Research For Effect Of Extracorporeal Cardiac Shock Wave Therapy On Ventricular Remodeling After Acute Myocardial Infarction In A Porcine Model

BackgroundCardiovascular disease (CVD) is a major threat to human health worldwide in 21 century. CAD is the leading cause of cardiac morbidity and mortality as more than 40 percent of cardiac death was attributed by CAD. AMI is associated with a loss of cardiomyocytes and subsequent development of left ventricular remodeling (LVRM), both of which lead to heart failure, sudden cardiac death, and poor prognosis. If sufficient angiogenesis can be induced in the border zone of infarct myocardium at early stage, the progression of LV remodeling could be suppressed, with resultant improved prognosis of patients with AMI. It was demonstrated that extracorporeal cardiac shock wave therapy at a low level of 10% of energy density that was used for urinary lithotripsy treatment, effectively induces coronary angiogenesis and improves myocardial ischemia and ameliorates LVRM ,in a porcine model of chronic myocardial ischemia in vivo. Nevertheless, the potential mechanism about cardiac shock wave therapy (CSWT) was less reported. On the basis of the promising results in animal studies, we have recently applied cardiac shock wave therapy to improved porcine model of acute ischemia with a less-invasive balloon embolus. We examine the expression level of the factor of angiogenesis and matrix metabolism, including VEGF, MMPs and TIMPs. At the same time, we detect the collateral circulation and microcirculation construction in the border zone of infarct myocardium. We aim to investigate the therapeutic effect of the cardiac shock wave and that of potential biological mechanism for improving LVRM, and determine whether the cardiac shock wave therapy is an optimal method for ventricular remodeling after AMI.PartⅠA novel methodology of balloon plus micro-embolis on porcine acute myocardial infarction model Objective To develop and establish an alternative acute myocardial infarction porcine model which is much safer, quicker and more convenient than routine methods. Compare performance between two modified methods for establishing porcine AMI model.Methods A total of 30 domestic miniature swine, mean weight 26.5±4.8 kg, were randomly divided into two groups, group A (n=13) and group B (n=17), according to experimental protocol. The balloon catheter was positioned in the mid-distal segment of left anterior descending (LAD),and dilated with rated pressure for 60 min after ischemia precondition, then the micro-embolis was sent to the distal of target vessel in group A; In group B, the micro-embolis was positioned in the distal segment of target vessel directly. Interventional procedure time and model success rate were collected in the two groups, respectively.Results Twenty-Six porcine AMI models were established successfully. Model success rate of group A was 84.6%, and 88.2% in group B. No statistic significance was found in the two groups. However mean operation time of group B was significantly shorter than that of group A,28.4±9.4min versus 105.8±27.6min, p< 0.001. Conclusions Balloon plus micro-embolis induced porcine acute myocardial infarction model shows the advantages of being feasible, safe, operation-time saving and therefore is a promising improvement for porcine AMI modelPart II Effects of extracorporeal cardiac shock wave therapy on angiogenesis and expression of VEGF in acute myocardial infarction pigsObjective Therapeutic angiogenesis is a process that seeks to stimulate collaterogenesis and to improve myocardial perfusion and function by delivery of proangiogenic factors to the ischemic myocardium. This experimental study aims to investigate the effect of inducing endogenous proangiogenic factors by extracorporeal cardiac shock wave therapy, at the same time, observe the effect of different energy protocol of extracorporeal cardiac shock wave therapy on angiogenesis and expression of VEGF in acute myocardial infarction pigs, and explore optimal CSWT regimen.Methods Thirty domestic miniature swine were randomly divided into four groups: CSWT group (n=15), pseudo-CSWT group (n=5), pseudo-operation group (n=5) and blank control group (n=5). According to the given protocol, CSWT group was then divided into three subgroups:standard CSWT, prolonged duration CSWT and extensive area CSWT. At 30 days, VEGF mRNA and protein expressions were measured and evaluated in different groups, respectively.Results Compared with pseudo-CSWT group, the expression of VEGF mRNA was significantly increased in CSWT group with statistic difference (2.90±0.40vs2.12±0.50,p<0.01), especially in the prolonged duration CSWT. Whereas, no significant differences were seen between standard and extensive area CSWT. Nevertheless, compared with pseudo-CSWT group, the expression of VEGF mRNA was increased significantly in all CSWT subgroups. In contracts, no significant differences were seen among all groups in expression of Flt mRNA.Conclusions It is obvious that extracorporeal cardiac shock wave therapy could effectively induce angiogenesis probably by up-regulating the expression of angiogenic factor. Furthermore, effects of CSWT on angiogenesis may be varied in different CSWT protocols. Prolonged duration CSWT at early stage of acute myocardial infarction can improve angiogenic of myocardium microenvironment and facilitate