Heart failure: Effects of beta receptor antagonists on left ventricular function in patients with clinical evidence of heart failure after myocardial infarction. A double-blind comparison of metoprolol and xamoterol Echocardiographic results from the Metoprolol and Xamoterol Infarction Study (MEXIS)

Two hundred and ten patients with clinical evidence of heartfailure, developing after an acute myocardial infarction, wererandomized to treatment with the ß₁ antagonist metoprolol50–100mg b.i.d. (n=106) or the ß₁ partial agonistxamoterol 100–200 mg bid. (n=104). Left ventricular systolicand diastolic function were assessed with echocardiography andtransmitral Doppler cardiography before and after 3 and 12 monthsof double-blind treatment. E-point septal separation and percent left ventricular fractional shortening were used as indicesof systolic function. The ratio between peak early and latemitral diastolic flow (E/A ratio) and isovolumic relaxationtime were used as indices of diastolic function. In the xamoterol group, there was a deterioration in E-pointseptal separation (P<0·05). A difference between thetreatment groups was present both at 3 months (E-point septalseparation 11·4 vs 13·0 mm, P<0·0l,fractional short ening 271 vs 252%, P<005) and 12 months(E-point septal separation Ill vs 13·2 mm, P<0·05fractional shortening 26·9 vs 25·0%, P<0·05).E/A ratio increased in the metoprolol group (P<0·05)but not in the xamoterol group. At 3 months there was a significantdifference (0·85 vs 0·67, P<0·005 betweenthe groups but not at 12 months. In comparison with the ß₁-receptor antagonist metoprolol,the ß₁ partial agonist xamoterol impaired left ventricularsystolic function in patients with clinical evidence of heartfailure after an acute myocardial infarction.     

ADM对LNNA诱导的高血压心肌肥大的作用及机制探讨

本工作在ＬＮＮＡ经慢性ＮＯ封闭诱导的大鼠高血压心肌肥大模型上研究了ＡＤＭ对其心肌肥大和Ｍ５ＬＶ钠一钙交换功能损伤的作用。结果：一、较之对照组，ＬＮＮＡ组ＭＡＯ和ＬＶＩ分别增加５７．４％和１８。０％（Ｐ＜０．０１）．其ＭＳＬＶ经钠－钙交换蛋白的钙摄取则明显降低（Ｐ＜０．０１或０．０５）：二．ＡＤＭ组的ＭＡＰ和ＬＶＩ则分别较ＬＮＮＡ组降低１９．６％和１１．３％，而其ＭＳＬＶ的钙摄取则高于ＬＮＮＡ组（Ｐ＜０．０５）；三、对照组、ＬＮＮＡ组和ＡＤＭ组钠－钙交换蛋白摄取钙的Ｋｍ值分别为７．５１．７．０４和７．５７ｕＭ，而Ｖｍａｘ则分别为６．３８，４．３２和５．４５ｎｍｏｌ／。ｍｇｐｒ／ｍｉｎ。表明：ＡＤＭ能拮抗ＬＮＮＡ诱导的高血压心肌肥大和减轻其ＭＳｌｌＶ钠－钙交换功能的损伤，并且后者可能是ＡＤＭ拮抗心肌肥大的机制之一。揭示内源性ＡＤＭ的诱导和外源性给予ＡＤＭ可能有预防和／或延缓高血压心肌肥大发生发展的作用。     

Nitrate administration to enhance the detection of myocardial viability by technetium-99m tetrofosmin single-photon emission tomography

