| Part1Preparation of swine models of myocardial infarction with interventional techniqueObjective To discuss the feasibility of preparation of swine models of myocardial infarction by left anterior descending artery obstruction. To establish swine models of myocardial infarction and to analyze the technology model preparation.Methods12healthy male adult Diannan Smalleared Pigs were chosen. Data of electrocardiogram (ECG), myocardial enzymology and myocardial biomarkers were collected preoperatively. Percutaneous femoral arterial puncture were taken after general anesthesia and Continuous ECG monitoring. Coronary angiography of both sides was taken then. Detachable balloon were positioned in the middle-distal1/3left anterior descending (LAD). Postoperatively, data of ECG, myocardial enzymology and myocardial biomarkers was collected repeatly at specific time(6hours,24hours,72hours and a week after operation). Animals were sacrificed at the corresponding time. TTC staining and pathology was established for the evaluation of model preparation.Results1. Coronary angiography of both sides were successfully completed.1swine model died of ventricular fibrillation20minutes after balloon positioned.11remaining swine models survived to the end of the experiment. The success rate of technique was100%and the success rate of model preparation was91.67%.2. Typical changes of ECG, myocardial enzymology and myocardial biomarkers were found with comparison of preoperative and postoperative data. The numerical value of myocardial enzymology and myocardial biomarkers obviously increased after operation. The data returned to the normal level1week later.3.The surface of macropathology sample were smooth. The areas of infarction at left ventricular wall and apex of heart were pale. Normal myocardium developed red by TTC staining and the position of infarction developed white or grey. The microscopic appearance of the infarction areas shows fracturing myocardial cell, exudation of inflammatory cell and fat metaplasia.Conclusion1.The technology of preparation of swine models of myocardial infarction by left anterior descending artery obstruction is feasible. High safety and repeatability, localized infarction areas and specific result of laboratory tests and pathology make it an appropriate way of preparation of swine models of myocardial infarction.2.The best location of obstruction is middle-distal1/3LAD, obstruction of artery segment has a effective advantage for the models.3.The necessity of ischemic preconditioning before implant of balloon needs further research.4.During the preparation, coronary angiography of both sides, reasonable intraoperative heparinize and timely treatment of ventricular arrhythmia could increase the success rate of the model preparation. Part2Assessment of swine models of myocardial infarction with DSCT myocardial perfusion imagingObjective To discuss the feasibility and accuracy of DSCT myocardial perfusion imaging for the swine models of myocardial infarction. To elaborate basic pathophysiological mechanisms in several time period integrate CT symptoms.Methods12healthy male adult Diannan Smalleared Pigs were chosen and divided into six groups of different time period of4h,6h,24h,72h,7days and30days. Preparation of swine models of myocardial infarction was finished by left anterior descending artery obstruction with detachable balloon. All models accepted DSCT myocardial perfusion imaging scanning of first-pass and delayed lmin,3min,5min, 7min. Animals were sacrificed at the corresponding time. TTC staining and pathology was established for the evaluation of model preparation.Results1. DSCT myocardial perfusion imaging could clearly show the anatomic structure of swine myocardium.90.9%segments of myocardium could be used for the diagnosis.2. For the group of supine position,76segments were showed,58segments were judged level1.3. The main influencing factors of imaging quality were respiration, heart rate and position.4.11swine models were successfully prepared. No abnormality of first-pass scanning of myocardial perfusion imaging is visible.5.Compared with non-infarction areas, CT value of infarction areas significantly decreased in11survived swine models. Iodine maps showed limited filling-defect. Statistically significant differences could be found in the CT value and iodine map comparison(p<0.01).6. Delayed enhancement of infarction areas appeared at the time of3min delayed scanning. Statistically significant differences between infarction and non-infarction areas(p<0.01).7.The value of troponin I in acute stage was linearly related with CT value of infarction areas(p<0.01).8. Location of infarction areas using DSCT myocardial perfusion imaging was significantly correlated with pathology results(p<0.01). The sensitivity of the diagnosis is100%. The specificity is84.62%. The positive predictive value is92.73%. The negative predictive value is100%.Conclusion1.The imaging quality of DSCT myocardial perfusion imaging is outstanding. The main influencing factors of imaging quality are respiration, heart rate and position of swine models.2. DSCT myocardial perfusion imaging can be used as an important means for the early diagnosis of myocardial infarction.3. DSCT myocardial perfusion imaging can achieve the "one-stop" examination of heart.4. Integrating the test of troponin I, DSCT myocardial perfusion imaging can provide important evidence for the extent of myocardial infarction. |
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