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PubMedDate not supplied

Autonomic variations after stellate ganglion block: are they evidence of an autonomic afference?

Sympathetic skin response and plethysomography were used to assess the sympatholytic effect of the stellate ganglion block with morphine and bupivacaine in patients affected by a sympathetic algodystrophy of the upper limb. Morphine did not show any analgesic or sympatholytic effect. The distribution of the sympatholytic effect and the clinical findings of pain relief without somatic sensory-motor impairments obtained with the local anaesthetic, support the presence of a blockade of the sympathetic efferent pathway as well as of an afferent contingent of fibres probably and mainly involved in sympathetic reflexes.

Afferent Pathways↗

PubMed2001

Radiofrequency energy modification of the atrioventricular junction in patients with atrial fibrillation: modes of ventricular response under autonomic blockade and long-term effect.

The short- and long-term effect of radiofrequency (RF) modification of the AV junction on ventricular rate and left ventricular function and the different types of ventricular response during energy application under autonomic nervous blockade were assessed in 28 patients with medically refractory atrial fibrillation. During the successful RF application, ventricular rate slowed progressively (type I response, ten patients) or accelerated at first and then slowed (type II response, 11 patients). Type II response was associated with a more anterior ablation site compared to Type I response. A primary successful outcome was achieved in 21 patients. Inadvertent complete AV block developed in three patients, while in four patients AV nodal ablation was performed after an unsuccessful modification attempt. During 6-month follow-up, the ventricular rate was adequately controlled in only four patients. Among the 16 patients with a recurrence of uncontrolled AF were all 10 patients with type I response and 6 of 11 patients with type II response. One patient died suddenly 10 weeks after the procedure.

Aged↗

PubMed1993

Total autonomic blockade eliminates the attenuated pressor response to angiotensin II in pregnant rats.

Pressor responses to angiotensin II (ANG II) are markedly attenuated in reflex-intact pregnant animals, a phenomenon widely attributed to intrinsic changes in vascular reactivity. To test the hypothesis that gestational augmentation of neural reflex activity contributes importantly to this phenomenon, changes in mean arterial pressure (MAP), cardiac output (CO), and total peripheral resistance (TPR) were compared during constant infusion (25-400 ng.kg-1.min-1) of ANG II in conscious virgin and pregnant rats, using a model of total autonomic blockade (chlorisondamine chloride and methscopolamine bromide), with restoration of baseline hemodynamics by infusion of norepinephrine. Basal CO was higher and TPR lower in pregnant (CO 121.8 +/- 3.8 ml/min; TPR 0.78 +/- 0.04 mmHg.ml-1.min) compared with virgin (CO 95.9 +/- 3.9 ml/min; TPR 1.05 +/- 0.08 mmHg.ml-1.min) rats (P < 0.005). Pressor responses to ANG II were similar in both groups of reflex-blocked animals due to comparable changes in TPR and CO (not significant by repeated-measures analysis of variance). Other experiments demonstrated that changes in MAP after bolus administration of ANG II did not differ in areflexic virgin and gravid rats. Thus in the absence of autonomic control ANG II has similar effects on systemic resistance in pregnant and nonpregnant rats, suggesting that reflex neural mechanisms contribute significantly to gestational changes in pressor responsiveness. These data further suggest that pregnancy is not accompanied by a generalized decrease in vascular reactivity to all pressor agents.

Angiotensin II↗

PubMed1999

Junctional tachycardia during radiofrequency ablation of the slow pathway in patients with AV nodal reentrant tachycardia: effects of autonomic blockade.

INTRODUCTION: The autonomic nervous system richly innervates the peri-AV nodal region and may be activated during radiofrequency (RF) ablation for AV nodal reentrant tachycardia, resulting in the generation of junctional tachycardia. The purpose of this prospective study was to determine the role of the autonomic nervous system in the genesis of junctional tachycardia. METHODS AND RESULTS: We compared the characteristics of junctional tachycardia in patients with (n = 10) and without (n = 10) autonomic blockade undergoing RF ablation for AV nodal reentrant tachycardia. Intravenous administration of atropine (0.04 mg/kg) and propranolol (0.2 mg/kg) were used to block the autonomic nervous system. There were no differences in clinical variables and baseline electrophysiologic characteristics between the two groups except for slightly longer effective refractory periods of the fast pathway and of the atrium in the autonomic blockade group. The autonomic blockade shortened the baseline sinus cycle length and effective refractory period of the ventricle only but not other electrophysiologic characteristics of the AV node. The junctional tachycardia was observed during ablation in each patient, but its occurrence and cycle length, as well as numbers of consecutive junctional beats, were not altered by the autonomic blockade. CONCLUSION: Our results indicate that the muscarinic and beta-adrenergic components of the autonomic nervous system play no role in the genesis of junctional tachycardia.

