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。     

脑活素治疗新生儿缺氧缺血性脑病27例疗效分析

本文对27例新生儿缺氧缺血性脑病(HIE)在常规治疗基础上加用脑活素与常规治疗相比较,发现两组治疗结果在统计学上比较差异有显著性(P<0.05),提示脑活素对治疗HIE有一定疗效,可提高治愈率,减少后遗症的发生。     

介入法和无创法评价急性心肌梗死溶栓后心肌再灌注的一致性研究

目的 探讨急性心肌梗死（AMI）溶栓治疗后无创法评价心肌再灌注的可行性。方法选择AMI溶栓治疗后行冠状动脉造影的患者，溶栓后90min血浆肌红蛋白（Mb）浓度与溶栓前血浆Mb浓度比值≥2．4或心电图ST段回落≥50％定义为成功再灌注（阳性）。上述两项指标均阳性为完全再灌注，仅一项阳性为部分再灌注，两项均阴性为无再灌注。再根据冠状动脉造影结果将患者分为完全再灌注（TIMI3级）、部分再灌注（TIMI2级）、无再灌注（TIMI0～1级）。对无创法和介入法进行一致性检验。共入选45例患者。结果无创法和介入法评价心肌再灌注经一致性检验，符合率为84．4％，Kappa=0．75（P〈0．01）。结论．心电图ST段回落和血浆Mb浓度变化两项指标合用可提高评价心肌再灌注准确性，和介入法有很高的符合率，简便易行，且结果可靠。     

Left ventricle haemodynamics and vaso-active hormones during graded supine exercise in healthy male subjects

Left ventricle systolic and diastolic functional parameters were measured by gated equilibrium radionuclide cardiography in 12 healthy men (age 33–51 years) at rest and during graded supine exercise. The leftventricle end-diastolic volume showed an initial small (11%) increase during low submaximal exercise [from mean 163 (SD 40) at rest to mean 181 (SD 48) ml], while left ventricle end-systolic volume decreased successively [from mean 59 (SD 19) to mean 39 (SD 21) ml] with increasing exercise. Stroke volume was therefore elevated at all exercise levels compared with rest [mean 104 (SD 23) ml], and the peak value [mean 128 (SD 33) ml] was found at the lowest exercise level, contributing 40% to the initial increase in cardiac output. Cardiac output increased from mean 6.2 (SD 1.4) at rest to mean 20.2 (SD 5.0) 1 · min^–1 at maximum. Left ventricle peak ejection and peak filling rates increased from mean 449 (SD 89) and mean 442 (SD 85) ml · s^–1 at rest to mean 996 (SD 227) and mean 1255 (SD 333) ml · s^–1, respectively, at maximum. The myocardium oxygen consumption, assumed to be proportional to the sum of the stroke work and the potential energy, increased fourfold, but absolute values were twice as high as expected, indicating that extrapolation from data obtained in dog hearts (as we have done) cannot be directly applied to humans. Selected vaso-active hormones were measured at all exercise intensities. Noradrenaline (NA), adrenaline (A) and angiotensin II (AII) concentrations showed a very pronounced increase at maximal exercise compared with the preceding lower intensites, while atrial natriuretic factor (ANF) and cyclic guanosinemonophosphate (cGMP) concentrations showed a more continuous increase, and dopamine (DA) remained almost unchanged. This speaks in favour of a crucial role for NA, A and AII in preserving blood pressure at maximum exercise, while DA probably has no importance for the cardiovascular homeostasis during exercise. Increases in concentrations of ANF and cGMP were highly correlated (r = 0.86). Our data supported the opinion that there is a cardiac limitation to maximal performance connected to the cardiac pumping capacity.     

Short and long term effects of exercise training on the tonic autonomic modulation of heart rate variability after myocardial infarction

We studied the effects of cardiac rehabilitation on the sympathovagalcontrol of heart rate variability in 30 patients after a first,uncomplicated myocardial infarction. Twenty-two patients completed8 weeks of endurance training (trained), while eight decidednot to engage in the rehabilitation programme for logisticalreasons, and were taken as untrained controls. Age, site ofinfarction, ejection fraction, ventricular diameter and stresstest duration were similar in the two groups at baseline. Heartrate variability was evaluated 4 weeks after infarction beforestarting rehabilitation, and repeated 8 weeks and one year laterin both trained and untrained patients. Measures of heart ratevariability, obtained from both time- and frequency- domainanalysis of a 15 min ECG recording in resting conditions, wereas follows: mean RR interval and its standard deviation (RRSD),the mean square successive differences (MSSD), the percent ofRR intervals differing >50 ms from the preceding RR (pNTN50),the low and high frequency components of the autoregressivepower spectrum of the RR intervals and their ratio (LF/HF).At baseline, heart rate variability was similar in trained anduntrained patients. In the short term (8 weeks after infarction),training increased RRSD by 25% (P<0·01), MSSD by 69%(P<0·01), pNN50 by 120% (P<0·01), and reducedLF/HF ratio by 30% (P<0·01). The effects persistedafter one year in trained patients. In untrained patients, theautonomic control of heart rate variability did not change 8weeks after myocardial infarction and was only slightly modifiedby time. Thus, exercise training, performed for 8 weeks aftera myocardial infarction, modifies the sympathovagal controlof heart rate variability toward a persistent increase in parasympathetictone, known to be associated with a better prognosis. This maypartly account for the favourable outcome of patients who undergorehabilitation.     

ONE-STAGE ARTERIOVENOUS REVERSAL FOR REVASCULARIZATION OF SEVERELY ISCHEMIC LIMBS

Staged arteriovenous reversal has been successfully established forrevascularization of severely ischemic limbs since 1984. The authors tried to constrict thecentral venous limb immediately after the arteriovenous fistula formation to make the pres-sure distal to the anastomosis raising to its maximum to shorten the time required for thedistal valves to become incompetent. Thus, the revascularization of the severely ischemiclimbs may be established much sooner than the staged arteriovenous reversal, and more di-seased limbs will be saved. Forty-two patients with a total of 60 upper and lower limbshave been operated on with good results.