Head-Up Tilt Testing with Different Nitroglycerin Dosages: Experience in Elderly Patients with Unexplained Syncope

AIMS: Protocols using sublingual nitrates have been increasingly used to improve diagnostic accuracy of head-up tilt testing (HUT). Nevertheless, exaggerated responses to nitrates have been frequently described, particularly in elderly patients. The aim of this article is to evaluate, in an elderly population with unexplained syncope, whether the impact of sublingual nitroglycerin (NTG) used as a provocative agent is dose-dependent. METHODS AND RESULTS: One hundred and twenty consecutive elderly patients submitted to HUT using NTG after an asymptomatic drug-free phase were studied. Patients were divided into three groups according to the NTG dosage: 500, 375 and 250 microg. The test was considered positive when there was reproduction of symptoms with bradycardia and/or arterial hypotension. A gradual decrease in the blood pressure after NTG was considered an exaggerated response to nitrates. There were no differences in the clinical characteristics of the different subgroups. A positive test was obtained in 50% of the patients in each group. The rate of exaggerated responses was identical in all groups and ranged between 15 and 17%. CONCLUSION: In an elderly population with syncope of unknown origin submitted to HUT, the response to NTG is not dose-dependent, and no difference was found in the rate of exaggerated responses to nitrates with different NTG dosages.

O Treino de Ortostatismo (Tilt Training) Aumenta a Reserva Vasoconstritora em Doentes com Síncope Reflexa Neurocardiogénica

A síncope neurocardiogénica (SNc) é uma entidade clínica comum, resultante de uma resposta autonómica reflexa excessiva durante o stress ortostático. As diferentes opções terapêuticas são controversas e de eficácia limitada. O treino de ortostatismo (TTr) tem-se mostrado uma alternativa prometedora no tratamento destes doentes (D). No entanto, permanece por esclarecer o seu mecanismo de acção e o impacto clínico numa população com SNc recorrente. Objectivo: Caracterizar a resposta hemodinâmica e autonómica durante um programa de TTr em doentes com SNc refratária às medidas convencionais. População e métodos: Foram estudados 28D (50% do sexo masculino, 41±14 anos), sem evidência de cardiopatia, com SNc documentada em teste de ortostatismo passivo. O TTr incluiu 9 sessões hospitalares (3x/semana, 30 minutos) com monitorizac¸ão contínua de pressão arterial e frequência cardíaca (60◦ - 6 sessões - 70◦ - 3 sessões), complementadas com treino diário no domicílio e elevação da cabeceira a 10◦ durante o sono. O volume sistólico, o débito cardíaco, a resistência vascular periférica, a sensibilidade do barorreflexo e a variabilidade da frequência cardíaca foram calculados. Todos os doentes foram reavaliados no fim do 1.◦ mês e no final de cada 6 meses num período máximo de 36 meses (follow-up 24±12 meses). Resultados: Ao longo das sessões de TTr verificou-se um aumento significativo e consistente da resistência total periférica (1485±225 vs. 1591±187 dyne*s/cm−5, p < 0,05) associado a uma diminuição do seu desvio-padrão (206±60 vs. 150±42, p < 0,05). Durante o período de follow-up, houve recorrência de síncope em 5D (19%), com redução significativa do número de síncopes (4,0±3,2/D nos 12 meses pre-TTr vs. 1,4±0,8/D pos-TTr, p < 0,05). Conclusão: Em doentes com SNc refratária, o TTr mostrou ser uma opção terapêutica eficaz, com benefício a longo prazo. A melhor tolerância ao ortostatismo parece resultar do aumento da reserva vasoconstritora e da sua menor variabilidade.

Tilt Training Increases Vasoconstrictor Reserve in Patients with Neurocardiogenic Syncope

Neurocardiogenic syncope (NCS) is a common clinical entity resulting from an excessive reflex autonomic response, particularly during orthostatism. Treatment options are controversial and of limited effectiveness. Tilt training (TT) is a promising option to treat these patients. However, its mechanism of action and clinical impact remain unclear. OBJECTIVE: To characterize hemodynamic and autonomic responses during a TT program in patients with NCS refractory to conventional measures. METHODS: We studied 28 patients (50% male, mean age 41±14 years) without structural heart disease, with NCS documented by tilt testing. The TT program included 9 tilt sessions (3 times a week, 30 min) (60° - 6 sessions, 70° - 3 sessions), under ECG and blood pressure monitoring combined with home orthostatic self-training and 10° head-up during sleep. Systolic volume, cardiac output, total peripheral resistance, baroreflex sensitivity and heart-rate variability were computed. Patients were reassessed at 1 month and every 6 months for a maximum of 36 months (24±12 months). RESULTS: Over the course of the TT program there was a significant increase in total peripheral resistance (1485±225 vs. 1591±187 dyn·s·cm(-5), p<0.05), with a decrease in standard deviation (206±60 vs. 150±42, p<0.05). During follow-up, syncope recurred in five patients (19%), with a significant reduction in the number of episodes (4.0±3.2/patient in the 12 months before TT vs. 1.4±0.8/patient post-TT, p<0.05). CONCLUSION: In refractory NCS, TT may be an effective therapeutic option, with long-term benefits. These results appear to be due to an increase in vasoconstrictor reserve combined with a reduction in its variance.

Impact of Syncope on Quality of Life: Validation of a Measure in Patients Undergoing Tilt Testing

INTRODUCTION AND OBJECTIVES: Recurrent syncope has a significant impact on quality of life. The development of measurement scales to assess this impact that are easy to use in clinical settings is crucial. The objective of the present study is a preliminary validation of the Impact of Syncope on Quality of Life questionnaire for the Portuguese population. METHODS: The instrument underwent a process of translation, validation, analysis of cultural appropriateness and cognitive debriefing. A population of 39 patients with a history of recurrent syncope (>1 year) who underwent tilt testing, aged 52.1 ± 16.4 years (21-83), 43.5% male, most in active employment (n=18) or retired (n=13), constituted a convenience sample. The resulting Portuguese version is similar to the original, with 12 items in a single aggregate score, and underwent statistical validation, with assessment of reliability, validity and stability over time. RESULTS: With regard to reliability, the internal consistency of the scale is 0.9. Assessment of convergent and discriminant validity showed statistically significant results (p<0.01). Regarding stability over time, a test-retest of this instrument at six months after tilt testing with 22 patients of the sample who had not undergone any clinical intervention found no statistically significant changes in quality of life. CONCLUSIONS: The results indicate that this instrument is of value for assessing quality of life in patients with recurrent syncope in Portugal.