Use of the 24-lead “standard” electrocardiogram to identify the site of acute coronary occlusion: A review paper

This review presents the added value for diagnosis of acute ischemia/infarction of considering ST elevation in the 12 inverted leads (−I, −II, −II, −aVR, etc) of the standard electrocardiogram in addition to ST elevation in 12 positive leads. A small number of studies have been published showing substantial increases in sensitivity at the “cost of” slight decreases in specificity. One recent study indicated that only 7 of the inverted leads should be considered, yielding a “19-lead electrocardiogram” encompassing the following leads (presented here in the logical secquences): −III, aVL, I, −aVR, II, aVF, III, −aVL, −I, aVR; and V1, V2, V3, V4, V5, V6, −V1, −V2, −V3. Studies have to be performed to establish the thresholds that should be applied to these leads for achievement of sensitivity/specificity.     

Twelve-lead electrocardiogram: the advantages of an orderly frontal lead display including lead -aVR

BACKGROUND: It is possible that efforts in ECG review by both young experienced clinicians are currently discouraged-and risk to be completely dismissed-by the conventional (ie, disorderly) display of the frontal plane leads, with lead aVR at -150 degrees. METHODS: We reviewed studies on the usefulness of leads aVR and -aVR as well as on the history of the frontal leads in electrocardiography. RESULTS: Lead aVR and particularly, lead -aVR, provide useful information when systematically analyzed. In addition, if lead -aVR is examined in its anatomically logical sequence, ie, aVL, I, -aVR, II, aVF, and III, the frontal plane of the 12-lead ECG is more easily understood. This "panoramic" or "orderly" display is in common use in countries such as Sweden, but it is rarely seen in the United States. CONCLUSIONS: ECG interpretation would be enhanced by displaying the limb leads in an orderly arrangement that starts with lead aVL and ends with lead III, and many ECG changes would be ideally displayed by a lead -aVR at 30 degrees.     

Use of the 24-lead "standard" electrocardiogram to identify the site of acute coronary occlusion. A review paper

This review presents the added value for diagnosis of acute ischemia/infarction of considering ST elevation in the 12 inverted leads (-I, -II, -II, -aVR, etc) of the standard electrocardiogram in addition to ST elevation in 12 positive leads. A small number of studies have been published showing substantial increases in sensitivity at the "cost of" slight decreases in specificity. One recent study indicated that only 7 of the inverted leads should be considered, yielding a "19-lead electrocardiogram" encompassing the following leads (presented here in the logical sequences): -III, aVL, I, -aVR, II, aVF, III, -aVL, -I, aVR; and V1, V2, V3, V4, V5, V6, -V1, -V2, -V3. Studies have to be performed to establish the thresholds that should be applied to these leads for achievement of sensitivity/specificity.     

The value of the 12-lead ECG for evaluation and optimization of cardiac resynchronization therapy in daily clinical practice

Based on existing literature and some new data we propose a simple three-step strategy using the standard 12-lead ECG for patient selection and optimal delivery of cardiac resynchronization therapy (CRT). (1) Complete LBBB with regard to the indication for CRT can probably best be identified by a QRS duration of ≥ 130 ms for women and ≥ 120 ms for men with the presence of mid-QRS notch-/slurring in ≥ 2 contiguous leads of V₁, V₂, V₅, V₆, I and aVL. (2) Left ventricular (LV) free wall pacing should result in a positive QRS complex in lead V₁, with estimation of the exact LV lead position in the circumferential and apico-basal direction using lead aVF and the precordial leads, respectively. Wide and fractionated LV-paced QRS complexes may indicate pacing in scar tissue. (3) Atrioventricular and interventricular stimulation intervals may be optimized by adjusting them until precordial leads show fusion patterns between left and right ventricular activation wavefronts in the QRS complex.     

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.     

