Q—T 间期延长系指Q—T_c大于0.44秒,临床特点为Q—T 间期延长,发作性晕厥及其诱发恶性心律失常,甚至发生猝死。本文报告二例家族性Q—T 间期延长综合征,以下简称(QTS)的发病情况,并对其进行了临床观察、治疗及家系调查。病例摘要例1(家系图(?)_(23)),见图1。男,13岁,第一胎。9岁开始晕厥,近2年加重,曾在我院及他院疑诊癫痫。体检:体温37℃,呼吸20次/分,脉搏 Q-T prolongation means Q-T_c is greater than 0.44 seconds, clinical features of Q-T interval prolongation, paroxysmal syncope and its induced malignant arrhythmia, and even sudden death. This article reports two cases of familial Q-T prolongation syndrome, the following abbreviation (QTS) of the incidence, and its clinical observation, treatment and pedigree investigation. Case summary 1 (pedigree (?) _ (23)), see Figure 1. Male, 13 years old, first child. 9-year-old began to faint, increased nearly 2 years, had suspected epilepsy in our hospital and his hospital. Physical examination: body temperature 37 ℃, breathing 20 beats / min, pulse