Hysteresis of the RT interval with exercise - A new marker for the long-QT syndrome?
Hysteresis of the RT interval with exercise - A new marker for the long-QT syndrome?
复制标题
DOI：
10.1161/01.cir.96.5.1551
复制
发表时间：
1997-09-02
期刊：
影响因子：
37.8
通讯作者：
Yee, R
中科院分区：
文献类型：
--
作者：
Krahn, AD;Klein, EJ;Yee, R
背景长QT综合征（LQTS）的诊断在QT间期正常或边缘性延长的患者中可能难以确定。需要无创标记物来识别LQTS患者。方法与结果14例已知LQTS患者、9例未患LQTS的家庭成员和40例对照组进行改良布鲁斯方案运动测试。在运动和恢复期间测量RT间隔（R波峰到T波峰）和速率校正RT间隔（RTc）。恢复后1分钟的RT间隔从运动时相似心率（ART）的RT间隔中减去。LQTS患者的RTc缩短了61毫秒（ms），而其他两组患者的RTc缩短了23至26毫秒（方差分析P= 0.003）。所有患者的RT时间间隔均以线性方式缩短，但在LQTS患者的恢复过程中持续缩短。这在RT间隔与周期长度的曲线中表现为一个滞后回路。14例LQTS患者中有13例存在迟滞环，而40例对照组中只有4例存在迟滞环。Delta RT >25 ms对LQTS的敏感性为73%，特异性为92%，阳性预测值为79%，阴性预测值为90%。结论运动时RT间隔的迟滞对LQTS的诊断有一定的参考价值。
Background The diagnosis of the long-QT syndrome (LQTS) may be difficult to establish in patients with normal or borderline prolongation of the QT interval. Noninvasive markers are needed to identify patients with LQTS.Methods and Results Fourteen patients with known LQTS, 9 unaffected family members, and 40 control subjects underwent modified Bruce protocol exercise testing. The RT interval (peak of R wave to peak of T wave) and rate-corrected RT interval (RTc) were measured during exercise and recovery. The RT interval at 1 minute into recovery was subtracted from the RT interval at a similar heart rate during exercise (ART). The RTc shortened by 61 milliseconds (ms) in the LQTS patients compared with 23 to 26 ms in the other two groups (P=.003 by ANOVA). The RT interval shortened in a linear fashion in all patients but demonstrated persistent shortening during recovery in the LQTS patients. This was manifested as a hysteresis loop in the curve relating the RT interval to cycle length. The hysteresis loop was present in 13 of 14 LQTS patients and only 4 of 40 control subjects. Delta RT >25 ms had a sensitivity of 73%, a specificity of 92%, a positive predictive value of 79%, and a negative predictive value of 90% for LQTS.Conclusions Hysteresis of the RT interval with exercise may be useful for the diagnosis of LQTS.