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Results for “cardiac autonomic function”

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At least 289 records · Page 16Linked to original sources
PubMed2004

Abnormalities of neurohormonal and cardiac autonomic nervous activities relate poorly to functional status in fontan patients.

BACKGROUND: Impaired cardiac autonomic nervous activities and increased neurohumoral activities (CANA, NHA) characterize Fontan patients. However, the clinical significance of these changes is not clearly understood. Our purpose was to clarify the clinical significance of the CANA and NHA in stable Fontan patients. METHODS AND RESULTS: We divided 22 atriopulmonary connection (APC) and 75 total cavopulmonary connection (TCPC) patients into 4 subgroups according to New York Heart Association (NYHA) class (1.8+/-0.6) and measured various CANA and NHA indices. All NHA indices were elevated in the symptomatic patients (P<0.001). Natriuretic peptides were higher in the APC than in the TCPC patients, and the hemodynamics showed no correlation with brain natriuretic peptide in the APC patients. Low arterial oxygen saturation and impaired hemodynamics greatly influenced all elevated NHA indices (P<0.01), except for plasma renin activity, in the TCPC patients. Impaired CANA indices did not relate to NYHA class, although surgeries were associated with lower heart rate variability. In addition to poor correlation between NHA and CANA, age and ventricular morphology had no impact on all CANA and NHA indices, except for high norepinephrine in right ventricular Fontan patients. CONCLUSIONS: Although symptomatic Fontan patients exhibit higher NHA, CANA is not related to either NYHA class or NHA. APC itself is responsible for higher natriuretic peptides, and arterial oxygen desaturation has a great impact on elevated NHA in the TCPC patients. These characteristics of the NHA and CANA differ from those of heart failure patients with biventricular physiology.

Adolescent↗
PubMed2003

Pulmonary function, cholinergic bronchomotor tone, and cardiac autonomic abnormalities in type 2 diabetic patients.

This prospective study analyzed the involvement of the autonomic nervous system in pulmonary and cardiac function by evaluating cardiovascular reflex and its correlation with pulmonary function abnormalities of type 2 diabetic patients. Diabetic patients (N = 17) and healthy subjects (N = 17) were evaluated by 1) pulmonary function tests including spirometry, He-dilution method, N2 washout test, and specific airway conductance (SGaw) determined by plethysmography before and after aerosol administration of atropine sulfate, and 2) autonomic cardiovascular activity by the passive tilting test and the magnitude of respiratory sinus arrhythmia (RSA). Basal heart rate was higher in the diabetic group (87.8 +/- 11.2 bpm; mean +/- SD) than in the control group (72.9 +/- 7.8 bpm, P<0.05). The increase of heart rate at 5 s of tilting was 11.8 +/- 6.5 bpm in diabetic patients and 17.6 +/- 6.2 bpm in the control group (P<0.05). Systemic arterial pressure and RSA analysis did not reveal significant differences between groups. Diabetes intragroup analysis revealed two behaviors: 10 patients with close to normal findings and 7 with significant abnormalities in terms of RSA, with the latter subgroup presenting one or more abnormalities in other tests and clear evidence of cardiovascular autonomic dysfunction. End-expiratory flows were significantly lower in diabetic patients than in the control group (P<0.05). Pulmonary function tests before and after atropine administration demonstrated comparable responses by both groups. Type 2 diabetic patients have cardiac autonomic dysfunction that is not associated with bronchomotor tone alterations, probably reflecting a less severe impairment than that of type 1 diabetes mellitus. Yet, a reduction of end-expiratory flow was detected.

Adult↗
PubMed1997

Autonomic neural control of cardiac function: modulation by adenosine and adenosine 5'-triphosphate.

Adenosine and adenosine 5'-triphosphate (ATP) are found in every cell of the human body. These molecules are released from cells into the extracellular fluid under physiologic and pathophysiologic conditions. Outside of cells, adenosine and ATP act as physiologic regulators of cells, tissues, and organs. In the heart, extracellular adenosine and ATP exert pronounced inotropic, lusitropic, electrophysiologic, and metabolic effects, which are mediated by specific cell surface receptors. In addition, both compounds can modulate sympathetic and parasympathetic input to the heart by interacting with neural elements within and without the heart, thereby modulating autonomic neural control of cardiac functions. This article briefly reviews these indirect, neurally-mediated actions of adenosine and ATP.

