Autonomic Nervous System Testing Research Articles

Relationship between autonomic nervous system test results, ejection fraction and inducibility of sustained ventricular arrhythmias by means of electrophysiological studies.

Autonomic nervous system dysfunction and low left ventricular ejection fraction have been associated with an increased incidence of cardiac arrhythmias and sudden death. This research was conducted to determine whether Valsalva ratio (longest to shortest R-R interval during Valsalva manoeuvre), R-R variability (standard deviation of R-R intervals in a 60-second electrocardiographic recording strip), and corrected QT interval permit the identification of those patients with an inducible sustained ventricular arrhythmia when submitted to electrophysiological studies. We also evaluated the ejection fraction as a predictive index of inducibility. We studied 42 patients (21 males), 38 +/- 19 years old, who were submitted to an electrophysiological study in order to evaluate supraventricular (control group: n = 16) or ventricular arrhythmias (n = 26). The patients studied for the evaluation of ventricular arrhythmias presented structural and functional cardiac damage. Their ejection fraction (0.41 +/- 0.17) was significantly reduced (p = 0.01) when compared to that of the control group (0.61 +/- 0.08). The patients with cardiac damage had abnormal autonomic nervous system test results. None of the measurements was significantly related to the inducibility of sustained ventricular tachyarrhythmias in the group of patients who had structural and functional involvement. The finding of abnormal cardiac autonomic nervous system indices and low ejection fraction can be related to structural heart disease, but neither the abnormal cardiac autonomic nervous system indices nor the low ejection fraction allows us to identify the patients who will develop inducible sustained ventricular tachyarrhythmias when submitted to electrophysiological study.

Autonomic Nervous System Disorders and Reflex Sympathetic Dystrophy in Lightning and Electrical Injuries

Both lightning and electrical injuries can cause autonomic nervous system (ANS) symptoms and signs (Table 1). Published descriptions of ANS involvement occurring with lightning and electrical injuries are rare. The most often reported neurologic complications of lightning injuries involve the central nervous system. ANS abnormalities have been documented with lightning, although the descriptions are scant. There is a lack of complete clinical information or ANS testing data in these cases. This is usually a result of the transient nature of ANS complications. In electrical injuries, ANS involvement is less well described than for lightning. Electrical injuries can be associated with peripheral nerve damage. As a result of peripheral nerve damage, reflex sympathetic dystrophy (RSD) may occur in patients with electrical injuries. Various treatment strategies for RSD associated with electrical injuries are found in single case reports. This article summarizes ANS involvement, predominantly in lightning injuries, and describes RSD and its treatment, predominantly in electrical injuries.

Effect of autonomic nervous system dysfunction on the circadian pattern of myocardial ischemia in diabetes mellitus

Objectives. The aim of this study was to determine the prevalence and characteristics of ambulatory myocardial ischemia in patients with diabetes mellitus and to delineate the relation between the presence and severity of autonomic nervous system dysfunction and the incidence and time of onset of myocardial ischemia.Background. Conflicting data exist with regard to the circadian pattern of myocardial infarction and other cardiovascular events, such as ambulatory ischemia, in diabetes.Methods. We performed ambulatory electrocardiographic monitoring in 60 patients with diabetes and coronary artery disease. Autonomic nervous system testing was performed in a subgroup of 25 patients with myocardial ischemia after discontinuation of all antianginal medications.Results. Thirty-eight of 60 patients had evidence of ambulatory ischemia; 91% of all ischemic episodes were asymptomatic. The 25 patients with ambulatory ischemia who underwent autonomic nervous system testing had a peak incidence of ischemia between 6 amand noon (46 of 133 ischemic episodes, p < 0.007), compared with the other three 6-h periods. Fifteen of the 25 patients had no or mild autonomic nervous system dysfunction and demonstrated a similar peak incidence of ischemia between 6 amand noon (p = 0.0009). However, the 10 patients with moderate to severe autonomic nervous system dysfunction did not experience a morning peak of ischemia, and the number of ischemic episodes was distributed evenly throughout the day (p = 0.4).Conclusions. Silent ischemia is highly prevalent among patients with diabetes and coronary artery disease. Time of onset of ischemia in diabetic patients follows a circadian distribution, with a peak incidence in the morning hours. However, patients with significant autonomic nervous system dysfunction did not demonstrate such a peak, suggesting that alterations in sympathovagal balance may have an effect on the circadian pattern of cardiovascular events.

