The initial electrocardiogram in patients seen by a mobile coronary care unit

The advent of thrombolytic therapy for patients with suspected acute myocardial infarction has highlighted the importance of the initial electrocardiogram (ECG) in decision making. Thus we analysed the initial ECGs of 94 consecutive cases with suspected myocardial infarction who were seen within six hours after the onset of chest pain by a mobile coronary care unit. The study included 91 patients (three patients admitted twice) (61 male), aged 27-83 years (mean 60.5). Median time from onset of chest pain to arrival of the mobile coronary care unit was 75 minutes (range 15-345), and mean mobile coronary care unit response time was 12.3 +/- 7 (SD) minutes (range 5-45). The majority of cases (65 of 94, 69.1 per cent) were seen within two hours of the onset of symptoms. A final diagnosis of myocardial infarction was made in 48 of 94 (51.1 per cent) cases; 38 had unstable angina and eight other diagnoses. Of the 48 with myocardial infarction the initial ECG showed ST segment elevation in 37, ST depression and or T wave inversion in six, Q waves only in three and left bundle branch block in two. No patient with an initially normal ECG had a myocardial infarction. Thrombolytic therapy was given out of hospital to 33 of 38 patients with ST segment elevation. In seven patients with ST elevation (median delay time to intensive care 60 minutes), rapid resolution of ST segment elevation occurred following thrombolytic therapy and there was no significant elevation of cardiac enzymes, suggesting that the infarct had been aborted.(ABSTRACT TRUNCATED AT 250 WORDS)     

Frequency and outcomes of transient myocardial ischemia in critically ill adults admitted for noncardiac conditions.

BACKGROUND: Critically ill adults admitted for noncardiac conditions are at risk for acute myocardial ischemia. OBJECTIVES: To detect myocardial ischemia and injury in patients admitted for noncardiac conditions and to examine the relationship of myocardial ischemia, injury, and acuity to cardiac events. METHODS: Transient myocardial ischemia, acuity, elevations in serum troponin I, and in-hospital cardiac events were examined in 76 consecutive patients. Transient myocardial ischemia, determined by using continuous electrocardiography, was defined as a 1-mm (0.1-mV) change in ST level from baseline to event in 1 or more leads lasting 1 or more minutes. Acuity was determined by scores on Acute Physiology and Chronic Health Evaluation II. RESULTS: A total of 37 ischemic events were detected in 8 patients (10.5%); 32 (86%) were ST-segment depressions, and 35 (96%) were silent. Twelve patients (15.8%) had elevated levels of troponin I. Transient myocardial ischemia, elevated troponin I levels, and advanced age were significant predictors of cardiac complications (R2 = 0.387, F = 15.2, P < .001). Acuity correlated only modestly with increased length of stay in the intensive care unit (r = 0.26, P = .02) and elevated troponin I levels (r = 0.25, P = .03). Patients with transient myocardial ischemia had significantly higher rates of elevations in troponin I (P < .001) and cardiac events (P < .001) than did patients without. CONCLUSIONS: Transient myocardial ischemia and advanced age are predictors of cardiac events and may indicate patients at risk for cardiac events.     

Ambulatory monitoring of silent myocardial ischemia: what is its utility?

In patients with angina pectoris, ambulatory ST segment monitoring has documented that asymptomatic myocardial ischemic episodes occur with greater frequency than previously suspected. During such episodes, ischemia has been verified by nuclear, echocardiographic, and biochemical techniques. Painless ST segment depression is consistent with severe coronary artery disease when detected by ambulatory monitoring in patients with angina and portends a worsened prognosis in patients about to have vascular surgical procedures. On the other hand, ST depression without angina has a better prognosis than ST depression with angina during treadmill exercise testing. Silent ischemia of prolonged duration per 24-hour period suggests a poor prognosis in patients with a history of unstable angina or myocardial infarction.     

Sensitivity of routine intensive care unit surveillance for detecting myocardial ischemia

