Detection of myocardial ischemia by vessel-specific leads derived from the 12-lead electrocardiogram and its subsets

Currently used electrocardiographic criteria for identifying patients with ST-elevation myocardial infarction (STEMI) perform with high specificity but low sensitivity. Our aim was to enhance ischemia-detection ability of conventional STEMI criteria based on 12-lead electrocardiogram (ECG) by adding new criteria using 3 vessel-specific leads (VSLs) derived from 12-lead ECG. Study data consisted of 12-lead ECGs acquired during 99 ischemic episodes caused by balloon inflation in, respectively, left anterior descending coronary artery (LAD; n = 35), right coronary artery (RCA; n = 47), and left circumflex coronary artery (LCx; n = 17). ST deviation was measured at J point in 12 standard leads, and for 3 VSLs, its value was derived from 12-lead ECG by using 8 independent predictor leads or just a pair of precordial leads combined with a pair of limb leads. Mean values of sensitivity (SE) and specificity (SP) of ischemia detection achieved with conventional STEMI vs VSL criteria were then obtained from bootstrap trials. We found that the detection of ischemic state by conventional criteria achieved the mean SE/SP of 60%/96% in the total set of ischemic episodes, 74%/97% in the LAD subgroup, 60%/94% in the RCA subgroup, and 36%/100% in the LCx subgroup. In comparison, the mean SE/SP values of VSLs derived from 8 independent leads of 12-lead ECG were, at 125-μV threshold, 76%/96% in the total set, 91%/97% in the LAD subgroup, 70%/94% in the RCA subgroup, and 71%/100% in the LCx subgroup (with asterisk denoting a statistically significant increase). The mean SE/SP of VSLs derived from some of the 4-predictor lead sets (namely, those including lead V₃) matched or exceeded values achieved by VSLs derived from 8 predictors; for instance, with predictor leads I, II, V₃, V₆ derived VSLs attained at 125-μV threshold the mean SE/SP of 80%/95% in the total set, 91%/97% in the LAD subgroup, 74%/92% in the RCA subgroup, and 71%/100% in the LCx subgroup. Based on these results, we conclude that, in our data set, 3 VSLs derived from the complete standard 12-lead ECG—and even from its subsets—can identify acute ischemia better than existing STEMI criteria.     

Reconstruction of standard 12-lead electrocardiograms from 12-lead electrocardiograms recorded with the Mason-Likar electrode configuration

Electrocardiograms (ECGs) made with Mason-Likar electrode configuration (ML-ECGs) show well-known differences from standard 12-lead ECGs (Std-ECGs). We recorded, simultaneously, Std-ECGs and ML-ECGs in 180 subjects. Using these ECGs, 8 × 8 individual and general conversion matrices were created by linear regression, and standard ECGs were reconstructed from ML-ECGs using these matrices. The performance of the matrices was assessed by the root mean square differences between the original Std-ECGs and the reconstructed standard ECGs, by the differences in major ECG parameters, and by comparison of computer-generated diagnostic statements. As a result, we conclude that, based on the root mean square differences, reconstructions with 8 × 8 individual matrices perform significantly better than reconstructions with the group matrix and perform equally well with respect to the calculation of major electrocardiographic parameters, which gives an improved reliability of the QRS frontal axis and the maximal QRS and T amplitudes. Both types of matrices were able to reverse the underdiagnosis of inferior myocardial infarctions and the erroneous statements about the QRS frontal axis that arose in the ECGs that were made by using the Mason-Likar electrode positions.     

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。     

Similarity of ST and T waveforms of 12-lead electrocardiogram acquired from different monitoring electrode positions

Background

It is not always feasible to use standard electrode placement for limb leads when recording the 12-lead electrocardiogram (ECG). Other electrode placements have been accepted during monitoring. Nonstandard electrode positions, however, fail to produce waveforms identical to those recorded from the distal limb positions that are standard for diagnostic interpretation. The purpose of the present study was to validate the ST-T-segment for an alternative “Lund system” of proximal limb electrode sites.

