Diagnostic value of the tilt-table test for the assessment of syncope in children and adolescents

OBJECTIVE - To assess the diagnostic value, the characteristics, and feasibility of tilt-table testing in children and adolescents. METHODS - From August 1991 to June 1997, we retrospectively assessed 94 patients under the age of 18 years who had a history of recurring syncope and presyncope of unknown origin and who were referred for tilt-table testing. These patients were divided into 2 groups: group I (children) - 36 patients with ages ranging from 3 to 12 (mean of 9.19±2.31) years; group II (adolescents) - 58 patients with ages ranging from 13 to 18 (mean of 16.05±1.40) years. We compared the positivity rate, the type of hemodynamic response, and the time period required for the test to become positive in the 2 groups. RESULTS - The positivity rates were 41.6 % and 50% for groups I and II, respectively. The pattern of positive hemodynamic response that predominated in both groups was the mixed response. The mean time period required for the test to become positive was shorter in group I (11.0±7.23 min) than in group II (18.44±7.83 min). No patient experienced technical difficulty or complications. CONCLUSION - No difference was observed in regard to feasibility, positivity rate, and pattern of positive response for the tilt-table test in children and adolescents. Pediatric patients had earlier positive responses.

Comparison between tilt-table testing results performed during different periods of the day

OBJECTIVE: To evaluate the influences of circadian variations on tilt-table testing (TTT) results by comparing the positivity rate of the test performed during the morning with that of the test performed in the afternoon and to evaluate the reproducibility of the results in different periods of the day. METHODS: One hundred twenty-three patients with recurrent unexplained syncope or near-syncope referred for TTT were randomized into 2 groups. In group I, 68 patients, TTT was performed first in the afternoon and then in the morning. In group II, 55 patients, the test was performed first in the morning and then in the afternoon. RESULTS: The TTT protocol was the prolonged passive test, without drug sensitization. Twenty-nine (23.5%) patients had a positive result in at least one of the periods. The positivity rate for each period was similar: 20 (16.2%) patients in the afternoon and 19 (15.4%) in the morning (p=1.000). Total reproducibility (positive/positive and negative/negative) was observed in 49 (89%) patients in group I and in 55 (81%) in group II. Reproducibility of the results was obtained in 94 (90.4%) patients with first negative tests but in 10 (34%) patients with first positive tests. CONCLUSION: TTT could be performed during any period of the day, and even in the 2 periods to enhance positivity. Considering the low reproducibility rate of the positive tests, serial TTT to evaluate therapeutic efficacy should be performed during the same period of the day.

Tilt teste no diagnóstico diferencial da "epilepsia" resistente ao tratamento

A epilepsia é uma das causas mais freqüentes de distúrbios neurológicos em adultos jovens. Relatamos um caso em que uma paciente conviveu durante doze anos com o diagnóstico de epilepsia resistente ao tratamento, quando, na verdade, a causa de seus sintomas pôde ser encontrada com a realização do teste de inclinação (tilt teste). O cardiologista deve estar alerta para o possível diagnóstico de síncope neurocardiogênica em pacientes previamente diagnosticados como portadores de epilepsia, especialmente naqueles com difícil controle terapêutico.

Teste de inclinação (Tilt-test): do necessário ao imprescindível

O teste de inclinação (TI) é muito utilizado para a investigação de síncopes e pré-síncopes, pois possibilita o diagnóstico de diferentes tipos de disautonomias. A principal causa de síncope é a Síndrome Vasovagal, cujo diagnóstico é o mais frequente entre as indicações de TI. O exame é utilizado há cerca de 20 anos, mas muitos médicos desconhecem a metodologia. São importantes a indicação apropriada, após exclusão de causas cardíacas de síncope, e a orientação do paciente para garantir a tranquilidade e a segurança do teste. Existem controvérsias na literatura sobre a capacidade diagnóstica e a confiabilidade dos resultados. Os estudos com protocolos diversos podem explicar a variabilidade dos resultados. Nesta revisão, são colocadas as indicações e a metodologia recomendadas pelas diretrizes, complicações, limitações e perspectivas desse exame.