OBJECTIVE: To assess the effectiveness of routine intensive care unit surveillance compared with frequent 12-lead electrocardiogram monitoring for detecting electrocardiogram evidence suggestive of prolonged myocardial ischemia in vascular surgery patients. DESIGN: Prospective cohort trial. SETTING: Intensive care unit. PARTICIPANTS: We studied 149 patients undergoing elective infrainguinal or aortic vascular surgery who were admitted to the intensive care unit postoperatively. INTERVENTIONS: Patients were simultaneously monitored with a 10-electrode/12-lead electrocardiogram obtained every 2 mins (criterion standard) and routine intensive care unit surveillance that included standard monitoring (five-electrode/two-lead electrocardiogram with ST segment trends and routine 12-lead electrocardiogram) and clinical assessment for detecting myocardial ischemia. The results of the criterion standard were not available to the caregivers. MEASUREMENTS AND MAIN RESULTS: We measured the ability of routine intensive care unit surveillance to detect the first 20 mins of electrocardiogram evidence suggestive of myocardial ischemia, defined as ST segment depression or elevation of >/=1 mm in two consecutive leads, during the first postoperative day. Seventeen patients (11%) had electrocardiogram evidence suggestive of prolonged myocardial ischemia, the majority of which occurred in leads V2-V4. The sensitivity of routine intensive care unit surveillance for detecting the first episode of electrocardiogram evidence suggestive of prolonged myocardial ischemia in a patient was 12% (95% confidence interval, 7-17%), and the specificity was 98% (95% confidence interval, 95-100%) with a positive predictive value of 40% (95% confidence interval, 32-48%), a negative predictive value of 90% (95% confidence interval, 85-94%), a positive likelihood ratio of 6, and a negative likelihood ratio of 1. The sensitivity of routine intensive care unit surveillance for detecting all episodes was 3% (95% confidence interval, 2-3%) and the specificity 99% (95% confidence interval, 99-100%) per 20-min monitoring interval, with a positive predictive value of 17% (95% confidence interval, 16-18%), negative predictive value of 95% (95% confidence interval, 95-96%), positive likelihood ratio of 3, and negative likelihood ratio of 1. CONCLUSIONS: Routine intensive care unit surveillance has low sensitivity for detecting electrocardiogram evidence suggestive of prolonged myocardial ischemia compared with frequent 12-lead electrocardiograms. Because detecting electrocardiogram evidence suggestive of prolonged postoperative myocardial ischemia is important, physicians should consider alternative strategies to detect myocardial ischemia.     

'Silent' Prinzmetal's ST elevation related to atenolol overdose

Prinzmetal's angina is a condition characterized by chest pain, transient ST elevation, and negative biochemical markers of myocardial cell necrosis. We describe a case of chemically-induced "silent" ST segment elevation related to Atenolol overdose in a patient without coronary artery stenosis. We conclude that the cause for the transient myocardial ischemia is coronary vasospasm, precipitated by beta-blocker overdose.     

Tl-201 myocardial SPECT in silent myocardial ischemia and angiographically proven coronary heart disease

Silent myocardial ischemia is defined as true myocardial ischemia without angina pectoris in patients with angiographically detected coronary artery disease. In this study 52 patients (46 male, 8 female: mean age 53 years) with a pathological exercise test but no symptoms were investigated. They showed stenosis of 75% or more of the diameter in at least one coronary segment on angiography. Prior to or after catheterization (within 14 days) Tl-201 SPECT was done and evaluated independently of angiography. A clear correlation between angiographically confirmed stenosis and reversible perfusion defects with Tl-201 SPECT was established (62 out of 76 lesions). Furthermore, there was a significant relation between angiographically detected subtotal or total occlusions of coronary vessels and irreversible perfusion defects using Tl-201 SPECT (35 in 44 lesions) (p less than 0.001). In patients with ST depression but without angina pectoris during the exercise test, the Tl-201 SPECT is highly suited to determine the hemodynamic effect of coronary stenoses.     

Myocardial ischemia, cardiac troponin, and long-term survival of high-cardiac risk critically ill intensive care unit patients

OBJECTIVES: To determine the incidence and association of myocardial ischemia with troponin elevation and survival in high-cardiac-risk intensive care patients. DESIGN: Prospective observational study. SETTING: Intensive care unit of a tertiary hospital. SUBJECTS: One-hundred one general intensive care unit patients having a history of coronary artery disease or at least two risk factors for coronary artery disease. INTERVENTIONS: Continuous 12-lead electrocardiographic monitoring with on-line ST-trend analysis, daily cardiac troponin measurements, clinical and physiologic assessment, and up to 2-yr follow-up for survival. MEASUREMENTS AND MAIN RESULTS: During 8,988 hrs or a mean +/- sd of 95 +/- 85 hrs/patient of continuous 12-lead electrocardiographic monitoring, 21 patients (21%) had ischemic ST-segment changes, characterized in most (19) by ST depression and lasting >60 mins in 15 (71.4%). Of the 38 patients (38%) with troponin elevation, myocardial infarction was clinically suspected in four and myocardial ischemia on continuous 12-lead electrocardiographic monitoring was observed in 14 (36.8%). Fourteen (66.7%) of the patients with ischemic ST changes and 12 (75%) of those with prolonged (>60 mins) ischemia had troponin elevation. The sensitivity, specificity, and positive and negative predictive values of prolonged (>60 mins) ischemia predicting troponin elevation were 31.6%, 95.2%, 80.0%, and 69.8%, respectively. Prolonged (>60 mins) ischemia was significantly associated with troponin elevation by both univariate and multivariate analyses (odds ratio = 9.0; p = .008). Acute Physiology and Chronic Health Evaluation II score, renal failure, and the use of norepinephrine also independently predicted troponin elevation. Troponin but not ischemia predicted increased 1-month, 6-month, and 2-yr mortality (odds ratio = 6.0, 3.2, and 2.99, respectively; p < .001). CONCLUSIONS: Silent ischemia is strongly associated with troponin elevation in high-cardiac-risk intensive care unit patients, and troponin elevation predicts both early and late mortality.     