A comparison was performed between technetium-99m tetrofosmin myocardial perfusion tomography at baseline and after nitrate administration, using a 2-day protocol, and rest-reinjection thallium-201 single-photon emission tomography (SPET) studies in order to assess whether nitrates enhance the detection of viable myocardium with^99mTc-tetrofosmin. Fifteen patients with coronary artery disease, previous myocardial infarction and a left ventricular ejection fraction <40% underwent²⁰¹T1 rest-injection and^99mTc-tetrofosmin. baseline-postnitroglycerin (0.4 mg sublingually) SPET studies, within 48 h. Tomograms based on the three spatial planes were divided into 15 segments and regional tracer uptake was quantitatively analysed. Viability was defined as presence of tracer uptake >50% of peak activity on baseline studies or after reversibility. The percentage of peak activity of^99mTc-tetrofosmin at baseline correlated with that of 201T1 (r=0.82,P <0.001). On baseline^99mTc-tetrofosmin studies, 73 of the 225 segments that were analysed had <50% of peal. activity. Fifteen percent of these segments showed reversibility after nitrate administration, with an increase in^99mTc-tetrofosmin uptake from 40%±9% to 57%±9% of peak activity (P=0.003). All reversible segments after nitrate administration had viability criteria on²⁰¹Tl studies, but 20 segments that were non-viable on^99mTc-tetrofosmin. studies were viable on²⁰¹Tl studies. Using a threshold value of >40% of peak activity, only seven segments remained non-viable on^99mTc-tetrofosmin studies. Overall agreement between^99mTc-tetrofosmin with nitrates and²⁰¹Tl-reinjection regarding the presence of myocardial viability was 90%. Detection of myocardial viability with^99mTc-tetrofosmin. was enhanced after nitrate administration, correlating with viability criteria observed on thallium studies.     

急性心肌梗死静脉溶栓后cTnT浓度比值对判断冠脉再通的价值

目的　探讨血清心肌肌钙蛋白T(cTnT) 3h 2h的浓度比值对急性心肌梗死 (AMI)溶栓后判定冠状动脉再通的价值。方法　采用ELISA法动态检测了 5 7例接受尿激酶静脉溶栓治疗的AMI患者和 31例正常健康对照血清cTnT ,CK MB及CK水平 ,并计算溶栓后 3h与 2h血清cTnT浓度比值。结果　①cTnT释放呈现两种特征 ,再通组呈双峰型 ,未通组呈单峰型 ,且再通组后期峰值较未通组峰值低 (P <0 .0 1)。②cTnT浓度 3h 2h比值再通组明显高于未通组 (P <0 .0 1) ,以该比值 >1.4 8作为判定再通的标准 ,其对判定冠状动脉再通的敏感性、特异性、预测值分别为 83.3% ,90 .5 % ,93.8%。与峰值时间判定冠脉再通比较差异无显著性 (P >0 .0 5 )。结论　cTnT的动态检测可有效地判定对AMI溶栓后再通与否 ,特别是溶栓后 3h 2h浓度比值 >1.4 8可作为早期判定冠脉再通的标准 ,且具有迅速、省时等优点 ,值得推广应用     

Myocardial protection in adult cardiac surgery: current options and future challenges

Current techniques of myocardial protection are evolving with the use of less conventional modalities of cardioplegia and have reduced the morbidity and mortality of cardiac operations. Blood cardioplegic solutions appear superior to cold cardioplegia in terms of myocardial protection and adjuncts as glutamate/aspartate enhancement, antioxidant supplementation, nitric oxide donors and maintenance of calcium homeostasis seem effective. In the near future, further experimental and clinical investigations about pharmacological preconditioning, sodium–hydrogen exchangers inhibition and gene therapy need to be addressed to well define their potential role in the improvement of current techniques of myocardial protection that are suboptimal in high-risk clinical settings.     

An Appraisal of Different Cardiac Risk Reduction Strategies in Vascular Surgery Patients

OBJECTIVES: to summarize existing evidence regarding the benefits and the risks of all available interventional and medical means aimed at cardiac risk reduction in patients undergoing vascular surgery. DESIGN: review of the literature. MATERIALS AND METHODS: a critical review of all studies examining the impact of various prophylactic cardiac maneuvers on perioperative outcome following vascular surgery was performed. Overall mortality, cardiac mortality and myocardial infarction rate were used as the outcome measures. RESULTS: coronary artery bypass grafting is associated with a 60% decrease in perioperative mortality in patients undergoing vascular surgery, but in most of the cases this decrease does not outweigh the combined risk of the cardiac and the subsequent noncardiac vascular procedure. Data supporting the cardioprotective effect of percutaneous transluminal angioplasty in the perioperative setting are insufficient. beta-blockade has been shown to decrease perioperative mortality and cardiac morbidity in both high-risk (strong evidence) and low-risk (weak evidence) patients. CONCLUSIONS: coronary revascularization is rarely indicated to simply get the patient through vascular surgery and should be reserved for patients who would need it irrespective of the scheduled vascular procedure. Among all available pharmacological agents, including beta-blockers, alpha-agonists, calcium channel blockers and nitrates, only beta-blockers have been proven to reduce the cardiac risk of vascular surgery.     