Heart rate variability in athletes and nonathletes at rest and during head-up tilt

The purpose of the present study was to determine if autonomic heart rate modulation, indicated by heart rate variability (HRV), differs during supine rest and head-up tilt (HUT) when sedentary and endurance-trained cyclists are compared. Eleven sedentary young men (S) and 10 trained cyclists (C) were studied. The volunteers were submitted to a dynamic ECG Holter to calculate HRV at rest and during a 70º HUT. The major aerobic capacity of athletes was expressed by higher values of at anaerobic threshold and peak conditions (P < 0.05). At rest the athletes had lower heart rates (P < 0.05) and higher values in the time domain of HRV compared with controls (SD of normal RR interval, SDNN, medians): 59.1 ms (S) vs 89.9 ms (C), P < 0.05. During tilt athletes also had higher values in the time domain of HRV compared with controls (SDNN, medians): 55.7 ms (S) vs 69.7 ms (C), P < 0.05. No differences in power spectral components of HRV at rest or during HUT were detected between groups. Based on the analysis of data by the frequency domain method, we conclude that in athletes the resting bradycardia seems to be much more related to changes in intrinsic mechanisms than to modifications in autonomic control. Also, HUT caused comparable changes in sympathetic and parasympathetic modulation of the sinus node in both groups.

Variabilidade da freqüência cardíaca em pacientes chagásicos com e sem hipertensão arterial

Avaliamos a função autonômica cardíaca de pacientes chagásicos, hipertensos, e chagásicos portadores de hipertensão arterial e comparamos com o grupo controle, por meio do estudo computadorizado da variabilidade da freqüência cardíaca no estado basal de repouso supino, esfriamento facial (estímulo parassimpático) e ortostatismo passivo (tilt test). Foram estudados 80 indivíduos em quatro grupos de 20: chagas (CHG), hipertenso (HAS), chagas-hipertenso (CHG-HAS) e controle (CONT), com idade entre 21 a 60 anos. Todos foram avaliados por eletrocardiograma, ecocardiograma, radiografia de tórax, bioquímica do sangue, sorologia para doença de Chagas e, nos chagásicos, estudo radiológico contrastado de esôfago e cólons para caracterização quanto à forma clínica. Não houve diferença entre os grupos quanto à idade, gênero, e uso de medicamentos, índices de desempenho ventricular esquerdo e diâmetros cavitários cardíacos. Os grupos CHG e CHG-HAS não diferiram quanto ao número de pacientes pertencentes a cada forma clínica da doença. Os níveis pressóricos dos pacientes hipertensos e chagásicos-hipertensos foram semelhantes e significativamente maiores do que os níveis dos chagásicos e controles. Na condição basal e durante o ortostatismo não se observou diferença estatística quanto aos índices temporais. As respostas autonômicas ao esfriamento facial não foram diferentes entre os grupos, sugerindo preservação da resposta vagal.

Does a Role Exist for Tilting-Guided Therapy in the Management of Neurocardiogenic Syncope?

PURPOSE: Upright tilt-table testing (UTT) is an useful method for identifying patients with neurocardiogenic syncope, but its role in the evaluation of therapeutic efficacy is controversial. The aim of this study was to determine the correlation between negative UTT after therapy introduction (acute efficacy) and symptom recurrence during follow-up (chronic efficacy). METHODS: We studied 56 severely symptomatic patients (age 27±19 years) with recurrent (7±12 episodes) neurocardiogenic syncope (positive UTT). Once empirical pharmacological therapy was initiated, all patients underwent another UTT (therapeutic evaluation test - TET). Therapy was not modified after TET results. The probability of symptom recurrence was analyzed with the Kaplan-Meier method and compared by log-rank test in patients with negative and positive TET. RESULTS: Negative UTT after therapy was related to a significantly lower probability of recurrence during follow-up (4.9 versus 52.4% in 12 months, P<0.0001). CONCLUSION: A good correlation exists between acute and long-term efficacy of pharmacological therapy for neurocardiogenic syncope, so that serial UTT may be considered a good method for identifying an effective therapeutic strategy.