Ambulatory ECG monitoring. How useful in detecting and quantitating transient ischemia?

ST segment shifts are reliable indicators of transient myocardial ischemia. Ambulatory ECG monitoring detects episodes of ST segment shift with and without chest pain in patients with coronary heart disease. Monitoring can provide valuable information on the presence and frequency of transient myocardial ischemia. Limited information is available on the use of ambulatory monitoring as a screening test, particularly in populations where the frequency of coronary heart disease is low.     

运动试验诱发心肌缺血和心绞痛的性别特点研究

目的：观察运动试验诱发男女心肌缺血和心绞痛的特点和差异。方法：将运动试验阳性中出现终止指征没完成次极量的94例患者分为男、女两组，分析其心电图、运动能力、临床症状等，并和部分患者的冠状动脉造影结果对照。结果：男性代谢当量、运动时间明显大于女性（P〈0．05），男性终止症状多见于Bruce2级，女性多见于Bruce1级结束时。ST段下移程度男性高于女性（P〈0．05），下移形态女性水平型多（P〈0．05）、男性近似水平型多（P〈0．05），男性T波倒置多（P〈0．05）。冠状动脉造影结果男性异常率高（78％），女性低（50％）。结论：运动试验对男性心肌缺血和心绞痛的诊断价值较女性大。男性运动试验诱发心肌缺血和心绞痛多发生于Bruce2级。     

不伴心肌梗死的冠状动脉完全闭塞病变心绞痛的临床分析

目的：探讨不伴心肌梗死的冠状动脉完全闭塞病变心绞痛患者的临床特点。方法：对24例不伴心肌梗死的冠状动脉完全闭塞患者的临床表现、心电图、超声心动图及冠状动脉造影资料进行回顾分析。结果：中、高危险组主要表现为静息心绞痛，低危险组和稳定性心绞痛组主要表现为劳力型心绞痛。冠状动脉造影显示左前降支闭塞10例（37％），右冠状动脉闭塞7例（26％），左回旋支闭塞6例（22％），合并多支血管病变23例（95．8％）。心电图ST段异常14例（58．3％）。62．5％的患者进行经皮冠脉血运重建术。结论：不伴心肌梗死的冠状动脉完全闭塞主要表现为劳力型心绞痛，心电图ST段异常是预测冠脉病变严重程度的主要危险因素。经皮冠状动脉介入治疗正成为慢性冠状动脉闭塞的主要手段之一。     

大剂量葛根素抗心绞痛作用的对比研究

目的 :探讨大剂量葛根素对心绞痛治疗的可行性。方法 :87例患者随机分为 2组 ,治疗组 42例 ,对照组 45例。治疗组应用葛根素注射液 12 0 0 m g加入 5 %葡萄糖 5 0 0 ml静滴 ,对照组用硝酸甘油 5 m g加入 5 %葡萄糖 2 5 0 ml静滴 ,比较 2组疗效。结果 :治疗组在减少心绞痛发作次数、显效率、总有效率、心电图缺血性 ST段恢复及心肌耗氧量减少等指标上 ,与对照组比较无显著差异 (P均 >0 .0 5 )。结论 :大剂量葛根素有改善心肌缺血、缓解冠状动脉痉挛等作用 ,抗心绞痛疗效显著     

Long-term prognosis of patients with silent ischemia, symptomatic ischemia and without ischemia after acute myocardial infarction

