Sympathovagal balance and graded orthostatic tilt.
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Blood Pressure↗
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Results for “Tilt-Table Test”
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Is neurally mediated hypotension an unrecognised cause of chronic fatigue?
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Atenolol↗
[Quantitative tilt table study with TCD monitoring. A reliable method for the diagnosis of neurocardiogenic syncope (vasovagal syncope)].
The clinical significance of quantitative tilt-table examination with TCD monitoring in the diagnosis of neurocardiogenic syncope is evaluated. A 50-year-old male suffered a neurocardiogenic syncope during tilt-table examination with a strong drop in blood pressure, an increase in cerebrovascular resistance as evidenced by transcranial Doppler monitoring, and a 30-s cardiac asystole, followed by a generalized seizure. No further syncope could be elicited during tilt-table examination after beta-blocker treatment. It was hypothesized that hyperactivity of the left ventricular mechanoreceptors due to increased force of ventricular contraction during a state of reduced venous backstream to the heart was responsible for eliciting the neurocardiogenic syncope. Tilt-table examination with an upright position for at least 45 min enables the diagnosis of a neurocardiogenic syncope to be made with sufficient sensitivity and specificity. Several studies have shown that medication with beta-blockers is successful in the treatment of neurocardiogenic syncope. The implantation of cardiac pacemakers should only be considered if medication is not successful.
Adrenergic beta-Antagonists↗
Femoral flow response to lower body negative pressure: an orthostatic tolerance test.
UNLABELLED: The objective was to check, during a lower body negative pressure (LBNP) test, new vascular parameters for the detection of orthostatic intolerance induced by head-down-tilt (HDT) and spaceflight. METHODS: The lower-limb volume flow and vascular resistance were evaluated by Doppler ultrasound. The HDT population consisted of two groups: control [6 subjects resting in a HDT (-6 degrees) position for 28 d] and countermeasure (6 subjects also in HDT for 28 d, but with repeated LBNP and exercise). The LBNP orthostatic test (four steps: -20, -30, -40, -50 mm Hg, of 3 min each) was performed before, during, and after the HDT. For the 14-d spaceflight (Antares) the cosmonaut underwent the LBNP test (10 min at -25 mm Hg and 10 min at -45 mm Hg), at preflight (3 times), inflight (day 11), and postflight (twice). RESULTS: HDT--As the LBNP pressure decreased, the femoral blood flow decreased and the lower-limb vascular resistances increased in both HDT groups. In the control group the femoral flow was less reduced, at each of the 4 levels of depressure (p < 0.01). The amplitude of the leg vascular resistances was reduced at -40 mm Hg, and at -50 mm Hg, on HDT day 15 in both groups (before LBNP, after 1 week's exercise for the countermeasure group), and on post-HDT day 1 (p < 0.01) only in the control group. The femoral vascular resistance response had completely recovered in the countermeasure group on post-HDT day 1. During the post-HDT tilt table test, all 6 controls had a drop in blood pressure of 20 mm Hg (4 subjects) or 10 mm Hg (2 subjects); 3 had pre-syncopal symptoms. The HDT countermeasure subjects had neither any clinical signs of orthostatic intolerance nor any blood pressure drop. 14d-Spaceflight--During the flight, the cosmonaut did not use any countermeasures (exercise, LBNP). On flight day +11, and on postflight day 3, the femoral vascular resistance response to LBNP was decreased as observed in the control group on HDT day +15 and post HDT. On postflight day 7, the femoral response had completely recovered. The middle cerebral flow response to the various pre-, in-, and postflight LBNP tests consisted of a slight decrease of the cerebral flow together with resistances of comparable amplitude (-10 to -20%) to those measured during the same LBNP test in the HDT control group. CONCLUSION: The femoral hemodynamics are much more disturbed than the cerebral ones in vascular deconditioning. The assessment of the lower limb vascular reactivity will be of interest in predicting orthostatic intolerance, and checking the efficiency of counter-measures.
Cardiovascular Deconditioning↗
Psychogenic syncope diagnosed by prolonged head-up tilt testing.
Four patients with 'syncope' during prolonged head-up tilt testing despite normal blood pressure and heart-rate behaviour are described. They represent 5.5% of all positive tilt-test outcomes from a prospective study of 181 consecutive patients with unexplained syncope. All four patients were female, and were both younger and more symptomatic than patients with vasovagal syncope or orthostatic hypotension. In three of the patients, clinical episodes of syncope were observed which closely resembled those provoked during tilt. It is suggested that the tilt response is psychogenic and reveals a psychiatric cause for recurrent syncope.
