Objective:To investigate the effect of Yiqi Huoxue Recipe(YHR,益气活血方)on the cardiac function and ultrastructure during the regression of myocardial hypertrophy induced by pressure overload in rats.Methods:The model of myocardial hypertrophy was established by abdominal aortic banding.Eighty male Wistar rats were divided into six groups,the normal control group Ⅰ(n=20),the normal control group Ⅱ(n=12),the hypertension model group [(n=12),the hypertension model group Ⅱ(n=12),the YHR group(n=12)and the Captopril group(n=12).The observation was carried out in the normal control group Ⅰ and the hypertension model group Ⅰ after 4weeks of modeling,and the other four groups were observed after 16 weeks of modeling(12 weeks of administration).The cardiac function was measured with a multichannel biological signal analysis system,and the myocardium ultrastructure was observed by a transmission electron microscope.Results:(1)Compared with the normal control group Ⅰ,the systolic blood pressure and cardiac coefficient(left ventricular weight/body weight)in the model Ⅰ group was higher(P＜0.05,P＜0.01).(2)In the YHR group,cardiac coefficient and -dp/dtmax were lower,left ventricular systolic pressure and +dp/dtmin were higher when compared with the model group Ⅱ and the Captopril group(P＜0.05or P＜0.01).In the Captopril group,only cardiac coefficient was lower when compared with the mode group Ⅱ(P＜0.05).(3)Compared with the normal control group Ⅱ,+dp/dtrmax was higher(P＜0.01),-dp/dtnmax and isovolumetric contraction time(ICT)was lower(P＜0.05,P＜0.01)in both the YHR group and the Captopril group.(4)Results of the myocardium ultrastructure showed edema under myocardium plasmalemma,enlarged sarcoplasmic reticulum and T tube,and significantly enlarged intercalated disc of the cardiac muscle in the model groups.In the Captopril group,the extension of sarcoplasmic reticulum and T tube as well as the pathological changes of intercalated disc were lighter,with slight edema under the myocardium plasmalemma.In the YHR group,the expansion of the sarcoplasmic reticulum was less than in the Captopril group,part of the pathological changes of intercalated discs was slightly more severe than that in the Captopril group,the dissolution of nuclear chromatin was not found,which was similar to that of the Captopril group,and no injury of the nucleus was found,either.Conclusion:YHR could reverse myocardial hypertrophy in rats with abdominal aortic banding and improve the systolic and diastolic function of the left ventricle.The ultrastructure of the myocardium such as arcoplasmic reticulum,intercalated disc,and cell nucleus in abdominal aortic banding rats could be partly reversed by the recipe.