The prognosis of 55 patients with silent ischemia (group I: asymptomatic ST segment depression of greater than or equal to 0.1 mV on symptom-limited ergometer exercise) was compared with that of 25 patients with angina and ST depression (group II), 22 patients with angina but without ST depression (group III) and 94 patients without angina and without ST depression (group IV) on ergometer testing in the first post-infarction month. Patients for whom PTCA or coronary artery bypass graft surgery was planned for the next months following discharge were excluded. Groups were well matched in terms of age, sex, diabetes, non-Q-wave infarctions and global left ventricular function, but groups I and II had more inferior wall infarctions (76% and 68% respectively) than groups III and IV (18% and 34%, p less than 0.0001). After a mean follow-up time of between 26 and 33 months 11% in group I, 16% in group II, 14% in group III, but only 6% in group IV had died from cardiac disease or reinfarcted (p = 0.06). Using Cox's model, the Killip index, presence of non-Q-wave infarction, maximal ST depression on ergometer exercise and global left ventricular ejection fraction were found to be important prognostic variables affecting reinfarction-free survival, whilst angina was not. Results suggest that the presence or absence of angina as an isolated symptom is not of prognostic important after acute myocardial infarction, in comparison with objectively determinable parameters.     

急性下壁心肌梗死心电图ST段改变与冠状动脉病变、梗死部位的关系探讨

目的：探讨急性下壁心肌梗死心电图胸前导联ST段改变与冠状动脉病变、梗死部位的关系。方法：42例急性下壁心肌梗死患者入院后均做心电图检查．并于发病后4周内做选择性冠状动脉造影。结果：42例患者中，单支血管病变16例(占38．1％)，多支血管病变26例(占61．9％)，其中伴心电图胸前导联ST段改变者23例(占88．5％)。11例急性下壁合并正后壁心肌梗死者心电图胸前导联ST段压低者8例(占72．7％)。结论：急性下壁心肌梗死伴心电图胸前导联ST段改变者提示多支血管病变，伴心电图胸前导联ST段压低者多提示合并正后壁心肌梗死。     

冠心病患者全血中miR-126表达的临床意义

目的探讨微小RNA(miR-126)在不同类型冠心病患者中的表达情况,为冠心病早期诊断、治疗及治疗后检测提供实验依据。方法将实验分成健康对照组(n=6)及冠心病组(n=36),对冠心病组(分为稳定性心绞痛组,不稳定性心绞痛组,非ST段抬高性心肌梗死组,ST段抬高性心肌梗死组,每组9例)接受经皮冠状动脉介入治疗(PCI)术前,术后第1天,术后第5天等时间点的观察。应用实时荧光定量PCR(qRT-qPCR)技术检测确诊为不同类型冠心病患者术前、术后全血标本中miR-126的表达量。结果 qRT-qPCR结果显示:①健康对照组、稳定性心绞痛组、不稳定性心绞痛组3组miR-126的表达量无显著性差异,但在急性心肌梗死组(包括非ST段抬高性组、ST段抬高性组)患者中miR-126的表达量与上述三组明显减少,有显著性差异(P0.05)。②miR-126在不同时间水平有显著性差异(P0.05),ST段抬高或非ST段抬高型心肌梗死的miR-126的表达量术前明显低,术后随观察时间延长逐渐增加。③在不同时间时不同分组之间miR-126的表达量存在显著的交互效应(P0.05)。结论 miR-126在急性心肌梗死患者中及冠心病各组术前、术后的表达量明显不同,这为miR-126应用于不同类型冠心病诊断及术后疗效判断提供实验依据。     

Evaluation of the efficacy of a course of verapamil and nifedipine in patients with stable stenocardia by daily monitoring of the electrocardiogram

The daily ECG monitoring was used in 20 patients with stable functional class II-III angina pectoris to study the antianginal and anti-ischemic effects of verapamil and nifedipine during the cross use of the drugs. Verapamil and nifedipine applied in the effective doses provoked a significant decrease of the number and total depth of painful depressions of the ST segment. The effect of verapamil on painful episodes of ST segment depressions was significantly more pronounced than that of nifedipine. At the same time nifedipine significantly reduced the number and total depth of painless episodes of myocardial ischemia whereas verapamil did not cause any significant lowering of these indicators. In cases where the drugs appeared ineffective, verapamil provoked a significant increase of the number of painless episodes of myocardial ischemia. This indicates that the painful threshold of sensitivity may change with the occurrence of myocardial ischemia in patients suffering from angina pectoris. In turn, nifedipine produced no significant effect on the number and intensity of painless episodes of myocardial ischemia.     