Knowledge Maps and Spatial-Verbal Processing: A Temporal Analysis

The present experiment served as an initial empirical investigation of the spatial-verbal processing model of Dansereau and colleagues. The model was developed as a framework for elucidating the processes associated with the acquisition of information from spatial text displays (e.g., knowledge maps). The assumptions of the model lead to the contention that main ideas (processed mainly through spatial channels) act to cross-cue details (processed mainly through verbal channels). Moreover, this main idea-detail relationship can be expected to differ as a function of the temporal nature of acquisition (i.e., initial comprehension, encoding/storage, and recall/utilization). Participants in the present experiment were divided into two experimental groups, map and text. Both groups studied a passage of information over the autonomic nervous system and completed recall tests after a 5-min. overview, after studying for 30 min., and two days after the completion of studying. Those in the map group studied the information in the form of knowledge maps, while those in the text group studied traditional text. Recall results indicated that retention of details did not decay from initial to delayed recall, while the retention of main ideas did. Further, the main idea-detail relationship was mediated by the temporal nature of recall and experimental group. Main ideas and details were strongly related initially but not on subsequent recall for the map group, while just the opposite was the case for the text group.

Autonomic Stress Tests in Obstructive Sleep Apnea Syndrome and Snoring

Apneic events in the obstructive sleep apnea syndrome (OSAS) are associated with cardiovascular responses mediated through the autonomic nervous system. We examined autonomic cardiovascular responses in 33 patients (median age = 50 years, range = 20-72 years) undergoing polysomnography for suspected OSAS. We examined these responses in the evening and at arousal in the morning. Tests consisted of heart rate responses to Valsalva maneuver, deep breathing and change from lying down to standing. In addition, systolic blood pressure (BP) response to standing and diastolic BP response to handgrip were studied. Each abnormal test scored +1 and each marginal result +0.5. Autonomic nervous system (ANS) test results were scored as abnormal if a subject had a score > 1 which included at least one abnormal test. The total scores for evening and morning tests combined showed 11/24 sets of scores > 1 in 12 severe OSAS patients [median RDI (apnea+hypopnea per hour slept) = 44 (range = 31-74)] compared to 3/22 in non-OSAS (p = 0.04). The response to deep breathing, expressed as an expiratory to inspiratory ratio (E/I), was the test most often found abnormal. A significant difference between normal abnormal autonomic stress test (AST) groups was observed in the evening and the morning as regards cumulative time spent under 90% SaO2 and minimal SaO2. We conclude that abnormal autonomic stress responses are common in OSAS and are probably a secondary defect.

Cardiovascular Evaluation After Withdrawal from Chronic Alcohol or Cocaine-Alcohol Abuse

Alcohol ingestion commonly accompanies cocaine abuse, but the effects of chronic cocaine-alcohol abuse on the circulation are undefined. Therefore, to test for evidence of cocaine-alcohol cardiac dysfunction and interference with cardiovascular nervous system reflexes, 10 normal volunteers (group I), 8 asymptomatic alcoholic patients (group II), and 15 age matched, asymptomatic cocaine and alcohol abusers (group III) underwent screening two-dimensional echocardiography, electrocardiography, a series of autonomic nervous system tests, and upright bicycle exercises. Echocardiographic indices did not differ among groups. R wave voltage was increased in group III, probably primarily due to a smaller body surface area. Heart rate (HR) and/or systolic blood pressure (SBP) responses to 60 degree tilt and to hyperventilation differed in group III (decreased HR response, while SBP increased inappropriately). Despite excellent exercise tolerance, HR response to exercise in group III (compared to group I) was decreased. These results suggest impairment of certain autonomic nervous system reflexes and, possibly, sinus node dysfunction from cocaine-alcohol abuse.

