Heart rate variability, the autonomic nervous system, and neuroeconomic experiments.

Measuring the activity of the autonomic nervous system may yield insights into individual stress levels. One small, nonintrusive instrument for collecting such data is a high-resolution heart rate monitor that allows measurement of heart rate variability (HRV). This complements brain-scanning methods and increases the number of participants that can be studied simultaneously. Combining HRV data with recorded data on the decisions made in experimental games throws light on how different individuals react in (economic) decision-making situations. This article therefore introduces the HRV measurement method and, using data from an ultimatum bargaining experiment in a laboratory environment, illustrates its application in experimental economic research. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Heart rate variability and heart rate in healthy volunteers. Is the female autonomic nervous system cardioprotective?

AIMS: Heart rate variability has been proposed as an indicator of cardiovascular health. Since women have a lower cardiovascular risk, we hypothesized that there are gender differences in autonomic modulation. METHODS AND RESULTS: In 276 healthy subjects (135 women, 141 men) between 18 and 71 years of age, 24 h heart rate and heart rate variability were determined. All heart rate variability parameters, except for pNN50 and high frequency power, were higher in men. After adjustment for heart rate, we obtained gender differences for: the standard deviation (P=0.049), the standard deviation of the 5 min average (P=0.047), low frequency power (absolute values, P=0.002; normalized units, P<0.001) and ratio low frequency/high frequency (P<0.001). There were no significant gender differences in heart rate variability parameters denoting vagal modulation. Gender differences were confined to age categories of less than 40 years of age. The majority of heart rate variability parameters decreased with age. Only in men, was a higher body mass index associated with a higher heart rate and with lower heart rate variability parameters (P<0.001). CONCLUSION: Cardiac autonomic modulation as determined by heart rate variability, is significantly lower in healthy women compared to healthy men. We hypothesize that this apparently paradoxical finding may be explained by lower sympathetic activity (low frequency power) in women. This may provide protection against arrhythmias and against the development of coronary heart disease.     

Heart and autonomic nervous system in connective tissue disorders

Heart rate variability (HRV) is a suitable diagnostic tool in identifying patients with autonomic nervous system (ANS) disorders even in pre-clinical stage. We have enrolled in this study all patients with large variety of connective tissue disorders, given the possibility of an involvement of ANS in these diseases. The study population consisted in eighty-five patients (68 females and 17 males), 35 of whom affected by systemic lupus erythematosus, 16 by rheumatoid arthritis, 14 by Sj?gren syndrome, 12 by progressive systemic sclerosis, 3 by Beh?et syndrome and 5 by antiphospholipid antibodies syndrome. The mean age ranged between 33.7 of patients with lupus erythematosus and 51.8 of those with Sj?gren syndrome. As control, we enrolled healthy subjects of different age, divided into two groups, to rule out the aging as potential source of considered parameters alteration. The autonomic function has been evaluated by 24 hours ambulatory monitoring, using a Zymed 1210 Scanner with Zymed 3.74-PC 1990 software. We have considered: in the time domain, the standard deviation of the RR intervals average (SDNN) and the percentage of RR adjacent intervals differing each other more than 50 msec (pNN50); in the frequency domain, the low (LF) and high (HF) frequencies, the LF/HF ratio, and the total power (RT). The HRV parameters resulted abnormal in every type of the connective tissue diseases considered: particularly SDNN, pNN50, LF, HF and RT (p < or = 0.01). In conclusion: the results of our study suggest that autonomic neuropathy may be present in any kind of connective tissue disorders even in preclinical stage.     

Blood pressure and heart rate variability in autonomic disorders: a critical review

Sulfhydryl compounds can protect DNA against free-radical-induced DNA damages not only by scavenging of radicals, but also by chemical non-enzymatic repair or modification of such damages by hydrogen-donation. To investigate the influence of chemical repair and modification on mutations, induced by gamma-radiation-generated free radicals (.OH, .H), phosphate-buffered aqueous solutions of double-stranded (ds) M13 DNA were exposed to gamma-rays under N2 in the presence of 5 mM cysteamine. The exposed DNA was subsequently transfected to wild-type E. coli and mutations in the mutational target were characterized. This target in fact contains three different target sequences, i.e., the lac promoter/operator, the lacZ alpha gene and a 144 bp inframe insert. The mutation spectrum obtained was compared with those in the absence of cysteamine under N2 and N2O. In the latter case, the ratio of .OH and .H available for reacting with DNA is about the same as under N2 + cysteamine. The results show that chemical repair and/or modification by cysteamine of potentially lethal lesions takes place, leading to a much higher survival of ds M13 DNA in the presence of cysteamine than could be expected on basis of scavenging of .OH and .H alone. This higher survival appeared to be accompanied with a higher mutation induction. However, the N2 + cysteamine mutation spectrum shows a remarkable resemblance with the N2O-spectrum. This holds for the total mutation target, as well as each of the three targets, although the mutations obtained in each of the three targets under the same irradiation conditions are quite different. Thus, it can be concluded that cysteamine is mainly effective on radiation-induced potentially lethal DNA lesions, and not so much on (pre)mutagenic damages. Moreover, the type of mutation appeared to be strongly dependent on the mutational target sequence.     

