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Effects of Multisite Electric Stimulations Applied during Absolute Refractory Period on Cardiac Function of Rabbits with Chronic Heart Failure

Author: QinChen
Tutor: QiXiaoYong
School: Hebei Medical University
Course: Internal Medicine
Keywords: Absolute refractory period Multisite electric stimulation chronic heart failure cardiac function
CLC: R541.6
Type: Master's thesis
Year: 2014
Downloads: 1
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Abstract

Chronic heart failure(CHF) is the final outcome of the occurrence anddevelopment of cardiovascular disease,and its treatment has been one of thedifficulties in the medical profession.Excessive activation of neurohumoralfactors，ventricular remodeling is important in the development of heart failuremechanism,for the treatment of the above mechanism can significantlyimprove the prognosis of patients with heart failure.Even so, still have theeffect of drug treatment in patients was poor.In recent years, with the progressof technology, constantly rise of non-drug treatments undoubtedly has madegreat progress,CCM is a new treatment method has been paid more and moreattention,Cardiac contractility modulation is a very promising new treatment,itdoes not induce myocardial cell action potentials but can boost the myocardialcontractility and improve the cardiac function through electric stimulationsapplied during absolute refractory period. At home and abroad, experimentsshow that CCM can obviously enhance the contractility of normalmyocardium and chronic heart failure myocardium, improve cardiac function,ventricular reverse remodeling，it may offers about new hope to many patientswho are ineffective through drug therapy. Previous animal experiments andclinical research absolutely should use the method of single site stimulation,whether multisite stimulation is better than single site stimulation inimproving heart function is more effective,the experiment will be discussed.Objective：we made the animal models of rabbits with chronic heartfailure by the method of ligating ascending aorta’s root. After the CCMtreatment, using non-invasive cardiac ultrasonic to examine the cardiacfunction and the ABC-ELISA method to examine BNP’s level to investigatethe effects of Multisite electric stimulations during absolute refractory period on cardiac function of rabbits with chronic heart failure,explore whetherMultisite electric stimulations during absolute refractory period is more thansingle site electric stimulations effective in improving cardiac function.Method:We selected forty6months of health New Zealand white rabbitsas experimental subject, whose weight is2.5kg to3.5kg no matter male orfemale. The experimental animals were provided by the Test Animal Center ofHebei Medical University. Forty Healthy rabbits were divided into fourgroups：control group, single site cardiac contractility modulation group(LVAWCCM),Double site cardiac contractility modulationgroup(LVAW-LVLW CCM),Multisite cardiac contractility modulationgroup(LVAW-LVLW-LVPW CCM). Rabbits models of chronic heart failurewere made by ligating ascending aortic root of rabbits. Then electricalstimulations during the absolute refractory period were delivered on theanterior wall of left ventricle in single site group(LVAW) and both on theanterior wall and the lateral wall of left ventricle in Double sitegroup(LVAW-LVLW) and on the anterior wall, the lateral wall and theposterior wall of left ventricle in Multisite group (LVAW-LVLW-LVPW)lasting six hours every day for seven days. Successful establishment standardheart failure model: Cardiac output decreased by30%or (and) Left ventricularend-diastolic pressureincreased to more than2.4Kpa (18mmHg) after12weeks.Changes in ventricular structure，cardiac function were observed before andafter CCM stimulation by means of non-invasive cardiac ultrasonic and theABC-ELISA method.Results:1.The result of the experimental animals: we made the animal models ofrabbits with CHF by the method of ligating ascending aorta’s root. There werethirty-five rabbits survived after the operation, and thirty-one were survivedafter12weeks.One of the animals died of pneumothorax in control group, ananimal died in the Anesthesia accident in single site group, an animal died ofpneumothorax in double site group, and one died of cardiac ruptur in Multisitegroup. According to the successful establishment standard,we made only thirty-one rabbits of the successful model, There are eight animals in controlgroup, eight animals in single site cardiac contractility modulation groupand Double site cardiac contractility modulation group，seven animals inMultisite cardiac contractility modulation group.2.The general status of animals before randomly assigned equally to thegroups: There were no statistical differences among the three groups ofanimals in general status(P＞0.05), such as age, weight, sex, breath and heartrate.3.The results of UCG: before CCM treatment, there were no statisticaldifferences among the four groups of animals(P＞0.05).After CCMstimulation, LVESD、LVEDD in three cardiac contractility modulation groupswere significantly decresed (P<0.05),while their LVEF and FS weresignificantly increased (P<0.05),especially in LVAM-LVLW CCM andLVAW-LVLW-LVPW CCM group. IVS,LVPM were similar among groups.Compared with LVAM-LVLW CCM and LVAW-LVLW-LVPW CCM group,all the results of UCG were not statistically significant(P＞0.05).4.BNP levels in four groups was no significant difference before CCMdelivered (P>0.05). However BNP levels were highest in single site cardiaccontractility modulation group, followed by the Double site cardiaccontractility modulation group and Multisite cardiac contractility modulationgroup. BNP levels in The Double site cardiac contractility modulation groupand Multisite cardiac contractility modulation group were similar.(P>0.05).Conclusion:1.Electric stimulations during absolute refractory period couldsignificantly boost the myocardial contractility and improve the cardiacfunction2.Double site and multisite electric stimulations during absoluterefractory period is better than single site electric stimulations in improvingcardiac function.3.The effects of double site and multisite electric stimulations duringabsolute refractory period on cardiac function of rabbits with chronic heart failure were similar.

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