| Objective: To study how to make a chronic heart failure(CHF)rats model by abdominal aortic constriction(AAC),and to investigate the effects of renal denervation(RDN)on cardiac function and cardiac histology,as well as the influence of cardiac electrophysiology and cardiac sympathetic discharge,in CHF rats and to provide the corresponding theoretical basis for renal denervation in the treatment of chronic heart failure.Methods: Forty male Sprague-Dawley rats were randomly divided into 3 groups: SHAM group(n=8),chronic heart failure group(CHF group,n=16)and chronic heart failure with renal denervation group(CHF+RDN group,n=16).Four weeks after AAC was applicated to make rats CHF model,RDN was made by microscopic physical cutting and phenol ethanol solution ablation in RDN group when the same procedure was carried on the CHF group without doing ablation.The effects of ablation were verified by means of electrical stimulation.Cardiac ultrasound was conducted in all three groups to calculate the parameter of left ventricular fractional shortening(LVFS)and left ventricular ejection fraction(LVEF).Then the blood pressure and ventricular pressure were measured by the catheter.To record the electrocardiogram,electrophysiology index of heart surface and sympathetic nerve discharge.Ventricular arrhythmia was induced by programmed electrical stimulation(PES).After that,analysis and calculation of parameters as QT interval,ventricular effective refractory period(VERP)and the action potential duration(APD)of epicardium was calculated and analysed.To observe the myocardial cell size and shape,myocardial interstitial hyperplasia,inflammatory infiltration and edema by HE staining;Observing the fibrosis of cardiac muscle and stroma,cardiovascular remodeling by Masson staining.The collagen volume fraction(CVF)and wall thickness of vessel(WTV)was calculated and analysed.Results: Nine weeks after beginning,rats in SHAM group,the CHF group and CHF+RDN group survived 8,12 and 11,respectively;1.The heart heavy,weight or heart-body ratio of CHF group rats were significantly increased than that in SHAM group(P<0.01);Heart-body ratio of rats still statistically higher in RDN group than in that CHF group though less weight decline was observed after intervention(P<0.01).RDN can significantly improve left ventricular ejection fraction(LVEF)and left ventricular short axis shortening rate(LVFS)in rats with CHF(P<0.01),indicating that RDN are better in lowing diastolic blood pressure and mean arterial pressure than systolic blood pressure.RDN can significantly reduce the left ventricular end-diastolic pressure(LVEDP)of CHF rats(P<0.01),and significantly improve the pressure change rate of isovolumetric contraction phase.RDN can significantly improve the pathological changes while myocardial cell diameter increased significantly in CHF rats and obviously interstitial edema and inflammatory cell infiltration compared with SHAM group under HE staining.RDN can also significantly reduce heart failure rat cardiac collagen volume fraction(CVF)and vessel wall thickness(WTV)(P<0.01),namely,as much as to say that could improve the myocardial fibrosis and vascular remodeling remarkably under Masson staining.2.Nine weeks after AAC,electrocardiogram QRS waves were broaden,left ventricular APD90 VERP and was extended,the frequency of the APD alternating was reduced,ventricular arrhythmia induced rate and the sympathetic nerve discharge were increased.Then the renal denervation can significantly improve the electrophysiological index all above(P<0.05),and rest parameters of ECG showed no statistical difference between groups.Conclusion: 1.Stable CHF rats model could achieved through proper proportion constriction of abdominal aorta;RDN can improve cardiac function,ventricular hypertrophy,vascular remodeling and reduce myocardial fibrosis of rat with CHF,probably through inhibiting the inflammatory response for its possible mechanism of action;2.The RDN may increase the electrical stability by reducing abnormal sympathetic nerve discharge of chronic heart failure rats. |
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