UNSUSPECTED ECHOCARDIOGRAPHIC ABNORMALITY IN THE LONG QT SYNDROME - DIAGNOSTIC, PROGNOSTIC, AND PATHOGENETIC IMPLICATIONS
UNSUSPECTED ECHOCARDIOGRAPHIC ABNORMALITY IN THE LONG QT SYNDROME - DIAGNOSTIC, PROGNOSTIC, AND PATHOGENETIC IMPLICATIONS
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DOI：
10.1161/01.cir.84.4.1530
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发表时间：
1991-10-01
期刊：
影响因子：
37.8
通讯作者：
SCHWARTZ, PJ
中科院分区：
文献类型：
--
作者：
NADOR, F;BERIA, G;SCHWARTZ, PJ
背景。特发性长QT综合征（LQTS）以心电图异常和致死性心律失常的高发为特征。本病例/对照研究表明，LQTS患者经常发生不寻常和特殊的心室壁运动异常，并与晕厥或心脏骤停病史相关。42例LQTS患者中有23例（55%）存在这些异常，42例健康对照中有2例（5%,p < 0.0001）存在年龄、性别、身高和体重匹配的异常。方法与结果。开发了两种新的测量方法来定量评估观察到的异常。第一个，Th1/2，是早期收缩阶段的速度指数；第二个，TSTh，是在增厚后期存在缓慢运动的指标。LQTS患者的Th1/2较小（15.0 +/- 4.1 vs 19.9 +/- 3.9%, p < 0.001），表明他们比对照组更快地达到半最大收缩。LQTS患者的TSTh更大（9.37 +/- 6.82 vs 2.88 +/- 4.46%, p < 0.001），表明他们在非常低的增厚率下花费了更多的时间。11例患者出现了特殊的双峰型晚期增厚，没有对照组。这些异常在有症状的患者中比在无症状的患者中更常见（26人中有20人占77%，16人中有3人占19%，p < 0.005；相对危险度为2.75）。它们不受-阻断剂或左心交感神经去支配的影响。9只麻醉犬中有9只在右星形切除术时出现相同的超声心动图异常，且与周期长度无关，后续左星形切除术也未改变超声心动图异常。本研究证实了LQTS患者的心室收缩模式存在先前未被怀疑的异常，并首次提供了无创检测到的心脏异常与晕厥/心脏骤停的高风险相关的证据。右星形切除术后超声心动图异常的实验再现表明，LQTS的这一新发现的临床特征与“交感神经失衡”假说并不矛盾。
Background. The idiopathic long QT syndrome (LQTS) is characterized by electrocardiographic abnormalities and by a high incidence of lethal arrhythmias. The present case/control study demonstrates the frequent occurrence of unusual and specific ventricular wall motion abnormalities in LQTS and their association with history of syncope or cardiac arrest. These anomalies were present in 23 of 42 LQTS patients (55%) and in two of 42 healthy controls (5%, p < 0.0001) matched for age, sex, height, and weight.Methods and Results. Two new measurements were developed to assess quantitatively the abnormalities observed. The first, Th1/2, is an index of the rapidity of the early contraction phase; the second, TSTh, is an index of the presence of a slow movement in the late thickening phase. Th1/2 was smaller in LQTS patients (15.0 +/- 4.1 versus 19.9 +/- 3.9% of the cardiac cycle, p < 0.001), indicating that they reach half-maximal systolic contraction more rapidly than controls. TSTh was greater in LQTS patients (9.37 +/- 6.82 versus 2.88 +/- 4.46%, p < 0.001), indicating that they spend more time at a very low thickening rate. A peculiar double peak pattern of late thickening was present in 11 patients and in no controls. These abnormalities were more frequent in symptomatic than in asymptomatic patients (20 of 26, 77%, versus three of 16, 19%, p < 0.005; relative risk, 2.75). They were not affected by beta-blockade or by left cardiac sympathetic denervation. The same echocardiographic abnormalities were produced by right stellectomy in nine of nine anesthetized dogs, were not dependent on cycle length, and were not modified by subsequent left stellectomy.Conclusions. This study demonstrates a previously unsuspected abnormality in the ventricular contraction pattern of LQTS patients and, for the first time, provides evidence that a noninvasively detected cardiac abnormality is associated with a higher risk for syncope/cardiac arrest. The experimental reproduction of this echocardiographic abnormality by right stellectomy indicates that this newly found clinical characteristic of LQTS does not contradict the "sympathetic imbalance" hypothesis.