Maury Philippe, Metzger Jacques
Division of Cardiology, Center Hospitalier, Universitaire Vaudois, Lausanne, Switzerland.
Pacing Clin Electrophysiol. 2002 Feb;25(2):142-50. doi: 10.1046/j.1460-9592.2002.00142.x.
Although the value of T wave alternans as an index of electrical instability has been extensively investigated, little is known about QRS alternans during VT. Intracardiac electrograms of 111 episodes of spontaneous monomorphic regular VT retrieved from implantable defibrillators in 25 patients were retrospectively selected. Three beat series, representing the total amplitudes and amplitudes from baseline to summit and from baseline to lower point of 16 or 32 successive QRS complexes before deliverance of electrical therapy were generated for each episode. Spectral analysis was then performed using the fast Fourier transform. VT was considered as alternans if the magnitude of the spectral power at the 0.5-cycle/beat frequency was greater than the mean +/- 3 SD of the noise in at least one of the three spectral curves. QRS alternans was present in 23 (20%) of 111 episodes and in 9 (36%) of 25 patients. Alternans was not related to the VT cycle length, QRS duration, QRS amplitude, signal amplification, nor to clinical variables. Alternans was more frequently detected in unipolar configuration and when a higher number of complexes was included in analysis. Failure of antitachycardia pacing was more frequent in case of alternans VT (50% vs 75% success in nonalternans VT, P = 0.05). Spontaneous termination before deliverance of therapy occurred in 16 non-alternans VT but never in alternans episodes (P = 0.02). Alternans in QRS amplitude is a relatively common finding during VT and could be associated with failure of antitachycardia pacing and lack of spontaneous termination. Lower efficacy of electrical therapies in case of QRS alternans must be confirmed in a way to improve the effectiveness of antitachycardia pacing.
尽管T波交替作为电不稳定指标的价值已得到广泛研究，但对于室性心动过速（VT）期间的QRS波交替却知之甚少。回顾性选取了25例患者植入式除颤器记录的111次自发性单形性规则室性心动过速发作的心内电图。针对每次发作，生成了三个搏动序列，分别代表电治疗前16或32个连续QRS波群的总振幅、从基线到波峰的振幅以及从基线到最低点的振幅。然后使用快速傅里叶变换进行频谱分析。如果在三个频谱曲线中至少有一条曲线的0.5周期/搏动频率处的频谱功率幅度大于噪声的均值±3标准差，则将室性心动过速视为交替现象。111次发作中有23次（20%）出现QRS波交替，25例患者中有9例（36%）出现。交替现象与室性心动过速的周期长度、QRS波时限、QRS波振幅、信号放大以及临床变量均无关。交替现象在单极配置中更常被检测到，且分析中纳入的复合波数量较多时也更常被检测到。对于交替性室性心动过速，抗心动过速起搏失败更为常见（交替性室性心动过速成功率为50%，非交替性室性心动过速为75%，P = 0.05）。治疗前有16次非交替性室性心动过速出现自发终止，但交替性发作中从未出现（P = 0.02）。QRS波振幅交替是室性心动过速期间相对常见的表现，可能与抗心动过速起搏失败和缺乏自发终止有关。QRS波交替情况下电治疗效果较低这一点必须通过某种方式加以证实，以提高抗心动过速起搏的有效性。