Adenosine↗
PubMedDate not supplied

Relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy in patients with non-insulin-dependent diabetes mellitus.

The relationship between cardiac autonomic neuropathy and diabetic microangiopathies and macroangiopathy was investigated in 103 patients with non-insulin-dependent diabetes mellitus. Cardiac autonomic nerve function was assessed by determining the uptake of [123I]metaiodobenzyl-guanidine into the myocardium. Cardioparasympathetic nerve function was assessed by comparing electrocardiographically the expiratory and inspiratory respiratory rate (RR) interval ratios, during a period of deep breathing, and the coefficients of variation of the RR intervals. Nerve conduction velocity measurements were used to assess diabetic somatic neuropathy, and measurement of pulse-wave velocity provided an indication of the extent of aortic sclerosis. The only correlations between the parameters of cardiac autonomic neuropathy and parameters of diabetic microangiopathies and macroangiopathy were between the expiratory to inspiratory RR interval ratio and both the conduction velocity of the tibial nerve and pulse-wave velocity, and between the heart to lung ratio (cardiac autonomic nerve function) and nephropathy. These correlations may have occurred by chance; alternatively they may indicate a difference in the onset mechanisms of cardiac parasympathetic and sympathetic neuropathies in diabetics.

Aged↗
PubMed1991

Autonomic control of cardiac chronotropic function in man as a function of age: assessment by power spectral analysis of heart rate variability.

The analysis of age-related features of the autonomic heart rate control during various periods of postnatal human ontogenesis is presented. The study was performed in 354 apparently healthy individuals of either sex, ranging in age from 3 months to 89 years. The method of spectral analysis of heart rate variability was used. We demonstrated different ratios between the sympathetic and the parasympathetic influences upon heart rate control in relation to age. In infancy and after 50 years, there is a prevalence of the sympathetic activity against a background of weak parasympathetic activity. In early years, the prevalence of the parasympathetic activity is observed at a sufficiently high sympathetic activity level.

Adolescent↗
PubMed1977

Functional autonomic innervation of mammalian cardiac pacemaker during the perinatal period.

Sinoatrial node pacemaker tissues from perinatal and adult rabbits, guinea pigs and rats were examined in vitro. Changes in spontaneous pacemaker rate produced by stimulation of intranodal vagal and sympathetic nerve endings, were taken as a measure of functional postganglionic innervation of the pacemaker. Results show marked species differences in the development of functional innervation of the cardiac pacemaker in the perinatal period.

Adrenergic Fibers↗
PubMed1990

The effect of aging on cardiac autonomic and postganglionic sudomotor function.

Little quantitative information is available on the effects of age on peripheral autonomic function. We studied the effect of age on the heart rate (HR) responses to deep breathing and the Valsalva maneuver in 122 and 155 subjects, respectively, aged 10 to 83 years. The quantitative sudomotor axon reflex test (QSART) was determined in 114 subjects in the same age group. The HR responses were not different between the sexes, but a consistently significant regression with age was demonstrated in response to deep breathing and the Valsalva ratio. The QSART responses were significantly larger in male subjects and were generally lower in older subjects of both sexes but a significant negative regression with age was found only in female subjects. Cardiac vagal function is impaired with age, but postganglionic sympathetic function is little affected by age, suggesting selectivity of effects of aging on autonomic function.

Adolescent↗
PubMed1976

Autonomic nervous system and arrhythmias: studies in the transplanted denervated human heart.

The function of the cardiac autonomic nervous system (ANS) was evaluated by comparison of normal subjects with cardiac transplant recipients. By use of standard intracardiac His bundle recording techniques, the following conclusions regarding basic cardiac electrophysiology were drawn: (1) the sinus node functions normally at rest despite autonomic denervation; (2) the AV node does not show the expected decrease in functional refractory period with increased heart rate in the denervated state, and (3) the adrenergic receptor of the cardiac conduction system does not depend upon autonomic innervation to function normally. Electrophysiologic studies of digitalis demonstrated: (1) in therapeutic doses, the AV nodal blocking effect of digitalis is autonomically mediated; (2) sinus node slowing by digitalis also requires an intact autonomic innervation. Arrhythmia analysis in 47 transplant patients revealed an increased incidence of ventricular arrhythmias in autonomic cardiac denervation. In addition, sudden death in the ischemic denervated heart does occur, weakening the concept of a primary role of the cardiac ANS in this phenomenon.

