De Ambroggi L, Bertoni T, Locati E, Stramba-Badiale M, Schwartz P J
Circulation. 1986 Dec;74(6):1334-45. doi: 10.1161/01.cir.74.6.1334.
Body surface potential maps were recorded from 140 chest leads in 25 patients affected by the idiopathic long QT syndrome (LQTS) and in 25 healthy control subjects matched for age and sex. Potential time integrals of the QRST and ST-T intervals were calculated at each lead point and displayed as isointegral (ISOI) maps. The main abnormalities noted on the QRST and ST-T ISOI maps were one area of negative values larger than normal in the right anterior and inferior thorax and a complex multipeak distribution of the integral values. At least one abnormality was present in 19 (76%) of the patients with LQTS and four (16%) of the control subjects (p less than .001). Each ISOI map was also represented as a weighted sum of nine fundamental components (eigenvectors) to detect and quantitate the nondipolar content. The percent contribution of the nondipolar eigenvectors (all eigenvectors beyond the third) was significantly higher in the LQTS group than in the control group (p less than .005). Specifically, an abnormally high nondipolar content on the QRST ISOI maps was observed much more frequently for patients with LQTS than for control subjects (nine or 36% vs one or 4%), and this was also true on the ST-T ISOI maps (14 or 56% vs one or 4%). No correlation was found between the major abnormalities on body surface maps and syncopal episodes. However, the high prevalence (76%) of these alterations among the patients with LQTS and their infrequent occurrence in the control population strongly suggests that they may be useful markers for the diagnosis of atypical cases. The prominent electronegative area on the anterior thorax can be related to delayed repolarization of a portion of the anterior wall of the heart. This finding is in agreement with the hypothesis that lower than normal right cardiac sympathetic activity is the main pathogenetic mechanism of LQTS. Multipeak distribution and high nondipolar content suggest regional electrical disparities in the ventricular recovery process. This may in part account for the high susceptibility of patients with LQTS to malignant arrhythmias.
对25例特发性长QT综合征（LQTS）患者及25名年龄和性别相匹配的健康对照者，记录了140个胸导联的体表电位图。计算每个导联点处QRST和ST-T间期的电位时间积分，并显示为等积分（ISOI）图。在QRST和ST-T ISOI图上观察到的主要异常为右前胸和下胸部一个比正常范围更大的负值区域以及积分值的复杂多峰分布。19例（76%）LQTS患者和4例（16%）对照者至少存在一种异常（p<0.001）。每个ISOI图还表示为九个基本成分（特征向量）的加权和，以检测和量化非偶极成分。LQTS组中非偶极特征向量（所有超过第三个特征向量）的贡献百分比显著高于对照组（p<0.005）。具体而言，LQTS患者在QRST ISOI图上出现异常高非偶极成分的频率远高于对照者（9例或36%对1例或4%），在ST-T ISOI图上也是如此（14例或56%对1例或4%）。体表图上的主要异常与晕厥发作之间未发现相关性。然而，这些改变在LQTS患者中的高发生率（76%）及其在对照人群中的罕见发生强烈提示它们可能是诊断非典型病例的有用标志物。前胸壁突出的电负性区域可能与心脏前壁一部分的复极延迟有关。这一发现与右心交感神经活动低于正常是LQTS主要发病机制的假说一致。多峰分布和高非偶极成分提示心室恢复过程中存在区域电差异。这可能部分解释了LQTS患者对恶性心律失常的高易感性。
