Emergency myocardial revascularization in acute evolving myocardial infarct

Immediate coronary artery bypass for acute evolving myocardial infarction could be the elective therapy if provided on useful time, because myocardial salvage can be achieved by early reperfusion. Thirty eight patients had emergency coronary artery by-pass graft for acute evolving myocardial infarction during the early phase: 35 were male, the mean age was 51 years (34 to 74). The mean interval between the onset of symptoms and surgery in this series of patients was two hours and a half. This interval seems to be also the time limit in our experience to get a partial or complete recovery of ischemic area. Four patients died in hospital, but they were in severe cardiogenic shock before emergency surgery. Twenty nine cases were free of symptoms at a mean follow-up of 18 months (6 to 36) and two suffered for residual angina. Three patients died after discharge few months later: two during redo emergency vein grafts operations, one in deep left ventricular failure, while he was waiting for heart transplant. All these patients operated on as emergency developed acute myocardial infarction during their stay in hospital waiting for catheter study, surgical operation or during percutaneous transluminal coronary angioplasty. Saphenous vein grafts, were used in twenty nine patients, left internal mammary artery in nine cases, single in four and associated to saphenous vein in five, with an average number of anastomoses of 2.6 (1 to 6) for patient. ECG was found to be normal in 76% of the patients operated on within two hours and a half from the beginning of symptoms.(ABSTRACT TRUNCATED AT 250 WORDS)     

Increase in myocardial cell cGMP concentration in pressure-induced myocardial hypertrophy

Development of ventricular hypertrophy is a well known consequence of increased outflow resistance. The increase in muscle mass is the result of an elevated rate of protein synthesis that results in the enlargement of existing myofilaments shortly after outflow resistance is increased [2, 6, 15]. The mechanism by which a mechanical stimulus is transformed into a well ordered biochemical response by the myocardial cell is not known. Various substances, including catecholamines and angiotensin II [10, 14] have been proposed as chemical mediators of the hypertrophic process. No definitive evidence, however, has been obtained favoring a specific agent with this role.Several indirect lines of evidence link the guanylate cyclase-cyclic guanosine mono phosphate (cGMP) system with cell growth. cGMP has been shown to increase protein synthesis and DNA synthesis, and promote growth of several cell species [8, 9]. Furthermore, substances like growth hormone and angiotensin II which stimulate protein synthesis and amino acid uptake in the myocardium and other tissues [4, 7] have been shown to increase guanylate cyclase activity in myocardial cells [12, 13]. In view of these observations, we thought it of interest to examine the possible changes in steady state levels of cGMP in the myocardium during the early stages of myocardial hypertrophy.     

Quantitative myocardial contrast echocardiography for prediction of thrombolysis in myocardial infarction flow in acute myocardial infarction

Clinical evaluation of arterial patency in acute ST-elevation myocardial infarction (STEMI) is unreliable. We sought to identify infarction and predict infarct-related artery patency measured by the Thrombolysis In Myocardial Infarction (TIMI) score with qualitative and quantitative intravenous myocardial contrast echocardiography (MCE). Thirty-four patients with suspected STEMI underwent MCE before emergency angiography and planned angioplasty. MCE was performed with harmonic imaging and variable triggering intervals during intravenous administration of Optison. Myocardial perfusion was quantified offline, fitting an exponential function to contrast intensity at various pulsing intervals. Plateau myocardial contrast intensity (A), rate of rise (beta), and myocardial flow (Q = A x beta) were assessed in 6 segments. Qualitative assessment of perfusion defects was sensitive for the diagnosis of infarction (sensitivity 93%) and did not differ between anterior and inferior infarctions. However, qualitative assessment had only moderate specificity (50%), and perfusion defects were unrelated to TIMI flow. In patients with STEMI, quantitatively derived myocardial blood flow Q (A x beta) was significantly lower in territories subtended by an artery with impaired (TIMI 0 to 2) flow than those territories supplied by a reperfused artery with TIMI 3 flow (10.2 +/- 9.1 vs 44.3 +/- 50.4, p = 0.03). Quantitative flow was also lower in segments with impaired flow in the subtending artery compared with "normal" patients with TIMI 3 flow (42.8 +/- 36.6, p = 0.006) and all segments with TIMI 3 flow (35.3 +/- 32.9, p = 0.018). An receiver-operator characteristic curve derived cut-off Q value of <11.3, representing impaired myocardial flow, was 73% sensitive and 67% specific for TIMI <3 flow at angiography. Thus, qualitative MCE identifies patients with STEMI but provides no information regarding infarct-related artery patency, whereas quantitative MCE can predict impaired flow in patients with acute STEMI.     

