CIRCADIAN RHYTHMICITY OF RATE-NORMALIZED QT INTERVAL IN HYPOTHYROIDISM AND ITS SIGNIFICANCE FOR DEVELOPMENT OF CLASS-III ANTIARRHYTHMIC AGENTS
CIRCADIAN RHYTHMICITY OF RATE-NORMALIZED QT INTERVAL IN HYPOTHYROIDISM AND ITS SIGNIFICANCE FOR DEVELOPMENT OF CLASS-III ANTIARRHYTHMIC AGENTS
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DOI：
10.1016/0002-9149(90)90933-r
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发表时间：
1990-10-15
影响因子：
2.8
通讯作者：
SINGH, BN
中科院分区：
文献类型：
--
作者：
SARMA, JSM;VENKATARAMAN, K;SINGH, BN
甲状腺功能减退患者复极延长且不易治愈；它与心律失常的可能性降低有关，而甲状腺机能亢进则相反。由于QT间期及其相对于心率的昼夜节律性在男性中定义不清，我们在分析10例甲状腺功能减退患者甲状腺素（T4）替代前后（8至12周）24小时动态心电图时使用了新的计算机辅助技术来测量QT间期；将结果与6名正常对照者进行比较。甲状腺功能减退时QTc间期延长（p < 0.02），心率降低（p < 0.005）。通过重复测量分析分析数据的昼夜节律性。在甲状腺功能减退和甲状腺功能正常状态下以及对照组，QTc和心率的昼夜节律变化有统计学意义（p < 0.001），但QTc间期和心率的昼夜节律不一致；QTc的最大延长发生在午夜到早上6点之间，这是心率最低的时候。T4置换8 ~ 12周后，甲状腺功能减退生化指标恢复正常，QTc间期明显延长。我们使用的计算机辅助QTc间隔测定技术，以及我们关于QTc和心率昼夜节律的数据，对开发新的III类抗心律失常药物具有重要意义。
Lengthening of repolarization and refractoriness occurs in hypothyroidism; it is associated with a reduced probability of arrhythmias, with the converse occurring in hyperthyroidism. Because the QT interval and its circadian rhythmicity relative to heart rate is poorly defined in man, we used our new computer-assisted technique to measure QT interval in our analysis of 24-hour Holter tapes before and after (8 to 12 weeks) thyroxine (T4) replacement in 10 patients with hypothyroidism; the findings were compared to those in 6 normal control subjects. QTc interval was prolonged (p < 0.02) and heart rate decreased (p < 0.005) during the hypothyroid state. Data were analyzed for circadian rhythmicity by repeated-measures analysis. Circadian variation in QTc and heart rate was statistically significant during hypothyroid and euthyroid states (p < 0.001) as well as in control subjects, but the circadian rhythmicity of QTc interval and heart rate were out of phase; the maximum prolongation of QTc occurred between midnight and 6 A.M., at a time when heart rate was at its lowest. QTc interval remained significantly prolonged after 8 to 12 weeks of T4 replacement, when biochemical indexes of hypothyroidism had returned to normal values. The computer-assisted QTc interval determination technique that we used, and our data on the circadian rhythmicity of QTc and heart rate, have significant implications for the development of new class III antiarrhythmic agents.