The Observations Of Super Early Left Ventricular Remodeling By ～(99m) Tc-MIBI Myocardial Imaging In Acute Experimental Myocardial Infarction And Prevention Of Captopril

PurposeThe classical definition of left ventricular remodeling(LVRM) is the changes in shape and size of the entire left ventricle after acute myocardial infarction(AMI). Many invesgators showed that left ventricular remodeling is related to clinical outcomes represent the natural history of the heart faiture symdrome , such as mortality. The aim of our study was to observe the super early left ventricular remodeling by 99m Tc-MIBI myocardial imaging in the dog model of acute experimental myocardial infaction and to know whether captopril administrated before acute myocardial infaction can prevent this process.MethodsExperimental subjects Thirty four healthy mongrel dogs(14-25kg) of either sex were studied under general anesthesia(sodium pentobarbital, 30mg/kg). All dogs were randomized to a control group G I (n=23,no treatment) or a group receiving captopril GII(20mg PO BID) for3 days before acute myocardial infaction . The left anterior descending(LAD) coronary artery was dissected and ligated between the first and second diagonal branches.7 dogs in G I and 3 dogs in G II died for the ventricular fibrillation after the LAD coronary artery was ligated.^99mTc-MIBI myocardial perfusion imagingStatic ^99mTc-MIBI myocardial imaging was performed with ADAC Vertex Dual-head SPECT. ^99mTc-MIBI kit was manufactured in Syncor,China.The auto-control of each dog was performed by ⁹9m Tc-MIBI myocardial imaging at 48-72 hours before ligated.Acquisition techniques for Gated SPECT:ECG synchronized data collection R wave trigger, 8 Frames/Cardiac cycle. Images were gathered by rotating the detectors for 180degrees at 6 degrees per frame. Each frame took35- 40 seconds. The dog position: supine. The images of each acquisition were recorded until 3 hours after LAD coronary artery was ligated.SPECT reconstruction parameters:Filter:Butterworth:cutoff 0.5 and order 6: filtered backprojection.Images:short axis,horizontal and vertical long axis.Data analysis:Quantitative analysis: Quantitative Gated SPECT (QGS) soltware used for getting End diastolic volume(EDV),End systolic volume (ESV) and Enjection fraction(EF).Qualitative analysis used for the assessments of shape,size of entire left ventricular and wall motion.SPSS statistics software was used for all data analysis. Differences between different time after operation and differences between treated and untreated animals were tested by t test. Statistical significance was accepted at /*<0.05. Data are expressed as mean±SD.ResultsA typical defect with complete absence of wall motion was found at apex in all dogs(G I andGH)after LAD was ligated and appeared as early as at 14 min after sucssceful ligation.In G I ,compared with pre-operation,EDV and ESV of post-operation significantly increased ,but EF of post-operation has no significant statistical difference.In G II , compared with pre-operation, ,EDV,ESV,and EFof post-operation have no significant statistical difference. The statistics analysis results for the quantitative data show on the table below.