Seed W A, Noble M I, Oldershaw P, Wanless R B, Drake-Holland A J, Redwood D, Pugh S, Mills C
Br Heart J. 1987 Jan;57(1):32-7. doi: 10.1136/hrt.57.1.32.
Fourteen patients undergoing routine cardiac catheterisation were paced at a steady frequency; after this test, stimuli were introduced with a variable preceding interval (test pulse interval). The QT interval of the electrocardiogram and the duration of the monophasic action potential of the right ventricle were measured. QT interval is a function of action potential duration; the two variables were very closely correlated in this study. Both these variables increased in duration with increasing test pulse interval. A biphasic response, as previously reported, was not seen. An increase in steady state pacing frequency caused QT interval and action potential duration to decrease for any given R-R interval. When frequency of stimulation was suddenly increased and then maintained, there was an immediate action potential shortening followed by a further more gradual shortening occurring over several minutes. These results imply that a simple correction of QT interval for heart rate (QTc) is inadequate. It is concluded that the relation between action potential duration (or QT interval) and heart rate depends on both the instantaneous interval between beats and the duration of the prevailing heart rate.
14名接受常规心导管检查的患者以稳定频率进行起搏；在此测试后，引入具有可变前导间期（测试脉冲间期）的刺激。测量心电图的QT间期和右心室单相动作电位的持续时间。QT间期是动作电位持续时间的函数；在本研究中，这两个变量密切相关。随着测试脉冲间期增加，这两个变量的持续时间均增加。未观察到如先前报道的双相反应。对于任何给定的R-R间期，稳态起搏频率增加会导致QT间期和动作电位持续时间缩短。当刺激频率突然增加然后维持时，动作电位立即缩短，随后在几分钟内进一步逐渐缩短。这些结果表明，简单地校正心率的QT间期（QTc）是不够的。结论是，动作电位持续时间（或QT间期）与心率之间的关系取决于心动周期的瞬时间期和当前心率的持续时间。
