Objective: To evaluate the beneficial effects of Tong-xin-luo on myocardial no-reflow after acute myocardial infarction (AMI) and reperfusion.
Methods: Forty mini-swine were randomized into 5 equal groups: control group, low-dose group (pretreated with Tong-xin-luo 0.05 g.kg(-1).d(-1) for 3 days), medium-dose group (pretreated with Tong-xin-luo 0.2 g .kg(-1).d(-1) for 3 days), high-dose group (pretreated with Tong-xin-luo 0.5 g.kg(-1).d(-1) for 3 days), and sham-operation group. The swine in the former four groups were subjected to 3 hours of coronary occlusion followed by 60 minutes of reperfusion. Left ventricle systolic pressure (LVSP), left ventricle end diastolic pressure (LVEDP), rate of maximum pressure change in left ventricle (+/- dp/dt(max)), cardiac output (CO), and heart rate (HR) were measured 5 min before AMI in all groups and 180 min after AMI and 60 min after reperfusion in the groups 1-4. Coronary blood volume (CBV) was recorded 5 min before AMI in all groups and immediately and 60 min after reperfusion in the group 1-4. Myocardial contrast echography (MCE) was used before AMI, 3 h after AMI, and 60 min after reperfusion in the group 1-4 so as to calculate the left ventricle wall area (LVWA), ligation area (LS), and %LA. Sixty minutes after reperfusion thioflavin-S was injected into the left ventricle to dye the reperfusion area, then the descending anterior branch was re-ligated at the original site and Evan's blue was injected into the left ventricle to dye the area outside the reperfusion area blue. The heart was taken out immediately to undergo pathological examination and calculation of LVWA, LS, area of no-reflow (SNR), LA, ANR. necrosis area (NS), and NA.
Results: (1) In the control group, systolic and diastolic blood pressures (SBP and DBP), LVSP, +/- dp/dt(max), and CO significantly decreased (P < 0.05 or P < 0.01), while LVEDP significantly increased (P < 0.01) 3 hour after AMI, and then LVSP was significantly recovered while +/- dp/dt(max) further significantly decreased (both P < 0.05) 60 minutes after reperfusion. In the 3 Tongxinluo groups, the changes of LVSP, +/- dp/dt(max), CO and LVEDP were the same as those in the control group 3 hours after AMI, and 60 minutes after reperfusion, +/- dp/dt(max), CO and LVEDP were recovered significantly in the high-dose group to degrees better than those in the control group (all P < 0.05). (2) In the control group, the LS values measured by MCE in vivo and by pathological evaluation were similar (P > 0.05), and the SNR was 78.5% by MCE in vivo and was 82.3% by pathological evaluation with the final NS reaching 98.5% of LS. There was no significant difference in LS by both MCE and pathological evaluation between the Tongxinluo groups and control group, though the values of SNR by both methods in the medium and high-dose groups were 41.1% and 42.4% and 24.1% and 25.0% respectively, all significantly lower than those in the control group and low-dose group (P < 0.05 or P < 0.01) with the values in the high-dose group being significantly lower than those in the median-dose group (P < 0.05 and P < 0.01). The final NS of pathological evaluation was also significantly decreased to 90.2%and 81.2% of LS (P < 0.05). In the control group, CBV was significantly decreased to 45.8% and 50.6% of the baseline value immediately at the beginning of reperfusion and 60 minutes after reperfusion (both P < 0.01). In the high-dose group, CBV was also significantly decreased to 76% and 73.5% of the baseline value immediately at the beginning of reperfusion and 60 minutes after reperfusion (both P < 0.05), however, both significantly higher than those in the control group (both P < 0.01).
Conclusion: Tongxinluo is effective in preventing myocardial no-reflow, improving left ventricular function and reducing infarct area during AMI and reperfusion.