Effects of non-excitatory electric stimulation on cardiac function in normal and infarcted heart rabbits and it's regional effect on myocardium |
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Authors: | ZHANG Hai-zhu CUI Chang-cong ZHAO Xiao-jing LEI Li-quan LIAN Jiang-fang |
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Institution: | 1. Department of Cardiology, First Hospital, Xi'an Jiaotong University, Xi'an 710061, China;
2. Department of Pathophysiology, Medical College, Xi'an Jiaotong University, Xi'an 710061, China;
3. Function Center, Xi'an Jiaotong University, Xi'an 710061, China |
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Abstract: | AIM: To investigate the influences of electric stimulation applied during the absolute refractory period (ARP) on the cardiac function of normal rabbits and rabbits after myocardial infarction (MI) and to observe the regional effects of this electric stimulation. METHODS: 64 rabbits were randomly assigned to normal and MI groups and each group was then divided into the anterior and posterior groups. A thoracotomy was performed 4 weeks after MI in rabbits. One set of electrodes was inserted into the anterior and posterior wall of left ventricle of the anterior and posterior groups, respectively. Current pulses were delivered during the ARP (called CCM) during sinus rhythm in rabbits. The left ventricular systolic pressure (LVSP) and the left ventricular end diastolic pressure(LVEDP) as well as maximum positive and negative left ventricular pressure change (±dp/dtmax) were observed. RESULTS: In the normal and MI groups, LVSP, +dp/dtmax significantly increased, and LVEDP, -dp/dtmax were reduced during CCM stimulation compared with the baseline (P<0.05). In the normal rabbits, electric stimulation in the anterior group improved the cardiac function more significantly than that in the posterior group (P<0.05). In the MI rabbits, there was no difference between the anterior and the posterior groups (P>0.05). CONCLUSION: Electric stimulation delivered during the ARP significantly enhances the contractility and the relaxation of myocardium in normal rabbits and rabbits after MI, and the effects of CCM stimulation on heart are regional. |
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Keywords: | Hemodynamics Myocardial infarction Absolute refractory period Electric stimulation Rabbits |
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