QTc 間期延長(QTcinterval prolongation) 是一個可能導致後續致命性心室性心律失常，引起心臟驟停(cardiac arrest) 和突然死亡的重要臨床症候。少數研究報告顯示甲狀腺功能亢進症也可以導致QTc 間期延長。我們報告一個甲狀腺功能亢進症患者由於QTc 間期延長，同時使用各種藥物和電解質紊亂而發生多型性心室心搏過速Torsade de pointes (TdP)。這名46 歲曾接受過手術的葛瑞夫茲氏病(Graves’ disease) 婦女，因胸悶、胸痛、呼吸困難、噁心、嘔吐來我們醫院就診，進一步甲狀腺功能檢查發現甲狀腺功能亢進症復發，游離T4、T3 值升高和TSH 值低下，心電圖顯示QTc 間期延長。入院後使用促進胃腸蠕動劑metoclopramide，利尿劑furosemide 治療兩天後，心臟驟停，失去意識，心電圖顯示多型性心室心搏過速TdP。經過心肺復甦術及除顫後，患者恢復了意識及自發性循環。甲狀腺功能亢進症患者，常規進行心電圖檢查有其重要性。QTc 間期延長如果沒有被及時的加以診斷，且同時併用了可能誘發TdP 的藥物，或電解質紊亂，有可能導致臨床嚴重的後果。

QTc interval prolongation is an important clinical symdrome that can lead to subsequent fatal ventricular arrhythmias, causing cardiac arrest and sudden death. A few studies have shown that hyperthyroidism can also lead to prolonged QTc interval. We report a multi-type ventricular tachycardia Torsade de pointes (TdP) in patient with hyperthyroidism due to prolonged QTc interval, concurrent use of various drugs and electrolyte disorders. The 46-year-old woman with Graves’ disease post subtotal thyroidectomy was admitted to our hospital for chest tightness, chest pain, dyspnea, nausea, and vomiting. Further thyroid function tests revealed recurrence of hyperthyroidism, with elevated free T4, T3 values, and low TSH values. The ECG shows an prolongation of the QTc interval. After two days of treatment with the gastrointestinal motility agent metoclopramide, the diuretic furosemide, she was found cardiac arrest, loss of consciousness and electrocardiogram showed polymorphic tachycardia TdP. After cardiopulmonary resuscitation and defibrillation, the patient recovered consciousness and spontaneous circulation. In patients with hyperthyroidism, it is important to have an electrocardiogram routinely performed. Prolonged QTc interval, if not been diagnosed in time, and concurrently been treated with medication that cause or potentially cause TdP, or electrolyte imbalance may have serious clinical consequences.