually have their syncope attacks early in the morning. Additionally, we can use QTc dispersion measurement as a new noninvasive electrocardiographic test to evaluate cardiac sympathetic nervous system in NMCS.

Adolescent↗
PubMed1983

Treatment of severely painful diabetic neuropathy with an aldose reductase inhibitor: relief of pain and improved somatic and autonomic nerve function.

11 patients with severely painful diabetic neuropathy previously unresponsive to numerous drugs were treated with an aldose reductase inhibitor ('Sorbinil'--Pfizer CP 45, 634); 8 also received a placebo. Response was assessed according to a 0-20 graphic rating scale for pain and by tests for motor and sensory nerve conduction velocities (NCV) and cardiac autonomic nerve function. 8 patients had moderate to marked relief of symptoms, generally beginning on the 3rd or 4th day of medication, 2 had equivocal responses, and 1 had no change. Each of 4 patients with diabetic amyotrophy reported striking improvement in pain and mild to moderate improvement in proximal leg muscle strength; 2 of these noticed improved sensory perception in their feet. Objective evidence of improved muscle strength was obtained in each of these 4 patients and of improved sensation in 3. On stopping medication, pain worsened in 7 of 8 responders, although generally with some delay, suggesting a carry over effect. During the course of treatment autonomic nerve function improved significantly in 6 of 7 patients tested and across the group, and NCV improved in 4 of 7 tested. Both of these variables deteriorated after withdrawal of the drug. A correlation between NCV response and clinical response was apparent. Very little toxicity was observed. These observations suggest that aldose reductase inhibitors may be important in the treatment of symptomatic somatic and autonomic neuropathies complicating diabetes.

Adult↗
PubMed1992

Prolonged QT interval in alcoholic autonomic nervous dysfunction.

QT prolongation on electrocardiography is related to sudden cardiac death and is frequently found in alcoholics. We studied QT prolongation in relation to the function of cardiac autonomic nerves assessed by the coefficient of variation of the R-R interval (CVRR) in three age-matched groups of men: 32 alcoholics with autonomic nervous dysfunction (AN), 32 alcoholics without AN, and 32 healthy controls. The QTc interval and CVRR were measured at rest on the 30th day of abstinence, when electrolyte imbalance had disappeared. Subjects with arrhythmia, conduction abnormality, cardiomegaly, ischemic heart disease or diabetes mellitus were excluded. A CVRR of less than 80% of standard predicted value was judged to represent AN. In alcoholics, QTc correlated negatively with the ratio of CVRR to its standard value (r = -0.49, p < 0.0001). The incidence of QTc prolongation was higher in alcoholics with AN (46.9%) than in alcoholics without AN (21.9%, p < 0.05). QTc prolongation was not observed in healthy controls. The QTc interval was significantly (p < 0.01) longer in alcoholics with AN (444 +/- 20 msec) than in alcoholics without AN (426 +/- 17) and in healthy controls (398 +/- 18). These results suggest that alcoholism causes dysfunction of the autonomic nerves as well as worsening QT prolongation, and this may predispose such patients to sudden cardiac death.

Adult↗
PubMed2003

Measures of cardiovascular autonomic nervous function: agreement, reproducibility, and reference values in middle age and elderly subjects.

AIMS/HYPOTHESIS: Currently, three categories of cardiovascular autonomic nervous function measures are used: classic Ewing-test measures, measures of heart-rate variability (HRV), and measures of baroreflex sensitivity (BRS). Little is known about the agreement between these measures, and reference and reproducibility values for these measures have not been reported within the same group. METHODS: As part of the Hoorn Study, 631 subjects aged 50 to 75 participated in a study of autonomic nervous function. Cardiac cycle duration (RR interval) and continuous finger arterial pressure were measured under three conditions: during spontaneous breathing, during six deep breaths over 1 min, and during an active change in position from lying to standing. From these readings, ten measures of autonomic function were assessed (mean heart rate, three Ewing test measures, five HRV measures and one BRS measure). RESULTS: Regression analysis in a healthy subgroup (n=191) showed sex differences for two of the ten measures and seven measures decreased with age. Therefore, appropriate age-specific and sex-specific reference values were calculated. Reproducibility (n=39) of most measures was moderate, with a reliability coefficient of around 50%. Agreement between the measures of autonomic nervous function varied greatly, between 0% and 87%. The HRV-power ratio measure and the blood pressure changes in the lying-to-standing test showed the lowest agreement with all other measures. CONCLUSION/INTERPRETATION: This study provides age-specific and sex-specific reference values for a wide range of different autonomic function measures in an elderly population. Agreement among the different measures varied widely and reproducibility was only moderate.