Severe acute myocardial infarction during a staphylococcal septicemia with meningoencephalitis

We report the first case of lethal intracranial haemorrhage complicating a treatment by rt-PA in a patient presenting with a simultaneous staphylococcal septicemia with meningoencephalitis and an acute myocardial infarction with cardiogenic shock. The presence of microvascular lesions in the central nervous system seems to be important risk factor for intracranial haemorrhage and we recommend extreme caution in the use of thrombolytic treatment in septicemic patients with acute myocardial infarction, particularly when neurological symptoms are present.     

极化心脏停搏液对离体大鼠心脏的保护作用

目的探讨Na+通道阻滞剂河豚毒素(tetraodontoxin,TTX)在极化状态下对离体大鼠心脏的保护作用. 方法将20只Wistar大鼠按体重均衡原则随机分成两组,每组10只.取出心脏建立Langendorff灌注模型和左心工作灌注模型,分别用去极化心脏停搏液(St.Thomas 2号液,STH-2组)和极化心脏停搏液(22 μmol/L TTX + K-H缓冲液,TTX组)停搏,低温保存5小时后再灌注心脏.观察两组心脏缺血前、后在心功能、心肌酶漏出量、三磷酸腺苷酶(ATPase)活性、再灌注后心肌胞浆游离Ca2+浓度和心肌超微结构等方面的改变. 结果恢复灌注后,TTX组心功能恢复明显优于STH-2组(P＜0.01),心肌酶漏出量较少(P＜0.05),各种ATPase维持较高的活性(P＜0.01),胞浆游离Ca2+浓度明显低于STH-2组(P＜0.01),心肌超微结构得到很好的保护. 结论以TTX阻断Na+通道为特点的极化心脏停搏液对大鼠心肌缺血-再灌注损伤的保护作用优于去极化心脏停搏液,有希望成为新型、有效的心脏停搏液和供者心脏保存液.     

老年糖尿病合并陈旧性心肌梗死患者新近发生冠状动脉事件的相关因素分析

目的 探讨老年糖尿病合并陈旧性心脲梗死(MI)患者新近发生冠状动脉事件的相关因素。方法 按照治疗方法，将346例老年糖尿病合并陈旧性心脲梗死患者分为磺脲类组，胰岛素组，二甲双胍类组，单纯饮食疗法组，分析各组治疗后新近冠状动脉事件的发生率及其影响因素。结果 新近冠状动脉事件的重要独立危险因素为：年龄(增加1岁危险率1．02)、吸烟(危险率1.36)、高血压病(危险率1．05)、LDL增高(危险率1.53)、HDL降低(危险率1.72)、使用磺脲类药物(危险率1．35)。结论 老年糖尿病合并陈旧性MI患者在饮食控制的基础上应选择胰岛素或二甲双胍类药物治疗，严格控制血压，积极降低LDL，提高HDL，避免单纯使用磺脲类药物。     

VEGF165cDNA治疗缺血心肌的实验研究

目的：观察VEGFl65cDNA治疗缺血心肌后心功能、血流动力学、心肌灌注和代谢的变化。方法：健康杂种犬36只，随机分为VEGFl65cDNA和空质粒(pcDNA3：1)组(n＝12)，心肌梗塞组为对照组。Amroid环致慢性心肌缺血模型。VEGFl65基因转染采用直接心肌注射法。结果：基因转染后4周、8周时VEGF165基因组LVEF和CO及前壁、前侧壁、前间壁心肌灌注量、代谢和FDG摄入量明显高于同期心肌梗塞组。结论：VEGFl65基因治疗后4周和8周时心功能显著改善；成活心肌的数量显著增加和/或称成活心肌功能显著恢复。