Using a tilt table to evaluate syncope

Serum Asymmetric Dimethylarginine Levels in Patients with Vasovagal Syncope

Background and Objectives: Vasovagal syncope (VVS) is the most common cause of syncope and has multiple pathophysiological mechanisms. Asymmetric dimethylarginine (ADMA) is the major inhibitor of nitric oxide (NO). In this study, we aimed to investigate the relationship between plasma ADMA levels and syncope during the head-up tilt (HUT) test. Materials and Methods: Overall, 97 patients were included in this study. They were above 18 years of age and were admitted to our clinic with the complaint of at least one episode of syncope consistent with VVS. The HUT test was performed in all patients. Patients were divided into the following two groups based on the HUT test results: group 1 included 57 patients with a positive HUT test and group 2 included 35 patients with a negative HUT test. Blood samples were taken before and immediately after the HUT test to measure ADMA levels. Results: No significant intergroup differences were observed concerning gender and age (female gender 68% vs 60%; mean age 24.85 ± 4.01 vs 25.62 ± 3.54 years, respectively, for groups 1 and 2). ADMA values were similar between groups 1 and 2 before the HUT test [ADMA of 958 (544–1418) vs 951 (519–1269); p = 0.794]. In the negative HUT group, no significant differences were observed in ADMA levels before and after the HUT test [ADMA of 951 (519–1269) vs 951 (519–1566); p = 0.764]. However, in the positive HUT group, ADMA levels were significantly decreased following the HUT test [pretest ADMA of 958 (544–1418) vs post-test ADMA of 115 (67–198); p < 0.001]. Conclusion: ADMA levels significantly decreased after the HUT test in patients with VVS.

Evaluation of the effect of radiofrequency catheter ablation on autonomic function in patients with atrioventricular nodal reentrant tachycardia by head-up tilt table test

Background:

One of the recommended treatments for atrioventricular nodal reentrant tachycardia (AVNRT), is radiofrequency catheter ablation (RFCA). However, RFCA may affect the autonomic system. This study aims to evaluate the effect of RFCA on autonomic system in patients with PSVT by head-up tilt table (HUTT) test.

Materials and Methods:

In a before–after study, 22 patients with PSVT were enrolled. Data were collected with a data collection form that included two parts. Electrocardiogram (ECG), echocardiogram, 24-h Holter monitoring, HUTT test, heart rate variability (HRV) indexes, and symptoms of all patients were recorded 24 h before and 1 month after the ablation. Wilcoxon, McNemar, Mann–Whitney U, and Chi-square tests were used to analyze the data.

Results:

Of the total 22 patients, 31.8% were male and 68.2% were female. There were significant differences in heart palpitation (P < 0.0001) and non-specific symptoms (P = 0.031) and no significant difference in head-up tilt test results and HRV indices before and after RFCA. The results showed that there were no significant differences in specific and non-specific symptoms in patients with AVNRT with positive and negative HUTT before and after RFCA.

Conclusions:

The observed difference in heart palpitation and non-specific symptoms emphasized the role of AVNRT in causing these symptoms. Autonomic dysfunction is more probably an accompanying condition of AVNRT than causing symptoms. We could not find any significance in the results of HUTT after RFCA. HUTT cannot determine or predict the symptoms after RFCA.

Physician reporting of medically impaired drivers

Emergency physicians frequently encounter patients whose medical conditions represent a risk of loss of control while driving, e.g., epilepsy and diabetes. In certain states, physicians are under a legal obligation to report such drivers to the motor vehicular authorities. To determine the uniformity of legislated reporting requirements for physicians caring for patients whose medical conditions represent an automotive hazard, we conducted a survey of Department of Motor Vehicles (DMV) legal departments of all the states in the United States for the academic year 1999-2000 regarding physician reporting of patients with medical conditions that might predispose them to a motor vehicle crash (MVC) and compared the results to a similar study done in 1986. Six (12%) of the states had mandatory reporting laws, 25 (49%) had permissive reporting laws, and 20 (39%) had no laws regarding physician reporting. There was a significant difference between the distribution of laws by year. There was no uniformity on a national level concerning such legislation.

Diagnostic value of history taking in reflex syncope

The medical history, in combination with the physical examination and a 12-lead electrocardiogram, plays a key role in the diagnosis and risk stratification of patients with syncope. However, diagnostic clinical criteria are not uniformly applied. In older studies, the diagnostic criteria for vasovagal or reflex syncope often included typical precipitating events and warning symptoms. More recent studies have documented that a variety of unrecognized stressors can trigger reflex syncope and that warning signs and symptoms may be minimal. A characteristic medical history (a trigger and/or prodromi) is enough to diagnose reflex syncope if the risk for a cardiac cause of syncope is low (e. g. patients < 65 yrs, without a history of heart disease and no ECG abnormalities). In elderly subjects with a higher risk of cardiac syncope, the yield of the medical history is lower. However, a prospective study of the value of the medical history for the diagnosis of syncope with long-term follow-up has not been performed.

The investigation of syncope

Patients with syncope are usually referred to either neurology or cardiology clinics, yet the facilities for detailed syncope investigation are mostly in cardiac units. The diagnosis rests principally upon the history, but investigations may be required to support the clinical diagnosis. Close collaboration between the epilepsy clinician and a cardiologist is essential for effective investigation and safe management of syncope. It is frequently misdiagnosed and often erroneously treated as epilepsy. Furthermore, it is potentially a marker of sudden death when associated with certain cardiac disorders. Here we review the main syncope types and explore diagnostic approaches.

[Convulsive syncope: characteristics and reproducibility using the tilt test]

OBJECTIVES

To establish the main clinical characteristics of convulsive syncope and the usefulness of the tilt test in its diagnosis.

METHODS

A total of 317 patients (aged 5-18 years old) under clinical suspicion of neurocardiogenic syncope underwent a multiparametric tilt test. Our tilt test protocol includes continuous noninvasive measurement of heart rate, blood pressure, and arterial oxygen saturation, as well as continuous noninvasive measurement of cerebral oxygen saturation by near-infrared spectrophotometry. In selected patients, simultaneous electroencephalogram (EEG) was performed.

RESULTS

The tilt test was positive in 216 patients (68.1 %). Of these, 25 (11.6 %) showed seizures during the test (convulsive syncope). Convulsions were asymmetric-tonic in 15 patients (60 %), generalized tonic in 5 (20 %), and tonic-clonic in 5 (20 %). In all patients, convulsive episodes lasted less than 30 seconds and spontaneously ceased upon placing the patient in a horizontal or Trendelenburg position. When simultaneous EEG was performed, diffuse brain wave slowing was observed, without paroxysmal activity.

CONCLUSIONS

Convulsive syncope is not an uncommon event in children and is easily elicited by means of the tilt test. Pediatricians should be aware of this finding in order to avoid the frequently established unidirectional association between seizures and epileptic disorders. Consequently, the tilt test should be considered an essential tool in the differential diagnosis between convulsive syncope and epilepsy.

Diagnostic evaluation and management of patients with syncope

This article focuses on the evaluation of patients with syncope, a symptom not a disease. Syncope is a transient loss of consciousness associated with loss of postural tone with spontaneous recovery. The authors discuss the utility of an indications for different diagnostic tests, the indications for hospital admission, and the management of patients with certain known causes of syncope, including vasovagal and arrhythmic.