Objective To explore the fusibility of establishing animal model of no reflow phenomenon in swine by super selecting LAD with 4F catheter, and injecting polyethylene microspheres and blood suspension (PMBS) into LAD.
Methods Total of 15 york swines were included in this study. CAG was performed by 4F micro-catheter technique, and PMBS was injected into the superselected LAD. The coronay blood flow was evaluated by TIMI frame counts and the level of myocardial tissues perfusion was evaluated by TMPG. The model of NRP of AMI was considered as success while TIMI blood flow being less than grade 2 or TFC more than 36.2 counts or TMPG less than grade 1. Left ventriculography was performed with 4F Pigtail and left ventricular systolic, diastolic pressure was recorded. MRAP, mRVP, mPAP and PCWP were measured by swan-ganz floating catheter, and CO was measured by thermodilution. ECG and blood pressure were monitored, and platelet aggregate ratio, CK-MB, TnI and blood gas analysis were measured. Ischaemic region, normal region and borderline were scissored respectively and sent to check for pathology, and the necrotic zone of myocardium was weighed and the percentage of which in left ventricle was calculated.
Results According to the standards of NRP, 11 animals achieved the NRP model of AMI successfully, achievement ratio of the models was 73.3%, average times of injection of PMBS were 3.2±0.6. While the model of NRP was established, instant ECG showed that ST segment elevated and formed single-direction curve with high T wave, and R wave was gradually depressed. Though PO2 was decreased after establishment of NRP model, the level of which was in normal range. PAP, PCWP and LVEDP were increased at instantly, 30, 60, 120, 180 min after NRP with AMI, which had statistical significance (p<0.05). SBP and DBP were decreased after successful establishment of NRP model. Heart rate was increased (p<0.05) and LVP was decreased (p<0.05) after successful establishment of NRP model. Decreasement of mean perfusion pressure was negative correlation with TFCs. Pathological examination showed that myocardium fibre swelling, sarcolysis, reticular formation and local liquefaction necrosis occurred. The area of myocardiolysis in the left ventricle was 28.6%.
Conclusion This model had advantages of direct-viewing, simplicity, repetitiveness, mild trauma, closed chest, high achievement ratio and more similar to NRP after PCI in clinical compared with myocardium dyeing and other methods. It might provide better experimental animal model for microcirculation disturbance after AMI.