Abstract: AIM: To evaluate myocardial relaxation function changes in an adriamycin-induced cardiomyopathy model using the transmitral flow velocity to mitral annular velocity ratio (E/E’), a strong positive relationship with left ventricular filling pressure and a good indicator for evaluating left ventricular diastolic relaxation abnormality. METHODS: Twenty-eight Japanese rabbits were divided into two groups. Adriamycin was administered at a dose of 2mg·kg^-1 intravenous once a week for 8 weeks (total dose of 16 mg·kg^-1) in 20 rabbits to induce the cardiomyopathy model.8 rabbits served as controls receiving the same amount of saline once a week for a total of 8 weeks. Conventional and tissue Doppler echocardiography (TDE) were performed at baseline, 4th, 6th, 8th, 10th and 12th week. RESULTS: In the adriamycin- treated group, LV chamber diameter significantly increased, while ejection fraction and fraction shortening significantly decreased in 10th and 12th week (P < 0.05). The significant changes were firstly found in 10th week. Mitral annulus systolic peak velocity (S’) by TDE significantly decreased in 8th, 10th and 12th week (P < 0.05). The significant changes were firstly found in 8th week. The ratio of E/E’ significantly increased in 6th, 8th, 10th and 12th week (P < 0.05). The significant changes were firstly found in 6th week. In the control group, no significant changes were found in all parameter by tissue Doppler conventional echocardiography (P > 0.05). CONCLUSION: Myocardial function is reduced in adriamycin-induced rabbit model of dilated cardiomyopathy. The relaxation parameter (E/E’) by TDE changes is earlier than contraction indices S’ by TDE and conventional echocardiography in adriamycin-induced cardiomyopathy rabbits, which provides a new sensitive and reliable method to evaluate LV relaxation function.

Key words: echocardiography, rabbit, adiamycin, cardiomyopathy, tissue Doppler imaging