myocardial micro-vascular circulation, which should be more effective CSWT protocol for the AMI management.PartⅢExtracorporeal cardiac shock wave therapy improved myocardial micro-vascular circulation after acute myocardial infarction at early stage in pigsObjective In the clinical prospect, the goal for the treatment of ischemic heart disease should include not only enhancement of angiogenesis but also reconstruction of region cardiomyocytes micro-vascular circulation and recovery of ischemia induced myocardial dysfunction. This experimental study aims to investigate the effects of CSWT on improving myocardial micro-vascular circulation after acute myocardial infarction at the early stage. Methods Thirty domestic miniature pigs were enrolled this study. The methods of grouping and treatment were same as those in partⅡexperiment. At 30 days, the number of endothelium cell, capillary density and collateral vessel Rentrop score were measured and evaluated by immunohistochemisty and coronary artery angiography, and then compared among every groups, respectively.Results Shock wave treatment up-regulated the mRNA expression of VEGF in model of acute myocardial infarction. At the same time, the number of capillaries was significantly higher in the shock wave group than that of pseudo-CSWT group (1856±78 vs.837±54/mm2, P<0.0001). There was no significant difference between pseudo-CSWT group and blank control group (837±54 vs.569±32/mm2, P>0.05); Furthermore, these improving effects in subgroup of prolonged duration CSWT were better than other two subgroups. Compared with pseudo-CSWT group, collateral vessel Rentrop score was significant higher in CSWT grouy(2.05±0.11vs0.98±0.09, P=0.03).Conclusions Extracorporeal cardiac shock wave therapy could not only effectively induce angiogenesis and up-regulate the expression of angiogenic factor, but also, result in an improvement in reconstructing micro-vascular circulation of ischemia myocardial, especially, prolonged duration CSWT at early stage of acute myocardial infarction could better improve myocardial micro-vascular circulation. This may be one of the most important mechanisms for CSWT angiogenesis strategy in treatment of human ischemia heart disease in early stage.PartⅣEffect of Extracorporeal cardiac shock wave therapy on matrix metalloproteinase 1& TIMP1 after acute myocardial infarction in PigsObjective This experiment aimed to observe the effect of CSWT on matrix metalloproteinase and relative inhibitive factors, and explore the potential biology mechanism that inhibit ventricular remodeling after acute myocardial infarction in pigs.Methods A total of 30 domestic miniature pigs were involved in this study. The methods of grouping and treatment were same with those in part experiment. At 30 days, the expression levels of mRNA of MMP1 and TIMP1 were measured and evaluated.Results At 30 days, compared to pseudo-CSWT group, the mRNA expression of TMP1 was up-regulated significantly in CSWT group(32.87±9.13vs20.17±6.31,P< 0.001), while the expression of MMP1 was significantly decreased 9.38±1.85vsl3.52±3.14,P<0.001; Which is consistent with the results of increased VEGF expression and higher collateral vessel Rentrop score in this group.Conclusions CSWT can induce angiogenesis, up-regulate the expression of angiogenic factor, depress promote factor of ventricular remodeling, promote micro-vascular circulation reconstruction of ischemia myocardial and inhibit ventricular remodeling. It may be the potential mechanism that cardiac shock wave therapy regulates metabolism balance of myocardial extra-cellular matrix and improve ventricular remodeling.PartV Effect of extracorporeal cardiac shock wave therapy on left ventricular morphology and function after acute myocardial infarction in a porcine modelObjective Experimental and initial clinical studies have suggested that CSWT could ameliorate metabolism of ischemia myocardium from the level of gene and cells. This section evaluates whether CSWT may bring about beneficial effect on post-infarction remodeling processes in morphology and ventricular function level?Methods A total of 30 domestic miniature pigs were involved in this study. The methods of grouping and treatments were same with part II of this experiment.At baseline and 30days, the morphology parameters about left ventricular volume, regional wall motion and global ventricular function were measured and evaluated.Results At 30 days, compared to positive control group, LVESV,LVEDV and LVEF were improved significantly in CSWT group, LVESV 53.0±1.5vs64.7±1.4ml,P< 0.001;LVEDV 90.2±7.8vs98.7±5.3ml,P<0.03;LVEF 47.8±4.6vs39.2±6.2%,P< 0.001;Furthermore, the wall thickness and wall motion score index was significantly better in CSWT group than that of positive and negative control groups;The significant differences of index about ventricular remodeling were not seen in CSWT subgroups, but improved significantly in comparison to other groups. Compared with positive control group, the index of WT and WMSI were improved significantly in all of CSWT subgroupsConclusions When started in the early phase after AMI, CSWT is a very effective and non-invasive therapy to improve regional and global ventricular function and ameliorate LV remodeling. This may also be one of the most important mechanisms for CSWT angiogenesis strategy in treatment of human post-infarction heart disease in early stage...