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At least 19 recordsLinked to original sources
PubMed1991

Utility of upright tilt-table testing in the evaluation and management of syncope of unknown origin.

PURPOSE: Vasovagally mediated hypotension and bradycardia are believed to be common, but difficult to diagnose, causes of syncope. Upright tilt-table testing has been proposed as a possible way to test for vasovagal episodes. This study investigated the clinical utility of this technique in the evaluation and management of patients with syncope of unknown origin. PATIENTS AND METHODS: Twenty-five patients with recurrent unexplained syncope and six control subjects were evaluated by use of an upright tilt-table test for 30 minutes, with or without an infusion of isoproterenol (1 to 3 micrograms/minute given intravenously), in an attempt to provoke bradycardia, hypotension, or both. Of the 25 patients, there were 14 males and 11 females, with a mean age of 50 +/- 16 years. Six control patients with no history of syncope were also studied. All tilt-positive patients received therapy with either beta-blockers, disopyramide, transdermal scopolamine, or hydroflurocortisone, the efficacy of which was evaluated by another tilt-table test. RESULTS: Syncope occurred in six patients (24%) during the baseline tilt and in nine patients (36%) during isoproterenol infusion (total positives, 60%). None of the controls had syncope during the test. All patients who had positive test results eventually became tilt-table-negative by therapy, and over a mean follow-up period of 16 +/- 2 months no further episodes have occurred. CONCLUSION: From this study we conclude that upright tilt-table testing combined with isoproterenol infusion is clinically useful in the diagnosis of vasovagal syncope and the evaluation of pharmacologic therapy.

Adolescent↗
PubMed1992

Reproducibility of isoproterenol tilt-table tests in patients with syncope.

To assess the reproducibility of head-up tilt-table testing 46 patients each underwent 2 isoproterenol tilt-table tests 1 to 6 weeks apart. Of 20 patients with an initially asymptomatic negative test result, 17 (85%) had a second negative test result. Of 20 patients whose initial test ended in syncope, 18 had a second test ending in syncope (n = 12) or presyncope (n = 6). Five of 6 patients whose first test ended in presyncope had a second test that ended in presyncope, and 1 had a second test that was asymptomatic. Finally, a total of 14 patients had at least 1 test (either the first or second) ending in presyncope, and 11 of these (79%) had another test ending in presyncope or syncope. The dose-dependence of isoproterenol was irreproducible. The reproducibility of the duration of head-up tilt necessary to elicit symptoms of presyncope or syncope was determined in the 23 patients who had these symptoms on both tests. Symptoms developed monoexponentially with duration of head-up tilt with half-times of 1.4 to 2.6 minutes, but these times did not correlate significantly between tests. In a selected subgroup of 12 patients who developed syncope in the first test and either presyncope or syncope in the second test during administration of isoproterenol (5 micrograms/min), the time of onset of presyncope correlated well (r = 0.73, p = 0.007) as did that of syncope (r = 0.86, p = 0.012). Finally, hemodynamic changes during symptoms were compared between the 2 tests.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Head-upright tilt-table testing in evaluation and management of the malignant vasovagal syndrome.