Arrhythmias, Cardiac↗
PubMed1987

Abnormal vagal function in irritable bowel syndrome.

Alimentary and cardiac autonomic nervous function was assessed in 25 patients with the irritable bowel syndrome. The vagally mediated increase in lower oesophageal sphincter pressure induced by abdominal compression was below that of 25 controls in 13 patients. Efferent vagal function, assessed by the ratio of peak acid output after insulin-induced hypoglycaemia to maximal acid output after pentagastrin, was subnormal in 7 of 23 patients. Pulse rate variability with deep respiration was subnormal in 6 of 23 patients. Abnormality in these tests did not correlate closely with the presence of oesophagitis at endoscopy or with that of gastro-oesophageal reflux on pH monitoring. Thus abnormalities in autonomic nervous reflexes might account for the frequent occurrence of gastro-oesophageal reflux and may be involved in the production of disordered gastrointestinal motility in irritable bowel syndrome.

Adult↗
PubMed1990

Relative effects of different spinal autonomic nuclei on cardiac sympathoexcitatory function.

Mean arterial pressure and heart rate were monitored in immobilized and artificially ventilated male Wistar rats either anesthetized with pentobarbital or decerebrated at midcollicular level. The rate of increase in the left ventricular pressure was also monitored in order to compute contractility index. L-glutamate (1.77 nmole) was microinjected (10 nl) into the following autonomic nuclei of the spinal cord at C8 to T4 levels: 1) intermediolateral column (IML), 2) n. intercalatus spinalis (IC) and 3) n. intercalatus pars paraependymalis (ICpe); this region is commonly known as the central autonomic area (CA). The site of microinjection was marked by injection of a dye; these studies suggested that microinjections of glutamate into the IML are likely to encompass the neurons in the nucleus (n.) intermediolateralis thoracolumbalis pars principalis (ILp) and n. intermediolateralis thoracolumbalis pars funicularis (ILf). Sympathoexcitatory cardiac responses to glutamate microinjections were elicited from T1 to T3 levels; these responses could not be evoked at C8 and T4 levels. In each of these segments, maximum responses were obtained from the IML while the responses evoked from the IC and the CA were minimal. These results suggest that at T1 to T3 levels of the spinal cord, IML is the main cell group regulating sympathetic cardiac function; CA and IC may play a relatively minor role in this function.

Adrenergic Fibers↗
PubMed1999

The Cox maze iii procedure: parallel normalization of sinus node dysfunction, improvement of atrial function, and recovery of the cardiac autonomic nervous system.

OBJECTIVE: The Cox maze III procedure includes isolation of the pulmonary veins and multiple incisions in both atria in what corresponds to partial autotransplantation and partial denervation of the heart. The aim of this prospective longitudinal study was to identify physiologic effects of reinnervation on changes in heart rate at rest and in response to various stimulations and on atrial function after the Cox maze III procedure. PATIENTS AND METHODS: Power spectral analysis of heart rate variability, exercise testing, 24-hour Holter monitoring, electrocardiography, and transthoracic and transesophageal echocardiography were performed in 30 adult patients after the combined Cox maze III procedure and mitral valve surgery (maze group). They were prospectively followed up at 1, 3, 6, and 12 months after the operation. The results were compared with those of 15 heart transplant recipients (transplant group) and normal probands (healthy adults, n = 12). RESULTS: The physiologic effects of denervation with no differences in cardiac autonomic activity between the groups were seen early after the operation. Later, evidence of autonomic reinnervation was observed only in the maze group but not in the transplant group. Inappropriate heart rate responses during physical exercise were clearly evident in both groups after 1 and 3 months, with progressive improvement seen between 6 and 12 months only in the maze group. Left atrial function after the Cox maze procedure improved parallel to the recovery of sinus node function. CONCLUSION: Progressive improvement of sinus node function and atrial contractions with significant functional normalization 1 year after the Cox maze procedure corresponded to functional reinnervation and recovery of the autonomic nervous system.

