[Syncope in children and adolescents].

The report presents a definition and causes of syncope in children. Syncope differs from other states with loss of consciousness by causes leading to decreased perfusion and resultant transient cerebral dysfunction with decreased muscle tone. The most common causes of syncope noted in almost 15% of children are neurocardiogenic. This group includes vasovagal, carotid sinus reflexive, situational (coughing, dysphagia, micturation and defecation disturbances) and post-exercise syncope. Another group is represented by orthostatic syncope that may be triggered by primary and secondary dis-autonomy, decreased blood volume (hemorrhage, diarrhea, Addison's disease), some medications and substances of abuse (alcohol). An important group, accounting for 2%-6% of all cases, are cardiogenic syncope, caused mainly by congenital/acquired obstructive cardiac sub- and valvar heart defects, various cardiomyopathies, some heart tumors (e.g. myxoma), exudative pericarditis, pulmonary embolus and hypertension, congenital and acquired coronary anomalies, various significant brady-tachyarrhythmias (sick sinus syndrome, supra- and ventricular tachycardias, congenital and acquired atrio-ventricular blocks). Subclavian steal syndrome as the cause of syncope is exceptional in children. Syncope does not include loss of consciousness due to neurological and metabolic (hypoglycemia) causes, hypoxia, hyperventilation with hypocapnia or CO intoxication. Differential diagnosis should also include pseudo-syncope (hysteria). Preliminary diagnostic management should include a detailed medical history, including family history, on the frequency and circumstances of syncope, sudden deaths, a physical exam with orthostatic assessment of peripheral blood pressure and standard ECG (heart rate, intraventricular and atrioventricular conduction defects, cardiac hypertrophy, arrhythmias, L-QT, changes in ST-T). Further specialist tests depend on preliminary findings.