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The 12-lead electrocardiogram (ECG) for the proband of L155. The proband is a 16-year-old boy: The left ECG showed very broad and notched or bifid even biphasic T waves on multi-leads (arrows) (QTc 620 ms) before he had received a pacemaker; the right one showed less abnormal ECG 5 months after pacemaker+propranolol 2 mg/Kg (QTc 514 ms).
