Autonomic modulation of the u wave during sympathomimetic stimulation and vagal inhibition in normal individuals.
Autonomic modulation of the u wave during sympathomimetic stimulation and vagal inhibition in normal individuals.
复制标题
正常个体拟交感神经刺激和迷走神经抑制期间 u 波的自主调节。
DOI：
10.1111/j.1540-8159.2004.00665.x
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发表时间：
2004
期刊：
影响因子：
--
通讯作者：
Bloomfield,DanielM
中科院分区：
文献类型：
--
作者：
Magnano,AnthonyR;Holleran,Steve;Ramakrishnan,Rajasekhar;Reiffel,JamesA;Bloomfield,DanielM
Prolonged repolarization time, an important contributor to the pathogenesis of ventricular arrhythmias, is usually identified by a long QT interval (QT) on the ECG but is frequently confounded by the presence of a U wave. The physiological basis and clinical relevance of the U wave is unresolved. To better understand the relationship between the T and U waves, this study examined their behavior during nonresting autonomic conditions. Twenty‐five healthy subjects were evaluated during sympathomimetic infusion with isoproterenol and vagal inhibition with atropine. As heart rate (HR) increased in response to isoproterenol, the QU interval (QU) decreased by an eightfold greater extent than QT. Furthermore, a marked increase in U wave amplitude and decrease in T wave amplitude were observed with T and U wave fusion at higher HRs. During atropine, QU decreased by only a threefold greater extent than QT, T and U wave amplitudes were affected only minimally, and T‐U wave fusion was not observed. These results demonstrate that sympathomimetic stimulation causes striking alterations in the timing and amplitude of U waves that differ from effects on the T wave. These effects are not observed during vagal inhibition. Thus, the U wave represents a component of cardiac repolarization that is electrocardiographically and physiologically distinct from the T wave with a unique response to sympathomimetic stimulation.