Methods

Twelve-lead ECGs (standard, Mason-Likar, and Lund lead placement) were collected from 167 patients.

Results

There were systematic differences between measurements from standard vs Mason-Likar, but not vs the Lund system. The 95% confidence intervals of measurement agreement were similar or less when comparing measurements from the Lund system vs the first standard recording with measurements for the 2 standard recordings.

Conclusion

The Lund system might constitute a uniform convention for “diagnostic” ECGs as well as for monitoring ECG applications with regard to ST-T waveforms.     

Comparison of EASI-derived 12-lead electrocardiograms versus paramedic-acquired 12-lead electrocardiograms using Mason-Likar limb lead configuration in patients with chest pain

INTRODUCTION: Monitoring or serial 12-lead electrocardiogram (ECG) recordings are the accepted requirement for prehospital data acquisition in patients with chest pain. The purpose of this study was to determine whether waveforms and clinical triage decision are similar in EASI-derived ECGs and paramedic-acquired 12-lead ECGs using Mason-Likar limb lead configuration when compared with standard 12-lead ECGs (stdECG). METHOD: Twenty patients with chest pain had a prehospital 12-lead ECG recorded in the ambulance, and paramedic-applied electrodes retained in place at hospital arrival. An ECG technician applied standard precordial and EASI electrodes in their correct positions. Twelve-lead ECGs were obtained from the paramedic-applied electrodes, using their Mason-Likar limb lead configuration, and derived from the EASI leads for comparison with the stdECG. Three computer-measured QRS-T waveform parameters were considered, and differences in waveform measurement between EASI and stdECG (EASIDeltastdECG) versus differences in waveform measurements between paramedic Mason-Likar and stdECG (PMLDeltastdECG) were calculated. Two physicians determined whether the EASI-derived or the paramedic Mason-Likar ECG contained information that would change their clinical triage decision from that indicated by the stdECG. RESULTS: EASIDeltastdECG and PMLDeltastdECG were identical in 28%, whereas EASIDeltastdECG was more than PMLDeltastdECG in 35%, and PMLDeltastdECG was accurate (both time) than EASIDeltastdECG in 37% (P = .62). The physicians were more likely to change the level of patient care based on the EASI-derived ECGs compared with the paramedic ECGs; however, this difference was not statistically significant (P = .27), but this may only be caused by the small study population. CONCLUSIONS: There are similar differences from stdECG waveforms in EASI-derived ECGs and those acquired via paramedic-applied precordial electrodes using Mason-Likar limb lead configuration. Either method can be used as a substitute for monitoring, but neither should be considered equivalent to the stdECG for diagnostic purposes.     

Effects of electrode placement errors in the EASI-derived 12-lead electrocardiogram

In this study, we assess the effects of electrode placement error on the EASI-derived 12-lead electrocardiogram (ECG). The study data set consisted of 744 body surface potential map (BSPM) recordings. The BSPMs, each of which was made up of 117 leads, were recorded from a mixture of healthy, myocardial infarction, and left ventricular hypertrophy subjects. The BSPMs were interpolated to increase the number of data points in the region of the EASI recording electrodes I, E, and A and the precordial leads. This facilitated 3 experiments. Firstly, recording sites I, E, and A were simultaneously moved ±5 cm vertically, in 0.5 cm increments, from their correct locations. Secondly, recording sites I and A were moved horizontally, again up to ±5 cm, in 0.5 cm increments. Finally, all 6 precordial leads were moved vertically in 0.5 cm increments up to ±5 cm. At each movement step, the resulting 12-lead ECG was compared with the original 12-lead ECG. Root mean square error was determined along with the absolute difference in J-point amplitude. Although the EASI leads were found to be less sensitive to electrode misplacement than the standard precordial leads, it was found that when precordial leads were moved up to ±3 cm vertically, the resulting 12-lead ECG more accurately resembled the original 12-lead ECG than a 12-lead ECG reconstructed from accurately positioned EASI leads. Further work is required to establish the effects of electrode misplacement beyond the ±5 cm limits assessed in this study.     