Atrioventricular Node↗

PubMed1985

Assessment of autonomic function in humans by heart rate spectral analysis.

Spectral analysis of spontaneous heart rate fluctuations were assessed by use of autonomic blocking agents and changes in posture. Low-frequency fluctuations (below 0.12 Hz) in the supine position are mediated entirely by the parasympathetic nervous system. On standing, the low-frequency fluctuations increase and are jointly mediated by the sympathetic and parasympathetic nervous systems. High-frequency fluctuations, at the respiratory frequency, are decreased by standing and are mediated solely by the parasympathetic system. Heart rate spectral analysis is a powerful noninvasive tool for quantifying autonomic nervous system activity.

Adult↗

PubMed1986

Chronic paroxysmal hemicrania. X. On the autonomic involvement.

In four patients with chronic paroxysmal hemicrania, two of whom could precipitate attacks mechanically, various autonomic function tests were carried out in connection with attacks. Not all features could be studied in all patients. Forehead sweating and temperature were measured. Sweating, tearing, and nasal secretion were studied after systemic atropine administration, which reduced attack-related sweating, tearing, and nasal secretion markedly. Intra-ocular pressure was measured before and after the topical administration of an alpha-receptor blocking agent, thymoxamine. After topical thymoxamine no definite intra-ocular pressure increase occurred during precipitated attacks. In attacks precipitated by head movements, forehead sweating occurred seconds (up to 30 sec) before the pain. This study indicates that at least in some CPH cases, forehead sweating is not caused by the pain. Nor is the pain secondary to increase in intra-ocular pressure. The thymoxamine experiments seem to indicate that alpha-receptors in some way may be connected with the intra-ocular pressure increase during attack.

Atropine↗

PubMed1980

Effects of pharmacological autonomic blockade upon cardiac rate and blood pressure conditioned and unconditioned responses in Macaca mulatta.

Heart rate, systolic and diastolic blood pressures were recorded during classical delay conditioning of rhesus macaque monkeys. When portions of the autonomic nervous system were selectively blocked by pharmacological agents, it appeared that the initial increases in heart rate and blood pressures in response to the conditioned stimulus were the result of increased sympathetic activity and a concomitant decrease in parasympathetic activity. Towards the end of the conditioned stimulus, an increase in parasympathetic activity was indicated. Blockade of the autonomic system which produced total elimination of the conditioned cardiac rate response and substantial reduction or elimination of the conditioned blood pressure response, was not necessarily or always accompanied by a corresponding elimination of the respective unconditioned responses. Such a finding suggests a different underlying neural mediation of these conditioned and unconditioned responses.

Animals↗

PubMed1995

[A transient sinus arrest after right stellate ganglion block--assessment of autonomic function by heart rate spectral analysis].

We experienced a case of sinus arrest probably induced by right stellate ganglion block (SGB). A healthy medical student volunteered in our study of the cardiac autonomic nervous system and received the SGB. After the Holter ECG had been attached, the SGB was performed with mepivacaine 8 ml. Horner's sign was observed after about 3 minutes. A transient (15 s) sinus arrest occurred suddenly after about 6 minutes of the tilt test probably due to a vasovagal reflex, and the subject lost consciousness. From spectral analysis of the Holter ECG recording, the right SGB may be closely involved in the induction of the sinus arrest. Our present case suggests that sinus arrest may occur if a patient stands up after right SGB.

Adult↗

PubMed1993

Autonomic regulation of heart rate and blood pressure in hemorrhaged toads.

Mean arterial blood pressure (P(a)) and heart rate (HR) were studied in normal conscious cane toads (Bufo marinus) or in autonomically blocked animals treated variously with bretylium, atropine, phentolamine, and propranolol. Partial or total autonomic blockade had no effect on resting values of the variables tested, with the exception that atropine treatment of bretylium-treated toads caused an increase of heart rate by 5.3 +/- 1.3 beats/min. In graded hemorrhage, aliquots of blood (1.68 ml/100 g body wt) were removed at 60-min intervals. There was extensive plasma recruitment, and blood could be removed up to 10.08 ml/100 g without inducing cardiovascular shock. Each hemorrhage caused an initial transient decrease in P(a) and increase in HR followed by recovery toward prehemorrhage values. Repeated hemorrhage caused a progressive rise in basal HR and fall in basal P(a). The effects of drug treatments suggest that transient increases in HR may be caused by the release of adrenal catecholamines. In addition, hemorrhage may increase sympathetic tone so that basal HR becomes elevated, which, together with sympathetic vasoconstriction, limits the progressive fall of basal P(a).

