The Study Of Remodeling Between 1 Week And 8 Week Myocardial Infarcted Swine Using Cardiac MRI

OBJEVTIVEThe aim of this study was to investigate the changes of myocardial movement, function and transmurality in infarcted swine model between 1 week and 8 week by serial CINE-MRI and delayed enhancement magnetic resonance imaging (DE-MRI). If successful, this research can be useful for study remodeling which related to heart failure (HF) after acute and chronic myocardial infarction, such as to narrow down the difficulties of finding out acute and chronic myocardial event, as well as for training in diagnostic and therapeutics interventions.METHODS1. Twelve swine model are taken, with the help of Seldinger method, via the femoral artery catheterization through 3F balloon catheter under the guiding the intervention surgery, we place the balloon in LAD artery and induced infarction. The angiography was obtained to insured the occlusion of LAD artery.2. Out of 12 swines,10 Sucessfully infarcted swines model are underwent Cine-MRI and delayed enhancement magnetic resonance imaging (DE-MRI) scanning at 1 weeks and after 8 week. The scanning sequences include balanced steady-state free precession and phase sensitive inversion recovery. After cine MRI finished, administration of intravascular gadolinium-chelate are given and then are examined by DE-MRI.3. LV (left ventricular) are divided in to 17 segments according to AHA (American Heart Association) standard.4. Transmurality in each segment are categories as in 5 degrees and 0-4 points. 0= Normal=0 points,Ⅰ=≤25%=1 point,Ⅱ= 25%-50%= 2point,Ⅲ= 51%-75%= 3point and Ⅳ=> 75%-100%=4points. And the DE-MRI score is sums of all 17 segments.5. Myocardial wall movement evaluation are divided as 5 degrees and 1-5points. Ⅰ= normal=1 point,Ⅱ= hypo-motility= 2point,Ⅲ= akenesis=3point, Ⅳ=counter move= 4points and V=ventricular aneurysm. And the motion score is sums of all 17 segments.6. Ejection fraction, LV(Left ventricular) maximum wall thickness, wall motion and wall motion rate of anterior segment are calculated by Phillips system cardiac explorer.7. All of datas were statistical analyzed by independent t-test, one-way ANOVA, and pearson chi-square.RESULTS1. In 12 swine,10 swine were successfully infarcted, the succeed rate was approximately 83.33%.2. Infarcted myocardial segments were found in 7th,8th,13th,14th,16th,17th segment. The totals of infarcted segments were 43(25.29%).3. There was no statistical difference of transmurality and DE-MRI score between 1 week and 8 week in infarcted swine model.4. There was no statistical difference of ejection fraction and wall motion score between 1 week and 8 week in infarcted swine model.5. In 1 week infarcted swine, there was statistical difference of maximal wall thickness, wall motion and wall motion rate among LV anterior segment. Maximal wall thickness comparison:Segment 7=Segment 8> Segment 1=Segment 2> Segment 13=Segment 14. Wall motion comparison:Segment 1=Segment 2=Segment 7=Segment 8> Segment 13= Segment 14. Wall motion rate comparison:Segment 1=Segment 2> Segment 7=Segment 8 > Segment 13=Segment 14. In 8 week infarcted swine, the LV segments in LAD artery distribution showed the same results.6. There was no statistical difference in the movement of the same segments between 1 week and 8 week infarcted swine models.CONCLUSION1. We have developed a swine model of 1 week and 8 week myocardial infarction by interventional ballooning blockage the intracoronary LAD characterized its evolution using cardiac MRI. This interventional technique consistently results in a myocardial infarction in swine model and its useful for researched to induced myocardial infarction of experiment model in future.2. DE-MRI and TTC comparison shows same involved infarcted segment that proved, the delayed myocardial enhancement cardiac MR imaging is a reliable tool for assessing myocardial infarction.3. Our study achieved infarcted myocardium DE-MRI score, transmural infarct score, maximal wall thickness, wall motion rate and EF (ejection fraction). Our study is considered as reliable and can be useful in future for research on remodeling changes after infarction.4. In our study 1 week and 8 week myocardial infarction hasn’t difference in DE-MRI score and its transmurality, ejection fraction, LV movement, maximal wall thickness, wall motion and wall motion rate in LAD artery distribution segments. This maybe the observation time duration infarction of 8 week is not well enough, and other reasons as following:(1) LAD blockage area is same in 1 week and 8 week. Therefore, the involved infarcted segment are same; (2) no reperfused blood supply given after 1 week infarction, (3) either due to one distal LAD coronary artery occlusion that might limited the size of infarction (4) the process of remodeling the myocardium and function were compassionate by adjacent myocardium wall. So further study is required to proved our hypothesis.