Tilt test in the etiological diagnosis of syncope unexplained by electrophysiological study

In order to determine the role of tilt testing in the aetiological diagnosis of syncope unexplained by electrophysiological investigation, the authors retrospectively studied the results of this test in 275 patients with a mean age of 64 +/- 16 years. These 275 patients were divided into two groups: group I: 43 patients with a mean age of 50 +/- 19 years presenting with vagal syncopes, group II: 232 patients with unexplained syncope, probably vagal: group IIa (120 patients, mean age: 67 +/- 15 years), sudden syncope: group IIb (112 patients, mean age: 67 +/- 13 years). The electrophysiological investigation was inconclusive in every case. In group II, 50% of tilt tests were positive (19% under basal conditions, 31% after isoproterenol), with 61% of positive tests in group IIa, including 31% on the basal test, and 38% of positive tests in group IIb, including 11% on the basal test. In group I, 84% of tests were positive (33% on the basal test, 51% after isoproterenol), indicating a sensitivity of the test of 84%. In 96 patients with a doubtful electrophysiological investigation, the tilt test was positive in 70% of cases, allowing specific treatment or a pacemaker to be avoided in the majority of cases. 84% of vasovagal syncopes were therefore confirmed by tilt testing; 50% of syncopes unexplained by electrophysiological investigation were demonstrated to be of vasovagal origin. The author emphasize the value of tilt testing in certain discordant situations in which the clinical context is disturbing and/or electrophysiological investigation is not completely reassuring.     

Urodynamic and cardiovascular measurements in patients with micturition syncope

We describe the findings of urodynamic studies, together with blood pressure and heart rate monitoring, in five patients with micturition syncope. All patients had almost normal storage and evacuation function and no evidence of prostate hypertrophy. Conventional head-up tilt testing with an empty urinary bladder caused no change in arterial blood pressure, but a moderate increase in heart rate. Urinary bladder filling caused minimal increases of the arterial pressure and heart rate. The sitting posture with a distended bladder caused mild orthostatic hypotension. Urinary bladder evacuation caused a fall in arterial pressure with a decrease in heart rate. These responses were similar to those described in vasovagal syncope. The central mechanism for the initiation of urinary evacuation, or sensory input from the lower urinary tract, may trigger micturition syncope.     

Hemodynamic mechanism of vasovagal syncope

Vasovagal syncope is a common clinical problem, however the hemodynamic mechanism is not clearly understood. The aim of the present study was to investigate the circulatory control mechanism of vasovagal syncope provoked by the head-up tilt test. Thirty two patients with recurrent unexplained syncope were studied using a head-up (60 degrees) tilt test. The electrocardiogram, arterial blood pressure, pulmonary arterial pressure and central venous pressure were monitored continuously, and the cardiac output was measured by the thermodilution method. Twenty patients (62.5%) had positive tilt test responses, of which 12 developed typical vasovagal syncope with marked hypotension and bradycardia; the others developed hypotension without bradycardia. There were five women and seven men with a mean age (+/- SD) of 53.3 +/- 15 years. The effect of head-up tilt resembled that of hypovolemia. The central venous pressure, pulmonary capillary wedge pressure and cardiac output declined with an increase of heart rate and systemic vascular resistance. However the mean blood pressure was maintained. During vasovagal syncope, the heart rate and blood pressure fell precipitously and significantly, the cardiac index was reduced from 2.22 +/- 0.43 to 1.51 +/- 0.32 liters/min/m2 (p value < 0.05) and the systemic vascular resistance index decreased from 3,689 +/- 859 to 1,999 +/- 543.9 dynes s cm5/m2 (p value < 0.05). The results of our study showed that both reduction of cardiac output and withdrawal of sympathetic vasoconstriction tone contribute to the development of hypotension in vasovagal syncope.     

Congenital pseudarthrosis of the tibia treated with free vascularized fibular graft

OBJECTIVE: To study propanthelin bromide efficacy in preventing vasovagal syncope relapse. SETTING: HGZ No. 3 IMSS, Mazatlán, Sinaloa, México, from 1992 to 1995. PATIENTS: 10 patients with vasovagal syncope were selected from 41 syncope patients. DESIGN: Prospective longitudinal. MEASURES: clinical charts, neurologic and cardiologic evaluation, electrocardiogram, electroencephalogram, C.A.T., Holter, stress test and chest X rays were made. In 10 patients, 15 to 30 mg of propanthelin bromide thrice a day were administered, 12 month survey on was made measured. RESULTS: Of the 10 patients, 7 were women mean age 18 years. In 9 of them no recurrence was evident abandoned 1 treatment, 4 had side effects. CONCLUSIONS: Propanthelin bromide decreases vasovagal syncope episodes with few side effects.     