Cardiovascular Autonomic Dysfunction: Diagnosis and Prognosis

The symptoms of cardiovascular autonomic dysfunction may be subtle and occur late in the course of diabetes. They include abnormal exercise-induced cardiovascular performance, postural hypotension, and cardiac denervation syndrome. Autonomic nervous system testing involves an evaluation of the responses of complex reflex pathways. Some of the most commonly used and validated cardiovascular autonomic tests are RR-variation, the Valsalva manoeuvre, and postural testing. Sinus arrhythmia during breathing is termed RR-variation. In diabetic patients with autonomic neuropathy the magnitude of the RR-variation is decreased. Abnormal exercise-induced cardiovascular performance has been observed in diabetic subjects with abnormal RR-variation due to autonomic neuropathy. The Valsalva manoeuvre consists of forced expiration against a standardized resistance for a specified period of time. The reflex bradycardia that follows the Valsalva period in normal subjects is lacking in diabetic patients with clinical evidence of autonomic neuropathy. Postural hypotension in diabetics may be due to neuropathy or to a variety of secondary causes. An algorithm is presented to facilitate assessment of diabetic patients with postural symptoms. Treatment of postural hypotension should be directed primarily to the correction of secondary causes, in the absence of which the symptoms can be controlled by mechanical measures, plasma volume expansion, and vasoconstriction. Cardiac denervation syndrome may result in denervation supersensitivity and afferent (pain) nerve dysfunction. The RR-variation is a sensitive indicator of impairment of cardiac autonomic innervation and is a simple method for identifying asymptomatic patients at risk for painless ischaemia. Formal cardiovascular stress testing may be prudent before initiating an exercise programme in such individuals.

Chagas' cardioneuropathy: Effect of ganglioside treatment in chronic dysautonomic patients—A randomized, double-blind, parallel, placebo-controlled study

To date, there is no effective pharmacologic treatment for Chagas' cardioneuropathy, one of the most common causes of congestive heart failure and sudden death in the world. Fifty-eight adults with positive serology for Chagas' disease and abnormal autonomic nervous system tests participated in this placebo-controlled clinical trial with Cronassial (mixed gangliosides), 40 mg daily intramuscular injection for 4 or 8 weeks. We measured postural response (heart rate, systolic and diastolic arterial blood pressure changes in response to standing); heart rate changes induced by cough and hyperventilation reflex tests; dizziness on standing; number of stress-induced arrhythmias; and periodic acid-Schiff (PAS)-positive T-lymphocyte percentage in blood samples. Cronassial is safe and significantly improves systolic blood pressure ( p = 0.050) and double product responses to postural stress ( p = 0.028), hyperventilation heart rate response ( p = 0.007), frequency of dizziness episodes ( p < 0.001), number of arrhythmias ( p = 0.033), and percentage of PAS-positive T-lymphocyte counts ( p < 0.001) compared with placebo.

Autonomic nervous system tests depend on resting heart rate and blood pressure

In order to study the effects of baseline blood pressure and heart frequency on autonomic function tests, 75 normal subjects (aged 8–96 years) were investigated. Heart rate variability was studied at rest, during deep breathing, following standing up and during a Valsalva manoeuvre. Blood pressure changes were recorded during standing up and during sustained handgrip. Responses were described as ratios and as differences to study the efficacy of both methods. Multiple regression analysis showed that significant relationships with the resting heart rate existed for ratios but not for differences. The blood pressure rise in the sustained handgrip test showed a significant relationship with resting blood pressure when the results were expressed as ratios, and the response to standing up was significantly related to the resting blood pressure regardless of the description method. As expected, relationships with age existed for all four heart rate tests regardless of the description method. The blood pressure responses were not significantly related to age. We advise that heart rate test results should be presented as differences, as this avoids the need for correction for the resting heart rate. Correction for the resting blood pressure improves the accuracy of the standing up blood pressure test. Correction for age remains necessary for heart rate tests but not for blood pressure tests.

Orthostatic Hypotension in Human Immunodeficiency Virus Infection May Be the Result of Generalized Autonomic Nervous System Dysfunction

We used an autonomic nervous system (ANS) testing battery to determine if generalized ANS dysfunction was present in five human immunodeficiency virus-positive (HIV+) patients presenting with severe orthostatic hypotension (OH). All five patients had abnormal ANS testing, which demonstrated both sympathetic and parasympathetic defects, i.e., generalized ANS dysfunction. Treatment with fludrocortisone effectively reversed the OH in four of the five patients. The OH was transient in these four patients. We believe it is important to recognize that OH may be the result of generalized ANS dysfunction in HIV-positive patients and that it can be effectively treated.

Multiple Sclerosis Patients with Fatigue: Relationship Among Temperature Regulation, Autonomic Dysfunction, and Exercise Capacity

Sixteen well-characterized MS patients with a prominent complaint of fatigue underwent exercise testing, with temperature monitoring, and autonomic nervous system (ANS) testing. It was postulated t...