Adolescent↗
Cognitive-behavioral management of motion sickness.
This monograph is intended to provide health professionals with information on a cognitive-behavioral technique which was developed to teach individuals who are prone to motion sickness to better cope with motion environments. It includes an overview of motion sickness, describing the signs and symptoms, etiology and incidence of this malady. Prevention and treatment are then reviewed, including both pharmacological and non-pharmacological therapies. The historical background on the cognitive-behavioral technique is then discussed. This is followed by a review of supporting experimental work, and an account of how such counselling should be carried out. Finally, a number of current military desensitization programs are compared and contrasted with cognitive-behavioral therapy.
Biofeedback, Psychology↗
[Hemodynamics and anaerobic glycolysis during the head-down tilt test in myocarditis patients].
The analysis is presented of the changes observed in hemodynamics and anaerobic metabolism in myocarditis patients given increasing preload. It is shown that the antiorthostatic test can specify substantial deposition of blood in the lesser or greater circulation. Patients with congestive cardiac insufficiency demonstrate more frequently increased lactate levels in the blood of the coronary sinus and reduced myocardial extraction of lactate.
Adolescent↗
Hemodynamic regulation during postural tilt assessed by heart rate- and blood-pressure variability combined with impedance cardiography.
Assessment of heart rate and heart rate variability (HRV) are used in sports medicine and space medicine to give conclusions about the functional state of the autonomic nervous system. Furthermore, reduced HRV and changed blood pressure variability (BPV) are accepted as risk factors in patients with cardiovascular diseases, metabolic syndrome and neurologic disorders. The aim of the first studies was to combine the evaluation of central hemodynamic (impedance cardiography) with HRV and BPV evaluation in the time and frequency domain (fft tracking) based on a standardized clinical test with automated protocol output. Data acquisition and -analysis was realized beat to beat (Kohto Ltd., Moscow) during forced breathing (150 s, 6 breath/min) and postural tilt (7 min, supine, transition to 55 degrees in 4 s, 7 min upright) allowing one to evaluate: orthostatic response type including impedance cardiography; activation of vagal afferences and efferences by forced breathing; vagal and sympathetic components during initial heart rate and blood pressure responses; characteristic changes of spectral balance of HRV and BPV (measured at the finger) during early regulation. First investigations on 34 normal volunteers subdivided into two age groups and on 13 patients with different diseases indicate that besides the age dependent changes (reduced HRV, reduced cardiac performance, reduced regulatory amplitudes and baroreflex sensitivity) individual response types can be described and dysfunction of different reflex loops can be detected. Consequently, the assessment of specific influences onto circulatory control by therapy, sport and rehabilitative training is possible and further studies are necessary.
Adult↗
Combined head-up tilt and lower body suction: a test of orthostatic tolerance.
A combined tilt-table and lower body suction chamber to provide a progressive test of orthostatic tolerance which avoided the use of drugs and had a defined end point even in most asymptomatic subjects has been constructed and evaluated. An air-tight cover, sealed to a tilt-table and to the subject at the level of the iliac crest, was used to study the responses to: head-up tilting for 20 min, then tilting plus lower body suction at -20 and -40 mmHg for 10 min at each. Blood pressure, heart rate and cardiac output were measured noninvasively and orthostatic tolerance was assessed as the time to imminent onset of syncope. All subjects tolerated tilt alone but 84% developed signs and symptoms of presyncope during the suction. Younger women had a lower orthostatic tolerance than other groups. Values of the variables measured during tilting alone did not correlate with the measured orthostatic tolerance, but during the suction subjects who developed early syncope showed larger decreases in cardiac output and smaller maximal heart rates than the more resistant subjects. The test is repeatable and is likely to be of value in the assessment of orthostatic tolerance in patients and for evaluating the effects of various interventions.
Adult↗
Orthostatic tolerance at different times of the day in physically average and very fit dayworkers.
We studied the relationship between the physical exercise capacity and the orthostatic tolerance of physically average fit and very fit dayworkers at different times of the day. Six male railroad workers were physically very fit and six were averagely fit (mean of the maximal oxygen consumption 57.4 and 34.6 ml.kg-1.min-1, respectively. The mean age was 32 years. The orthostatic tests were performed with a tilt-table at 2.00, 6.00, 10.00, 14.00, 18.00, and 22.00 hours on six different days. Orthostatic lability at night was seen in both groups. At 14.00 and 18.00 hours the orthostatic tolerance in average fit men was slightly lower than in very fit men. This difference in the orthostatic tolerance between the groups may be a sign of the interdependence of good exercise tolerance and orthostatic tolerance.