Vasovagally mediated cardiac asystole has been proposed as a potential cause of sudden cardiac death. To assess this possibility and identify characteristics that define patients with vasovagally mediated asystole, head-upright tilt-table testing was performed in 50 consecutive patients (26 women and 24 men, mean age 42 +/- 10 years) with recurrent unexplained syncope. The upright tilt-table test was performed in the fasting state for 30 minutes, with or without the use of intravenous isoproterenol (1 to 3 micrograms/min). The production of ventricular asystole lasting greater than 4 seconds was considered a positive result. All patients with tilt-induced asystole received therapy with either beta blockers, disopyramide, transdermal scopolamine or atrioventricular permanent pacing, the efficacy of which was evaluated with serial tilt-table tests. Reproducible tilt-induced asystole occurred in 10 patients (7 men and 3 women, mean age 23 +/- 12 years) (7 patients during baseline tilt, and 3 during isoproterenol infusion). Analysis of this group revealed that they had significantly more frequent and severe syncopal episodes (3 patients had episodes needing bystander cardiopulmonary resuscitation) than did those patients with tilt-induced syncope without asystole. All patients who had tilt-induced asystole eventually became tilt-table negative with therapy (4 with beta blockers, 2 with disopyramide, and 4 with atrioventricular permanent pacing), and over a mean follow-up of 21 +/- 6 months no further syncopal episodes occurred. It is concluded that patients with recurrent tilt-induced asystole represent a distinct subgroup that has recurrent severe syncope that may mimic or result in sudden cardiac death. Thus, the predischarge electrophysiologic study could predict late outcome with recurrence of preexicitation or supraventricular tachycardia in patients who had undergone surgical ablation of the accessory pathway with an overall predictive accuracy of 95% (107 of 113 patients), negative predictive value of 96% (103 of 107), and positive predictive value of 67% (4 of 6).

Adolescent↗
PubMed1992

Reproducibility of head-up tilt-table testing for eliciting susceptibility to neurally mediated syncope in patients without structural heart disease.

Head-up tilt testing has gained acceptance as a tool for assessing susceptibility to neurally mediated syncopal syndromes (e.g., vasovagal syncope), and is currently being evaluated as a means of testing therapeutic interventions in these conditions. To assess reproducibility of head-up tilt testing and thereby assess the potential of such testing for immediate evaluation of a planned treatment, findings during 2 sequential 80 degrees head-up tilt tests were compared in 23 patients (age range 6.5 to 74 years) undergoing evaluation of syncope of unknown origin. Upright tilt was performed initially in the absence of drugs, and repeated if necessary during pharmacologic provocation by means of isoproterenol infusions of 1 and 3 micrograms/min (tilt 1). End points were syncope, maximal tolerated isoproterenol dose, or a tilt duration of 10 minutes. The second tilt test (tilt 2) was conducted after approximately 30 minutes of supine rest using the maximal provocative conditions used in tilt 1. Fifteen of 23 patients (65%) developed syncope in either tilt 1 or 2, while 8 of 23 (35%) remained asymptomatic. Tilt testing results were concordant (i.e., positive in both tests, or negative in both tests) in 20 of 23 (87%) patients. Concordance was, however, less among tilt-positive patients (12 of 15, 80%) since 3 patients were tilt-positive in tilt 1 only.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1992

Head-upright tilt-table testing: a useful tool in the evaluation and management of recurrent vertigo of unknown origin associated with near-syncope or syncope.

Recurrent idiopathic vertigo associated with near-syncope and syncope is a common perplexing problem, some cases of which are considered autonomically mediated (vasovagal). Upright-tilt-table testing has emerged as a potential method to test for vasovagal episodes. This study evaluated the use of this technique in the evaluation and management of patients with recurrent idiopathic vertigo associated with near-syncope or syncope. Twenty-one patients with recurrent unexplained vertigo and syncope/near-syncope and 11 control subjects were evaluated by use of an upright-tilt-table test for 30 minutes, with or without a graded isoproterenol infusion (1 to 4 micrograms/min given intravenously), in an attempt to provoke hypotension, bradycardia, or both, which reproduced the patient's symptoms. The patients included 10 men and 11 women (mean age, 51 +/- 16 years). Eleven controls with no history of vertigo were also studied. Transcranial Doppler sonography was used to assess cerebral arteriolar blood flow during tilt. All tilt-positive patients were placed on therapy with either beta-blockers, disopyramide, or transdermal scopolamine, the effectiveness of which was determined with another tilt-table study. Symptoms occurred in seven patients (33%) during the baseline tilt and in eight patients (38%) during isoproterenol infusion (total positives, 71%). Transcranial Doppler sonography demonstrated a 225% +/- 192% increase in pulsatility index and a 70% +/- 29% increase in resistance index (indicative of cerebral arteriolar vasoconstriction) at the time of vertigo. No control subject experienced syncope during this test. Each tilt-positive patient eventually became tilt-negative with therapy, and over a mean follow-up period of 26 months, no further episodes have occurred.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMedDate not supplied

Provoking vasodepressor syncope with head-up tilt-table testing.