正常成人QTmax,QTmin在十二导心电图的分布规律及临床意义

目的 找出正常成人最大ＱＴ间期（ＱＴｍａｘ）和最小ＱＴ间期（ＱＴｍｉｎ）在十二导心电图的分布规律,提高ＱＴ离散度的敏感性。方法 在５８２例正常成人进行十二导心电图同步记录检查,找出ＱＴｍａｘ和ＱＴｍｉｎ在各导联的数量和在十二导心电图中的分布规律,统计各导联缺失和不同导联组合缺失时的ＱＴ离散度均值,观察其对ＱＴｄ的影响。结果 ５８２例心电图平均ＱＴｄ３５．３±９．５ｍｓ,各导联ＱＴ间期均值ａｖＬ最小     

Simultaneous comparison of 3 derived 12-lead electrocardiograms with standard electrocardiogram at rest and during percutaneous coronary occlusion

Aim

The aim of the study was to simultaneously test the EASI lead system and two other derived ECG methods against the standard 12-lead ECG during percutaneous coronary intervention (PCI).

Methods

During 44 percutaneous coronary interventions, a simultaneously recorded 12-lead and EASI ECG were marked at the start of the PCI (baseline) and at known ischemia caused by balloon inflation (peak). ST deviations were measured 60 ms after the J point at baseline and peak in all leads and were summated (SUMST) to assess overall changes. For regional changes, the lead with the highest ST deviation (PEAKST) was marked. For each patient, derived 12-lead ECGs were computed from the EASI leads and a lead subset using patient-specific coefficients (PS) and coefficients based on a patient population (GEN). Absolute differences were computed between each derived and routine ECG for SUMST and PEAKST.

Results

SUMST was at baseline 567 μV (range: 150-1707) and increased at peak to 871 μV (range: 350-2101). SUMST difference at peak was for EASI: 163 μV (CI: 90-236, P <.001), GEN: 46 μV (CI: 2-91, P = .40), and PS: 16 μV (CI: 3-30, P = .15). PEAKST difference at peak was for EASI: 49 μV (CI: 19-220, P = .02), GEN: 48 μV (CI: -43-154, P = .26), and PS: 20 μV (CI: -51-32, P = .65).

Conclusion

Simultaneous direct comparison of three derived ECG methods shows overall and regional differences in accuracy across PS, GEN, and EASI. Median SUMST and PEAKST differences for PS are lower than for GEN and EASI, and show a more accurate reconstruction.     

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.     

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.     

276例无症状室性早搏体表心电图特征与起源分析

目的 借鉴心内电生理诊断无症状室性早搏（PVCs）的12导联心电图起源定位特征,分析健康中青年人群无症状PVCs的心电图定位分类,探讨无症状PVCs起源及其临床意义。方法 对在本院门诊体检的年龄小于40岁的健康人群中276例无症状PVCs患者,采集12导联静息心电图,按照右室流出道、三尖瓣、二尖瓣、主动脉根部以及分支来源的心电图特征进行分类。结果 276例无症状性PVCs,男女比例分别为88（31. 9%） 、188 （68.1%）,男女比率为0. 47;右室流出道、三尖瓣、二尖瓣、主动脉根部以及分支来源PVCs所占比例分别39. 9%,16.3%,19. 6%,10. 9%,13. 4%;总计来源于右室的比例为56. 2%,来源于左室比例为43. 8%;三尖瓣与分支来源的PVCs男女比例相近,二尖瓣与主动脉根部来源的PVCs女性比例大于男性。结论 在健康中青年人群,无症状PVCs右室来源多于左室,女性多于男性。     

