Biagetti Marcelo O, Arini Pedro D, Valverde Esteban R, Bretran Guillermo C, Quinteiro Ricardo A
Cardiac Electrophysiology Laboratory, Department of Physiology, Favaloro University, Buenos Aires, Argentina.
J Cardiovasc Electrophysiol. 2004 Mar;15(3):356-63. doi: 10.1046/j.1540-8167.2004.03466.x.
Repolarization heterogeneity has been shown to constitute a substrate for malignant ventricular arrhythmias. Noninvasive measurement of abnormal repolarization through assessment of QT interval dispersion from the resting standard 12-lead ECG initially had shown promise in assessing arrhythmia risk but was challenged recently. The relative T wave residuum (TWR) has been proposed recently to reflect regional repolarization dispersion more accurately. We analyzed the role played by the dipolar and nondipolar components in determining TWR.
Singular value decomposition was applied to the repolarization signals obtained from isolated rabbit hearts using a 5 x 8 array multielectrode recording system during premature beats (N = 11) and after d-sotalol (N = 9) exposure. Both the dipolar and nondipolar components of the T wave increased significantly during premature stimulation and after d-sotalol exposure. The relative TWR decreased significantly during premature stimulation but did not change after d-sotalol. Changes in the dipolar and nondipolar components of the second half of the T wave were significantly greater than those corresponding to the first half during premature stimulation, and a significant correlation was observed between the nondipolar components of the second half of the T wave and the T(peak-end) interval.
Conditions exist during which both the dipolar and nondipolar components can change simultaneously. Under these conditions, the relative TWR may not reflect regional heterogeneity of repolarization with accuracy. The nondipolar components of the second half of the T wave can be linked to assessment of the transmural dispersion of repolarization.
复极异质性已被证明是恶性室性心律失常的基础。通过评估静息标准12导联心电图的QT间期离散度来无创测量异常复极，最初在评估心律失常风险方面显示出前景，但最近受到了挑战。最近有人提出相对T波残差（TWR）能更准确地反映区域复极离散度。我们分析了偶极和非偶极成分在确定TWR中所起的作用。
应用奇异值分解对使用5×8阵列多电极记录系统从离体兔心获得的复极信号进行分析，这些信号来自早搏期间（N = 11）和暴露于d - 索他洛尔后（N = 9）。在早搏刺激期间和暴露于d - 索他洛尔后，T波的偶极和非偶极成分均显著增加。在早搏刺激期间，相对TWR显著降低，但在d - 索他洛尔作用后未发生变化。早搏刺激期间，T波后半部分的偶极和非偶极成分变化显著大于前半部分，并且观察到T波后半部分的非偶极成分与T（峰 - 末）间期之间存在显著相关性。
存在偶极和非偶极成分可同时变化的情况。在这些情况下，相对TWR可能无法准确反映复极的区域异质性。T波后半部分的非偶极成分可与复极跨壁离散度的评估相关联。
