Beneficial effects of adrenomedullin on left ventricular remodeling after myocardial infarction in rats

OBJECTIVE: We previously reported that plasma adrenomedullin (AM) levels increase in patients with acute myocardial infarction (MI) and AM inhibits growth of rat cardiac myocytes and fibroblasts. The aim of this study was to examine the effects of long-term administration of AM on left ventricular (LV) remodeling, hemodynamic and hormonal parameters in a rat model of MI. METHODS: Rats with MI induced by left coronary ligation were intravenously infused with 1.0 microg/h of recombinant human AM or saline by osmotic mini-pump. After infusion for 4 weeks, hemodynamic and hormonal studies were performed, and the myocyte size and collagen volume in non-infarct LV area were quantified morphometrically. RESULTS: When compared with the MI rats infused with saline, continuous infusion of AM reduced the heart weight/body weight (4.4+/-0.2 vs. 3.6+/-0.1 g/kg, P<0.01), myocyte size (922+/-23 vs. 868+/-10 microm(2), P<0.05) and collagen volume fraction of non-infarct LV area (7.6+/-0.8 vs. 4.8+/-0.5%, P<0.05), without affecting the infarct size. The AM infusion had no significant effect on the arterial pressure, but decreased the LV end-diastolic pressure (8.8+/-1.8 vs. 4.4+/-0.5 mmHg, P<0.05) in the MI rats. The plasma level of endogenous rat AM in the MI rats infused with human AM was reduced by 27% (P<0.05), with a slight reduction of plasma atrial natriuretic peptide, compared with the control. CONCLUSIONS: Continuous administration of AM had beneficial effects on LV remodeling and hemodynamics in MI rats, suggesting the possibility that this peptide could be a useful therapeutic tool for acute MI.     

Beneficial effects of an open artery on left ventricular remodeling after myocardial infarction

During the last 2 decades researchers have developed a clearer understanding of the pathophysiology of acute myocardial infarction (AMI). The use of thrombolysis and coronary angioplasty early in the course of AMI salvages myocardium and preserves left ventricular function, which results in improved survival rates. Late reperfusion after AMI, however, may provide beneficial effects on long-term prognosis, especially owing to attenuation of left ventricular remodeling. This article reviews the evidence of the benefits of an open infarct-related artery on left ventricular remodeling after AMI. Copyright © 2000 by W.B. Saunders Company

Progress in Cardiovascular Diseases, Vol. 42, No. 6 (May/June), 2000: pp 471-483     

心肌梗死后左室重构发病机制进展

急性心肌梗死(AMI)是威胁人类健康的重大疾病,心肌梗死(MI)后30 min,部分心肌细胞即发生不可逆的坏死,因此,MI有效救治的时间窗极为短暂,许多患者不能够得到及时有效的治疗,使得MI后心力衰竭(HF)的发生率仍然居高不下。最新调查研究表明,MI后1年HF的发生率约为14.2%。因MI后HF再次入院的患者,1年死亡率高达为45.5%。MI后HF的主要原因是部分心肌细胞坏死,左室重构,心脏扩张,继而引发HF。目前,MI后左室重构的机制尚未完全阐明。本文介绍了AMI后左室重构的发病机制主要进展。     

卡维地洛对心肌梗死后左室重塑的影响

目的：观察卡维地洛对急性心肌梗死（AMI）左室重塑的影响。方法：将80例AMI患随机分为常规治疗组（n=20)，依那普利组（n=30)及卡维地洛组（n=30)在AMI后1周，24周用超声心动图分别测定3组病人的左房内径（LA），左室舒张末期内径（LVDd)，左室收缩末期内径（LVDs)，室间膈舒张末期厚度（IVSd)，左室后壁舒张末期厚度（LVPWd)，计算左室重量（LWM），左室重量质数（LVMI）及左室射血分数（LVEF）。结果：AMI后24周，卡维地洛组和依那普利组与常规治疗组比较LA，LVDd,IVDs均明显缩小，IVSd,LVPWd,LVM及LVMI明显减小，而LVEF明显升高（P＜0．01），以上指标卡维地洛组与依那普利组比较无显性差异（P＞0．05），结论：卡维地洛可以防治AMI后左室重塑，改善心功能，其作用与依那普利相同。     