兔心肌缺血再灌注心电图分析

目的 探讨兔心肌缺血40min再灌注40min心电图变化。方法 采用兔缺血再灌注模型10只，观察心电图Ⅰ、Ⅱ导联ST段、T波、QRS波群的变化及心律失常的发生情况。结果 ①ST—T改变：9只在结扎即刻—20min ST段、T波进行性抬高，此后相对恒定；再灌注早期ST段、T被快速回落，8只20min内ST段回落＞50％。②QRS波群改变：5例在缺血早期5min内出现R波增高(急性损伤阻滞)，4只在缺血期出现R波降低或q波加深(其中1只R波降低同时出现终末r’波)。③心律失常发生情况：缺血期1只发生室性期前收缩；再灌注期3只发生室性心律失常。结论 兔急性心肌缺血早期常表现为ST段抬高、T波增高；再灌注早期ST段快速回落，20min内ST段回落＞50％，可作为免冠状动脉再通的指标。     

Comparison of epicardial potential maps derived from the 12-lead electrocardiograms with scintigraphic images during controlled myocardial ischemia

Our aim was to cross-validate electrocardiographic (ECG) and scintigraphic imaging of acute myocardial ischemia. The former method was based on inverse calculation of heart-surface potentials from the body-surface ECGs, and the latter, on a single photon emission computed tomography (SPECT). A boundary-element torso model with 352 body-surface and 202 heart-surface nodes was used to perform the ECG inverse solution. Potentials at 352 body-surface nodes were calculated from those acquired at 12-lead ECG measurement sites using regression coefficients developed from a design set (n = 892) of body-surface potential mapping (BSPM) data. The test set (n = 18) consisted of BSPM data from patients who underwent a balloon-inflation angioplasty of either the left anterior descending coronary artery (LAD) (n = 7), left circumflex coronary artery (LCx) (n = 2), or the right coronary artery (RCA) (n = 9). Body-surface potential mapping distributions at J point for 352 nodes were estimated from the 12-lead ECG, and an agreement with those estimated from 120 leads was assessed by a correlation coefficient (CC) (in percent). These estimates yielded very similar BSPM distributions, with a CC of 91.0% ± 8.1% (mean ± SD) for the entire test set and 94.1% ± 1.4%, 96.7% ± 0.8%, and 87.4% ± 10.3% for LAD, LCx, and RCA subgroups, respectively. Corresponding heart-surface potential distributions obtained by inverse solution correlated with a lower CC of 69.3% ± 18.0% overall and 73.7% ± 10.8%, 84.7% ± 1.1%, and 62.6% ± 21.8%, respectively, for subgroups. Bull's-eye displays of heart-surface potentials calculated from estimated BSPM distributions had an area of positive potentials that qualitatively corresponded, in general, with the underperfused territory suggested by SPECT images. For the LAD and LCx groups, all 9 ECG-derived bull's-eye images indicated the expected territory; for the RCA group, 6 of 9 ECG-derived images were as expected; 2 of 3 misclassified cases had very small ECG changes in response to coronary-artery occlusion, and their SPECT images showed indiscernible patterns. In conclusion, our findings demonstrate that noninvasive ECG imaging based on just the 12-lead ECG might provide useful estimates of the regions of myocardial ischemia that agree with those provided by scintigraphic techniques.     

急性心肌梗死患者早期心电图改变与临床的相关研究

目的　探讨急性心肌梗死 (AMI)患者早期心电图 (ECG)梗死面积大小 ,ΣST↑ ,QTc离散度与左心衰竭、心源性休克、室性心律失常等并发症的关系 ,以探讨心电图对AMI的诊断价值。方法　 188例AMI患者发病 4 8h内的心电图与临床心脏事件进行对比分析。结果　①QRS积分≥ 7组并发症发生率与病死率均高于QRS积分 <7组 ,P<0 0 5 ;②死亡组 15例平均ΣST↑为 (15 4± 10 9)mm ,存活组 173例为 (10 7± 7 9)mm ,P <0 0 5 ;③室性心律失常组与无室性心律失常组Q -Tcd分别为 (71 37± 9 5 1)ms、(4 9 11± 16 2 4 )ms ,P <0 0 5。结论　早期心电图改变对AMI患者的心功能有密切关系 ,对预后的评估有一定的意义 ,可作为临床诊断的重要参考依据。     

