EASI 12导联与标准监护Ⅱ导联监测心肌缺血的观察

目的评价目前常规选择的标准监护Ⅱ导联和EASI12导联心电监测对于发现心肌缺血的有效性和敏感性。方法采用诊断试验的评价研究设计，将研究期间收住北京市宣武医院CCU病房的57例有ST段改变的病人作为病例组，43例无ST段改变的病人作为非病例组，选用标准12导联心电图为金标准，评价CCU标准监护Ⅱ导联和EASI12导联发现心肌缺血的有效性和敏感性。两组病人均同时描记标准12导联、EASI12导联和标准监护Ⅱ导联心电图。比较3种心电图中ST段的改变情况。结果标准监护Ⅱ导联心肌缺血检出率明显低于标准12导联心电图，敏感度、特异度、假阳性率和假阴性率分别为24．6％、95.3％、4.7％和75.4％，一致性检验Kappa值仅为0.178。而EASI12导联对心肌缺血的检出率与标准12导联心电图相仿，敏感度、特异度、假阳性率和假阴性率分别为89.5％、97．7％、2.3％和10．5％，Kappa=0．859。结论临床上通常选用的标准监护Ⅱ导联并不能有效地发现心肌缺血，而EASI12导联较标准Ⅱ导联能够更有效地发现心肌缺血，具有较好的敏感度和特异度。     

Assessment of QT-measurement accuracy using the 12-lead electrocardiogram derived from EASI leads

The purpose of the present study is to assess QT-interval measurements from the EASI 12-lead electrocardiogram (ECG) as compared with the standard 12-lead ECG. The QT interval was automatically determined in simultaneously recorded standard and EASI 12-lead ECGs, using a validated wavelet-based delineator. The agreement between the 2 sets of measurements was quantified both on a lead-by-lead basis and a multilead basis with global definitions of QRS onset and T-wave end.The results show that the agreement between QT-interval measurements from the 2 lead systems is acceptable, with negligible mean differences and with correlation coefficients ranging from 0.91 to 0.98 depending on the lead studied. Although the SD shows a clear dependence on the selected lead (ranging from 9.2 to 26.4 milliseconds), differences are within the accepted tolerances for automatic delineation. In a few patients, large differences were found, mainly because of changes in morphology present in both lead systems. QT intervals measured by the multilead approach were considerably more stable than single-lead measurements and resulted in a much better agreement between the 2 lead systems (correlation coefficient, 0.98; QT difference, 1.1 ± 9.8 milliseconds). Thus, the EASI 12-lead ECG may be used for reliable QT monitoring when the multilead delineation approach is adopted.     

Role of the 12-lead electrocardiogram in diagnosing pulmonary embolism

We investigated the role of the standard 12-lead electrocardiogram (ECG) to improve the pretest probability of pulmonary embolism before performing computed tomographic (CT) pulmonary angiography. A retrospective chart analysis was performed on patients who underwent CT pulmonary angiography at a tertiary care hospital during a 30-month period. Comparison of 15 ECG parameters was made between those with CT pulmonary angiograms positive for pulmonary embolism and a matched control group with negative CT pulmonary angiograms. Data were analyzed by chi-squared tests and logistic regression. Sinus tachycardia (39% vs. 24%, P <0.01), an S1 Q3 T3 pattern (12% vs. 3%, P <0.01), atrial tachyarrhythmias (15% vs. 4%, P <0.005), a Q wave in lead III (40% vs. 26%, P <0.02), and a Q3 T3 pattern (8% vs. 1%, P <0.02) were the findings significantly associated with pulmonary embolism. We conclude that 1) standard 12-lead ECG findings can increase the pretest probability of pulmonary embolism before performing CT pulmonary angiography; and that 2) the ECG findings have relatively low likelihood ratios to have clinical use.     

A comparison of the standard 12-lead electrocardiogram to exercise electrode placements

In order to determine the effect of electrode placement and standing on the 12-lead electrocardiogram required prior to exercise testing, 104 male patients with stable coronary heart disease were studied. Electrocardiograms were recorded with two different placements of the arm electrodes commonly used for exercise testing with the patient supine and standing. These were compared to a standard ECG with the electrodes placed at the wrists and ankles with the patient supine. The four ECGs gathered on each patient were analyzed using standard visual techniques for diagnostic changes and using a computer for analysis of axis, amplitudes, and durations. There were important differences between the standard 12-lead ECG and the ECGs gathered with the pre-exercise test modifications. These differences were minimized by placing the arm electrodes as close to the shoulders as possible and by recording the ECG with the patient supine.     

Adaptation of the standard 12-lead electrocardiogram system dedicated to the analysis of atrial fibrillation

Objective

The objective of the study was to design a lead system aimed at studying atrial fibrillation (AF), while being anchored to the standard 12-lead system.