Diabetic autonomic neuropathy—Part II: Coefficient of variation of RR-variation and valsalva maneuver tests

To confirm the reliability and validity of cardiovascular autonomic nervous system tests, RR-variation and Valsalva maneuver, coefficient of variation for triplicate tests was calculated. The testing data were collected from patients participating in the Statil Neuropathy Trial. Triplicate testing was done within a three-week period at three different time points: baseline, 12 months, and 18 months. BMDP Statistical Software was used in the analysis. There is no significant difference between the coefficients of variation between clinics for either RR-variation or Valsalva maneuver tests. The coefficient of variation of pooled data was not significantly different from the coefficient of variation of individual clinics. Furthermore, there was no evidence that there was a significant worsening of coefficient of variation with time. Thus, RR-variation and Valsalva maneuver provide reliable and reproducible results that do not vary in consistency over time.

Diabetic autonomic neuropathy—part I: Autonomic nervous system data analysis by a computerized central unit in a multicenter trial

To determine the feasibility of utilizing a central, computerized unit to analyze autonomic nervous system function tests for a 10-year, multicenter, clinical trial, the Autonomic Nervous System Reading Center was established. The Reading Center selected and standardized testing methods, designed the testing protocol, developed testing equipment, computerized data analysis, and instituted measures to monitor data quality. Three cardiovascular testing methods, RR-variation, Valsalva maneuver, and postural testing, were selected because each is a simple, non-invasive, quantitative, sensitive, and reproducible test. Furthermore, a hierarchy of sensitivity has been established with these cardiovascular autonomic nervous system measurements: RR-variation, Valsalva maneuver, and finally postural testing. Confounding variables were minimized by prescribing eligibility criteria. Testing equipment, designed to record time between RR intervals in a form easily read into a computer, has been in 21 clinics for three years and a total of 54 technicians have been trained. Over 85 percent of the autonomic nervous system tests performed have been usable at initial testing. A central reading center is an efficient and necessary means of collecting and analyzing data for a multicenter clinical trial.

The Usefulness of Head‐Up Tilt Testing and Hemodynamic Investigations in the Workup of Syncope of Unknown Origin

To enhance the clinical evaluation of patients suffering from recurrent syncope of unknown origin, the integrity of mechanisms controlling blood pressure was examined in 151 patients utilizing a screening tilt test. Ninety-eight patients had an abnormal blood pressure and/or heart rate response to tilt testing, including provoked syncopal attacks in 63 patients. Whenever indicated, the screening tilt test was followed by blood volume and hemodynamic determinations, as well as autonomic nervous system testing to identify contributing pathophysiological abnormalities (hypovolemia, venous pooling, autonomic dysfunction). Detailed analysis of this battery of tests allowed us to conclude that: (1) The tilt test is commonly a provocative tool in the workup of patients with recurrent syncope due to vasovagal - vasodepressor reactions and other abnormalities of blood pressure regulation; (2) Its usefulness is augmented by associated hemodynamic and blood volume evaluations; (3) The identification of contributory pathophysiological mechanisms of blood pressure control facilitates specific therapeutic interventions.

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.

Correlations among autonomic, sensory, and motor neural function tests in untreated non-insulin-dependent diabetic individuals.

A well-defined group of untreated non-insulin-dependent (NIDD) subjects were evaluated to determine whether involvement of neural function measurements is generalized and symmetrical and to compare the autonomic, sensory, and motor neural measurements. After age adjustment, the sensory and motor neural function measurements were significantly slower in the diabetic group than in normal subjects (P less than 0.01). Similarly, the autonomic nervous system function measurements were also abnormal in the NIDD group (P less than 0.01). Further analysis revealed that each of the specific measurements--median motor nerve conduction velocity (NCV,P less than 0.005), peroneal motor NCV (P less than 0.005), median sensory NCV (P less than 0.005), dark-adapted pupil size after muscarinic blockade (P less than 0.02), pupillary latency time (P less than 0.02), and RR-variation after beta adrenergic blockade (P less than 0.001)--was significantly less by analysis of covariance after age adjustment in the NIDD group than in normal subjects. Thus, there was evidence of motor and sensory neural impairment in the upper and lower extremities as well as evidence of impairment of the reflex arcs involving the parasympathetic nerves to the heart and eye and the sympathetic nerves to the iris. Further analysis revealed that right and left NCV were correlated (P less than 0.01), as were the median motor and median sensory NCV (P less than 0.01), the median motor and peroneal motor NCV (P less than 0.001), and the peroneal motor and median sensory NCV (P less than 0.001). Thus, there was evidence of symmetrical upper and lower limb, as well as motor and sensory proportional involvement of large nerve fiber NCV in this group of NIDD subjects.(ABSTRACT TRUNCATED AT 250 WORDS)