Aged↗
PubMed1999

Regional patterns of myocardial sympathetic denervation in dilated cardiomyopathy: an analysis using carbon-11 hydroxyephedrine and positron emission tomography.

OBJECTIVE: To assess presynaptic function of cardiac autonomic innervation in patients with advanced congestive heart failure using positron emission tomography (PET) and the recently developed radiolabelled catecholamine analogue carbon-11 hydroxyephedrine (HED) as a marker for neuronal catecholamine uptake function. DESIGN AND PATIENTS: 29 patients suffering from dilated cardiomyopathy with moderate to severe heart failure were compared with eight healthy controls. Perfusion scan was followed by HED dynamic PET imaging of cardiac sympathetic innervation. The scintigraphic results were compared with markers of disease severity and the degree of sympathetic dysfunction assessed by means of heart rate variability. RESULTS: In contrast to nearly normal perfusions, mean (SD) HED retention in dilated cardiomyopathy patients was abnormal in 64 (32)% of the left ventricle. Absolute myocardial HED retention was 10.7 (1.0)%/min in controls v 6.2 (1.6)%/min in dilated cardiomyopathy patients (p < 0.001). Moreover, significant regional reduction of HED retention was demonstrated in apical and inferoapical segments. HED retention was significantly correlated with New York Heart Association functional class (r = -0.55, p = 0. 002) and ejection fraction (r = 0.63, p < 0.001), but not, however, with plasma noradrenaline concentrations as well as parameters of heart rate variability. CONCLUSIONS: In this study, using PET in combination with HED in patients with dilated cardiomyopathy, not only global reduction but also regional abnormalities of cardiac sympathetic tracer uptake were demonstrated. The degree of abnormality was positively correlated to markers of severity of heart failure. The pathogenetic mechanisms leading to the regional differences of neuronal damage as well as the prognostic significance of these findings remain to be defined.

Adult↗
PubMed2005

Association of small fiber neuropathy with cardiac sympathetic dysfunction in sarcoidosis.

BACKGROUND AND AIM: Recently we found that small fiber neuropathy (SFN) occurs frequently in sarcoidosis. Autonomic dysfunction may be a feature of SFN. Since cardiac autonomic dysfunction has been identified as a strong predictor of morbidity and mortality, recognition of cardiac autonomic involvement is of clinical relevance. It was hypothesised that SFN might be related to cardiac sympathetic denervation in sarcoidosis. METHODS: In the present study 45 consecutive sarcoidosis patients (13 without SFN assessed by thermal threshold testing (TTT), 32 with SFN (abnormal TTT) were enrolled. To rule out bias due to myocardial ischemia, cases with abnormal Thallium (201Tl) perfusion scintigraphy were excluded (n = 2). Cardiovascular autonomic function testing (Ewing tests) and 123I-MIBG (metaiodobenzylguanidine) scintigraphy were used to assess cardiac autonomic function. Further cardiac diagnostic work-up included ECG, Holter recording and echo Doppler cardiography. RESULTS: Mild to moderate heterogeneity of 123I-MIBG uptake regional in the myocardium was demonstrated in a substantial number of the studied sarcoidosis population, especially in those with SFN (abnormal TTT). Mean inferior-anterior ratios were 0.85+/-0.17 (SFN) and 1.0+/-0.17 (no SFN; p = 0.003), respectively. Four out of the 14 cases with abnormal MIBG scintigraphy and SFN showed an abnormal Ewing test. CONCLUSION: Cardiac sympathetic dysfunction assessed by use of 123I-MIBG myocardial scanning appeared to be heterogeneous in sarcoidosis patients and dependent on the presence or absence of SFN. MIBG scintigraphy may be of additional value in the management and follow-up of sarcoidosis patients. Future study is warranted to explore possible prognostic and therapeutic implications of these findings in sarcoidosis.

3-Iodobenzylguanidine↗
PubMed1999

Role of nitric oxide in the regulation of cardiovascular autonomic control.