Animals↗

PubMed1985

The effect of cardiac autonomic blockade on ventricular response to changes in preload.

Echocardiographic (E) assessment of left ventricular response to increases (I) and decreases (D) in preload of 9 volunteer male subjects (mean age 25 +/- 2.0 years) was made during both control (C) and cardiac blocked (B) conditions. Cardiac autonomic blockade was produced by intravenous administration of atropine (0.04 mg/kg) and propranolol (0.2 mg/kg), while I was produced by 5 degrees head-down tilt (T) for 90 min and D by lower body negative pressure to -40 Torr. Increases in resting heart rate of 44% and diastolic blood pressure of 13% occurred after B, (P less than 0.05). During C, the alterations in preload produced mean changes in end-diastolic volume (EDV) ranging from 135 +/- 10 cm3 for I to 96 +/- 9.1 cm3 for D. Changes in stroke volume during condition C were significantly related to changes in EDV during preload alterations and conformed to a normal LV function curve and were described by SV = 0.6 EDV + 4.5 cm3 (r = 0.85; P less than 0.001). Similarly during B, SV = 0.43 EDV + 5.8 cm3 (r = 0.75; P less than 0.001). Comparison of the LV function curves produced during C and B showed that both slope of regression and r were significantly different (P less than 0.01). These data indicate that cardiac autonomic blockade produces a downward shift in the LV function curve indicating a depression in myocardial contractility. In addition, the data indicate that changes observed in LV function during wide variations in preload are independent of autonomic nervous system influences and are independent of the intrinsic heart rate.

Adult↗

PubMed1984

The role of the autonomic nervous system on sinus node function in patients with intermittent sinoatrial block.

Sinus node (SN) function was analyzed with and without autonomic blockade (AB) in 31 patients (mean age: 57.6 +/- 12.8) with intermittent sinoatrial block. Twenty-one patients had organic heart disease; in the remaining ten signs of underlying heart disease were not present. Nineteen patients had dizziness or syncope. Sinus cycle length, sinus rate, corrected sinus node recovery time (CSRT) and sinoatrial conduction time (SACT) were analyzed. After control measurements, AB was produced by i.v. propranolol (0.2 mg/Kg) and atropine (0.04 mg/Kg). Measurements of electrophysiological parameters were then repeated. After AB sinus rate and CSRT did not show statistically significant differences, whereas SACT decreased significantly (P less than 0.001). When intrinsic heart rate (IHR) was abnormal (11 cases), intrinsic CSRT was always abnormal, whereas when IHR was normal, intrinsic CSRT was normal in 11 patients and abnormal in nine. In several cases, when sinus rate increased after AB, CSRT decreased and vice-versa. The parameters of intrinsic SN function were normal in 80% of patients with a normal heart and only in 14.2% of patients with organic heart disease. These data indicate that: (1) during the control period SACT is mainly conditioned by the vagal tone; (2) abnormalities in control CSRT are not uniformly abolished after AB in patients with normal IHR; (3) AB has a differential effect on the two variables of SN automaticity; i.e. sinus rate and CSRT; and (4) in patients without underlying heart disease, the SN dysfunction is almost exclusively related to alterations of the autonomic nervous system.

Adult↗

PubMed1992

Afferent control of vasopressin and renin release during haemorrhage in normal and autonomically blocked rabbits.