A Comparison of Autonomic Nervous System Activity between Physically Trained and Untrained Individuals

Abstract The study is concerned with the comparison of autonomic nervous system (ANS) activity between highly trained collegiate track and field athletes and untrained individuals. An ANS test battery consisting of six individual measures of autonomic activity was used: (a) sublingual temperature, (b) salivary output, (c) volar skin resistance, (d) palmar skin resistance, (e) diastolic blood pressure, and (f) heart period. One group of athletes, track runners, were found to have a mean autonomic balance score significantly higher (at the .02 level) than the norm group of college students. The autonomic scores of field event athletes, however, were not significantly different from the norm. An analysis of the type of ANS activity demonstrated by the runners showed a dominance by the parasympathetic as compared to a mixed pattern demonstrated by the normative sample. It was concluded that highly trained track runners demonstrated a significantly higher autonomic balance score than did normal college student...

Autonomic testing (Funkenstein test) in epileptic disorders.

Various techniques to activate or accentuate electrical dysrhythmias are standard procedures in electroencephalograph (EEG) laboratories. On the other hand, except for research purposes, activation of emotional storms in psychiatric patients is entirely fortuitous, to be avoided whenever possible. However, during the course of autonomic nervous system testing (Funkenstein test), these fortuitous events are not unusual. The two drugs used, epinephrine and methacholine, often stimulate frank anxiety attacks or somatic symptoms, which are typical of the patient's usual complaints. Because of the apparent, albeit inconsistent, relationship between psychological phenomena and epileptic seizures, we were interested in finding out whether or not epinephrine, methacholine, or both would have the same activating effect on epileptic patients as it did on psychiatric patients. Would either drug activate sensory or psychic aurae, if not clinical seizures, as the psychiatric patient's sensory symptoms and anxiety are activated? Procedure Ten patients with different

Reliability of mecholyl test.

Introduction Funkenstein and his collaborators, in a series of papers, described an autonomic nervous system test of prognostic significance in relation to electroshock. This test originally consisted of intravenous injection of epinephrine (adrenergic stimulation) and intramuscular injection of methacholine U. S. P. (Mecholyl) (cholinergic stimulation). Subsequently, it was found that the Mecholyl test alone predicted the results of the electroshock treatment at a better than P=0.01 level.* Mecholyl is a cholinergic drug, which when injected produces a fall of blood pressure, due to a peripheral action on the blood vessels. This may be followed by a rise in the blood pressure due to a homeostatic reaction of the higher hypothalamic sympathetic center (Gellhorn5). Subjects, irrespective of their diagnosis, who react to injection of Mecholyl by a pronounced fall of the blood pressure respond to the electroshock therapy much better than subjects who respond by a rise of the blood

An evaluation of intravenous ether as a treatment for psychiatric patients.

1. Seventy-three committed patients diagnosed as having affective psychoses were divided at random into 3 treatment groups: one group received intravenous ether, one group intravenous saline, and a third group electric shock treatment. 2. Of the 37 patients who received intravenous ether 37.8% were scored as "improved"; 52.9% of the 17 patients who received intravenous saline were scored as "improved"; and 89.4% of the 19 patients who received electric shock treatment were so scored. A comparison of the results obtained following intravenous ether and intravenous saline showed statistically no significant difference. The improvement following electric shock treatment was significantly higher than that obtained following either intravenous ether or intravenous saline. 3. Twenty-two of the patients who failed to improve with intravenous ether were then given electric shock treatment, and 19 of these improved sufficiently to leave the hospital; 7 of the patients who failed to improve with intravenous saline were then given electric shock treatment and all 7 improved sufficiently to leave the hospital. A comparison of the results obtained by electric shock treatment alone with those obtained by a combination of ether and electric shock or saline and electric shock showed no differences considered significant by statistical methods. 4. Autonomic nervous system tests(6) showed that patients whose autonomic reaction was classified as "favorable" as far as electric shock treatment was concerned showed a higher rate of improvement with ether than did patients whose autonomic reaction would indicate a poor prognosis with electric shock treatment. However, the improvement rate in the "favorable" autonomic group cases was poor as compared with the expected improvement rate of similar cases treated with electric shock treatment. 5. It is concluded that intravenous ether as a treatment for affective psychoses showed no specific treatment effect that could not be obtained by intravenous saline, and that electric shock treatment was a much more efficacious treatment than ether in such cases.