Head-up tilt testing has proven effective in identifying individuals prone to vasodepressor syncope (VDS). VDS refers to the transient loss of consciousness/cerebral anoxia seen with hypotension produced by autonomic imbalance. In this case, the hypotension is the result of parasympathetic domination. Most episodes appear to be triggered by reduced venous return which stimulates the cardiac mechanoreceptors in the inferior-posterior left ventricle. Once activated, these receptors send out afferent signals along the unmyelinated C of the vagus nerve and cause vasodilation. Once venous return is restored, the usual sympathetic compensations (increased heart rate/force of contraction and vasoconstriction) overcome the parasympathetic domination. A tilt-study allows one to passively tilt the patient up to 40-80 degrees and abruptly reduce venous return in a controlled environment. One can then determine which mechanism will dominate--the usual sympathetic vasoconstriction or the parasympathetic reflex (Bezold-Jarisch)--by frequent observations of blood pressure and ECG. Bradycardia/ventricular standstill may also occur during parasympathetic domination. Once susceptibility to vasodepressor syncope is identified by a tilt study, medications to expand the blood volume and/or minimize venous pooling are often needed. Other drugs to block the parasympathetic pathway and/or the effects of excessive catecholamine levels may also be ordered. Dual chamber pacing may be required for malignant episodes of bradycardia or ventricular standstill.

Electrocardiography↗
PubMed1992

Syncope: causes, clinical evaluation, and current therapy.

Syncope is a common clinical problem comprising the sudden loss of both consciousness and postural tone, with a subsequent spontaneous and relatively prompt recovery. Often it is difficult to differentiate a true syncopal spell from other conditions, such as seizure disorders, or from some simple accidents. Even more difficult is the identification of the cause of syncopal episodes. Nonetheless, establishing a definitive diagnosis ia an important task given the high risk of recurrent symptoms. Careful use of noninvasive and invasive cardiovascular studies (including electrophysiologic testing and tilt-table testing) along with selected hematologic, biochemical, and neurologic studies provides, in the majority of cases, the most effective strategy for obtaining a specific diagnosis and for directing therapy.

Diagnosis, Differential↗
PubMed1992

Free plasma catecholamine levels in healthy subjects: a basal and dynamic study. The influence of age.

We studied the levels of free plasma noradrenaline (norepinephrine, NE), adrenaline (epinephrine, E), and dopamine (DA) in 143 normal subjects, either basally or, in a part of them, in response to four tests stimulating the sympathoadrenomedullary activity: the tilt-table test (TTT), the cold-pressor test (CPT), the mental-arithmetic test (MAT), and the insulin tolerance test (ITT). In both cases we evaluated the influence of age, which is considered the main physiological variable affecting the peripheral sympathetic activity. A normal distribution of values was observed, in the basal study, only for NE, while E and particularly, DA levels were distributed in an non-homogeneous fashion; a direct correlation was observed between age of subjects and NE levels, while neither E, nor DA levels showed any correlation with the aging process; sex did not influence any of the catecholamines. In the dynamic study, CPT, ITT and, above all, TTT elicited a significant rise in NE levels, while the E release was greatly stimulated by the insulin-induced hypoglycaemia. Neither NE, nor E levels rose after the MAT stimulation. Also in this case, the elderly showed an increased noradrenergic responsiveness when compared with the young subjects, confirming the existence of an 'up-regulation' of the peripheral sympathetic tone in old people.

Adolescent↗
PubMed1992

A controlled trial of acute and long-term medical therapy in tilt-induced neurally mediated syncope.

