Changes in Systolic and Diastolic Function Indexes Throughout Dobutamine Stress Echocardiography in Healthy Volunteers and Patients with Ischemic Heart Disease

Biomarkers and Hemodynamic Parameters in the Diagnosis and Treatment of Children with Postural Tachycardia Syndrome and Vasovagal Syncope

In children, vasovagal syncope and postural tachycardia syndrome constitute the major types of orthostatic intolerance. The clinical characteristics of postural tachycardia syndrome and vasovagal syncope are similar but their treatments differ. Therefore, their differential diagnosis is important to guide the correct treatment. Therapeutic methods vary in patients with the same diagnosis because of different pathomechanisms. Hence, in patients with vasovagal syncope or postural tachycardia syndrome, routine treatments have an unsatisfactory efficacy. However, biomarkers could increase the therapeutic efficacy significantly, allowing for an accurate and detailed assessment of patients and leading to improved therapeutic effects. In the present review, we aimed to summarize the current state of research into biomarkers for distinguishing the diagnosis of pediatric vasovagal syncope from that of postural tachycardia syndrome. We also discuss the biomarkers that predict treatment outcomes during personalized therapy for each subtype.

Prognostic Value of Biomarkers in Children and Adolescents With Orthostatic Intolerance

Orthostatic intolerance (OI) refers to a series of symptoms that occur during upright standing, which can be relieved when returned to the supine position. OI is a common cause of syncope in children and adolescents. In recent years, more and more studies have been carried out to assess the prognosis of OI by using biomarkers, among which, flow-mediated vasodilation, left ventricular ejection fraction and fractional shortening, hemodynamic change during head-up tilt test, detection of 24-h urinary sodium excretion, body mass index, midregional pro-adrenomedullin, and erythrocytic H2S producing rate are relatively stable, inexpensive, and easy to obtain. With the help of biomarkers, individualized treatment can be carried out to improve the long-term prognosis of children and adolescents with OI. This article reviews the prognostic value of biomarkers in children and adolescents with OI.

Left Ventricular Ejection Fraction and Fractional Shortening are Useful for the Prediction of the Therapeutic Response to Metoprolol in Children with Vasovagal Syncope

The objective of this manuscript was to explore if left ventricular ejection fraction (LVEF) and left ventricular fractional shortening (LVFS) could predict the efficacy of metoprolol therapy on vasovagal syncope (VVS) in children. Forty-nine children, including 30 with VVS and 19 gender- and age-matched healthy controls, were included in the study. Metoprolol was prescribed to the VVS subjects. The clinical data were obtained during follow-up at 2 and 6 months. The results showed that LVEF and LVFS of responders were significantly higher than those of non-responders both at the 2-month follow-up (LVEF: 72.5 ± 3.2% vs. 64.6 ± 3.4%; LVFS: 40.9 ± 2.3% vs. 34.9 ± 2.9%), and at the 6-month follow-up (LVEF: 72.8 ± 2.8% vs. 65.5 ± 4.6%; LVFS: 41.1 ± 1.9% vs. 35.8 ± 3.6%). The receiver operating characteristic curve (ROC) analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 80% and a specificity of 100% in predicting the therapeutic effectiveness of metoprolol at 2 months. For baseline LVFS, 38.5% as a cutoff value yielded a sensitivity of 90% and a specificity of 90%. At the 6-month follow-up, the ROC analysis demonstrated that 70.5% as a cutoff value of baseline LVEF yielded a sensitivity of 81.3% and a specificity of 88.9% in the prediction of metoprolol efficacy. For baseline LVFS, 37.5% as a cutoff value yielded a sensitivity of 93.8% and a specificity of 66.7%. In conclusion, baseline LVEF and LVFS might be useful predictors of the efficacy of β-blocker therapy on VVS in children.