Prevention of left ventricular remodeling after myocardial infarction

Opinion statement Postinfarction left ventricular remodeling begins early after acute myocardial infarction and may continue for months to years afterward. Early re-establishment of flow in the occluded artery is associated with smaller left ventricular cavity volumes and reduced remodeling. Acute percutaneous coronary intervention (PCI) or thrombolytic therapy (for patients more than 1 hour away from a catheterization facility) as early as possible after symptoms is critical. Late reperfusion (PCI more than 12 hours after infarction) may prove useful, and this will be determined by the results of ongoing clinical trials. Recurrent MI is reduced by antiplatelet agents (aspirin in most patients) and by 3-hydroxy-3-methylglutaryl coenzyme A reductase inhibitors. Intravenous nitroglycerin may limit early (initial 24 hours) dilatation following infarction, but long-term use in asymptomatic patients is not efficacious. Betaadrenergic receptor antagonists and angiotensin-converting enzyme (ACE) inhibitors have independent efficacy in attenuating the early and late phases of remodeling. The combined use of a beta-blocker and an ACE inhibitor has greater efficacy than either agent alone, provided they are tolerated hemodynamically. Although angiotensin II receptor antagonists have similar efficacy to ACE inhibitors and have fewer side effects, the angiotensin II receptor blockers should be reserved for patients intolerant to ACE inhibitors. In patients requiring diuretic therapy, spironolactone is preferred because of its salutary properties regarding extracellular matrix remodeling, specifically in reducing fibrosis. Surgical revascularization with or without associated mitral valve repair is useful in selected patients with severe ischemic mitral regurgitation or hibernating myocardium. New therapies directed at modulating the remodeling process may focus on manipulating the components of the extracellular matrix to reduce the deleterious impact of this process.     

Prediction of left ventricular remodeling after acute myocardial infarction

Prediction of adverse left ventricular remodeling after acute myocardial infarction (AMI) may have important clinical implications. In this study, we evaluated the incidence of unfavorable changes of left ventricular volumes and ejection fraction after AMI. The ability of several cardiac markers, electrocardiographic and echocardiographic (including tissue Doppler) variables to predict adverse remodeling was demonstrated. The prognostic algorithm based on the investigated variables may help improve the treatment of patients after AMI.     

辛伐他汀对心肌梗死大鼠心室重构的影响

目的采用超声心动图检测评价辛伐他汀对改善大鼠心肌梗死(MI)后心室重构的作用。方法34只大鼠分3组:(1)MI组:仅结扎左冠状动脉前降支(LAD);(2)治疗组:结扎LAD,并用辛伐他汀40 mg.kg-1.d-1进行灌胃;(3)假手术组:开胸,但不结扎LAD。超声心动图检查心脏结构和功能,逆转录-聚合酶链式反应(RT-PCR)测定梗死区和非梗死区肿瘤坏死因子(TNF)-αmRNA表达,免疫印迹法和免疫组织化学染色法测定TNF-α蛋白的产生。结果超声心动图显示,MI组与假手术组比较,左心室舒张末期内径(LVEDd)显著增大,分别为(7.5±0.4)mm和(4.5±0.3)mm,短轴缩短率〔FS,分别为(20.5±2.5)%和(51.6±3.1)%〕和射血分数〔EF,分别为(41.4±4.3)%和(85.2±3.7)%〕明显降低(均为P<0.05)。与MI组比较,辛伐他汀显著减轻左心室扩张,改善左心室功能(P<0.05)。MI组TNF-αmRNA表达和蛋白质的产生较假手术组增加(均为P<0.01),而治疗组TNF-αmRNA表达和蛋白质的产生比MI组明显下降(P<0.05)。TNF-αmRNA表达和蛋白质生成与心功能下降呈正相关,辛伐他汀减轻TNF-α基因表达,改善心功能。结论辛伐他汀改善大鼠MI后心室的不良重塑,其机制可能与降低非梗死区和梗死区心肌内TNF-α基因表达和蛋白质合成有关。     