To study the efficacy of medical treatment for preventing syncopal recurrences in patients affected by tilt-induced neurally mediated syncope, a randomized placebo-treatment prospective study was performed in 30 patients (10 men and 20 women, mean age 42 +/- 21 years) who had syncope reproduced in 2 consecutive head-up tilt-table tests without pharmacologic intervention (n = 20) or during isoproterenol infusion (n = 10). Patients were randomly assigned to 2 groups: 15 to placebo, and 15 to drug therapy (determined on the basis of serial pharmacologic tilting tests). Therapy was either atenolol (n = 7), dihydroergotamine (n = 2), domperidone (n = 2), cafedrine (n = 1), or elastic compression stockings, alone or in association with drugs (n = 3). During a mean of 10 +/- 7 months of follow-up, syncope recurred in 3 patients (20%) in the treatment group and in 4 (27%) in the placebo group; actuarial rates of absence of syncopal recurrences after 20 months were 70 and 67%, respectively. Thus, the outcome of either treated or untreated patients was favorable (with a low recurrence rate of syncope), and the usefulness of tilting-guided medical therapy remains uncertain.

Adult↗
PubMed1992

Medically unexplained syncope: relationship to psychiatric illness.

The purpose of this article is to review the literature and present new data concerning the relationship between psychiatric disorders and unexplained syncope. Several case series are presented of patients with syncope in whom psychiatric structured interviews were undertaken, tilt-table (physiologic) testing was performed, and health-related quality of life was measured. Patients seen in a syncope specialty clinic underwent structured psychiatric interviews in addition to in-depth medical evaluations. Tilt-table testing was performed on a separate series of patients to determine susceptibility to syncope during the orthostatic challenge of head-up tilt; in some cases, tilt studies included simultaneous electroencephalographic (EEG) monitoring and cerebral blood flow measurements. Formal functional status assessment was carried out using the Sickness Impact Profile, the Symptom Check List 90, and the Medical Outcomes Study Short-Form 36. Psychiatric disorders (in particular, panic disorders and major depression) were a common cause of syncope (24-31% of syncope patients). Tilt table studies showed several physiologic profiles in syncope: (a) a typical vasovagal (hypotension-bradycardia) response, (b) a "psychosomatic" response (fainting with normal vital signs), and (c) a gradual decline in blood pressure (dysautonomic response). EEG and cerebral blood flow measurements in three patients with the psychosomatic response to tilt were normal during fainting. Functional status measurements showed serious impairment in two series of syncope patients. Conclusions were as follows: (a) Psychiatric disorders are common in syncope. (b) Tilt-table methodology may elucidate underlying mechanisms of syncope in these subjects. (c) Syncope can seriously disrupt a patient's life and result in important psychosocial sequelae. (d) There is an intimate relationship between unexplained syncope and psychiatric illness, mandating a combined medical and psychiatric approach to such patients.

Humans↗
PubMed2026

The effect of drysuit diving in warm water on body temperature and post immersion orthostatic hypotension.