Heart rate variability in depressed patients and differential effects of paroxetine and amitriptyline on cardiovascular autonomic functions

Twenty-four unmedicated patients with episodes of major depression (DSM-III-R) and an age- and sex-matched group of 24 normal subjects underwent a heart rate analysis. The battery of cardiovascular reflex tests included the coefficient of variation while resting (CVr) and during deep breathing (CVdr), a spectral analysis of heart rate variability, the Valsalva test, and the posture index. The depressed patients showed no significant abnormalities in any of the tests as compared to the healthy subjects. The 24 patients were randomly allocated for treatment with either amitriptyline or paroxetine. During treatment with 20 mg paroxetine per day, patients showed no changes in cardiovascular autonomic function tests after 14 days. However, treatment with 150 mg amitriptyline per day decreased all heart rate parameters significantly due to anticholinergic side effects, except heart rate, which increased significantly. As autonomic side effects are a potential hazard of antidepressant therapy, the data suggest that paroxetine is an appropriate antidepressant for cases with pre-existing cardiovascular autonomic neuropathy.     

PC-based noninvasive measurement of the autonomic nervous system. Detecting the onset of diabetic autonomic neuropathy

In this review, hyposensitization or immunotherapy will be discussed. The earliest immunotherapy was applicated in allergic respiratory diseases such as asthma and rhinitis. The most important indication has become the treatment of hymenoptera allergy. Some less frequently indications are associated with drug allergy. Immunotherapy is most frequently indicated in IgE mediated diseases, but new applications for cell mediated reactions will be described. With the introduction of molecular biology in allergology new theoretical possibilities emerged: use of peptide antigens, recombinant allergens, anticytokines.... Unfortunately, these newer approaches did not (yet) cause a breakthrough. The cost of these products will be a major draw back, even when ethical problems for using them on a larger scale will have been solved.     

Heart rate variability in coronary artery disease

Heart rate variability (HRV) reflects the modulation of cardiac function by autonomic and other physiological systems, and its measurement from ambulatory electrocardiograph (ECG) recordings is a useful method for both clinical and scientific purposes. Heart rate variability can be measured by several linear and non-linear methods, and various methods can give different information on neural and other physiological influences on the heart. Heart rate variability is abnormal in various settings of ischaemic heart disease, and the most important current application of HRV analysis in clinical cardiology is its measurement in postinfarction patients, in whom abnormal HRV indicates an increased risk of cardiac mortality. Future research may expand the clinical utility of HRV measurement to other clinical situations.     

Heart rate variability and newborn heart rate responses to illumination changes.

Investigated heart rate (HR) response patterns to the onset and offset of a 30-sec increase in illumination in 16 human newborns. Ss were divided into 2 groups based on a measure of pretrial HR variability. Only Ss with the high pretrial HR variability responded significantly to the change in stimulation. The response to onset was characterized by a significant quartic trend containing both decelerative and accelerative components. The response to offset only approached significance and had a pattern similar to the onset response. Although the occurrence of systematic response patterns was related to the level of pretrial HR variability, this measure of autonomic lability may have been related to influences associated with delivery and not to stable individual differences. (16 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Heart rate variability and preoperative anxiety

Power spectral analysis of heart rate variability has been used to gain some understanding of the activity of the autonomic nervous system. In this study various indices of heart rate variability were related to the degree of preoperative anxiety experienced by 32 patients presenting for day case surgery. It was found that there was no correlation between anxiety and mean heart rate, or between anxiety and the spectral power in the mid frequency band (0.05-0.15 Hz). However, there was an increase in the relative power of the higher frequency band (0.15-0.5 Hz) with increasing anxiety levels (Spearman correlation r = 0.4034). This suggests that preoperative anxiety may often be associated with a relative vagal predominance in the sympathovagal balance.     

Chemical mediators of autonomic nervous system activity

Several modifications have improved the sensitivity and specificity of neurochemical tests to diagnose and distinguish multiple system atrophy and pure autonomic failure. These include [3H]-norepinephrine infusion to estimate plasma norepinephrine clearance; neuroendocrine stimulation tests; and simultaneous measurements of levels of levodopa, catecholamines, and catecholamine metabolites. New clinical imaging approaches have the potential to visualize alterations in neurotransmitter function in the brain and periphery. Patients with multiple system atrophy have decreased striatal radioactivity after injection of positron-emitting ligands at dopamine receptors or uptake sites, and patients with diffuse sympathetic denervation have decreased myocardial radioactivity after injection of radioactive sympathoneural imaging agents.     

