
Keywords: ECG، الکتروکاردیوگرافی; autonomic function; electrocardiography; QT interval dispersionBP, Blood pressure; ECG, Electrocardiography; HR, Heart rate; HUT, Head-up test; OI, Orthostatic intolerance; POTS, Postural tachycardia syndrome; QTd, QT interval dispersion; QTcmax, Maximum