Adult↗
Significance of daily rhythm for the interpretation of functional diagnostic procedures.
For the first time, the reaction of the cardiovascular system during day and night in young people was examined. We were mostly interested in the influence of the nervous system and any autonomic mechanism. We examined 20 subjects at 4-hour intervals on the ergometer (active exercise) and on the tilt-table (passive exercise) to find out the rhythm in the circulatory regulation. The test person was kept in vertical position on the tilt-table for 10 minutes. On the ergometer he had to perform a work-load of 100 Watt for 10 minutes. We measured pulse rate and blood pressure; we introduced new terms for the evaluation. "Orthostatic Index" and "Performance Index" will be further explained. The results were: A minimum in the orthostatic stability around 1 p.m. and 1--5 am, and a performance maximum at 1 p.m. and 5 p.m. Further details will be reported.
Blood Pressure↗
Syncope: current diagnostic evaluation and management.
OBJECTIVE: To provide a comprehensive review of the causes, current diagnostic evaluation, and treatment of syncope. DATA IDENTIFICATION: New data and knowledge in this evolving field were critically analyzed by doing a MEDLINE search on syncope supplemented by selective review of English language literature citations in the Index Medicus before 1980. STUDY SELECTION: We reviewed approximately 200 published articles on syncope and closely related topics as well as using our own clinical experience. We selected articles if they addressed the pathophysiology of syncope, classification and causes, differential diagnosis, noninvasive and invasive evaluation, and current therapy. RESULTS OF DATA SYNTHESIS: Syncope is a common clinical problem, occurring in 30% to 50% of the adult population. The prognosis for syncope depends on its cause. Cardiac syncope has the worst prognosis and therefore mandates thorough evaluation and prompt treatment. Diagnostic evaluation is made difficult by the transient nature of the episodes and the many causes. Noninvasive testing reveals the cause of syncope in approximately 50% of cases. More extensive evaluation, including invasive electrophysiologic studies, has assumed a larger role in defining the cause of syncope in selected patients with structural heart disease in whom a noninvasive evaluation has been nondiagnostic. Recently tilt-table studies have been proposed as a clinically useful noninvasive test for vagally mediated syncope. CONCLUSIONS: A rational stepwise diagnostic and therapeutic approach to patients with syncope can be developed by initially doing a careful history and physical examination followed by a noninvasive evaluation and selective use of additional, more specialized or invasive tests. Future research should focus on defining the validity and utility of current diagnostic testing in syncope and on exploring further the pathophysiology of patients with recurrent, unexplained syncope.
Cardiovascular Diseases↗
Case reports and studies of paraneoplastic hypotension: abnormal low pressure baroreceptor responses.
Intrathoracic stretch receptors regulate adjustments of the vasculature to gravitational changes and influence urinary water and solute excretion. Few reports of pathologic states involving interruption of these regulatory mechanisms have appeared. Two patients with orthostatic hypotenstion related to advanced intrathoracic carcinoma were studied, utilizing tilt-table examinations and immersion of the entire body in water to test the function of their intrathoracic baroreceptor reflex arcs. Both patients showed abnormalities of antidiuretic hormone level and sodium excretion as compared with normal controls. This suggests that total immersion is a safe and convenient test of the low-pressure baroreceptor system in patients with suspected dysfunction. Three patients are also reported whose charts were reviewed posthumously. Although they were not tested in the laboratory, their clinical data suggest that they too had been suffering from an interference with the transmission of impulses from the intrathoracic receptors.
Adult↗
Transcranial Doppler evaluation of syncope: an application in aerospace physiology.
A non-invasive method which combines the simultaneous measurement of mean arterial blood pressure (MBP), heart rate (HR) and mean cerebral blood flow velocity (MFV) was used to monitor patients with history of syncope, in horizontal and vertical posture tilt at 80 degrees. MFV in the right middle cerebral artery was measured using a transcranial Doppler instrument (TCD). MFV decreased concurrently with the onset of symptoms, and at the time of syncope reached an average of 68% below pre-tilt values. At the same time MBP showed an average decline of 25%, and HR increased by 38%. There was no correlation between MBP and MFV, at the onset of tilt, presyncope and syncope. MFV, but not HR or MBP, showed significant transition from one condition to the other. These data suggest that there may be a useful application of TCD measurements of MFV in aeromedical evaluation of syncope or syncopal tendency. These measurements would necessarily be used in conjunction with a tilt-table procedure. The possibility exists that MFV might be useful to preclude the actual occurrence of syncope in test subjects, or to show an abnormal tendency toward syncope, but will require more extensive testing than that carried out in the present study.