经静脉心肌声学造影评价心肌梗死后存活心肌的价值

目的　探讨经静脉心肌声学造影 (MCE)对心肌梗死后存活心肌的诊断价值。方法　 2 4例心肌梗死患者用二维超声评价室壁运动情况 ,同时经静脉进行MCE ,以 3个月后静态超声心动图左室心肌节段性运动改善为依据评价MCE对心肌梗死后存活心肌的诊断价值。结果　在 2 4例病人的 384个心肌节段中 ,运动异常节段 184个。在运动异常的 184个节段中 ,MCE1分 39段 ,0 5分 5 0段 ,0分 95段。 3个月复查 79个节段有运动改善 ,其中 39段来自MCE1分的心肌 ,4 0段来自MCE0 5分的心肌。MCE对预测心肌梗死后室壁运动改善的敏感性、特异性、阳性预测值、阴性预测值及准确率分别为 :10 0 %、89 7%、84 8%、10 0 %和 94 6 %。结论　MCE能比较准确地预测心肌梗死后心肌的存活性     

Dual-isotope myocardial SPECT in patients with redefined myocardial infarction

BACKGROUND: According to the redefinition of myocardial infarction (MI) by the ESC/ACC Committee, patients with unstable angina (UA) without significant elevation of creatine kinase (CK) but with elevation of troponin T should be diagnosed as MI. METHODS: One hundred and forty-six consecutive patients formerly diagnosed as UA, with peak CK levels0.10 ng/ml). Dual SPECT findings were analyzed qualitatively and quantitatively in blinded manner. RESULTS: Forty-seven patients (32%) were redefined as MI and 99 patients (68%) were redefined as UA. On admission, there were small but statistically significant elevations in laboratory parameters such as white blood cell count, C-reactive protein, CK and CK-MB in the redefined MI group compared with the redefined UA group. The proportion of patients with perfusion and metabolic abnormalities was significantly higher in the redefined MI group (Tl defect 36% vs. 4%, odds ratio: 13.5, p<0.001; BMIPP defect 64% vs. 23%, odds ratio: 5.8, p<0.001). Semi-quantitative evaluation revealed that the total Tl and BMIPP scores were significantly higher in the redefined MI patients (p<0.001). CONCLUSIONS: In the redefined MI patients, perfusion and metabolic abnormalities occurred frequently and more extensively. However, Tl/BMIPP dual SPECT had limited ability to detect minor myocardial infarcts classified as redefined MI. A more sensitive stratification combined with troponin T directed assignment should be established to incorporate the ongoing minor infarcts which could not be assessed by serial dual-scintigraphic evaluations.     

血栓抽吸术改善急性心肌梗死心肌再灌注的临床研究

目的探讨冠状动脉内血栓抽吸并联合球囊成型及支架置入术治疗急性心肌梗死（AMI）对梗死心肌再灌注的影响。方法进行急诊PCI的AMI患者共156例,对其中78例进行冠状动脉内血栓抽吸,然后进行球囊扩张及支架置入治疗。术后造影观察冠状动脉扩张效果及梗死相关血管血流及心肌灌注、心电图STR情况。结果抽吸血栓组与同期入选未抽吸组相比,TIMI血流3级分别为89％和78％;TMP灌注3级分别为88％和45％,STR〉50％者分别为68％和50％。结论经导管进行冠状动脉内血栓抽吸是治疗急性心肌梗死简单有效的方法,并可提高经皮冠状动脉介入治疗的成功率,减少无再流等并发症的发生。     

Value of the myocardial performance index in myocardial infarction

The myocardial performance index represents an easy and reproducible parameter of both systolic and diastolic left ventricular function for the risk stratification of patients following acute myocardial infarction.     