Difficulties and complications during surgical treatment of otosclerosis

Orthostatic intolerance can present a very serious limitation to astronauts attempting any functions requiring the upright position. Vasovagal syncope is a common cause of fainting characterized by paradoxic bradycardia and vasodilation in the presence of decreasing arterial pressure. Several mechanisms have been proposed to mediate vasovagal syncope and it seems likely that redundant mechanisms exist both centrally and peripherally which can mediate these responses. Spaceflight alters reflex control of cardiovascular function in several ways which may influence susceptibility to vasovagal syncope provoked by the Bezold-Jarisch reflex.     

The head-up tilt test with nitroglycerin provocation in the diagnosis of vasovagal syncope

The study compares the diagnostical values of "head-up tilt" tests both with or without nitroglycerin the provocation. On the basis of the comparison of a group of 60 patients and 20 healthy people we can state that the "head-up tilt" test with the provocation by nitroglycerin is appropriate for the statement of diagnosis of the cardioinhibitory type of vasovagal syncopes. (Tab. 4, Ref. 14.)     

Vasovagal syncope and unexplained syncope: Concepts, treatments, and future perspectives.

Syncope (transient loss of consciousness) can lead to significant psychosocial and physical impairment and have a profound impact on the quality of life of the sufferer. While infrequently attended to, a psychological perspective may have much to offer within a comprehensive treatment plan. The present article reviews 26 articles that evaluate conventional (education, medication, cardiac pacemakers) and to a greater extent, complementary treatments (orthostatic training, applied tension, psychologically oriented interventions) designed to reduce the frequency and negative consequences of vasovagal and unexplained syncope. Applied tension demonstrated the greatest efficacy in reducing the frequency of vasovagal syncope. However, this intervention applies only to patients who experience a prodrome prior to fainting. Currently, no clinically proven treatment exists for patients with unexplained syncope or with vasovagal syncope without a prodromal phase. Suggestions regarding appropriate cognitive and/or behavioural interventions are provided based on the characteristics of the patients. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Response to head-up tilt testing in patients with situational syncope

The results of head-up tilt testing were compared between 24 patients with situational syncope and 44 age-matched patients with typical vasovagal syncope. Patients with situational syncope showed poor positive responses, especially in the passive tilt results (8.3% vs. 39%, p = 0.0078).     

Recurrent unexplained syncope: the role of head-upright tilt table testing

Recurrent episodes of sudden unexplained syncope are a common complaint of patients referred to health care professionals for evaluation. Traditional evaluations are both time consuming and expensive and leave many patients without a diagnosis. Although vasovagally mediated episodes of hypotension and bradycardia have been thought to be a common cause of unexplained syncope, this was traditionally a diagnosis of exclusion. Head-upright tilt table testing has recently emerged as a valuable method for confirming the diagnosis of vasovagal syncope and has allowed a better understanding of this phenomena. This article reviews the pathophysiology of vasovagal syncope, the use of head-upright tilt table testing in its diagnosis, and potential therapies used to prevent recurrences.     

Management of the complications of long-term venous access

A syncope is defined as a sudden, temporary loss of consciousness, associated with loss of postural tone with spontaneous recovery. The incidence is high and the differential diagnosis broad; therefore, the first observations are essential for the management of the patient. In this review diseases will be described which manifest themselves with syncopes that fall under the auspices of either internal medicine or neurology. First, the etiologies of syncopes are discussed in the strict sense of the word, i.e. due to a global cerebral ischemia such as in orthostatic hypotension and vasopressor syncopes. Thereafter, a discussion concerning the differential diagnosis of syncopes will be introduced, including mainly psychogenic and epileptic seizures as well as vertebrobasilar hypoperfusion. Depending on the reason of the loss of consciousness, it can be a common benign disorder or a severe life-threatening disease. The personal history or witness account of the incidence provides the most useful information concerning diagnosis. The cardiological diagnostic procedures are discussed elsewhere. In some instances an EEG can further help with the diagnosis. In many cases an etiology can't be found, even if extensive investigations have been performed.     

