长QT综合征患者运动试验特征及左心交感神经切除术的影响

目的探讨左心交感神经切除术(LCSD)降低长QT综合征(LQTS)患者心脏事件发生率的机制。方法观察12例LQTS患者在运动试验过程中模拟交感神经活性增高的情况,总结其变化特征,比较LCSD手术前后这些特征的改变情况。结果手术使静息时的心率校正QT间期(QTc)缩短(0.54s±0.04s到0.50s±0.04s,P=0.026),使运动时所达到的最大心率降低(141次/min±18次/min到124次/min±14次/min,P=0.003)。运动过程中LQTS患者表现为运动中的QTc有所缩短,在运动末和/或恢复早期显著延长(运动前:0.54s±0.02s,运动10min:0.46s±0.02s,恢复4min:0.55s±0.03s);手术使恢复早期QT间期骤然升降的程度明显减小(术后运动前:0.53s±0.03s,运动10min:0.48s±0.03s,恢复4min:0.53s±0.05s)。代表QT间期对心率适应性反应的参数———QT对RR间期的斜率,运动后与运动前相比,变得明显陡峭,从运动前的0.61±0.06升高到运动后的0.71±0.07,P<0.01。手术使运动前的斜率变得明显平缓(术前0.61±0.06,术后0.55±0.07,P=0.013);同时使运动后的斜率也变得明显平缓(术前0.71±0.07,术后0.66±0.06,P=0.018)。手术前有7例患者在运动末和/或恢复早期有顿挫T波的形态变化,手术使其中的4例变化消失。结论LCSD手术可使LQTS患者运动前后的QT/RR间期斜率都变平缓,从而降低了运动引起的QT间期过度延长,这可能是其有效治疗LQTS的机制之一。

The characteristics during exercise test in long QT syndrome patients and the effects of left cardiac sympathetic denervation

OBJECTIVE: To explore the mechanism of the left cardiac sympathetic denervation (LCSD) surgery to reduce the incidence of cardiac events for long QT syndrome (LQTS) patients. METHODS: 12 LQTS patients were selected to do exercise test (ET) to mimic sympathetic activation. The dynamic alterations on ECG during exercise and recovery phases (Rec) were observed and the exercise test characteristics for LQTS patients before and after surgery were summarized and compared. RESULTS: The QTc at resting was shortened from 0.54 s +/- 0.04 s to 0.50 s +/- 0.04 s, P = 0.026, while the maximum heart rate during exercise decreased from 141 beat/min +/- 18 beat/min to 124 beat/min +/- 14 beat/min, P = 0.003. QTc was shortened during exercise, however, it was prolonged during the early recovery phase (before ET 0.54 s +/- 0.02 s, ET 10 min 0.46 s +/- 0.02 s, Rec 4 min 0.55 s +/- 0.03 s); LCSD could reduce such abrupt alteration of QTc during early recovery phase (after surgery: before ET 0.53 s +/- 0.03 s, ET 10 min 0.48 s +/- 0.03 s, Rec 4 min 0.53 s +/- 0.05 s). QT/RR interval slope, representing the adaptation response of QT interval to heart rate, became steeper after exercise (from 0.61 +/- 0.06 to 0.71 +/- 0.07 after exercise, P < 0.01). LCSD made the slopes become less steep both before exercise (from 0.61 +/- 0.06 before surgery to 0.55 +/- 0.07 after surgery, P = 0.013) and after exercise (from 0.71 +/- 0.07 before surgery to 0.66 +/- 0.06 after surgery, P = 0.018). Notched T wave alterations occurred in 7 patients at the end of exercise and/or during early recovery phase before surgery, and LCSD diminished such alteration in 4 patients. CONCLUSION: The slope between QT and RR both the pre-exercise and post-exercise slopes, interval becomes less steep after LCSD, which suggests that exaggerated delay in repolarization with decreasing heart rate for LQTS patients is improved by LCSD. This may be one of the mechanisms of LCSD efficacy for treating LQTS patients. Exercise test is one of tools to evaluate the effect of LCSD on LQTS patients.