Thrombolysis in myocardial infarction myocardial perfusion grade in angiography correlates with myocardial salvage in patients with acute myocardial infarction treated with stenting or thrombolysis

OBJECTIVES: We sought to assess the relationship between the Thrombolysis In Myocardial Infarction (TIMI) myocardial perfusion (TMP) grade and myocardial salvage as well as the usefulness of TMP grade in comparing two different reperfusion strategies. BACKGROUND: The angiographic index of TMP grade correlates with infarct size and mortality after thrombolysis for acute myocardial infarction (AMI). Its relationship to myocardial salvage and its usefulness in comparing different reperfusion strategies are not known. METHODS: We analyzed the TMP grade on angiograms obtained at one to two weeks after treatment in 267 patients enrolled in two randomized trials that compared stenting with thrombolysis in AMI. Patients were classified into two groups: 159 patients with TMP grade 2/3 and 108 patients with TMP grade 0/1. Two scintigraphic studies were performed: before and one to two weeks after reperfusion. The salvage index was calculated as the proportion of the area at risk salvaged by reperfusion. RESULTS: Patients with TMP grade 2/3 had a higher salvage index (0.49 +/- 0.42 vs. 0.34 +/- 0.49, p = 0.01), a smaller final infarct size (15.4 +/- 15.5% vs. 22.1 +/- 16.2% of the left ventricle, p = 0.001), and a trend toward lower one-year mortality (3.8% vs. 8.3%, p = 0.11) than patients with TMP grade 0/1. The relationship between TMP and salvage index was independent of the form of reperfusion therapy. The proportion of patients with TMP grade 2/3 was significantly higher after stenting than after thrombolysis (70.9% vs. 48.1%, p = 0.001). CONCLUSIONS: These findings show that the TMP grade is a useful marker of the degree of myocardial salvage achieved with reperfusion and a sensitive indicator of the efficacy of reperfusion strategies in patients with AMI.     

Assessment of myocardial oxidative stress in patients after myocardial revascularization

A homogeneous group of six patients, who underwent coronary artery bypass surgery, was studied to determine the presence of oxidative stress caused by oxygen-derived free radicals and its relationship with reperfusion cell damage. Biopsies were performed before ischemia and 10 minutes after reperfusion. The samples were assayed for hydroperoxide-initiated chemiluminescence and histochemical succinic dehydrogenase activity; the specimens were also studied by electron microscopy. The preischemic biopsy specimens showed chemiluminescence of 40 +/- 2 (cpm/mg protein) x 10(3), normal succinic dehydrogenase activity (grade 4), and generally preserved ultrastructure (necrotic/normal cells 5/100). However, the reperfusion biopsy specimens showed an increase in chemiluminescence to 91 +/- 19 (cpm/mg protein) x 10(3) (p less than 0.025), a partial loss of enzymatic activity (grade 2.6), and ultrastructural changes characterized by mitochondrial swelling and focal myofibrillar disorganization (necrotic/normal cells: 15/100; p less than 0.001). These observations seem to indicate the presence of oxidative stress during reoxygenation, a situation that may play a major role in the genesis of reperfusion injury. It appears to be the first observation relating free radical-induced oxidative stress to reperfusion injury in humans.     

Evaluation of transmural myocardial perfusion by ultra-harmonic myocardial contrast echocardiography in reperfused acute myocardial infarction.

BACKGROUND: The transmural distribution of myocardial perfusion is important for predicting the contractile reverse of an infarcted wall in reperfused acute myocardial infarction (AMI). Evaluating transmural myocardial perfusion by myocardial contrast echocardiography (MCE) could predict the long-term recovery of left ventricular (LV) function. METHODS AND RESULTS: The study group comprised 20 consecutive patients with a first-episode anterior AMI with total occlusion of the proximal left anterior descending artery, who underwent successful percutaneous coronary intervention within 24 h of onset. MCE was performed on the 15th day after the onset, using ultraharmonic gray-scale imaging with intermittent end-systolic triggering every 4 beats or every 6 beats. Regions of interest were placed over both the endocardial and epicardial region at the mid-septal level. Regional wall motion (RWM) of the infarcted anterior wall and global LV function were assessed by 2-dimensional echocardiography and left ventriculography in both the acute and chronic phase. The transmural distribution of myocardial perfusion by MCE demonstrated a significant relation with RWM score index (r = 0.75, p = 0.0004). Recovery of RWM and LV ejection fraction (LVEF) at 6 months after reperfusion was significantly greater in the group with good perfusion of the epicardium according to MCE than in the poor perfusion group [RWM (SD/cord); -1.23+/-0.91 vs -3.51+/-0.84, p = 0.001, LVEF (%); 63.8+/-10.4 vs 47.0+/-3.4, p = 0.04]. CONCLUSIONS: Assessing the transmural distribution of myocardial perfusion by MCE can predict the long-term recovery of LV function after a reperfused AMI.     