1. The role of the arterial and cardiac baroreceptors on the arginine vasopressin (AVP) and plasma renin activity (PRA) responses to haemorrhage was studied in conscious rabbits. They were bled at a rate of approximately 3% of their blood volume (BV)/min, both when the autonomic nervous system (ANS) was intact and during ANS blockade, which markedly enhances the AVP response due to the much greater haemodynamic disturbance. Under each condition of ANS function 2 x 2 factorial analysis was performed, each with four groups of rabbits, including animals with both sets of baroreceptors working, one or other set working and neither set working. 2. With intact ANS, haemorrhage had to be terminated at different times in the four groups. This presents problems for factorial analysis due to differences in the relationship between plasma AVP (or PRA) and release rate. A method for overcoming this was developed by extrapolating the BV-log AVP curves to a common time from the start of bleeding. 3. Under both conditions of ANS function the arterial and cardiac baroreceptors together accounted for 90-95% of the rise in AVP during haemorrhage. With normal ANS function, the rise in AVP was about 70% through cardiac (probably ventricular) baroreceptors (P = 0.01) and about 30% through arterial baroreceptors (P = 0.08). This compares with an earlier study at a rate of bleeding of 1.8% BV/min, where the entire drive came from the cardiac receptors. During ANS blockade, plasma AVP was enhanced approximately five-fold, which was mostly mediated through the arterial baroreceptors, but the cardiac baroreceptor component was also greater; arterial/cardiac baroreceptor drive was 2/1. 4. Baroreflexes played no role in renin release during haemorrhage, but the experiments with ANS blockade suggest that a hormonal factor, which was related to the cardiac innervation, may limit the rise in PRA in the latter part of haemorrhage.

Afferent Pathways↗

PubMed2000

Relationship between cortical electrical and cardiac autonomic activities in the awake lizard, Gallotia galloti.

ECG and EEG signals were simultaneously recorded in lizards, Gallotia galloti, both in control conditions and under autonomic nervous system (ANS) blockade, in order to evaluate possible relationships between the ANS control of heart rate and the integrated central nervous system activity in reptiles. The ANS blockers used were prazosin, propranolol, and atropine. Time-domain summary statistics were derived from the series of consecutive R-R intervals (RRI) of the ECG to measure beat-to-beat heart rate variability (HRV), and spectral analysis techniques were applied to the EEG activity to assess its frequency content. Both prazosin and atropine did not alter the power spectral density (PSD) of the EEG low frequency (LF: 0.5-7.5 Hz) and high frequency (HF: 7.6-30 Hz) bands, whereas propranolol decreased the PSD in these bands. These findings suggest that central beta-adrenergic receptor mechanisms could mediate the reptilian waking EEG activity without taking part any alpha(1)-adrenergic and/or cholinergic receptor systems. In 55% of the lizards in control conditions, and in approximately 43% of the lizards under prazosin and atropine, a negative correlation between the coefficient of variation of the series of RRI value (CV(RRI)) and the mean power frequency (MPF) of the EEG spectra was found, but not under propranolol. Consequently, the lizards' HRV-EEG-activity relationship appears to be independent of alpha(1)-adrenergic and cholinergic receptor systems and mediated by beta-adrenergic receptor mechanisms.

Animals↗

PubMed2002

Pathways of anesthetic from the thoracic paravertebral region to the celiac ganglion.

Communication between the lower thoracic paravertebral region and the celiac ganglion through the retrocrural space was investigated. After dye was injected into the endothoracic fascia in the lower thoracic paravertebral region at the T11 level, its spread to the celiac ganglion was examined in fifteen cadavers. The dye reached the celiac ganglion in nine cadavers (60%) by passing through the retrocrural space, along the greater and lesser splanchnic nerves and through the split in the crus of the diaphragm through which the splanchnic nerves traveled. In the remaining six cadavers, dye spread toward the ganglion along the crus of the diaphragm. In three living subjects the spread of a radio-opaque dye injected in the same manner was studied using 3D-computed tomography. This study confirmed that the radio-opaque dye traveled toward the celiac ganglion along the crus of the diaphragm. From our results we suggest that a fluid communication may exist between the lower thoracic paravertebral region and the celiac ganglion in cadavers and in living humans and that clinicians should be aware of this possible route of spread when administering lower thoracic paravertebral anesthesia.

Adult↗

PubMed1996

Intravenous instrumentation alters the autonomic state in humans.

Intravascular instrumentation may induce syncope or presyncope. It is not known whether asymptomatic subjects also have autonomic reactions, albeit concealed. We addressed this issue by studying 44 healthy young male subjects of various levels of fitness, ranging from inactivity to athletic [mean maximal oxygen uptake was 49.1 (SD 10.7) ml*kg(-1)*min(-1), range 28.7-71.9 ml*kg(-1)*min(-1)]. The autonomic response to venous cannulation was quantified by measuring heart rate before cannulation (HR(1)), after cannulation (HR(2)), and after complete pharmacological autonomic blockade (HR(0) = the intrinsic heart rate). The sympathovagal balance before and after cannulation was computed as HR(1)/HR(0) and HR(2)/HR(0), respectively. The group means of heart rate and sympathovagal balance decreased significantly (paired Student's t-test P <0.01) from 62.5 to 59.9 beats*min(-1), and from 0.71 to 0.68, respectively. The maximal decrease in heart rate was 8.8 beats*min(-1), and in the sympathovagal balance was 0.11. Our study demonstrated that the asymptomatic subjects responded to intravenous instrumentation with a concealed autonomic reaction. Thus, from our findings it would seem that intravenous instrumentation interferes with measurements relating to autonomic nervous system activity.