Adult↗
PubMedDate not supplied

Cardiac autonomic involvement and peripheral nerve function in patients with diabetic neuropathy.

The aim of our study was to investigate the relationship between cardiac autonomic neuropathy and dysfunction of myelinated and unmyelinated nerve fibres in the peripheral nerve. We measured nerve conduction velocities, warmth/cold perception thresholds at the foot dorsum, sympathetic skin response (SSR), and performed the quantitative sudomotor axon reflex test (QSART). Forty-three diabetic patients with distal-symmetric polyneuropathy were included. According to the results of heart rate variation, 20 patients had cardiac autonomic neuropathy (CAN+). Apart from motor nerve conduction velocities, all tests were more often abnormal in CAN+ patients. Warmth thresholds (afferent C-fibres) and reduced compound muscle action potentials (CMAPs) of the tibial and peroneal nerve, indicating axonal damage, were more often abnormal in CAN+. Cold threshold and sural nerve conduction velocity were indicators of involvement of myelinated small and large nerve fibres, but not of the cardiac autonomic system. Ninety-four percent (94%) of patients with absent SSR and 78% of patients with abnormal QSART had CAN+. SSR and QSART may be useful for assessment of autonomic neuropathy in diabetic patients with cardiac arrhythmia where direct measurement of heart rate variability is not possible. In the majority of our patients with CAN+, the vagal-cardiac and the sudomotor-sympathetic systems were involved simultaneously, although two entirely different systems were tested. This may reflect a C-fibre directed selectivity of the pathological process in autonomic diabetic neuropathy. In conclusion our results show that diabetics with and without cardiac autonomic neuropathy have a different profile of involvement of peripheral nerve fibres.

Adult↗
PubMed2006

Imaging cardiac neuronal function and dysfunction.

In recent years, the importance of alterations of cardiac autonomic nerve function in the pathophysiology of heart diseases including heart failure, arrhythmia, ische-mic heart disease, and diabetes has been increasingly recognized. Several radiolabeled compounds have been synthesized for noninvasive imaging, including single photon emission CT and positron emission tomography (PET). The catecholamine analogue I-123 metaiodobenzylguanidine (MIBG) is the most commonly used tracer for mapping of myocardial presynaptic sympathetic innervation on a broad clinical basis. In addition, radiolabeled catecholamines and catecholamine analogues are available for PET imaging, which allows absolute quantification and tracer kinetics modeling. Postsynaptic receptor PET imaging added new insights into mechanisms of heart disease. These advanced imaging techniques provide noninvasive, repeatable in vivo information of autonomic nerve function in the human heart and are promising for providing profound insights into molecular pathophysiology, monitoring of treatment, and determination of individual outcome.

Arrhythmias, Cardiac↗
PubMed1978

Influence of digitalis on cardiac function before and after autonomic blockade.

The influence of Deslanoside C (D), 1.2 mg intravenously on the systolic time intervals (STI) was assessed in 15 individuals with right ventricular pacemakers, who were studied on two occasions, ten days apart. In the first case D was given under basal conditions, and in the second after autonomic blockade (with practolol 20 mg intravenously and atropine 1.5 and 1.0 mg intravenously) at 1 hour's interval. There were similar changes of the STI with digitalis administration both before and after automic blockade. Autonomic blockade is not necessary for full expression of digitalis action on the human heart, as advocated by some authors to be the case in experimental animals.

Adult↗
PubMed2004

Effects of spironolactone on endothelial function, vascular angiotensin converting enzyme activity, and other prognostic markers in patients with mild heart failure already taking optimal treatment.

