简化利多卡因与钾输注在诊断QTc间期临界延长患者长QT综合征中的效用。
Utility of a simplified lidocaine and potassium infusion in diagnosing long QT syndrome among patients with borderline QTc interval prolongation.
作者信息
Chauhan Vijay S, Krahn Andrew D, Klein George J, Skanes Allan C, Yee Raymond
机构信息
Division of Cardiology, University of Western Ontario, London, ON, Canada.
出版信息
Ann Noninvasive Electrocardiol. 2004 Jan;9(1):12-8. doi: 10.1111/j.1542-474x.2004.91520.x.
BACKGROUND
Congenital long QT syndrome (LQTS) is caused by mutations in the cardiac Na+ or K+ channels that result in a prolonged QTc interval and increased QT dispersion. Na+ channel blockers and K+ can reverse the repolarization abnormalities in the Na+ channel variant (LQT3) and K+ channel variant (LQT1, LQT2), respectively. The phenotype of LQTS can be difficult to recognize, especially when the QTc interval is mildly prolonged. Additional noninvasive testing methods are needed to enhance the diagnosis of LQTS. This study compared the response of the QTc interval and QT dispersion to a sequential lidocaine/K+ infusion in LQTS patients with borderline QTc interval prolongation and control patients as a means of diagnosing LQTS.
METHODS
In this study, eight LQTS patients with borderline QTc, defined as QTc < 470 ms, and 10 healthy controls received sequential lidocaine/K+ infusion.
RESULTS
At baseline, LQTS patients had a longer QTc (446 +/- 29 vs 416 +/- 28 ms, P < 0.05) but similar QT dispersion (43 +/- 14 vs 29 +/- 10 ms) compared to controls. After lidocaine administration, baseline QTc and QT dispersion did not change in either LQTS or controls. One LQTS patient had a 54 ms (12%) reduction in his QTc but no change in QT dispersion. Following K+ infusion, baseline QTc and QT dispersion decreased by 9% (P < 0.005) and 45% (P < 0.005), respectively in LQTS. No effect was seen in control patients, where QTc and QT dispersion shortened by 1% (5 +/- 14 ms) and 20% (6 +/- 7 ms), respectively, compared to baseline. The combined lidocaine/K+ infusion had a sensitivity, specificity, and accuracy of 88%, 100%, and 94%, respectively, in diagnosing LQTS.
CONCLUSIONS
A simplified sequential lidocaine/K+ challenge is accurate in diagnosing LQTS among patients with borderline QTc prolongation.
背景
先天性长QT综合征（LQTS）由心脏钠通道或钾通道突变引起，导致QTc间期延长和QT离散度增加。钠通道阻滞剂和钾分别可逆转钠通道变异型（LQT3）和钾通道变异型（LQT1、LQT2）中的复极异常。LQTS的表型可能难以识别，尤其是当QTc间期轻度延长时。需要额外的非侵入性检测方法来加强LQTS的诊断。本研究比较了QTc间期和QT离散度对LQTS患者（QTc间期临界延长）和对照患者进行利多卡因/钾顺序输注的反应，以此作为诊断LQTS的一种方法。
方法
在本研究中，8例QTc临界（定义为QTc<470毫秒）的LQTS患者和10例健康对照接受了利多卡因/钾顺序输注。
结果
基线时，与对照组相比，LQTS患者的QTc更长（446±29对416±28毫秒，P<0.05），但QT离散度相似（43±14对29±10毫秒）。给予利多卡因后，LQTS患者和对照组的基线QTc和QT离散度均未改变。1例LQTS患者的QTc降低了54毫秒（12%），但QT离散度无变化。钾输注后，LQTS患者的基线QTc和QT离散度分别降低了9%（P<0.005）和45%（P<0.005）。对照患者未见效应，与基线相比，QTc和QT离散度分别缩短了1%（5±14毫秒）和20%（6±7毫秒）。联合利多卡因/钾输注诊断LQTS的敏感性、特异性和准确性分别为88%、100%和94%。
结论
简化的利多卡因/钾顺序激发试验在诊断QTc临界延长患者的LQTS方面是准确的。
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