急性心肌梗死后左室重构的诊断及干预

急性心肌梗死（AMI）后左室重构（VR）是梗死后心肌组织结构和心室功能变化的病理生理过程,影响梗死后患者的心脏血流动力学状态,并且是决定梗死后心脏事件发生率和远期预后的主要因素。     

卡维地洛防治大鼠急性心肌梗死左室重塑的作用

目的评价第三代β-受体阻滞剂卡维地洛防治大鼠急性心肌梗死(AMI)左室重塑(LVRM)的作用.方法 100只雌性SD大鼠AMI术后24h随机分成(1)AMI对照组(n=25);(2) 卡维地洛组(n=25)(1 mg·kg-1·d-1);(3)西拉普利组(n=25)(1 mg·kg-1·d-1)和(4)氯沙坦组(n=25)(3 mg·kg-1·     

左室造影对急性心肌梗死后左室重构发生的评价

目的 :探讨左室造影对急性心肌梗死 (AMI)后左室重构发生的评价及其临床意义。方法 :用左室造影投影系统计算出心肌梗死 (MI)急性期及恢复期左室容积指标 ,根据左室容积指标将患者分为重构组和非重构组 (均为 2 0例 ) ;用漂浮导管测定血流动力学指标 ;用99m 锝心血池扫描测定左室射血分数 (LVEF) ;用2 0 1铊心肌血流扫描测定梗死的面积积分 (ES)和重症度积分(SS)。结果 :重构组恢复期左室舒张末期及收缩末期容积均显著高于非重构组 (P <0 .0 1) ,亦显著高于该组急性期左室容积 (P <0 .0 1)。重构组急性期肌酸磷酸激酶峰值、急性期及恢复期肺小动脉嵌压、恢复期左室舒张末压力以及恢复期ES和SS均显著高于非重构组 ,而LVEF显著低于非重构组。重构组恢复期左室收缩末期容积及舒张末期容积与LVEF之间存在有意义的相关关系 (r =- 0 .72 ,P <0 .0 1;r =- 0 .6 7,P <0 .0 1)。结论 :AMI后进行左室造影能较准确地评价左室重构的发生及严重程度。发生左室重构的患者其心肌坏死量较大 ,且其恢复期左室功能显著降低。恢复期左室功能与左室容积指标之间存在密切相关。     

急性心肌梗死后左室重构临床研究

目的　探讨溶栓治疗对急性心肌梗死后左室结构和功能的影响。方法　对 36例首发急性心肌梗死患者于梗死后 4周和 12周进行超声心动图观察。分别测定左室舒张末期容积指数 (LVEDVI)、左室收缩末期容积指数 (LVESVI)、射血分数 (EF) ,作为反映左室结构和功能变化的指标。结果　急性心肌梗死后LVEDVI、LVESVI均明显增高 (分别为P <0 0 1,P <0 0 5 )。 4周和 12周检查发现 ,溶栓组LVEDVI、LVESVI无明显差异 (分别P>0 0 5 ,P >0 0 5 ) ,EF值明显增大 (P <0 0 5 ) ;未溶栓组LVEDVI、LVESVI明显增大 (分别为P <0 0 5 ,P <0 0 5 ) ,EF值无明显变化 (P >0 0 5 ) ;对 4周和 12周的检查结果作组间比较发现 ,溶栓组LVEDVI、LVESVI均小于未溶栓组 (P <0 0 5 ) ,EF值溶栓组高于未溶栓组 (P <0 0 5 )。结论　溶栓治疗能有效地抑制急性心肌梗死后左室重构 ,改善心功能。     