Adult↗
Tilt-table/ankle-actuator system for the study of vestibulospinal reflexes.
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Ankle↗
[Vestibular ataxia caused by meningeal carcinomatosis].
A 74-year-old man developed progressive deafness and unsteady gait two years after gastrectomy for a gastric cancer. Neurological examination revealed an alert and intelligent Japanese male in no acute distress. The optic fundi were normal. The pupils and the extraocular muscles were normal, however, horizontal nystagmus was noted in right and left gaze. He showed marked bilateral deafness, and loss of caloric response bilaterally. No muscle atrophy nor weakness was noted. His gait was wide-based and ataxic. Tandem gait was impossible. Romberg sign was present. No cerebellar ataxia was noted in the finger-to-nose or the heel-to-knee test. No adiadochokinesis was noted. Hyperextensibility was noted in the lower extremities. Deep reflexes were normal in the upper limbs, and diminished in the lower extremities. Sensation was intact. He showed the jumbling phenomenon, and the disturbance of the righting reflex in the tilt-table examination. Neuroradiological as well as laboratory studies were unremarkable except for the high titer of CEA in the CSF. Four months after his admission, malignant tumor cells were found in the CSF. It seemed likely that he had completely lost bilateral vestibular and auditory functions caused by meningeal carcinomatosis. His disturbance of gait and station was apparently similar to cerebellar ataxic gait, however, he did not have limb ataxia. The cranial CT scans failed to show cerebellar atrophy. It was our impression that his motor disturbance was in all likelihood caused by the bilateral loss of vestibular functions, i.e., vestibular ataxia.(ABSTRACT TRUNCATED AT 250 WORDS)
Aged↗
Evaluation of the effects of muscle stretch and weight load in patients with spastic paraplegia.
Clinical observations on patients with spastic paraplegia have indicated that a training regime including weight load on the lower limbs may reduce the muscular hypertonus. Due to the spontaneous fluctuations and great variability in muscle tone it is difficult to judge from clinical findings how the effects may be related to muscle stretch and weight load. Therefore, quantitative determination of the effects on muscle tone by stretch and loading was made in 9 paraplegic patients. Muscle tone was measured before and after 30 min of stretch or weight load in 8 sessions on 4 consecutive days. Stretch was obtained by bracing the foot in maximal dorsal flexion with patient in supine position. For weight load on the lower limbs, the patient stood on a tilt-table at an angle of 85 degrees with feet in 15 degrees dorsal or plantar flexion. Resistance to passive movements was determined during a series of sinusoidal ankle joint movements at three different speeds. After weight load in standing with the feet in dorsal or plantar flexion, the average reduction was 32 and 26%, respectively. After stretch in supine, the average reduction was 17%. Thus, the three procedures tested all resulted in reduction of muscle tone. The largest reductions were obtained by weight load with stretch imposed upon the calf muscles.
Adult↗
Effects of a single session of prolonged plantarflexor stretch on muscle activations during gait in spastic cerebral palsy.
Activations of the triceps surae (TS) and tibialis anterior (TA) muscles during gait were studied in children with spastic cerebral palsy (CP) immediately before and after 30 min of standing on a tilt-table with the ankle dorsiflexed to stretch the TS in the experimental group (n = 8) or after a rest period in the control group (n = 11). The EMG activity from the TS and TA was recorded concomitantly with electronic footswitch signals by a computer. Video records were made of the sagittal gait movements. Effects of PMS were determined by comparing change scores for selected spatiotemporal and muscle activation parameters between the groups. The change scores defined for the muscle activations were: a post-test/pre-test ratio of the EMG activity in specific segments of the gait cycle and a locomotor spasticity index. PMS did not significantly (p greater than 0.05) affect any of the spatiotemporal parameters nor did it alter any of the TS and most of the TA activation parameters or the SI indexes for the TS and TA. Only the TA post/pre activation ratio for the 0-16% segment of the gait cycle was smaller (p less than 0.01), indicating a decrease in TA activation post-PMS.
Adolescent↗