Acute myocardial infarction in myocardial bridge treated by coronary stent

The authors report the case of a symptomatic myocardial bridge treated in the acute phase of anterior wall myocardial infarction by classical stenting of the mid and distal left anterior descending artery. One and a half months later, intrastent restenosis at the two dilated sites, led to another angioplasty procedure with implantation of sirolimus-eluding stents. The outcome was good with no recurrence of angina at 16 months and control coronary angiography was totally normal at the 8th month.     

Regional myocardial shape alterations in patients with anterior myocardial infarction

Objective: To assess the impact of regional left ventricular curvature in patients with an acute anterior myocardial infarction on ventricular volume.Methods: Left ventricular curvature was calculated at 100 points from apical four chamber echocardiograms of 68 patients with an acute anterior wall infarction. Curvature at any point of the contour was defined as the reciprocal of the radius of the circle that intersects that point tangentially and was independent of volume and geometric assumptions. Curvature, volume and shape of the patient group was compared with these measurements in 20 normal volunteers.Results: Diastolic curvature differed at the borderzone of the infarct and the apical area. In the basal septal area (point 9–18) mean curvature was lower in the patient group (0.1±2.7 versus 2.1±0.7; p<0.0001) as compared to the normal individuals. In the mid-septal area (point 22 to 27), mean curvature was more concave (– 0.1±2.6) in the patient group corresponding to in the normal population (– 0.4±1.3) p<0.005. In the apex point 52 and 53 diverged with a curvature of 9.9±1.9 in patients versus 9.4±2.9 p<0.005 in normal individuals. Systolic curvature diverged at the basal septum (point 1–4) with a mean curvature of 1.4±1.1 in patients compared to 3.5±2.5 in normal individuals p<0.01. Curvature differed also in the mid-septal region (point 9–29) with a curvature of – 1.7±1.2 in patients versus 0.4±0.9 (p<0.01) in normal individuals and in the apical septum (point 48–52) with a curvature of 16.6±5.2 in patients and 13.9±2.6 (p<0.0001) in healthy individuals. Separation of patients with the greatest curvature alteration to those with minor curvature change revealed, that baseline curvature analysis can discriminate patients at risk for left ventricular remodelling.Conclusion: Regional curvature analysis correctly identifies the geometric changes induced by myocardial infarction. Apical systolic curvature can distinguish those patients that are at risk for left ventricular remodelling from those who are not at risk.     

sST2参与急性心肌梗死后心肌纤维化

目的探索可溶性生长刺激表达基因2(sST2)与急性心肌梗死(AMI)后心肌纤维化的关系。方法入选2015年1月至2016年9月入住兰州大学第一医院心脏中心的患者249例,AMI组为首次诊断AMI的166例患者,对照组为冠状动脉造影阴性的83例患者。测定患者血清sST2、Ⅲ型前胶原氨基端肽(PⅢNP)及N末端B型利钠肽原(NT-pro BNP)水平,并收集心脏超声中与左心室收缩功能相关的指标:左心室射血分数(LVEF)、左心室收缩期末容积(LVESV)、左心室舒张期末容积(LVEDV),并进行比较、分析。结果 AMI组血清sST2、PⅢNP、NTpro BNP水平及LVESV、LVEDV值均高于对照组,LVEF值明显低于对照组(P0.05或P0.01)。AMI组中,LVEF50%亚组血清sST2水平高于LVEF≥50%亚组(P=0.031)。AMI组中血清sST2与PⅢNP呈正相关(r=0.181,P=0.02),与LVEF呈负相关(r=-0.179,P=0.021)。AMI组中血清sST2、NT-pro BNP及sST2+NT-pro BNP诊断AMI后心力衰竭的ROC曲线下面积分别为0.608、0.683和0.732。结论血清sST2参与AMI后心肌纤维化过程,并与左心室收缩功能有关。血清sST2水平对AMI后心力衰竭具有诊断价值。     

Arterial counterpulsation in continuing myocardial ischaemia after acute myocardial infarction

Twenty-six patients underwent arterial counterpulsation for refractory heart failure without shock complicating acute myocardial infarction. Patients were divided into a group of 12 with continuing myocardial ischaemia, evidenced by anginal pain associated with abnormal ST segment elevation, and a group of 14 without continuing ischaemia. Clinical features (apart from pain) and prognostic indices were similar in the two groups when counterpulsation was started but short- and long-term results were different. Hospital survival was 92 per cent (11/12) and 43 per cent (6/14), respectively, in the groups with and without ischaemia and four-year survival was 73 per cent and 7 per cent. Counterpulsation is of greatest value in acute infarction when used to relieve myocardial ischaemia.