Complex demodulation of cardiorespiratory dynamics preceding vasovagal syncope

BACKGROUND: The dynamic autonomic processes leading to vasovagal syncope are poorly understood. METHODS AND RESULTS: We used complex demodulation to continuously assess changes in respiration, R-R interval, and arterial pressure (blood pressure) variability during 60 degree head-up tilt in 25 healthy subjects with tilt-induced vasovagal syncope and 25 age-matched nonsyncopal control subjects. Coherence and transfer function analyses were used to examine the relation between respiration and R-R interval variability before syncope. Baseline blood pressure, R-R, and ventilation were similar between syncope subjects and control subjects. Syncope subjects experienced an increase in tidal volume and decrease in BP beginning 3 minutes before impending syncope (systolic blood pressure <80 mm Hg) necessitated termination of tilt. Approximately 90 seconds before syncope there was a sudden prolongation of R-R interval and increase in amplitude of high and low frequency R-R interval variability, indicating an abrupt enhancement of vagal tone. The increase in respiratory amplitude between 180 and 90 seconds before syncope was not accompanied by changes in R-R interval or R-R variability, suggesting a dissociation between respiration and the respiratory sinus arrhythmia. The coherence analysis showed fewer syncope subjects with coherence between respiratory and R-R interval variabilities and lower transfer magnitudes in syncope subjects compared with control subjects. Nonsyncopal subjects had no change in respiratory, R-R interval, or blood pressure dynamics during matched time periods before the time of syncope. CONCLUSIONS: Vasovagal syncope is preceded by a period of hyperpnea and cardiorespiratory decoupling followed by an abrupt increase in cardiovagal tone. Respiratory pumping without inspiratory cardiac slowing may partially counteract preload reduction until sudden bradycardia precipitates syncope.     

Malignant vasovagal syncope: a case of prolonged asystole induced by the "tilt" test and aggravated by therapy with a beta blocker (a clinical case and diagnostic, physiopathologic and therapeutic review)

The authors describe a case of a middle-age male with recurrent syncope, in whom the tilt test was useful in the diagnosis and therapeutic evaluation. Malignant criteria of vasovagal syncope were established and the beta blocking worsening effect was documented, in spite of the general agreement of the first choice drug.     

Adenosine: potential modulator for vasovagal syncope

OBJECTIVES: This study examined the hypothesis that adenosine could provoke a vasovagal response in susceptible patients. Mechanisms of the vasovagal response were further explored by studying the adenosine-mediated reactions. BACKGROUND: Increased sympathetic activity is frequently observed before vasovagal syncope. Recent studies have demonstrated that adenosine, in addition to its direct bradycardiac and vasodilatory effects, can increase sympathetic discharge by activating cardiovascular afferent nerves. METHODS: The effects of adenosine and head-up tilt-table testing with or without isoproterenol were prospectively evaluated in 85 patients examined for syncope after negative results of electrophysiologic testing (51 men and 34 women, mean [+/- SD] age 61 +/- 17 years). Adenosine bolus injections of 6 mg and 12 mg were sequentially administered to patients in the upright position. The same protocol was implemented in 14 normal control subjects (7 men and 7 women, mean [+/- SD] age 38 +/- 10 years). RESULTS: Transient hypertension or tachycardia was observed in 57 (67%) and 20 (24%) patients after administration of 6 mg and 12 mg of adenosine, respectively, during the immediate phase (first 15 s), suggesting direct sympathetic activation. Hypotension and reflex tachycardia were observed in all patients during the delayed phase (15 to 60 s after adenosine injection), suggesting baroreceptor unloading. A vasovagal response was induced in 22 (26%) and 29 (34%) patients after adenosine administration and during tilt-table testing. Inducibility of a vasovagal response by these two methods was comparable (p = 0.12). Of the control subjects, one (7%) had a vasovagal response after adenosine administration and one (7%) had a positive response during tilt-table testing. CONCLUSIONS: These observations support the idea that adenosine is an endogenous modulator of the cardiac excitatory afferent nerves. Sympathetic activation by adenosine can be direct (i.e., cardiac excitatory afferent nerves) and indirect (i.e., vasodilation and reflex sympathetic activation). Adenosine could be an important modulator in triggering a vasovagal response in susceptible patients during examination for syncope.     

Present trends in the pathogenesis, diagnosis and therapy of vasovagal syncope

Vasovagal syncope is the most frequent cause of syncopal conditions. In its pathogenesis autonomic nervous, neurohumoral, cerebrovascular and other mechanisms participate. The gold standard in the diagnosis of vasovagal syncope is in recent years the head up tilt test. In treatment pharmacotherapy, cardiac pacing or their combination can be used.     