High dose aspirin and left ventricular remodeling after myocardial infarction

Background Proinflammatory proteins like inflammatory cytokines are implicated in myocardial depression and left ventricular remodeling after myocardial infarction. High-dose aspirin inhibits cytokine activation. Therefore, we tested the influence of high-dose aspirin treatment on left ventricular remodeling in mice after myocardial infarction. Methods and results Mice were treated for 4 weeks with placebo or aspirin (120 mg/kg per day) by Alzet mini-osmotic pumps after ligation of the left anterior descending coronary artery. Serial transthoracic echocardiography was performed at days 1, 7, and 28. Over the 4 weeks, mortality was not different between the groups (placebo 30.8%, aspirin 30.8%). On echocardiography, animals after myocardial infarction exhibited left ventricular dilatation (week 4, end-systolic area, placebo sham 8.9 ± 1.7 vs. placebo MI 15.9 ± 2.5 mm²), which was not changed by aspirin treatment (week 4, end-systolic area, aspirin MI 14.5 ± 1.3 mm², p= ns vs. placebo MI). The expression of the proinflammatory cytokines TNF and IL-1β were markedly upregulated in mice with myocardial infarction on placebo. Cytokine expression was significantly reduced by aspirin treatment while collagen deposition was not influenced. Conclusion Continuous aspirin treatment (120 mg/kg/d) reduces the expression of proinflammatory cytokines after myocardial infarction, but does not affect post-infarct cardiac remodeling and cardiac function.     

芪苈强心胶囊对大鼠心肌梗死后心肌重构及心功能的影响

目的 探讨芪苈强心胶囊对心肌梗死后大鼠心肌重构及心功能的影响.方法 结扎大鼠左前降支,建立AMI模型,存活者随机分为梗死对照组（MI组）和芪苈强心胶囊治疗组（MI-D组）,另设假手术组（Sham组）.MI-D组术后4周每天予芪苈强心胶囊生药4 g/kg（生理盐水溶为1.5 ml溶液）治疗,MI组和Sham组仅以等体积生理盐水灌胃,4周后对相关指标进行检测.结果 术后4周大鼠心脏超声及血流动力学均显示左室功能减低;基质金属蛋白酶2,9活性升高;α-MHC/β-MHC mRNA的比值下降.经芪苈强心胶囊治疗后左室功能有明显改善;基质金属蛋白酶2,9活性降低,α-MHC/β-MHC mRNA的比值升高.结论 芪苈强心胶囊治疗AMI可以改善心肌重构和心功能.芪苈强心胶囊治疗有效改善心功能的作用机制至少部分与其抑制心肌重构有关.     

氟伐他汀对心肌梗死大鼠左室重塑和功能的影响

目的探讨羟甲基戊二酰辅酶A(HMGCoA)还原酶抑制剂氟伐他汀对急性心肌梗死(AMI)大鼠左室结构和功能的影响。方法雌性SD大鼠AMI后6h随机分为AMI组和氟伐他汀组;另设假手术组。三组大鼠直接灌胃给药或自来水8周后行高频多普勒超声、血流动力学、心脏重塑指标及左心室心肌α、β肌球蛋白重链(α、βMHC)mRNA表达的测定。结果与假手术组相比,AMI组左室舒张末期内径(LVEDD)、左室舒张末期容积(LVEDV)、E峰、E峰减速度、E/A、左室舒张末压(LVEDP)、左、右心室心肌肥厚指数、非梗死区胶原容积分数(CVF)和βMHCmRNA均明显增加(P<0.01),左室短轴缩短率(FS)、射血分数(EF)和αMHCmRNA显著降低(P<0.01)。与AMI组相比,氟伐他汀组的LVEDD、LVEDV、E峰、E峰减速度、E/A、LVEDP、左、右心室心肌肥厚指数、CVF和βMHCmRNA均显著降低或减少(P<0.01),FS、EF和αMHCmRNA显著升高(P<0.01)。结论氟伐他汀能抑制大鼠AMI后左室重塑,改善血流动力学异常和左室功能。