Methods

The location of 4 of the 6 precordial electrodes was optimized while leaving the remaining 5 of the 9 electrodes of the standard 12-lead system in place. The analysis was based on episodes of 11 different variants of AF simulated by a biophysical model of the atria positioned inside an inhomogeneous thorax. The optimization criterion used was derived from the singular value decomposition of the data matrices.

Results

While maintaining VR, VL, VF, V₁ and V₄, the 4 new electrode positions increased the ratio of the eighth and the first singular values of the data matrices of the new configuration about 5-fold compared with that of the conventional electrode positions.

Conclusion

The adapted lead system produces a more complete view on AF compared with that of the standard 12-lead system.     

EASI 12导联心电监测系统的临床应用

目的探讨EASI12导联心电监测系统的临床意义。方法对CCU病房的530例（EASI12导联监测系统监测205例、传统单导联监测系统监测325例）患者持续心电监测24～72h，并对监测结果进行比较分析。结果应用EASI12导联监测系统监测的205例中，可见房性心律失常57例（27．8％），室性心律失常79例（38．5％），房室传导阻滞26例（12．7％），心肌缺血性ST段改变85例（41．5％），而应用传统单导联监测系统的325例中，可见房性心律失常56例（17．2％），室性心律失常82例（25．2％），房室传导阻滞22例（6．8％），心肌缺血性ST段改变81例（24．9％），前者检出率显著提高（x^2=6．103、6．898、4．218、10．456，P均〈0．05）。结论EASI12导联监测系统为临床提供了即时和准确的数据，有助于及时发现心律失常和心肌缺血事件。     

Derived 12-lead electrocardiogram in the assessment of ST-segment deviation and cardiac rhythm

BACKGROUND: There are little data on the validation of 12-lead electrocardiogram (ECG) derived by the EASI lead system used for continuous monitoring in critical care settings. OBJECTIVE: The objectives of this study were to determine the accuracy of 12-lead ECG derived by the EASI lead system in the detection of ST-segment deviation and cardiac rhythm compared with the standard 12-lead ECG. METHODS: All patients admitted to the coronary care unit were studied. Kappa statistics was used to calculate the agreement between both ECG systems in the determination of cardiac rhythm and premature ventricular complex morphology. ST-segment analysis was performed in patients with acute coronary syndromes. Pearson correlation was used to correlate the ST-segment deviation between both techniques. The sensitivity and specificity of the determination of significant ST-segment deviation by the EASI lead system were calculated. RESULTS: There were a total of 282 patients enrolled in this study. There was a complete agreement in the interpretation of cardiac rhythm between the 2 methods (kappa = 1). Analysis of ST-segment deviation of 12-lead ECG also showed a significant correlation (correlation coefficient varied from 0.62 in lead I to 0.823 in lead aVF with a P value of <.001 in all leads) between the 2 methods with very high sensitivity and specificity in the detection of significant ST-segment elevation and depression. CONCLUSION: The 12-lead ECG derived by the EASI lead system is an accurate and reliable information for the assessment of ST-segment deviation and cardiac rhythm in critically ill patients.     

The effects of electrode misplacement on clinicians' interpretation of the standard 12-lead electrocardiogram

IntroductionThis study investigates how a particular incorrect electrode configuration affects the 12-lead Electrocardiogram (ECG).MethodsA correct and an incorrect 12-lead ECG were extracted from a 192-lead BSPM. This was done for 232 BSPMs yielding 464 12-lead ECGs. The particular incorrect ECG involved displacing electrodes V1 and V2 in the second intercostal space whilst also offsetting the remaining electrodes. These ECGs were examined in two stages: (a) analysis of the effects of electrode misplacement on signal morphology and (b) analysis of how often the incorrect electrode configuration changed the diagnosis of two clinicians in a random sample of 75 patients.ResultsAccording to the Root Mean Square Error (RMSE) of the difference between PQRST intervals in the correct and incorrect ECGs, lead V2 is the most affected lead (mean: 185 μV ± 82 μV), followed by lead V4 (mean: 114 μV ± 59 μV) and lead V1 (mean: 100 μV ± 47 μV). It was found that if the incorrect electrode configuration is applied, there is a 17% to a 24% chance the diagnostic interpretation will be different. Quantified using Similarity Coefficient (SC) leads V1 and V2 were found to be more alike when misplaced in the second intercostal space. The average SC between these leads when correctly placed was 0.08 (± 0.65), however when incorrectly placed, the average SC was 0.43 (± 0.3).ConclusionThere is a reasonable chance this particular incorrect electrode configuration will change the diagnosis of the 12-lead ECG. This highlights the importance of developing algorithms to detect electrode misplacement along with better education regarding ECG acquisition.     

