Parasympathetic Nervous System

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Review Article

I – Evaluation of Cardiovascular Autonomic Function in Healthy Individuals

Benedito Carlos Maciel et al. Lourenço Gallo-Jr André Schmidt José Antonio Marin-Neto

Abstract

This first part of the review presents nearly 60 years of experience from our laboratory in standardizing cardiovascular autonomic tests in healthy individuals. The wide range of tests includes pharmacological blockade of both the sympathetic and parasympathetic divisions, baroreflex sensitivity assessment through transient hypertension and hypotension, the Valsalva maneuver, head-up tilt testing, isometric and dynamic exercise, facial immersion in cold water, respiratory sinus arrhythmia, heart rate variability analysis in the frequency domain, and imaging with ¹²³I-metaiodobenzylguanidine. Autonomic function was evaluated based on test responses under baseline conditions in healthy individuals. The analysis also covers physiological adaptations to endurance training and aging, providing a reference framework for identifying autonomic dysfunction involving both parasympathetic and adrenergic components in patients with various pathophysiological conditions, as discussed in the second part of this review.

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Review Article

II – Evaluation of Autonomic Control of Heart Rate in Various Clinical Conditions

Benedito Carlos Maciel et al. Lourenço Gallo-Jr André Schmidt José Antonio Marin-Neto

Abstract

Through the comparison of responses of normal volunteers, assessment of autonomic function under abnormal clinical conditions focused on the detection of dysautonomia involving both the parasympathetic and adrenergic limbs in patients with Chagas heart disease, post-cardiac surgery, chronic heart failure, mitral valve prolapse, and hyperthyroidism. In particular, the autonomic impairment observed in Chagas disease patients involved predominantly the parasympathetic control of heart rate at the sinus node level, and the adrenergic innervation at the myocardial ventricular level. The autonomic derangements observed in Chagas cardiomyopathy patients have only recently been explored in terms of their prognostic relevance, and their potential clinical implications for therapeutic purposes remain to be investigated.

Over the last nearly seven decades, our laboratory has accumulated significant expertise using several tests described above to evaluate autonomic control of heart rate, now focusing on various pathophysiological clinical conditions. The effect of endurance physical training and of aging was mostly focused on studies of normal volunteers whose responses at baseline served as controls to be compared during tests employed in individuals with some morbid clinical conditions. By far, the pathophysiology of Chagas heart disease involving the autonomic nervous system was the most predominant subject studied in our laboratory, since the early studies in the 1960s until the late studies just recently published in international journals (Central Illustration). Other pathological conditions focused on our studies were mitral valve prolapse, heart failure, post-cardiac surgery, and hyperthyroidism.

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Editorial

The Neurolinguistics of the Heart

Esteban Wisnivesky Rivarola et al. Mauricio Scanavacca

The association between mental stress and cardiac function has always been of major interest. In the 19^th century, Claude Bernard, the father of evidence-based medicine, first acknowledged the vagus nerve as a structural and functional link connecting the heart and the brain. Nowadays, stress is considered one of the most significant health problems in modern society, related to the physiopathology of psychiatric, metabolic and cardiovascular diseases, and the search for its biomarkers remains a challenging task for researchers and clinicians.

But what is stress? How can we define it, before we tackle it?

[…]

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Original Article

Introduction of Application of Gini Coefficient to Heart Rate Variability Spectrum for Mental Stress Evaluation

Miguel Enrique Sánchez-Hechavarría et al. Shreya Ghiya Ramon Carrazana-Escalona Sergio Cortina-Reyna … Adán Andreu-Heredia Carlos Acosta-Batista Nicolás Armando Saá-Muñoz

Abstract

Background:

The Gini coefficient is a statistical tool generally used by economists to quantify income inequality. However, it can be applied to any kind of data with unequal distribution, including heart rate variability (HRV).

Objectives:

To assess the application of the Gini coefficient to measure inequality in power spectral density of RR intervals, and to use this application as a psychophysiological indicator of mental stress.

Methods:

Thirteen healthy subjects (19 ± 1.5 years) participated in this study, and their RR intervals were obtained by electrocardiogram during rest (five minutes) and during mental stress (arithmetic challenge; five minutes). These RR intervals were used to obtain the estimates of power spectral densities (PSD). The limits for the PSD bands were defined from 0.15 to 0.40 Hz for high frequency band (HF), from 0.04 to 0.15 Hz for low frequency band (LF), from 0.04 to 0.085 Hz for first low frequency sub-band (LF1) and from 0.085 to 0.15 Hz for second low frequency sub-band (LF2). The spectral Gini coefficient (SpG) was proposed to measure the inequality in the power distribution of the RR intervals in each of above-mentioned HRV bands. SpG from each band was compared with its respective traditional index of HRV during the conditions of rest and mental stress. All the differences were considered statistically significant for p < 0.05.

Results:

There was a significant decrease in HF power (p = 0.046), as well as significant increases in heart rate (p = 0.004), LF power (p = 0.033), LF2 power (p = 0.019) and LF/HF (p = 0.002) during mental stress. There was also a significant increase in SpG(LF) (p = 0.009) and SpG(LF2) (p = 0.033) during mental stress. Coefficient of variation showed SpG has more homogeneity compared to the traditional index of HRV during mental stress.

Conclusions:

This pilot study suggested that spectral inequality of Heart Rate Variability analyzed using the Gini coefficient seems to be an independent and homogeneous psychophysiological indicator of mental stress. Also, HR, LF/HF, SpG(LF) of HRV are possibly important, reliable and valid indicators of mental stress.

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I – Evaluation of Cardiovascular Autonomic Function in Healthy Individuals

Abstract

II – Evaluation of Autonomic Control of Heart Rate in Various Clinical Conditions

Abstract

The Neurolinguistics of the Heart

Introduction of Application of Gini Coefficient to Heart Rate Variability Spectrum for Mental Stress Evaluation

Abstract

Background:

Objectives:

Methods:

Results:

Conclusions:

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