13±3(8～20)岁的21(男7、女14)例患者至少有一次原因不明的晕厥,且倾斜试验阳性即能诱发晕厥或先兆晕厥。初次倾斜试验,A组14例在基础状态下诱发晕厥(7例)或先兆晕厥(7例)B组7例在静脉给予异丙肾上腺素(0.03～0.1μg/kg/min)时诱发晕厥(3例)或先兆晕厥(4例)。1例表现为心脏抑制(心率减慢≥20％或症状开始时心脏停搏≥ At least one unexplained syncope occurred in 13 ± 3 (8-20) years of age (male 7, female 14), and syncope or pre-syncope could be induced by a positive tilt test. In the initial tilt test, 14 patients in group A developed syncope (n = 7) or 7 patients in group B (n = 7). Group B received syncope (0.03-0.1 μg / kg / min) with isoproterenol 3 cases) or threatened syncope (4 cases). One patient showed cardiac suppression (heart rate slowed ≥20% or cardiac arrest ≥ at onset of symptoms