Assessment of Autonomic Function by Phase Rectification of RRInterval Histogram Analysis in Chagas Disease

Background:In chronic Chagas disease (ChD), impairment of cardiac autonomic function bears prognostic implications. Phase‑rectification of RR-interval series isolates the sympathetic, acceleration phase (AC) and parasympathetic, deceleration phase (DC) influences on cardiac autonomic modulation.Objective:This study investigated heart rate variability (HRV) as a function of RR-interval to assess autonomic function in healthy and ChD subjects.Methods:Control (n = 20) and ChD (n = 20) groups were studied. All underwent 60-min head-up tilt table test under ECG recording. Histogram of RR-interval series was calculated, with 100 ms class, ranging from 600–1100 ms. In each class, mean RR-intervals (MNN) and root-mean-squared difference (RMSNN) of consecutive normal RR-intervals that suited a particular class were calculated. Average of all RMSNN values in each class was analyzed as function of MNN, in the whole series (RMSNNT), and in AC (RMSNNAC) and DC (RMSNNDC) phases. Slopes of linear regression lines were compared between groups using Student t-test. Correlation coefficients were tested before comparisons. RMSNN was log-transformed. (α < 0.05).Results:Correlation coefficient was significant in all regressions (p < 0.05). In the control group, RMSNNT, RMSNNAC, and RMSNNDCsignificantly increased linearly with MNN (p < 0.05). In ChD, only RMSNNAC showed significant increase as a function of MNN, whereas RMSNNT and RMSNNDC did not.Conclusion:HRV increases in proportion with the RR-interval in healthy subjects. This behavior is lost in ChD, particularly in the DC phase, indicating cardiac vagal incompetence.

Facial paralysis and vestibular syndrome in feedlot cattle in Argentina

This paper reports 6 outbreaks of neurological disease associated with paralysis of the facial and vestibulocochlear nerves caused by intracranial space occupying lesions in feedlot cattle. The clinical signs observed were characterized by head tilt, uni or bilateral drooping and paralysis of the ears, eyelid ptosis, keratoconjunctivitis, and different degrees of ataxia. Morbidity and mortality rates ranged from 1.1 to 50% and 0 to 1%, respectively. Gross lesions observed included yellow, thickened leptomeninges, and marked enlargement of the roots of cranial nerves VII (facial) and VIII (vestibulocochlear). Histopathologically, there was severe, chronic, granulomatous meningitis and, in one case, chronic, granulomatous neuritis of the VII and VIII cranial nerves. Attempts to identify bacterial, viral, or parasitic agents were unsuccessful. Based on the morphologic lesions, the clinical condition was diagnosed as facial paralysis and vestibular syndrome associated with space occupying lesions in the meninges and the cranial nerves VII and VIII. Feedlot is a practice of growing diffusion in our country and this is a first report of outbreaks of facial paralysis and vestibular disease associated with space occupying lesions in Argentina.

Critical analysis of autoregressive and fast Fourier transform markers of cardiovascular variability in rats and humans

The autonomic nervous system plays an important role in physiological and pathological conditions, and has been extensively evaluated by parametric and non-parametric spectral analysis. To compare the results obtained with fast Fourier transform (FFT) and the autoregressive (AR) method, we performed a comprehensive comparative study using data from humans and rats during pharmacological blockade (in rats), a postural test (in humans), and in the hypertensive state (in both humans and rats). Although postural hypotension in humans induced an increase in normalized low-frequency (LFnu) of systolic blood pressure, the increase in the ratio was detected only by AR. In rats, AR and FFT analysis did not agree for LFnu and high frequency (HFnu) under basal conditions and after vagal blockade. The increase in the LF/HF ratio of the pulse interval, induced by methylatropine, was detected only by FFT. In hypertensive patients, changes in LF and HF for systolic blood pressure were observed only by AR; FFT was able to detect the reduction in both blood pressure variance and total power. In hypertensive rats, AR presented different values of variance and total power for systolic blood pressure. Moreover, AR and FFT presented discordant results for LF, LFnu, HF, LF/HF ratio, and total power for pulse interval. We provide evidence for disagreement in 23% of the indices of blood pressure and heart rate variability in humans and 67% discordance in rats when these variables are evaluated by AR and FFT under physiological and pathological conditions. The overall disagreement between AR and FFT in this study was 43%.