Experimental study of the effect of autonomic nervous system on the transmural dispersion of ventricular repolarization under acute myocardial ischemiain vivo |
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Authors: | Zhang Cuntai Xu Dawen Li Yang Liu Nian Zhong Jianghua Wang Lin Lu Zaiying |
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Institution: | (1) Department of Cardiology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, 430030 Wuhan |
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Abstract: | Summary The effect of the autonomic nerves on the transmural dispersion of ventricular repolarization (TDR) under acute myocardial
ischemia in intact canine was investigated. Using the monophasic action potential (MAP) recording technique, MAPs of the epicardium
(Epi), midmyocardium (Mid) and endocardium (Endo) were recorded simultaneously by specially designed plunge-needle electrodes
at the left ventricular free wall under acute myocardial ischemia in 12 open-chest dogs. MAPD90 and TDR among three myocardial layers as well as the incidence of the early afterdepolarization (EAD) before autonomic nervous
stimulation and during autonomic nervous stimulation were compared. It was found that 10 min after acute myocardial ischemia,
TDR was increased from 55±8 ms to 86±15 ms during sympathetic stimulation (P<0.01). The TDR (53±9 ms) during parasympathetic stimulation was not significantly different from that of the control (55±8
ms) (P>0.05). The EAD was elicited in the Mid of 2 dogs (16%) 10 min after acute myocardial ischemia, but the EAD were elicited
in the Mid of 7 dogs (58%) during sympathetic stimulation (P<0.01). It was concluded that: (1) Sympathetic stimulation can increase the transmural dispersion of repolarization and induce
early afterdepolarizations in the Mid under acute myocardial ischemia, which provide the opportunity for the ventricular arrhythmia
developing; (2) Parasympathetic stimulation has no significant effect on the transmural dispersion of repolarization under
myocardial ischemia.
Zhang Cuntai, male, born in 1963, Associate Professor |
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Keywords: | autonomic nervous system acute myocardial ischemia monophasic action potential transmural dispersion of repolarization early afterdepolarization |
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