不稳定型心绞痛的心电图改变及冠状动脉造影的比较研究

目的分析不稳定型心绞痛的心电图改变及冠状动脉造影的比较研究。方法选取本院2016年6月-2018年11月64例不稳定型心绞痛患者,并分为两组,对照组32例在心绞痛发作时进行12导联心电图检查,研究组32例在入院1星期内进行冠状动脉造影,对比两种检查结果。结果前壁缺血17例,心电图显示T波倒置5例,ST段升高4例,ST段下移8例;冠脉造影检查结果显示,LMCA罪犯血管0例,LAD罪犯血管9例,LCX罪犯血管8例,RCA罪犯血管0例,病变率LAD>LCX>LMCA、RCA,差异有统计学意义(P<0.05);下壁缺血15例,心电图显示ST段升高7例,ST段下移8例;冠脉造影检查结果显示,LMCA罪犯血管0例,LAD罪犯血管3例,LCX罪犯血管5例,RCA罪犯血管7例,病变率RCA>LAD>LCX>LMCA,差异有统计学意义(P<0.05)。结论不稳定型心绞痛患者采用心电图可正确评估病情,能在必要情况下进行冠状动脉造影能够进一步提高准确率,避免或减少遗漏或误诊现象,值得临床推广使用。     

Electrical Alternans of the ST Segment in Non-PrinzmetaPs Angina

Elevated electrical alternans of the elevated ST segment (STEA) was documented in a patient with non-Prinzmetal's or classical angina and severe atherosclerotic coronary artery disease. STEA was precipitated during graded exercise testing. The disappearance of this phenomenon after aortocoronary bypass surgery suggests that the coronary obstructions were the etiologic factors. These findings emphasize that the STEA may occur in myocardial ischemia caused by conditions other than Prinzmetal's angina.     

A basic approach to the interpretation of the exercise test

To interpret the exercise test, the following parameters need to be evaluated: the heart rate and blood pressure response, symptoms, dysrhythmias, aerobic capacity, and evidence for myocardial ischemia. When analyzing the ST segment for ischemia, the amount and type of ST depression and the time of onset and resolution are examined. The exercise test results are best used to determine a post-test probability that the patient has significant coronary disease, predict its severity, and provide a prognosis of the patient. The test allows primary care physicians to decide which patients with coronary artery disease can be safely managed medically and which high-risk patients need further evaluation and consideration for revascularization.     

Transcutaneous electrical nerve stimulation (TENS) in angina pectoris

The aim of this study was to determine the efficacy of transcutaneous electrical nerve stimulation (TENS) in the treatment of chronic stable severe angina pectoris. In a short-term study the effect of TENS was studied in 10 male patients with angina pectoris (functional class III and IV). All patients had previously been stabilized on long-term maximal oral treatment. The effects of the treatment were measured by means of repeated bicycle ergometer tests. All patients had an increased working capacity (16-85%), decreased ST segment depression and reduced recovery time during TENS. No adverse effects were observed. A long-term study of TENS on similarly selected patients showed beneficial effects in terms of pain reduction, reduced frequency of anginal attacks, increased physical activity and increased working capacity during bicycle ergometer tests. An invasive study was carried out with respect to systemic and coronary hemodynamics and myocardial metabolism during pacing provoked myocardial ischemia in 13 patients. The results showed that TENS led to an increased tolerance to pacing, improved lactate metabolism, less pronounced ST segment depression. A drop in systolic blood pressure during TENS treatment at identical pacing rates indicated a decreased afterload. An increased coronary flow to ischemic areas in the myocardium was supported by the fact that the rate pressure product during anginal pain increased during TENS.     

急性下壁心肌梗死胸前导联ST段压低的临床意义

目的分析急性下壁心肌梗死伴胸前导联ST段压低的临床意义。方法选择84例急性下壁心肌梗死患者常规心电图及24h动态心电图进行对照分析。结果急性下壁心肌梗死伴胸前导联ST段压低多于不伴胸前导联ST段压低（P〈0．01）;下壁伴正后壁心肌梗死伴胸前导联ST段压低多于不伴胸前导联ST段压低（P〈0．01）;下壁伴右心室心肌梗死与胸前导联ST段压低无明显关联（P〈0．01）;急性下壁心肌梗死伴胸前导联ST段压低者严重室性心律失常与房室传导阻滞的发生率较不伴胸前导联ST段压低者高（P〈0．01）。结论急性下壁心肌梗死伴胸前导联ST段压低往往提示梗死范围大或同时存在心肌缺血、冠脉病变广泛、心功能损害较严重,并且严重室性心律失常与房室传导阻滞的发生率明显增高,心肌酶峰值明显增高临床预后较差。