Palytoxin-induced transmitter release in the autonomic nervous system of the rat

A combination of pharmacological, histochemical, immunocytochemical, neurochemical and microscopic techniques has been used to test the hypothesis that smooth muscle contractions caused by palytoxin are primarily a response to toxin-induced release of transmitter from motor nerve terminals. In the anococcygeus, palytoxin caused a dose-dependent contraction; the dose-response curve was particularly steep in the dose range 0.3-100 nM. This part of the response was abolished by phentolamine and absent in the muscles of reserpinized animals. A single, large dose of palytoxin (100 nM) caused a biphasic contraction. Phentolamine blocked the first phase by 50% and the second by > 80%. Transmitter overflow studies showed that the toxin enhanced the release of 3H after loading with 3H-NA, and immunofluorescence showed the loss of adrenergic transmitters from the innervation. In the vas deferens, palytoxin caused a biphasic contraction of the muscle. Phentolamine blocked first phase by > 80% and the second by 47%. Immunofluorescence studies showed that stores of adrenergic transmitter were depleted but stores of NPY were not greatly affected. Indirect evidence suggested that palytoxin did not cause the release of purinergic transmitters. A direct component to the contraction was apparently present in most preparations, but though variable in extent it was usually slight. It is concluded that the contractions of smooth muscle caused by palytoxin are primarily the result of toxin-induced transmitter release.     

Airway autonomic nervous system dysfunction and asthma

Airways are richly innervated by 4 nervous systems: adrenergic, cholinergic, inhibitory nonadrenergic noncholinergic (i-NANC), and excitatory NANC (e-NANC) nervous systems. Dysfunction or hyperfunction of these systems may be involved in the inflammation or airway hyperresponsiveness observed in asthmatic patients. The cholinergic nervous system is the predominant neural bronchoconstrictor pathway in humans. Airway inflammation results in exaggerated acetylcholine release from cholinergic nerves via dysfunction of the autoreceptor, muscarinic M2, which is possibly caused by a major basic protein or IgE. Vasoactive intestinal peptide (VIP) and nitric oxide (NO) released from i-NANC nerves act as an airway smooth muscle dilator. The effects of VIP and NO are diminished after allergic reaction by inflammatory cell-mediated tryptase and reactive oxygen species. Thus, in asthmatic airways, the inflammatory change-mediated neural imbalance may result in airway hyperresponsiveness. Tachykinins derived from e-NANC nerves have a variety of actions including airway smooth muscle contraction, mucus secretion, vascular leakage, and neutrophil attachment; and they may be involved in the pathogenesis of asthma. Since tachykinin receptor antagonists are effective for bradykinin- and exercise-induced bronchoconstriction in asthmatic patients, these drugs may be useful for asthma therapy.     

The autonomic nervous system and the immune system in juvenile rheumatoid arthritis

CD16, the low affinity receptor for monomeric IgG (Fc gamma RIIIA), is a well characterized activation molecule on NK cells. In this study we investigated the role of CD16 in NK cell-mediated regulation of immunoglobulin production. Cocultures of the CD16+ human NK clone CNK6 and highly purified SAC/IL-2-activated B lymphocytes with various CD16 antibodies showed significantly diminished NK-enhanced immunoglobulin production in a dose-dependent manner, indicating that CD16 is relevant in NK-B cell interaction. Similarly, recombinant soluble CD16 incubated with B cells before cultures, suppressed the NK cell-stimulated B cell antibody response. Enhanced immunoglobulin production was also inhibited by Fc-specific F(ab')2 anti-body fragments. Coculture of NK cells with B lymphocytes resulted in induction of mRNA for IFN-gamma and TNF-alpha. The accumulation of mRNA for these cytokines was prevented by addition of CD16 and Fc-specific antibodies. It is proposed that interaction of CD16 on NK cells with B cell bound immunoglobulin leads to induction of cytokines in NK cells which stimulate immunoglobulin production by B cells.     

Heart rate variability as an index of regulated emotional responding.

The study of individual differences in emotional responding can provide considerable insight into interpersonal dynamics and the etiology of psychopathology. Heart rate variability (HRV) analysis is emerging as an objective measure of regulated emotional responding (generating emotional responses of appropriate timing and magnitude). This review provides a theoretical and empirical rationale for the use of HRV as an index of individual differences in regulated emotional responding. Two major theoretical frameworks that articulate the role of HRV in emotional responding are presented, and relevant empirical literature is reviewed. The case is made that HRV is an accessible research tool that can increase the understanding of emotion in social and psychopathological processes. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Neuropeptides of the autonomic nervous system in Sj?gren''s syndrome

Posterior spinal tuberculosis or arch tuberculosis is a form of skeletal tuberculosis that selectively involves the vertebral arch. It may mimic skeletal neoplasm clinically and radiographically. Although posterior spinal tuberculosis has been reported in developing countries it has rarely been found in the United States. As a result, there is limited information about this entity in the US literature. We are presenting our experience in a patient born in the United States.