Optimization of the precordial leads of the 12-lead electrocardiogram may improve detection of ST-segment elevation myocardial infarction

Background

For the assessment of patients with chest pain, the 12-lead electrocardiogram (ECG) is the initial investigation. Major management decisions are based on the ECG findings, both for attempted coronary artery revascularization and risk stratification. The aim of this study was to determine if the current 6 precordial leads (V₁-V₆) are optimally located for the detection of ST-segment elevation in ST-segment elevation myocardial infarction (STEMI).

Methods

We analyzed 528 (38% anterior [200], 44% inferior [233], and 18% lateral [95]) patients with STEMI with both a 12-lead ECG and an 80-lead body surface map (BSM) ECG (Prime ECG, Heartscape Technologies, Bangor, Northern Ireland). Body surface map was recorded within 15 minutes of the 12-lead ECG during the acute event and before revascularization. ST-segment elevation of each lead on the BSM was compared with the corresponding 12-lead precordial leads (V₁-V₆) for anterior STEMI. In addition, for lateral STEMI, leads I and aVL of the BSM were also compared; and limb leads II, III, aVF of the BSM were compared with inferior unipolar BSM leads for inferior STEMI. Leads with the greatest mean ST-segment elevation were selected, and significance was determined by analysis of variance of the mean ST segment.

Results

For anterior STEMI, leads V₁, V₂, 32, 42, 51, and 57 had the greatest mean ST elevation. These leads are located in the same horizontal plane as that of V₁ and V₂. Lead 32 had a significantly greater mean ST elevation than the corresponding precordial lead V₃ (P = .012); and leads 42, 51, and 57 were also significantly greater than corresponding leads V₄, V₅, V₆, respectively (P < .001). Similar findings were also found for lateral STEMI. For inferior STEMI, the limb leads of the BSM (II, III, and aVF) had the greatest mean ST-segment elevation; and lead III was significantly superior to the inferior unipolar leads (7, 17, 27, 37, 47, 55, and 61) of the BSM (P < .001).

Conclusion

Leads placed on a horizontal strip, in line with leads V₁ and V₂, provided the optimal placement for the diagnosis of anterior and lateral STEMI and appear superior to leads V₃, V₄, V₅, and V₆. This is of significant clinical interest, not only for ease and replication of lead placement but also may lead to increased recruitment of patients eligible for revascularization with none or borderline ST-segment elevation on the initial 12-lead ECG.     

Left atrial appendage activity translation in the standard 12-lead ECG

LAA Activity in Surface ECG. Introduction: Interatrial frequency gradient is used to guide catheter ablation of atrial fibrillation (AF). Lead V1 adequately reflects right atrial activity, but reliable tools for noninvasive estimation of right versus left fibrillatory frequency are lacking. In this study, patients with dissociated left and right atrial rhythms were studied in order to identify which surface electrocardiographic (ECG) leads that most closely reflect the left atrial activity. Methods: Two consecutive patients with atrial tachycardia confined to the left atrial appendage (LAA) detected during catheter ablation of AF were included (2 men, 54 and 72 years old). A 12‐lead ECG was recorded simultaneously with electrograms from the right and left atrial appendages (RAA/LAA). AF frequency spectra were calculated from all 12 leads using spatiotemporal QRST cancellation and Welch periodogram. The dominating atrial cycle length (DACL) in the surface ECG leads was subsequently compared with the invasively measured LAA cycle length. Results: LAA activation frequency was seen as a prominent peak in the frequency–power spectrum derived from frontal plane leads as well as lead V1. The absolute difference in noninvasively and invasively measured LAA cycle length was lowest for leads aVR, II, aVF, III, and V1 in which it was in the range of 2–4 ms. Conclusion: Prominent left atrial component is present in the majority of standard ECG leads, including those traditionally associated with right atrial activity such as V1. Spectral analysis is able to extract the LAA component on surface ECG. (J Cardiovasc Electrophysiol, Vol. 22, pp. 706‐710, June 2011)     

Choice of an alternative lead for QT interval measurement in serial ECGs when Lead II is not suitable for analysis

