Abstract: Objective To observe the effects of Tongxinluo on myocardial hypertrophy, QT dispersion and connexin 43 (Cx43) expression in rats under pressure overload. Methods Total 45 male SD rats were randomly divided into three groups:control (group C), model (group M) and treatment (group T). A model of rats under pressure overload was established by abdominal aortic banding. After 12 weeks of treatment with Tongxinluo[1.5 g/(kg·d)], echocardiogram examination was conducted, and cardiac electrophysiological recorder was used to record the QT dispersion of rats. After these rats were sacrificed, HE staining was performed to observe the pathological morphology of left ventricle myocardial tissue, immunohistochemistry (IHC) was conducted to determine the expression and distribution of Cx43, and RT-PCR method was employed to determine Cx43 mRNA expression. Results A model of rats with myocardial hypertrophy under pressure overload was successfully established. Echocardiographic detection indicates that compared with group C, group M had obvious Ventricular hypertrophy, IVSs, VPWs, LIVSd and LVPWd were increased obviously (P<0.01); compared with group M, the above parameters in group T were improved (P<0.01). Compared with group C, the QT dispersion of group M was obviously increased (P<0.01), and Tongxinluo intervention could reduce the QT dispersion of rats under pressure overload (P<0.01). Compared with group C, cardiomyocyte hypertrophy and irregular arrangement could be seen in group M, and the expressions of Cx43 and Cx43 mRNA in left ventricle myocardial tissue were greatly reduced (P<0.05). Compared with group M, irregular arrangement of myocardial cells in group T was improved, and the expressions of Cx43 and Cx43 mRNA were significantly up-regulated (P<0.05). Conclusion For rats under pressure overload, Tongxinluo can improve myocardial hypertrophy, shorten QT dispersion and improve Cx43 reconstruction.