Adult↗

PubMed1980

A study of profound hypothermia by surface cooling.

Profound hypothermia below 20 degrees C achieved by surface cooling using simple ice water bath equipment and deep ether anaesthesia is used with the aid of autonomic nerve blocking agents to obtain cardiac arrest for periods of over one hour for open-heart surgery. Blood levels of ether were between 40.6 mg/dl and 285.7 mg/dl during anaesthesia. No arrhythmia occurred and vital signs were quite stable. Hypocarbia throughout the procedure, severe base deficit after circulatory arrest, spontaneous recovery of metabolic acidosis, and a nearly normal cH+ (pH) were observed. Catecholamine increased moderately after circulatory arrest, but was far below shock levels. Plasma renin activity was markedly elevated but angiotensin II stayed at non-significant levels throughout the procedure. Excess lactate showed no significant change. Hyperglycaemia was noted. The mortality rate was 7.7 per cent and neurological disorders occurred in less than 5.8 per cent of the recent 52 cases.

Acid-Base Equilibrium↗

PubMed1999

Suppressive mechanism of gastric motility by whole-body vibration.

OBJECTIVE: To investigate the mechanism of gastric motility suppression by exposure to whole-body vibration (WBV). METHODS: The gastric motility was evaluated by electrogastrography (EGG) under food intake and autonomic nerve blocking agents in ten healthy volunteers. Sinusoidal vertical vibration with a frequency of 4 Hz (1.0 ms(-2) rms) was given to the subject for 10 min. RESULTS: The amplitude of EGG wave and the power spectrum corresponding to the slow wave component was remarkably decreased by vibration exposure. Food intake enhanced the gastric motility about 2.5-fold in the power spectral density. During and after vibration exposure, the response mode was similar to those at fasting states. Under the influence of anticholinergic (scopolamine) and alpha-adrenergic blocking agents (prazosin), the power spectra were decreased. A further decrease was observed during vibration exposure. A beta-adrenergic blocking agent (propranolol) led to a marked increase in the amplitude of EGG and its power spectrum. With pretreatment by a beta-adrenergic blocking agent, however, vibration exposure reduced both of them. CONCLUSIONS: These results suggest that short-term exposure to WBV can suppress the gastric myoelectric activity, the responses on which may be mediating by neurohumoral effects as well as the mechanical effect of WBV.

Adrenergic Antagonists↗

PubMed1988

Assessment by autonomic blockade of age-related changes of the sinus node function and autonomic regulation in sick sinus syndrome.

Age-related changes of the sinus node (SN) function and the autonomic influence on the SN function were evaluated in 65 patients with sick sinus syndrome (range 14 to 84 years). Heart rate (HR), corrected SN recovery time and sinoatrial conduction time were measured before (basic) and after (intrinsic) autonomic blockade (propranolol 0.2 mg/kg plus atropine 0.04 mg/kg intravenously). Percent of autonomic chronotropies of the SN function were calculated by the following formulas: (1)--(intrinsic HR--basic HR/intrinsic HR) X 100; (2) (intrinsic corrected SN recovery time--basic corrected SN recovery time/intrinsic corrected SN recovery time) X 100; (3) (intrinsic sinoatrial conduction time--basic sinoatrial conduction time/intrinsic sinoatrial conduction time) X 100. Basic HR, basic corrected SN recovery time and basic sinoatrial conduction time did not vary with age. Intrinsic HR decreased with age, but this correlation was weak (r = -0.54, p less than 0.001). Intrinsic corrected SN recovery time and intrinsic sinoatrial conduction time tended to increase with age (r = 0.26, p less than 0.05; r = 0.29, p less than 0.05, respectively). Percent chronotropies of HR, corrected SN recovery time and sinoatrial conduction time were negative values in younger patients and positive values in elderly patients; they correlated positively with age (r = 0.59, p less than 0.001; r = 0.60, p less than 0.001; r = 0.43, p less than 0.001, respectively). Thus, the basic SN function did not change with age, while the intrinsic SN function deteriorated with age.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