IntroductionConventionally, QT interval is measured in lead II. There are no data to select an alternative lead for QT measurement when it cannot be measured in Lead II for any reason.Methods and resultsWe retrospectively analyzed ECGs from 1906 healthy volunteers from 41 phase I studies. QT interval was measured on the median beat in all 12 leads. The mean difference in QT interval between lead aVR and in Lead II was the least, followed by aVF, V5, V6 and V4; lead aVL had maximum difference. The T wave was flat (<0.1 mV) in Lead II in 6.9% of ECGs; it was also flat in 20% of these ECGs (1.4% of all ECGs) in Leads aVR, aVF and V5.ConclusionsWhen QT interval cannot be measured in Lead II, the best alternative leads are aVR, aVF, V5, V6 and V4 in that sequence. It differs maximally from that in Lead II in Lead aVL.     

An evaluation of ECG leads used to assess QT prolongation

AIMS: The aim of the present study is to elucidate the optimal lead to be selected for the evaluation of drug-induced QT prolongation. METHODS AND RESULTS: We assessed the validity of each electrocardiography (ECG) lead for the evaluation of QT intervals in 688 patients receiving psychotropic drugs. Abnormal QTc prolongation was observed in 96 (14%) patients using the longest ECG lead. Prevalence of QTc prolongation was larger when using leads I, III, aVR, aVL, aVF, V1, and V6 (> 18%), and smaller when using lead V2 (10%). In the remaining 4 ECG leads, the overall accuracy to predict QTc prolongation was higher when using lead V3 (94%) compared with lead II (89%) or lead V5 (90%). Sensitivity to predict QTc prolongation was higher when using lead V4 (81%) compared with lead II (66%) or lead V2 (63%). CONCLUSION: When a single lead was used for the evaluation of QT prolongation, the results were not always similar to those using the lead which demonstrated the longest QT interval, and if only one lead is to be chosen, lead V3 or V4 should be selected.     

Improving the ECG classification of inferior and lateral myocardial infarction by inversion of lead aVR

OBJECTIVE—To assess whether the use of inverted lead aVR (?aVR) would improve the classification of acute inferior or lateral myocardial infarction presenting with ST elevation.DESIGN—Observational study. The presence of ? 1 mm ST elevation in lead ?aVR (derived by manual assessment of ST depression in conventional lead aVR) was determined by a single investigator, blinded to patient outcome.PATIENTS—173 consecutive patients with chest pain for ? 12 hours and ST elevation of ? 1 mm in inferior leads (II, III, aVF) or lateral leads (I, aVL, V5, V6), excluding those with anterolateral ST elevation.MAIN OUTCOME MEASURE—Incidence of ST elevation in lead ?aVR in patients with inferior or lateral ST elevation, or both.RESULTS—ST elevation in lead ?aVR was present in 25 of 136 patients (18%) with inferior but no lateral ST elevation (indicating greater superior involvement) and in three of 11 patients (27%) with lateral but no inferior ST elevation (indicating greater inferior involvement). ST elevation in lead ?aVR bridged the gap between inferior and lateral ST elevation in 15 of 25 (60%) patients with inferior and lateral chest lead (V5/V6) ST elevation, and in all patients with inferior and lateral limb lead (I/aVL) ST elevation. The presence of ST elevation in lead ?aVR was associated with a larger infarct size as defined by median peak creatine kinase on serial sampling: 1780 v 987  mmol/l; p = 0.021.CONCLUSIONS—Use of lead ?aVR improves the ECG classification of acute inferior or lateral acute myocardial infarction and thus may be useful as part of the routine 12 lead ECG assessment of such patients.     

