左心交感神经切除术对长QT综合征患者U波的调节作用

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。

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

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.