左心交感神经切除术对长QT综合征患者U波的调节作用

Autonomic modulation of the U wave by left cardiac sympathetic denervation in long QT syndrome patients

目的为进一步理解T波和U波的关系及U波在长QT综合征(LQTS)中的病理生理学意义。方法对11例LQTS患者行左心交感神经切除(LCSD)手术,评价其手术前后及跟踪期间ECG上U波和T波变化。结果术后QTc(校正的QT间期:从0.50±0.05s到0.47±0.03s,P=0.02)、QTp(从QRS波起始到T波顶点的时间间隔:0.37±0.07s到0.33±0.06s,P=0.041)和QTpc(校正的QTp:从0.37±0.07s到0.34±0.05s,P=0.006)均显著缩短。同时QU间期(从QRS波起始到U波结束)、QUc(校正的QU间期)、QUp(从QRS波起始到U波顶点的时间间隔)、QUpc(校正的QUp)却无显著改变。TpTe(同一导联上T波顶点到T波结束点的时间间隔)无显著变化,但TpTe-max(12导联中最早的T波顶点到最晚的T波结束点的时间间隔,代表跨壁复极离散度:0.21±0.09s到0.18±0.07s,P=0.02)显著降低。U波幅度、T波幅度及U/T幅度比值均无显著变化,但TpUp(T波顶点到U波顶点的时间间隔:0.16±0.06s到0.19±0.05s,P=0.041)显著增加。手术后2天内,多数患者U波更明显并叠加于T波之上形成T-U融合现象;但随后融合程度逐渐减轻。结论LQTS患者的U波与T波具有不同的起源机制,因此在诊断LQTS测量QT间期时不应包含U波。

Objective To further explore the relationship between T and U waves and the pathophysiologic and clinical relevance of U wave. Methods 11 long QT syndrome （LQTS） patients undergone left cardiac sympathetic denervation （LCSD） surgery were followed up and 12 lead-ECG were recorded. U and T waves were assessed before and after surgery. Results QTc （ corrected QT interval ： from 0.50 ± 0.05 s to 0.47 ± 0.03 s, P = 0.02）, QTp （ the interval from QRS onset to T peak ： from 0.37 ± 0.07 s to 0.33 ± 0.06 s, P = 0. 041 ） and QTpc （ corrected QTp ： from 0.37 ± 0.07 s to 0.34 ± 0.05 s, P = 0. 006） all significantly shortened. Meanwhile, Qu interval, QUc （ corrected QU）, QUp （ the interval from QRS onset to U peak） and QUpc （corrected QUp） did not changed. TpTe （the interval from T peak to T end on the same lead） did not change,but TpTe-max [ the interval from the earliest T peak to the latest T end across 12 leads, representing transmural dispersion of repolarization （TDR） ： 0. 21 ±0. 09 s to 0. 18 ±0. 07s, P =0.02] significantly decreased. The amplitude of U and T waves and U/T ratio did not alter. However, the TpUp （the interval from T peak to U peak ： from 0. 16 ± 0.06 s to 0.19 ± 0.05 s, P = 0. 041 ） significantly increased. Enlarged U waves and T-U merging occurred within 2 days after surgery and then gradually decreased for most patients. Conclusions U wave has different origin from the T wave for the LQTS patients and U wave should not be included for the QT measurement in LQTS diagnosis.