Assessing computerized eye tracking technology for gaining insight into expert interpretation of the 12-lead electrocardiogram: an objective quantitative approach

IntroductionIt is well known that accurate interpretation of the 12-lead electrocardiogram (ECG) requires a high degree of skill. There is also a moderate degree of variability among those who interpret the ECG. While this is the case, there are no best practice guidelines for the actual ECG interpretation process. Hence, this study adopts computerized eye tracking technology to investigate whether eye-gaze can be used to gain a deeper insight into how expert annotators interpret the ECG. Annotators were recruited in San Jose, California at the 2013 International Society of Computerised Electrocardiology (ISCE).MethodsEach annotator was recruited to interpret a number of 12-lead ECGs (N = 12) while their eye gaze was recorded using a Tobii X60 eye tracker. The device is based on corneal reflection and is non-intrusive. With a sampling rate of 60 Hz, eye gaze coordinates were acquired every 16.7 ms. Fixations were determined using a predefined computerized classification algorithm, which was then used to generate heat maps of where the annotators looked. The ECGs used in this study form four groups (3 = ST elevation myocardial infarction [STEMI], 3 = hypertrophy, 3 = arrhythmias and 3 = exhibiting unique artefacts). There was also an equal distribution of difficulty levels (3 = easy to interpret, 3 = average and 3 = difficult). ECGs were displayed using the 4x3 + 1 display format and computerized annotations were concealed.ResultsPrecisely 252 expert ECG interpretations (21 annotators × 12 ECGs) were recorded. Average duration for ECG interpretation was 58 s (SD = 23). Fleiss' generalized kappa coefficient (P_a = 0.56) indicated a moderate inter-rater reliability among the annotators. There was a 79% inter-rater agreement for STEMI cases, 71% agreement for arrhythmia cases, 65% for the lead misplacement and dextrocardia cases and only 37% agreement for the hypertrophy cases. In analyzing the total fixation duration, it was found that on average annotators study lead V1 the most (4.29 s), followed by leads V2 (3.83 s), the rhythm strip (3.47 s), II (2.74 s), V3 (2.63 s), I (2.53 s), aVL (2.45 s), V5 (2.27 s), aVF (1.74 s), aVR (1.63 s), V6 (1.39 s), III (1.32 s) and V4 (1.19 s). It was also found that on average the annotator spends an equal amount of time studying leads in the frontal plane (15.89 s) when compared to leads in the transverse plane (15.70 s). It was found that on average the annotators fixated on lead I first followed by leads V2, aVL, V1, II, aVR, V3, rhythm strip, III, aVF, V5, V4 and V6. We found a strong correlation (r = 0.67) between time to first fixation on a lead and the total fixation duration on each lead. This indicates that leads studied first are studied the longest. There was a weak negative correlation between duration and accuracy (r = − 0.2) and a strong correlation between age and accuracy (r = 0.67).ConclusionsEye tracking facilitated a deeper insight into how expert annotators interpret the 12-lead ECG. As a result, the authors recommend ECG annotators to adopt an initial first impression/pattern recognition approach followed by a conventional systematic protocol to ECG interpretation. This recommendation is based on observing misdiagnoses given due to first impression only. In summary, this research presents eye gaze results from expert ECG annotators and provides scope for future work that involves exploiting computerized eye tracking technology to further the science of ECG interpretation.     

ECG findings after myocardial infarction in children after Kawasaki disease

Standard 12-lead ECGs were evaluated in 17 children with myocardial infarction and 78 children without myocardial infarction after Kawasaki disease; sensitivity and specificity of the ECG infarction criteria were determined. The presence or absence of myocardial infarction was determined from either clinical examination results (coronary angiography, ventriculography, and thallium-201 myocardial imaging) or autopsy findings. Of seven patients with inferior infarction, abnormally deep Q waves in lead II, III, or aVF were observed in six, but the duration was greater than 0.04 second in only one (14%). The sensitivity and specificity of inferior infarction criteria based on Q wave amplitude were 86% and 97%, respectively. Of eight patients with anterior infarction, seven (88%) had abnormally deep and wide (greater than or equal to 0.04 second) Q waves in anterior chest leads. The sensitivity and specificity of the infarction criteria based on the amplitude and duration of the Q wave were 75% and 99%, respectively. Of seven patients with lateral infarction, Q waves were observed in lead I, aVL, or both in four patients, and in all of these patients Q waves were wider than 0.04 second. In two patients with both inferior and anterior infarction, Q waves were observed only in leads II, III, and aVF; in only one patient were the Q waves wider than 0.04 second. Thus deep Q waves in lead II, III, or aVF that are not wider than 0.04 second may indicate inferior infarction in children. Q waves in lead I, aVL, and chest leads associated with anterolateral infarction are in most instances deep and wide.     