INTRODUCTION: Warm-water diving can limit heat dissipation, particularly when performed in fully encapsulating protective gear, leading to substantial thermal and cardiovascular strain that may impair diver safety. Following immersion, removal of hydrostatic support combined with heat-induced vasodilation may reduce central blood volume and increase susceptibility to orthostatic intolerance during egress and recovery. The extent to which this thermal strain impairs post-immersion orthostatic tolerance remains unknown. METHODS: Four randomised, crossover immersion trials were conducted at 28&#xb0;C, 33&#xb0;C, 38&#xb0;C without precooling (38&#xb0;C), and 38&#xb0;C with precooling (38&#xb0;C + Cool), with subjects wearing fully encapsulating dive gear. Subjects walked for up to 60 minutes at approximately 50% of O2max heart rate (HR) or until core temperature (Tc) reached 38.5&#xb0;C, or they voluntarily stopped. Tc, HR, and perceptual measures were recorded every 10 minutes. Orthostatic tolerance was assessed after immersion via a 70&#xb0; head-up tilt test. RESULTS: Eight healthy adults completed all aspects of the study. Tc and HR were higher during both 38&#xb0;C conditions compared with 28&#xb0;C and 33&#xb0;C (all P < 0.01) with no differences between 38&#xb0;C and 38&#xb0;C + Cool. Sweat loss exceeded 1.2 (SD 0.67) L&#x22c5;h-1 in both 38&#xb0;C conditions compared with &#x2264; 0.3 (0.32) L&#x22c5;h-1 at 28&#xb0;C and 33&#xb0;C (P < 0.01). Survival analysis showed orthostatic tolerance decreased with increasing thermal stress (log-rank P = 0.027; trend P = 0.003). Precooling did not reduce peak Tc or HR, nor did it improve tolerance time in 38&#xb0;C water. CONCLUSIONS: Encapsulated warm-water diving causes heat stress and cardiovascular strain that persists after immersion, impairing orthostatic tolerance. Precooling does not significantly reduce these outcomes.

Humans↗
PubMed2026

Electroencephalographic evidence of cortical network disruption preceding overt cardioinhibition during tilt-induced reflex syncope.

OBJECTIVE: Reflex syncope is a common cause of transient loss of consciousness. However, the early cerebral mechanisms underlying cardiovascular changes remain poorly understood. Our objective was to investigate early cerebral changes by quantitatively analyzing EEG activity preceding overt cardioinhibition during tilt-induced reflex syncope. METHODS: EEG recordings from patients undergoing tilt testing were retrospectively analyzed. Patients who experienced reflex syncope were compared to those who did not. Spectral and functional connectivity analyses were performed across baseline, pre-cardioinhibition, and syncopal phases. RESULTS: Prior to the onset of cardioinhibitory pathological reflex, a significant increase in theta-band spectral power was observed in the right temporal region, accompanied by a widespread increase in functional connectivity within the same frequency band. These findings suggest the involvement of brain networks before cardioinhibition. CONCLUSIONS: EEG changes in the theta band (power and functional connectivity) were observed before overt cardioinhibition during tilt-induced reflex syncope. SIGNIFICANCE: Our findings support the hypothesis of cortical processing preceding cardioinhibition in reflex syncope. EEG may represent a valuable complementary tool for improving the understanding and diagnosis of these events.

Humans↗
PubMed2026

Bedtime tetrahydrocannabinol ingestion reduces morning orthostatic cardiovascular reactivity in adults: An exploratory study.

Acute cannabis use and its primary psychoactive constituent tetrahydrocannabinol (THC) can induce postural dizziness, indicating increased risk of orthostatic instability. However, it is unknown if vulnerabilities persist the morning after bedtime THC consumption. This study investigated the influence of bedtime THC consumption on cardiovascular variables during an orthostatic challenge. Nine individuals with no cannabis use and eight individuals who regularly use cannabis participated in a tilt table test associated with a 3-day in-laboratory stay. Participants underwent an acclimatization day, followed by a placebo dosing day, and a 10&#x2009;mg THC dosing day. Placebo and THC pills were given 1&#x2009;h before a participant's habitual bedtime, and the tilt table test was performed ~1&#x2009;h upon awakening. Participants were instrumented with an electrocardiogram and an automated sphygmomanometer. Fluid intake and output were measured throughout the study. The morning after THC administration, individuals with no cannabis use reported a higher frequency of dizziness and exhibited a significant reduction in both diastolic blood pressure and heart rate reactivity to tilt (reactivity&#x2009;=&#x2009;tilt - baseline) compared to the morning after placebo. Our results indicate a potential increased risk for orthostatic instability the morning after cannabis consumption in individuals with no cannabis use history.

Humans↗
PubMed1976

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↗