ELECTROCARDIOGRAPHY PATTERNS OF TILT-INDUCED CARDIOINHIBITORY SYNCOPE IN CHILDREN AND ADOLESCENTS

Abstract

Aim. To study electrocardiographic patterns of tilt-induced cardioinhibitory (CI) reactions in children and adolescents. Material and methods. The study included 16 children and adolescents (10 boys), aged 8-18 years, with recurrent syncope in anamnesis and CI syncope mechanisms confirmed by the tilt table test (TTT) results. Medication-free TTT was performed according to the Westminster protocol, with continuous electrocardiography; all records were processed manually. The following electrocardiogram (ECG) records (3 minutes each) were analysed: before the table tilt; in the head-up position; before the syncope; during the syncope; and during the recovery phase. Results. In children and adolescents with CI syncope, the baseline ECG demonstrated increased parasympathetic influence on heart rate (HR) regulation. Early orthostasis was characterised by increased HR (+35,8±11,5%). During the increase in orthostatic stress and before the syncope development, HR additionally and significantly increased (p=0,001 vs. early orthostasis). Syncope development was associated with HR reduction and subsequent cardioinhibition, either acute, or after a short period of disturbed sinoatrial and/or atrioventricular conductivity. The recovery phase was characterised by a significant HR reduction, compared to the baseline (p=0,0006), and frequent vagal-associated arrhythmias. Conclusion. ECG patterns of CI syncope in children and adolescents demonstrate increased sympathetic influences on HR regulation, followed by acute parasympathetic activation. The degree of vagal activation defines ECG patterns during syncope development and recovery phase.