Electrocardiographic changes in acute myocardial infarction with acute occlusion of all triple coronary arteries

The 66-year-old woman was diagnosed with “acute myocardial infarction” due to acute triple vessel occlusion based on clinical symptoms, laboratory examination, and coronary angiography (CAG), but her ECG showed ST-segment depression in leads aVR and aVL, in addition to ST-segment elevation in a wide range of leads (V1–V9, V3R–V5R, II, III, and aVF). Thus, a perfect explanation with the existing theory is difficult, and only the case is presented here.     

Hypothermia-induced J waves

A 36 years old woman with acquired immunodeficiency syndrome was admitted to the hospital for pulmonary Mycobacterium Avis Complex infection. Seventy-two hours after the admission she became hypothermic and bradycardic. The ECG showed sinus bradycardia, J waves in leads II, III, aVF, aVR, aVL, V5 and V6 along with QT prolongation and T wave abnormalities. After rewarming the J waves and repolarization abnormalities disappeared. The proposed cellular basis of hypothermia-induced J waves is the accentuation of the spike-and-dome morphology of the action potential of M and epicardial cells.     

QRST time integral values in 12-lead electrocardiograms before and after radiofrequency catheter ablation in patients with Wolff-Parkinson-White syndrome

Objectives. We investigated the usefulness of QRST values obtained from 12-lead electrocardiograms (ECGs) for identification of repolarization abnormalities before and after radiofrequency ablation in patients with Wolff-Parkinson-White syndrome.

Background. Marked T wave abnormalities often appear after ablation and have been attributed to a continuation of repolarization abnormalities present before ablation (cardiac memory). However, to our knowledge repolarization properties before and after ablation have not been assessed quantitatively.

Methods. We calculated the ECG QRST values from 53 patients with Wolff-Parkinson-White syndrome and compared these values before, immediately after and 1 day and 1 week after successful ablation in 25 patients.

Results. QRST values were abnormally high in lead V₁ in 7 of 28 patients with a left-sided accessory pathway and abnormally low in leads III and aVF and high in lead aVL in 12, 9 and 10 of 20 patients, respectively, with a right-sided accessory pathway. Preexisting QRST abnormalities were still present immediately and 1 day after ablation but were usually absent by 1 week after ablation. QRST values before, immediately after and 1 day after ablation were not significantly different in any lead. In 14 patients with ablation of a left-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in lead V₁ and immediately after ablation in leads I, aVR and V₂ were significantly different from QRST values in those leads 1 week after ablation. In six patients with ablation of a right-sided accessory pathway, QRST values before, immediately after and 1 day after ablation in leads III, aVL and aVF and immediately after ablation in lead II were significantly different from QRST values in those leads 1 week after ablation.

Conclusions. Electrocardiographic QRST values may provide useful quantitative information with respect to repolarization properties before and after ablation in patients with Wolff-Parkinson-White syndrome that is otherwise difficult to obtain by conventional ECG analysis.     

Value of the 12-lead resting electrocardiogram for the diagnosis of previous myocardial infarction in paced patients

Aim

This study was conducted to assess the clinical value of the 12-lead electrocardiogram (ECG) for the diagnosis of previous myocardial infarction (MI) in permanently paced patients.

