ABSTRACT
Objective : The aim of this study was to investigate the effects of sympathomimetic medication on the cardiovascular system of children with attention-deficit / hyperactivity disorder (ADHD). Methods : Cardiovascular functioning of children with ADHD (n = 19) was tested while the children were stimulant free and during a period in which they were on stimulant medication. Electrocardiograms (ECGs) were obtained by means of a Schiller CardioLaptop AT-110 ECG recorder using the standard 12-lead cable positioning for a resting ECG. Blood pressure was measured by means of a stethoscope and mercury sphygmomanometer. Results : The main findings of this study were that methylphenidate usage is associated with increases in heart rate (HR) and blood pressure (BP); and that it does not adversely affect HR-corrected QT and JT intervals or cardiac dispersion values. Conclusion : Methylphenidate causes an increase in HR as well as increases in both systolic and diastolic BP; but no change in cardiac depolarisation and repolarisation duration or homogeneity