Maximal increase in sensitivity with minimal loss of specificity for diagnosis of acute coronary occlusion achieved by sequentially adding leads from the 24-lead electrocardiogram to the orderly sequenced 12-lead electrocardiogram

Objectives

This study investigates whether sequential addition of inverted (negative) leads from the 24-lead electrocardiogram (ECG) to the orderly sequenced 12-lead ECG would identify a number of leads with which the sensitivity for diagnosis of acute transmural ischemia is significantly increased with minimal loss of specificity.

Background

Acute transmural ischemia due to thrombotic coronary occlusion typically progresses to infarction. Its recognition is based on currently accepted ST-elevation myocardial infarction (STEMI) criteria with suboptimal sensitivity, which could be potentially increased by consideration of the principle that each of the 12 ECG leads can be inverted to provide an additional lead with the opposite (180°) orientation, generating a 24-lead ECG.

Methods

The study population included 162 patients who underwent prolonged coronary occlusion during elective percutaneous transluminal coronary angioplasty. Balloon occlusion was performed in the left anterior descending coronary artery (51 patients), in the right coronary artery (67 patients), or in the left circumflex coronary artery (44 patients). To be classified as indicative of the epicardial injury current of acute ischemia, the ECGs had to fulfill either the criteria of a consensus document from the American College of Cardiology or the European Society of Cardiology or thresholds for the inverted leads based on a population study from Scotland.

Results

The addition of −V1, −V2, −V3, −aVL, −I, aVR, and −III increased sensitivity from 61% to 78% (P ≤ .01) and decreased specificity from 96% to 93% (P = .06).

Conclusions

Addition of 7 leads from the 24-lead ECG, thus creating a 19-lead ECG, was found optimal for attaining high sensitivity while retaining high specificity when compared with the performance of the standard 12-lead ECG.     

A simple procedure for estimation of the spatial QRS/T angle from the standard 12-lead electrocardiogram

The spatial QRS/T angle has been identified as a strong predictor of adverse cardiac events. Mean QRS and T amplitudes from X, Y, and Z leads generated by a matrix transformation method are often used to calculate the QRS/T angle (QRS/T_matrix). Many investigators find this procedure cumbersome. We used electrocardiographic data files of 14 881 men and women aged 45 to 65 years from the Atherosclerosis in Communities study to derive a simple formula for estimated spatial QRS/T angle (QRS/T_simple). QRS/T_simple is calculated as the inverse cosine between the mean QRS and T vectors, which are approximated by 3 QRS_net and T_net amplitudes for each vector. QRS/T_simple explained 79% of the variance of QRS/T_matrix (r = 0.89)_. Using sex-specific thresholds, QRS/T_simple detected abnormally wide QRS/T_matrix values with a sensitivity of 91% and specificity of 88%. It is concluded that this simple method may provide a satisfactory substitute for QRS/T from the matrix transformation method.     

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。     

急性肺栓塞心电图分析

目的对急性肺栓塞的心电图特征进行总结及分析,旨在提高急性肺栓塞的诊断及治疗水平。方法随机选取我院2008年3月至2013年3月期间所收治的86例急性肺栓塞患者,回顾性分析心电图改变。结果86份心电图中,有79例心电图异常,占据总体的91．8％,有7例心电图正常,占据总体的8．2％。结论在急性肺栓塞的临床诊断过程中,心电图检查及心电图变化特征是非常重要的,具备着不可或缺的作用及价值,医务人员应当提起高度重视,并且在临床诊断中加以应用及推广。     

Gender-affirming hormone treatment causes changes in gender phenotype in a 12-lead electrocardiogram

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