Methods

A total of 107 unselected patients with permanent pacemakers were retrospectively studied and divided into 3 groups: group 1 (control group): 38 patients without a history of MI (mean age, 67 ± 16 years; 20 men; ejection fraction 63% ± 8%); group 2: 44 patients (mean age, 72 ± 11 years; 41 men) with documented previous MI (21 anterior, 23 inferior; ejection fraction 38% ± 13%; P < .0001 vs group 1); group 3: 25 patients (mean age, 71 ± 14 years; 24 men) with biventricular pacing for severe heart failure (16 ischemic, 9 nonischemic; ejection fraction 28% ± 8%; P = .001 vs group 2, P < .0001 vs group 1). A surface 12-lead ECG with full ventricular capture was used for analysis. Comparing group 1 and group 2, the sensitivity, specificity, positive predictive value, negative predictive value, and overall accuracy of 5 criteria was calculated: (1) Cabrera's sign (notching in the ascending limb of the S wave in lead V₃, V₄, or V₅); (2) Chapman's sign (notching of the R wave in lead I, aVL, or V₆); (3) presence of a qR in lead I, aVL, or V₆; (4) notching of QRS in lead II, III, or aVF; (5) presence of a qR in lead II, III, or aVF.

Results

To detect prior MI, sensitivity was moderate for Cabrera's sign (63.6%) and poor for all other ECG criteria ranging from 9.1% to 40.9%. Specificity was relatively high for all ECG criteria ranging from 81.6% to 100%. Combining all 5 ECG signs increased sensitivity to 86.4%, with a specificity of 65.8% and an overall accuracy of 76.8% for the diagnosis of previous MI. None of the 5 criteria was particularly useful to assess the site of prior MI.In patients with biventricular pacing, the accuracy of the 5 ECG criteria was poor and the presence of a qR wave in lead I, aVL, or V6 appears nonspecific and related to pacing site.

Conclusion

The ECG diagnosis of previous MI in paced patients remains a difficult challenge but the presence of 1 or more of the aforementioned ECG criteria may be clinically useful to detect previous MI, suggesting that these ECG signs should be widely taught during medical training. However, in patients with biventricular pacing, these ECG signs are of no value.     

Activation-recovery intervals of 12-lead electrocardiograms before and after catheter ablation in patients with Wolff-Parkinson-White syndrome

Preexcitation in Wolff-Parkinson-White syndrome (WPW) has been reported to induce long-lasting changes in ventricular recovery properties. However, there has not been a report concerning changes in the activation-recovery interval (ARI) in 12-lead ECGs before and after catheter ablation (CA) in patients with WPW syndrome. The present study compared changes in ARIs from 12-lead ECGs with those from body surface unipolar leads before and after CA to examine whether ARIs from limb leads of 12-lead ECGs provide useful information on changes in recovery properties in addition to the ARIs from precordial leads. The study population consisted of 27 manifest WPW patients with a left- (n=18, group A) or right-sided accessory pathway (n=9, group B). ARIs in leads I, II, and III were strongly correlated with those in unipolar leads over the left lateral, left lower, and right lower chest, respectively. ARIs in leads aVR, aVL, and aVF showed a significant correlation with those in unipolar leads over the right upper, left upper, and lower anterior chest, respectively. These correlations were maintained before and after CA. Furthermore, in group A, ARIs in lead V1 tended to increase on day 7 post CA compared with before CA and on day 1. In group B, ARIs in lead III significantly decreased on day 7 compared with before CA and on day 1. These findings suggest that ARIs from the limb leads of 12-lead ECGs may represent those from unipolar leads of a particular area over the body surface, and that ARIs from 12-lead ECGs may provide useful quantitative information on changes in recovery properties before and after CA in patients with manifest WPW syndrome.     