OBJECTIVES: To examine whether the favourable effects on endothelial function, vascular angiotensin converting enzyme (ACE) activity, cardiac remodelling, autonomic function, and QT intervals of spironolactone in combination with ACE inhibitor also occur in patients with New York Heart Association class I-II congestive heart failure (CHF) taking optimal treatment (including beta blockers). METHODS: Double blind, crossover study comparing 12.5-50 mg/24 hours spironolactone (three months) with placebo in 43 patients with class I-II CHF taking ACE inhibitors and beta blockers. RESULTS: Acetylcholine induced vasodilatation improved with spironolactone (p = 0.044). Vascular ACE activity fell (p = 0.006). QTc and QTd fell (mean (SD) QTc 473 (43.1) ms with placebo, 455 (35.4) ms with spironolactone, p = 0.002; QTd 84.5 (41.3) ms with placebo, 72.1 (32.3) ms with spironolactone, p = 0.037). beta-Type natriuretic peptide (BNP) and procollagen III N-terminal peptide (PIIINP) concentrations were also reduced by spironolactone (mean (SD) BNP 48.5 (29.6) pg/ml with placebo, 36.8 (28.5) pg/ml with spironolactone, p = 0.039; PIIINP 3.767 (1.157) microg/ml with placebo, 3.156 (1.123) microg/ml with spironolactone, p = 0.000). CONCLUSIONS: Spironolactone improves vascular function (endothelial function, vascular ACE activity) and other markers of prognosis (BNP, collagen markers, and QT interval length) in asymptomatic or mild CHF when added to optimal treatment including beta blockade. This gives support to the hypothesis that the prognostic benefit seen in RALES (randomised aldactone evaluation study) and EPHESUS (eplerenone postacute myocardial infarction heart failure efficacy and survival study) may also occur in patients with milder CHF already taking standard optimal treatment.

Adrenergic beta-Antagonists↗
PubMed1988

Long-term effects of parathyroidectomy on cardiac and autonomic nervous system functions in haemodialysis patients.

Ten patients receiving regular haemodialysis therapy who underwent parathyroidectomy for secondary hyperparathyroidism were investigated to evaluate the effects of parathyroid hormone on left ventricular and autonomic nervous system functions. The study which included M-mode echocardiography and autonomic nervous system tests (hormonal and cardiovascular response to the postural test, cold pressor test, handgrip test, diving reflex test and Valsalva manoeuvre) were performed prior to parathyroidectomy, and 5-8 months after, on a nondialysis day. The cardiovascular response and plasma noradrenaline changes to postural test remained unchanged following parathyroidectomy. The resting heart rate decreased from 73.1 +/- 2.4 to 66.4 +/- 2.3 beats/min (P less than 0.05) but mean blood pressure did not change post-parathyroidectomy. Mean blood pressure and heart rate changes during the cold pressor test, handgrip test, diving test and Valsalva manoeuvre were unaffected by parathyroidectomy. End-diastolic and end-systolic dimensions, fractional fibre shortening, mean velocity of fibre shortening and the ratio of the pre-ejection period to the left ventricular ejection time were normal prior to parathyroidectomy and remained unchanged following it. This study suggests that the reduction in parathyroid hormone concentrations obtained by parathyroidectomy does not significantly modify heart function and autonomic nervous system activity in the long term.

Adult↗
PubMed2004

Cardiac autonomic activity in obstructive sleep apnea: time-dependent and spectral analysis of heart rate variability using 24-hour Holter electrocardiograms.

To analyze the function of cardiac autonomic regulation in patients with obstructive sleep apnea syndrome (OSAS), we enrolled 36 patients with OSAS and divided them according to the apnea hypopnea index (AHI) into 2 groups: Group I (n=19) had mild OSAS (AHI < 20) and Group II (n=17) had severe OSAS (AHI > or = 20). The findings were compared with those of 24 healthy control subjects who were matched for age, sex, blood pressure, and body mass index. All participants underwent 24-hour Holter monitoring, with continuous time-dependent and spectral analysis of heart rate variability. In addition, we performed arrhythmia analysis. Frequent or repetitive ventricular arrhythmias (> or = 30 premature ventricular beats/hour) were detected in 15 (42%) patients with OSAS and in 6 (25%) members of the control group. In both mild and severe OSAS, SDNN was significantly lower than in controls, and SDANN findings were similar. In mild OSAS, RMSSD values were not significantly lower than in controls, but in severe OSAS they were. The ULF, VLF, LF and LF/HF values of both groups of OSAS patients were significantly higher than those of controls, but their HF values were lower. The mean LF/HF ratio during the same period was significantly higher in Group II than in Group I and the control group. Our results suggest that cardiac autonomic activity may be altered in patients with OSAS throughout a 24-hour period, that this alteration occurs even in the absence of hypertension, heart failure, or other disease states, and that it is linked to the severity of OSAS.

Adult↗