Evaluation of the effects of diverse therapeutic treatments versus no treatment of patients with neurocardiogenic syncope

Head-up tilt test was introduced in clinical practice to assess vasovagal syncope and its use has further been extended to evaluate the efficacy of drug administration in these patients. Nevertheless, the effects of tilt test on vasovagal syncope have never been compared with those obtained by ethylephrine or propranolol administration. One hundred and sixty-nine consecutive patients with vasovagal syncope and positive baseline or nitrate-potentiated tilt test (60 degrees upright position for 45 min, or until syncope occurred; 5 mg sublingual isosorbide dinitrate administration if no symptoms occurred) were randomly distributed among three groups: Group A (57 control patients discharged without medical therapy); Group B (56 patients discharged with 75 mg/die ethylephrine); Group C (56 patients discharged with 80 mg/die propranolol). Tilt test was repeated after 1 month, while clinical outcome was evaluated monthly for a mean follow-up of 37.1 +/- 15.6 months. No significant differences in acute tilt-induced syncope recurrence rates were obtained among groups at test repetition since 70.2% of Group A, 69.6% of Group B and 62.5% of Group C experienced syncope. At 3-year follow-up 82.4% of Group A, 83.9% of Group B and 87.5% of Group C (NS among groups) remained symptom free, the most important clinical result being obtained in untreated patients. These data suggest that tilt test execution may prevent syncope recurrence as ethylephrine or propranolol administration. Irrespective of the therapeutical choice, the "controlled reproduction" of symptoms and some psychophysical training of patients to avoid precipitating circumstances, to recognize early symptoms promptly to be reverted by Trendelemburg position, may produce the same clinical improvement as (empiric) ethylephrine or propranolol therapy.     

Morphological changes in a hyperfunctioning thyroid adenoma after percutaneous ethanol injection: histological, enzymatic and sub-microscopical alterations

Autonomic nervous dysfunction has recently been considered to be an etiological factor in syncope and sudden death in cases of hypertrophic cardiomyopathy. However, the precise mechanism is still unknown. A 73-year-old woman with obstructive hypertrophic cardiomyopathy was hospitalized with complaints of impaired consciousness; faintness 3 to 4 h after meals, lightheadedness while walking, and syncope during and after defecation and micturition. Faintness was induced by alimentary hypoglycemia related to gastrectomy performed 5 years previously. Lightheadedness and syncope were accounted for by autonomic nervous failure combined with an impairment of alpha 1-adrenoceptor in vasoconstriction and the carotid sinus hypersensitivity which accompanied preceding events such as abdominal pain, defecation and micturition, which could enhance the vagally-mediated baroreceptor reflex.     

Applied tension and blood donation symptoms: The importance of anxiety reduction.

Objective: Despite being a voluntary activity, many blood donors experience anxiety, and fainting (syncope) is not unusual. The muscle-tensing technique applied tension (AT) has been found to be effective in reducing vasovagal symptoms and syncope. A series of studies was developed to investigate the role of AT on anxiety and fainting. Methods: The mechanisms of AT were examined in the laboratory and the blood donor clinic. In Study 1, 70 participants were assigned randomly to either a control group or an experimental group who learned AT before watching a video depicting blood draws. In Study 2, 667 volunteer blood donors completed similar questionnaires. Results: In Study 1, a significant Condition × Sex × Needle Fear interaction, F(1, 59)=4.97, p=.03, indicated that AT reduced vasovagal symptoms in higher-fear women. Study 2 also found a significant Condition × Sex × Needle Fear effect on vasovagal symptoms, F(2, 653)=3.95, p=.02, indicating that AT reduced symptoms but primarily among women with more pronounced fear of needles. Conclusions: Analysis of the physiological data and self-reported anxiety supports the conclusion that the reduction in vasovagal symptoms was due more to decreased anxiety rather than exercise-related cardiovascular change. These results suggest that AT may provide a useful means of coping with invasive medical procedures in part by reducing anxiety. (PsycINFO Database Record (c) 2011 APA, all rights reserved)     

Permanent cardiac pacing in elderly patients with recurrent falls, dizziness and syncope, and a hypersensitive cardioinhibitory reflex

The study was designed to assess the outcome of treatment with permanent dual-chamber pacing of elderly patients with falls, dizziness and syncope associated with the demonstration of a hypersensitive cardioinhibitory reflex. Questionnaires were sent to patients (and their general practitioners) who had been referred to a regional pacing centre with recurrent falls, dizziness or syncope diagnosed as likely to be secondary to cardioinhibitory carotid sinus syndrome or predominantly cardioinhibitory vasovagal syndrome. After pacemaker insertion, 84% of patients had no further syncope over a mean follow-up period of 10 (range 1.5 to 30) months. Minor symptoms persisted in only 40% of all patients. Symptoms were unchanged in 22%. It was concluded that permanent dual-chamber pacing is an effective treatment for elderly patients with recurrent falls, dizziness and syncope in whom a hypersensitive cardioinhibitory reflex is found. Good results were obtained in this group with a simple diagnostic work-up.