Carpenter R E, D'Silva L A, Emery S J, Uzun O, Rassi D, Lewis M J
College of Engineering, Swansea University, Swansea, UK.
Physiol Meas. 2015 Mar;36(3):531-45. doi: 10.1088/0967-3334/36/3/531. Epub 2015 Feb 18.
The risk of new-onset arrhythmia during pregnancy is high, presumably relating to changes in both haemodynamic and cardiac autonomic function. The ability to non-invasively assess an individual's risk of developing arrhythmia during pregnancy would therefore be clinically significant. We aimed to quantify electrocardiographic temporal characteristics during the first trimester of pregnancy and to compare these with non-pregnant controls. Ninety-nine pregnant women and sixty-three non-pregnant women underwent non-invasive cardiovascular and haemodynamic assessment during a protocol consisting of various physiological states (postural manoeurvres, light exercise and metronomic breathing). Variables measured included stroke volume, cardiac output, heart rate, heart rate variability, QT and QT variability and QTVI (a measure of the variability of QT relative to that of RR). Heart rate (p < 0.0005, p < 0.0005, p < 0.0005) and cardiac output (p = 0.043, p < 0.0005, p < 0.0005) were greater in pregnant women in all physiological states (respectively for the supine position, light exercise and metronomic breathing state), whilst stroke volume was lower in pregnancy only during the supine position (p < 0.0005). QTe (Q wave onset to T wave end) and QTa (T wave apex) were significantly shortened (p < 0.05) and QTeVI and QTaVI were increased in pregnancy in all physiological states (p < 0.0005). QT variability (p < 0.002) was greater in pregnant women during the supine position, whilst heart rate variability was reduced in pregnancy in all states (p < 0.0005). Early pregnancy is associated with substantial changes in heart rate variability, reflecting a reduction in parasympathetic tone and an increase in sympathetic activity. QTVI shifted to a less favourable value, reflecting a greater than normal amount of QT variability. QTVI appears to be a useful method for quantifying changes in QT variability relative to RR (or heart rate) variability, being sensitive not only to physiological state but also to gestational age. We support the use of non-invasive markers of cardiac electrical variability to evaluate the risk of arrhythmic events in pregnancy, and we recommend the use of multiple physiological states during the assessment protocol.
孕期新发心律失常的风险很高，这可能与血流动力学和心脏自主神经功能的变化有关。因此，能够非侵入性地评估个体在孕期发生心律失常的风险在临床上具有重要意义。我们旨在量化妊娠早期的心电图时间特征，并将其与非孕对照组进行比较。99名孕妇和63名非孕妇在包含各种生理状态（体位改变、轻度运动和节律性呼吸）的方案中接受了非侵入性心血管和血流动力学评估。测量的变量包括每搏输出量、心输出量、心率、心率变异性、QT间期和QT变异性以及QTVI（QT相对于RR变异性的一种测量指标）。在所有生理状态下（分别为仰卧位、轻度运动和节律性呼吸状态），孕妇的心率（p < 0.0005，p < 0.0005，p < 0.0005）和心输出量（p = 0.043，p < 0.0005，p < 0.0005）均更高，而仅在仰卧位时孕期的每搏输出量较低（p < 0.0005）。在所有生理状态下，孕期的QTe（Q波起点至T波终点）和QTa（T波顶点）均显著缩短（p < 0.05），且QTeVI和QTaVI增加（p < 0.0005）。孕妇在仰卧位时QT变异性更大（p < 0.002），而在所有状态下孕期心率变异性均降低（p < 0.0005）。妊娠早期与心率变异性的显著变化相关，反映出副交感神经张力降低和交感神经活动增加。QTVI转变为不太有利的值，反映出QT变异性高于正常水平。QTVI似乎是一种量化QT相对于RR（或心率）变异性变化的有用方法，不仅对生理状态敏感，而且对孕周敏感。我们支持使用心脏电变异性的非侵入性标志物来评估孕期心律失常事件的风险，并且我们建议在评估方案中使用多种生理状态。
