RESUMO
OBJECTIVE: To investigate the total peripheral vascular resistance (TPVR), cardiac output (CO), and plasma C-type natriuretic peptide (CNP) levels in children with postural tachycardia syndrome (POTS) during supine, upright, and return to supine. STUDY DESIGN: Twenty-nine children with POTS, aged 12 ± 3 years, were recruited, and 32 healthy children, aged 11 ± 2 years, served as controls. Heart rate (HR), blood pressure, TPVR, and CO were continuously monitored with Finapres Medical System, and plasma CNP levels were detected with Sandwich immunoluminescence assay. RESULTS: In children with POTS, upright TPVR and CO were significantly lower than those in supine position, and they rose again when they returned to supine position. However, in healthy control patients, both TPVR and CO did not change during supine, upright, and supine again positions. Also, in the supine position, there was no significant difference in TPVR and CO between POTS children and control subjects (P > .05). When upright, however, TPVR and CO in children with POTS were significantly lower than those of controls. Plasma CNP levels were significantly greater in children with POTS than that of controls (32.8 ± 9.7 vs 24.2 ± 8.4 [pg/mL], P < .01), and symptom scores and ΔHR positively correlated with plasma CNP levels in children with POTS (symptom scores: r = 0.490, P < .01; ΔHR: r = 0.508, P < .001), but CO negatively correlated with plasma CNP levels (r = -0.446, P < .01). CONCLUSION: Reduced TPVR and CO associated with the elevated plasma CNP might be involved in the pathogenesis of POTS.
Assuntos
Débito Cardíaco , Peptídeo Natriurético Tipo C/sangue , Síndrome da Taquicardia Postural Ortostática/sangue , Síndrome da Taquicardia Postural Ortostática/fisiopatologia , Resistência Vascular , Criança , Feminino , Humanos , Masculino , PosturaRESUMO
OBJECTIVES: Midodrine hydrochloride is used clinically to treat children with postural tachycardia syndrome (POTS), but it is not effective in all patients. This study was designed to explore the changes in plasma copeptin and its predictive value in assessing the therapeutic efficacy of midodrine hydrochloride in children with POTS. STUDY DESIGN: The study included 33 children with POTS and 26 healthy children. The group with POTS received midodrine hydrochloride treatment for 1.5-3 months. The plasma copeptin was measured using a sandwich immunoluminometric assay. A receiver operating characteristic curve was used to explore the predictive value of plasma copeptin. RESULTS: The plasma copeptin in the group with POTS was significantly higher than that of the control group (10.827±2.459 pmol/L vs 8.845±1.471 pmol/L, P<.001). The plasma copeptin in responders to midodrine hydrochloride was significantly higher than that of nonresponders (12.082±1.998 pmol/L vs 9.646±2.301 pmol/L, P=.003). Receiver operating characteristic analysis on the predictive value of plasma copeptin showed that the area under the curve was 0.800 with a 95% CI of 0.640-0.959. Using a plasma copeptin level of 10.482 pmol/L as the cutoff point produced both favorite sensitivity (81.3%) and specificity (76.5%) in predicting the efficacy of midodrine hydrochloride therapy in children with POTS. CONCLUSIONS: Plasma copeptin may be considered as a predictive biomarker for the likelihood of successful treatment of children with POTS with midodrine hydrochloride.
Assuntos
Agonistas de Receptores Adrenérgicos alfa 1/uso terapêutico , Biomarcadores/sangue , Glicopeptídeos/sangue , Midodrina/uso terapêutico , Síndrome da Taquicardia Postural Ortostática/tratamento farmacológico , Adolescente , Criança , Pré-Escolar , Feminino , Frequência Cardíaca , Humanos , Masculino , Síndrome da Taquicardia Postural Ortostática/sangue , Curva ROC , Sensibilidade e Especificidade , Resultado do TratamentoRESUMO
OBJECTIVES: To evaluate the use of erythrocytic hydrogen sulfide (H2S) in predicting the therapeutic efficacy of midodrine hydrochloride for children with postural orthostatic tachycardia syndrome (POTS). STUDY DESIGN: Fifty-five children were included in this study, involving 28 children with POTS (POTS group) and 27 healthy children (control group). Children in the POTS group received midodrine hydrochloride treatment. Erythrocytic H2S production was measured; a receiver operating characteristic curve was used to assess if erythrocytic H2S could predict the therapeutic response to midodrine hydrochloride treatment. RESULTS: H2S production from erythrocytes was significantly higher in the POTS group than in the control group (P < .01). H2S production was also significantly higher in responders to midodrine hydrochloride than in non-responders (P < .05). The change in symptom score and baseline erythrocytic H2S production had a positive linear relationship (P < .01). There was also a positive correlation with the change in heart rate (P < .05). The receiver operating characteristic curve showed an area under curve value of 0.813. Erythrocytic H2S production yielded a sensitivity of 78.9% and a specificity of 77.8% in predicting the efficacy of midodrine hydrochloride therapy for children with POTS. CONCLUSION: Erythrocytic H2S could serve as a useful predictor of therapeutic response to midodrine hydrochloride in children with POTS.
Assuntos
Eritrócitos/metabolismo , Sulfeto de Hidrogênio/sangue , Midodrina/uso terapêutico , Síndrome da Taquicardia Postural Ortostática/sangue , Síndrome da Taquicardia Postural Ortostática/diagnóstico , Área Sob a Curva , Estudos de Casos e Controles , Criança , Pré-Escolar , Eletrocardiografia , Eritrócitos/citologia , Feminino , Frequência Cardíaca , Humanos , Masculino , Curva ROC , Sensibilidade e Especificidade , Simpatomiméticos/uso terapêuticoRESUMO
OBJECTIVE: To explore the predictive value of plasma hydrogen sulfide (H(2)S) in differentiating between vasovagal syncope (VVS) and postural orthostatic tachycardia syndrome (POTS) in children. STUDY DESIGN: Patients were divided between the POTS group (n=60) and VVS group (n=17) by using either the head-up test or head-up tilt test. Twenty-eight healthy children were selected for the control group. Plasma concentrations of H(2)S were determined for children in all groups (POTS, VVS, and control). RESULTS: Plasma levels of H(2)S were significantly higher in children with VVS (95.3±3.8 µmol/L) and POTS (100.9±2.1 µmol/L) than in children in the control group (82.6±6.5 µmol/L). Compared with the VVS group, the POTS group had plasma levels of H(2)S that were significantly increased. The receiver operating characteristic curve for the predictive value of H(2)S differentiation of VVS from POTS showed a H(2)S plasma level of 98 µmol/L as the cutoff value for high probability of distinction. Such a level produced both high sensitivity (90%) and specificity (80%) rates of correctly discriminating between patients with VVS and patients with POTS. CONCLUSION: H(2)S plasma level has both high sensitivity and specificity rates to predict the probability of correctly differentiating between patients with VVS and patients with POTS.