Stafford P J, Cooper J, Fothergill J, Schlindwein F, deBono D P, Garratt C J
Department of Cardiology, Glenfield Hospital, Leicester, United Kingdom.
Heart. 1997 May;77(5):412-6. doi: 10.1136/hrt.77.5.412.
To assess the reproducibility of time and frequency domain variables derived from the signal averaged P wave.
Longitudinal within patient study.
Regional cardiothoracic centre.
20 patients (10 with documented paroxysmal atrial fibrillation and 10 normal controls) were studied on three occasions to assess the reproducibility of repeated signal averaged P wave recordings. Digital P wave recordings were made on a further 10 patients on a single occasion and the recordings signal averaged twice in order to assess the reproducibility of the averaging system itself in the absence of biological variation.
P wave duration, spatial velocity, and energies contained in frequency bands from 20, 30, and 60-150 Hz of the P wave spectrum were measured after P wave specific signal averaging. Coefficients of reproducibility were calculated for paired signal averaged P waves derived by signal averaging the same digital recordings on two separate occasions, for recordings performed in the same patients immediately after each other ("back to back") and those performed one week apart.
System reproducibility when the same digital P wave recordings were signal averaged on two separate occasions was high (< 11% for all variables). For P wave duration the coefficient of reproducibility was 11.4% for back to back recordings and 13.1% for those one week apart. The reproducibility of spatial velocity and P wave energy was low. Variation in P wave morphology was noted when successive P waves from the same subject were examined. If recordings with the same P wave morphology were analysed the reproducibility of spatial velocity and P wave energy improved but remained significantly poorer than that for P wave duration.
P wave duration is reproducible within subjects in the short and medium term. Frequency domain and spatial velocity analysis are poorly reproducible, due more to spontaneous variation in P wave morphology than to instability of the signal averaging process. This may limit the utility of signal averaged P wave variables other than duration for the prediction of atrial arrhythmia.
评估从信号平均P波得出的时域和频域变量的可重复性。
患者自身纵向研究。
地区心胸中心。
对20名患者（10名有阵发性心房颤动记录者和10名正常对照者）进行了三次研究，以评估重复信号平均P波记录的可重复性。另外对10名患者进行了单次数字P波记录，并对记录进行了两次信号平均，以评估在无生物变异情况下平均系统本身的可重复性。
在进行P波特异性信号平均后，测量P波持续时间、空间速度以及P波频谱中20、30和60 - 150Hz频段所含能量。计算通过在两个不同时间对相同数字记录进行信号平均得出的配对信号平均P波的可重复性系数，包括在同一患者中紧挨着进行的记录（“背靠背”）以及相隔一周进行的记录。
当在两个不同时间对相同数字P波记录进行信号平均时，系统可重复性较高（所有变量均<11%）。对于P波持续时间，“背靠背”记录的可重复性系数为11.4%，相隔一周记录的为13.1%。空间速度和P波能量的可重复性较低。检查同一受试者连续的P波时，发现P波形态存在变化。如果分析具有相同P波形态的记录，空间速度和P波能量的可重复性有所改善，但仍明显低于P波持续时间的可重复性。
P波持续时间在受试者的短期和中期内具有可重复性。频域和空间速度分析的可重复性较差，更多是由于P波形态的自发变化而非信号平均过程的不稳定性。这可能会限制除持续时间外的信号平均P波变量在预测房性心律失常方面的实用性。