Alteration in function of the cardiac autonomic nervous system has proved to be a powerful predictor of cardiac death or serious arrhythmia in patients with cardiac disease, yet little is known about the mechanisms by which this system is regulated. Recent evidence suggests that the gaseous molecule nitric oxide (NO) may act as an important mediator in this pathway. Histochemical staining techniques have identified neuronal populations that contain NO synthase within medullary cardio-regulatory sites and their peripheral autonomic pathways. Drugs that modulate the NO pathway (administered both systemically and into the central nervous system) cause changes in pre- and post-ganglionic sympathetic nerve activity that imply that NO serves to inhibit central sympathetic outflow. There is also evidence that NO may attenuate cardiovascular end-organ responses to sympathetic stimulation. Studies suggest that NO modulates cardiac vagal control, increasing the activity of central vagal motoneurons and, more contentiously, contributing to the bradycardic effects of vagal stimulation. NO also modulates so-called 'indirect' vagal inhibition of sympathetic cardiac responses. Additionally, central attenuation of baroreflex-mediated vagal control has been described. There is relatively little information available on the importance of NO in the regulation of human cardiovascular autonomic control. Further well-controlled studies are required.

Autonomic Nervous System↗
PubMed1996

Ventricular repolarization is correlated with metabolic control in newly diagnosed type 2 diabetes.

Good metabolic control may improve cardiac function in diabetic patients. It is not known, however, whether this functional improvement is associated with concomitant electrocardiographic changes. The aim of the present prospective study was to evaluate the quantitative electrocardiographic and vectorcardiographic correlates of metabolic control, left ventricular function and dimensions, and autonomic nervous function in patients with newly diagnosed Type 2 diabetes. We studied 35 patients (20 men, 15 women; age 52 +/- 6 years (mean +/- SD) with normal electrocardiograms at 1.5 and 15 months after the diagnosis of Type 2 (non-insulin-dependent) diabetes. During the follow-up, body weight decreased, and significant improvement was observed in metabolic control, cardiac function and autonomic nervous function. Concomitantly, maximal spatial vector of T wave increased from 238 +/- 122 to 284 +/- 141 microV (P < 0.01), and this increase was correlated with a decrease in glycosylated haemoglobin A1C (r = -0.45, P < 0.01) and plasma insulin (r = -0.46, P < 0.01). In addition, duration of QRS complex shortened from 94 +/- 9 to 92 +/- 8 ms (P < 0.05), and this shortening was correlated with an increase in heart rate variability (r = -0.34; P < 0.05) and a decrease in peak early to late left ventricular filling flow velocity (r = 0.35, P < 0.05). These changes were most prominent in patients with co-existing hypertension and coronary artery disease. In conclusion, improving metabolic control of diabetes is associated with changes in ventricular repolarization and shortening of QRS complex duration.

Adult↗
PubMed2003

The relationship between heart rate variability and prostaglandin E2 in patients with renal insufficiencies.

OBJECTIVE: To investigate the relationship between heart rate variability (HRV) and prostaglandin E2 (PGE2) in patients with renal insufficiencies. METHODS: HRV blood and 24-hour urine prostaglandin E2 (PGE2) detection were detected in the following 4 groups of people: group A was a control group comprised of 20 normal individuals; group B had 20 patients with renal disease but exhibiting normal renal function; group C contained 20 patients with renal disease and compensatory renal function; group D had 20 patients demonstrating renal insufficiencies. The indices standard deviation of all NN intervals (SDNN), index of standard deviation of the averages of NN intervals (SDANN), mean of the standard deviation of all NN intervals performed on all 5-minute segments of the entire recording (SDNNindex), square root of the mean of the sum of the squares of differences between adjacent NN intervals (rMSSD) and NN50 count divided by the total number of all NN intervals (PNN50) were used to evaluate HRV, blood and 24-hour urine were determined by specific radioimmunoassay (RIA). RESULTS: PGE2 in blood and urine and HRV exactly within 24 hours in patients with renal insufficiencies, negatively correlated with worsening damage to renal function. There was a slight or moderate correlation between blood and urine PGE2 and the SDNNindex, SDANNindex, SDNN, rMSSD and PNN50 indices (P < 0.05). CONCLUSIONS: HRV and cardiac autonomic regulatory functions are decreased in the patients with renal insufficiencies, while lower levels of PGE2 may be a related factor.

Adolescent↗