Halámek J, Jurák P, Vondra V, Viščor I, Plachý M, Leinveber P
Institute of Scientific Instruments, Academy of Sciences, Czech Republic, Kralovopolska 147, 612 64 Brno, Czech Republic.
Annu Int Conf IEEE Eng Med Biol Soc. 2011;2011:961-4. doi: 10.1109/IEMBS.2011.6090217.
The excitation specificity of QT dynamic parameters was tested on three groups of subjects: healthy subjects; non-medicated hypertensive subjects with metabolic syndrome; and subjects with essential hypertension. Four different excitations of RR were used: bicycling exercise; tilt with breathing 0.1 and 0.33 Hz; and deep breathing. Linear dynamic feedback model of QT/RR coupling was supposed at the analysis and next repolarization parameters were tested: QTc; gain of QT/RR coupling for slow and fast RR variability; time constant of QT adaptation; and random QT variability.
Dynamic repolarization parameters statistically significantly depend on the type of RR excitation. The gain of QT/RR coupling for slow RR variability, the time constant of QT adaptation and QTc are maximal at RR excitation given by the bicycling exercise. The frequency of breathing, i.e. corresponding vagal modulation has no effect on repolarization parameters. The measurements with deep breathing, without any other slow excitation of heart rate, has low signal-to-noise ratio of analyzed data and resulting QT parameters are inaccurate.
The use of heart rate excitation and all measurements conditions should be defined for the exact analysis of the repolarization dynamic parameters.
在三组受试者身上测试了QT动态参数的激发特异性：健康受试者；患有代谢综合征的未用药高血压受试者；以及原发性高血压受试者。使用了四种不同的RR激发方式：骑自行车运动；以0.1和0.33Hz呼吸频率进行倾斜试验；以及深呼吸。分析时假设QT/RR耦合的线性动态反馈模型，然后测试以下复极化参数：校正QT间期（QTc）；QT/RR耦合对RR慢变异性和快变异性的增益；QT适应的时间常数；以及随机QT变异性。
动态复极化参数在统计学上显著依赖于RR激发的类型。对于RR慢变异性，QT/RR耦合的增益、QT适应的时间常数以及QTc在骑自行车运动所给予的RR激发时最大。呼吸频率，即相应的迷走神经调制，对复极化参数没有影响。在没有任何其他心率慢激发的情况下进行深呼吸测量，分析数据的信噪比很低，由此得到的QT参数不准确。
为了准确分析复极化动态参数，应明确心率激发的使用方式和所有测量条件。