Diagnostic value of the 12-lead electrocardiogram during conventional and biventricular pacing for cardiac resynchronization

The paced 12-lead ECG is a valuable tool in the assessment of patients with pacemakers, and ideally should be recorded routinely at the time of implantation and during follow-up. It has become particularly important in patients undergoing cardiac resynchronization. The multiplicity of clinical situations described in this review highlight the pitfalls of using a single ECG lead in the overall evaluation of pacemaker patients. The design of programmers capable of registering a 12-lead ECG would obviate the need of an additional electrocardiograph and encourage the routine recording of the paced 12-lead ECG with each patient encounter. Such an arrangement would improve the care of pacemaker patients.     

EASI 3导联衍生的12导联心电图的应用研究

目的在亚洲人群中导出EASI导联和常规12导联心电图的转换系数和方程,比较亚洲人群与北美人群之间导联转换上的差异性,同时观察导联转换是否受年龄、性别、身高和体重的影响。方法627例受试者同步记录常规12导联心电图和EASI导联心电图。同时记录年龄、性别、身高和体重。结论在亚洲人群和北美人群之间,导联转换无显著性差异,年龄、性别、身高和体重对导联转换无显著影响。     

Vectorcardiogram synthesized from the 12-lead electrocardiogram to image ischemia

Background

Knowledge of the location and size of ischemic myocardium at risk for infarction could impact prehospital patient triage and reperfusion therapy. The 12-lead electrocardiogram (ECG) can roughly estimate ischemia size; however, individual precordial ECG leads are at different distances from the left ventricle (LV) and certain LV walls have greater effects on the ECG. Vectorcardiographic corrected orthogonal lead systems can display the magnitude and direction of the ST-segment “injury current” vector in 3-dimensional space. We assessed whether the vectorcardiographic ST-vector direction and magnitude derived from the ECG by the inverse-Dower method can estimate the location and size of ischemia.

Methods and Results

Thirty-two patients underwent elective coronary angioplasty with control and 5-minute balloon-occlusion ECG and sestamibi injection followed by single photon emission computed tomography (SPECT). The ST-vector direction derived from the inverse-Dower method was projected to an LV model with normal coronary artery anatomy. The graphical display of ST-vector location could discriminate among occlusions of the different coronaries. The ST-vector located ischemia within the SPECT defect in 75% (24/32) of all patients and 96% (24/25) of patients with ischemia in more than 12% of the LV. ST-vector magnitude had a Spearman correlation of r = 0.68 (P < .0001) with SPECT ischemia size.

Conclusions

The 3-dimensional ST vector derived from the ECG can be graphically projected onto an LV model to localize ischemia, and ST-vector magnitude correlates with ischemia size. Further study is warranted to assess the ability of vectorcardiographic imaging to risk-stratify and provide decision-support for patients with acute myocardial infarction.     

Detection of acute ischemia from the EASI-derived 12-lead electrocardiogram and from the 12-lead electrocardiogram acquired in clinical practice

ST-segment measurements in the standard 12-lead electrocardiogram (ECG) of patients with acute coronary syndromes are crucial for these patients' management. Our objective was to determine whether the 12-lead ECG derived from the 3-lead EASI system can attain a level of diagnostic performance similar to that of the Mason-Likar (ML) 12-lead ECG acquired in clinical practice (CP) by paramedics and emergency department technicians. Using 120-lead body surface potential maps recorded before and during balloon inflation angioplasty from 88 patients (divided into “responders” and “nonresponders”), and electrode placement data from 60 applications of precordial leads in CP, we generated for the “nonischemic” and “ischemic” states of each patient the following lead sets: the ML 12-lead ECG, the EASI-derived 12-lead ECG, and 60 sets of 12-lead CP ECGs. We extracted ST deviations at J + 60 milliseconds, summed them for all 12 leads of each lead set to obtain ΣST, and, by using the bootstrap method, determined the mean sensitivity and specificity for recognizing the “ischemic” state at various thresholds of ΣST. Results were displayed as receiver operating characteristics, and the area under these curves (AUC) ± SE was used as the measure of diagnostic performance. AUC ± SE for all patients were ML ECG, 0.66 ± 0.03; EASI ECG, 0.64 ± 0.03; and CP ECG, 0.67 ± 0.03. Corresponding results for responders only were 0.81 ± 0.04 for ML ECG, 0.78 ± 0.04 for EASI ECG, and 0.81 ± 0.04 for CP ECG. The differences between the AUCs for the different lead sets were not significant (P > .05). Thus, the EASI-derived 12-lead ECG is as good for detecting acute ischemia as is the 12-lead ECG acquired in CP.