BACKGROUND: Although myocardial contrast 2D echocardiography is a good method to diagnose and evaluate myocardial ischemia and reperfusion, it has required intracoronary or intra aortic root injection of contrast agent and furthemore, the degree of myocardial contrast produced is small. Second harmonic imaging which is based on the non linear emission of harmonics by resonant microbubble in the ultrasound field improves the ultrasound contrast single to noise ratio. METHODS: We measure the videointensity of interventricular septum(IVS) and lateral wall(LW) of second harmonic imaging myocardial contrast 2D echocardiography before and after LV injection of Levovist(300mg/ml, 0.4ml/Kg) in both pre and post left anterior descending coronary artery(LAD) ligation in 7 open chest pigs. RESULTS: 1) The mean(+/-SD) pre LAD ligation videointensity is significantly greater with after contrast than before contrast(IVS : 111.1+/-33.9 vs 31.1+/-7.6 ; p=0.00046, LW : 120.5+/-21.5 vs 42.2+/-10.0 ; p=0.00006). The post LAD ligation videointensity is also significantly greater with after contrast than before contrast(IVS : 62.8+/-24.6 vs 35.6+/-15.1 ; p=0.00379, LW : 129.9+/-10.9 vs 48.7+/-21.1 ; p=0.00006). 2) The videointensity of IVS is significantly greater with after contrast than before contrast in both pre and post LAD ligation(62.8+/-24.6 vs 111.1+/-33.9 ; p=0.0031). The post LAD ligation videointensity of LW after contrast is not different from that of pre LAD ligation(129.9+/-10.9 vs 120.5+/-21.5 ; p=0.1037). 3) The post LAD ligation videointensity increase of IVS is lower than pre LAD ligantion videointensity increase(27.2+/-18.3 vs 79.9+/-35.0 ; p=0.0006). But the videointensity increase of LW is not different between pre and post LAD ligation(78.2+/-23.4 vs 81.2+/-24.5 ; p=0.3778). CONCLUSION: These findings indicate that the myocardial blood flow and its decrease due to LAD ligation can be evaluated accurately by second harmonic imaging myocardial contrast 2D echocardiography.