Assessment of derived 12-lead electrocardiograms using general and patient-specific reconstruction strategies at rest and during transient myocardial ischemia

Twelve-lead ST-segment monitoring is a widely used tool for capturing focal ischemia and transient intermittent episodes. However, continuous registration of all 10 electrodes is impractical in clinical settings. This study investigated the accuracy of 2 derived 12-lead strategies that required 6 electrodes, including all limb leads, and 2 precordial leads by using population-based (generalized) and individualized (patient-specific) reconstruction coefficients to derive the additional 4 chest leads. A total of 26,880 simultaneous digital conventional 12-lead generalized and patient-specific electrocardiograms were monitored over 112 hours in 39 patients during percutaneous coronary intervention, including 159 balloon occlusions in 63 arteries, to test accuracy at rest and during ischemia. Occlusion duration was 78 seconds (range 42 to 96) in the left main coronary in 2 patients, the left anterior descending artery in 15, the right coronary artery in 10, the circumflex artery in 2, and graft segments in 5 patients. Average summated 12-lead ST deviation over the study population at baseline was 377 microV (range 104 to 1,718), which increased at peak ischemia to an average of 1,086 microV (range 282 to 4,099). Median absolute differences at peak ischemic ST deviation were 25 microV in lead V(1), 0 microV in lead V(2), 35 microV in lead V(3), 34 microV in lead V(4), 0 microV in lead V(5), 11 microV in lead V(6), and 114 microV for summated 12-lead ST deviation with the generalized method and 7 microV in lead V(1), 4 microV in lead V(2), 1 muV in lead V(3), 5 microV in lead V(4), 4 microV in lead V(5), 9 microV in lead V(6), and 83 microV for the summated 12-lead ST deviation with the patient-specific method. Limb leads (I, II, III, aVR, aVL, and aVF) were identical in all patients. Thus, generalized and patient-specific methods derived from 12-lead electrocardiography using actual limb and 2 precordial electrodes accurately derived the additional chest leads at rest and during ischemia. These approaches appear to be more practical than conventional 10-electrode monitoring but preserve high accuracy.     

镜像右位心的F导联心电图特征读析

目的 探讨F导联心电图诊断镜像右位心的特征。方法 在健康体检中应用F导联采集镜像右位心心电图并解读。结果 F导联检测到13例(0.018%)镜像右位心。在镜像右位心中Ⅰ导联各波形态均倒置,即P、QRS及T波均倒置;F2(Ⅱ)与F6(Ⅲ)导联、F3(aVR)与F1(aVL)导联波形互换;V3R、V5R导联波形类似正常时的V3、V5导联,代表左室波形;V1和V2导联代表右室波形。结论 镜像右位心的特征显示:P波F1(aVL)、F2(Ⅰ)导联显示镜像QRS波形;F1(aVL)、F2(Ⅰ)、F3(-aVR)、F4(Ⅱ)导联P-QRS-T波群均主波向下,呈rS型,其R波波幅递增;QRS波F5(aVF)不变;胸导联V1～V6呈rS型,其R波波幅递减,其S波呈逐渐相对增深,R/S比例逐渐减小的规律;V1导联R波高尖;常伴有其他心电图改变。     

Value of the 12-lead electrocardiogram to define the level of obstruction in acute anterior wall myocardial infarction: correlation to coronary angiography and clinical outcome in the DANAMI-2 trial

BACKGROUND: Acute anterior myocardial infarction (MI) caused by proximal occlusion of the left anterior descending coronary artery (LAD), is associated with unfavourable outcome and should be recognized by simple noninvasive methods like the 12-lead electrocardiogram (ECG). METHODS: In a prospective post-hoc DANAMI-2 substudy we compared two pre-specified ECG patterns to determine the level of LAD occlusion. The ECG findings were correlated to coronary angiography from the acute phase. The impact on clinical outcome of ECG and angiographic signs of proximal versus distal LAD occlusion was studied. RESULTS: In 146 patients without confounding factors on the ECG, either ST-elevation>or=0.5 mm in lead aVL or any ST-elevation in lead aVR in association with precordial ST-segment elevation in at least two contiguous leads (including V2, V3 or V4) had a sensitivity of 94%, specificity of 49%, positive predictive value of 85% and negative predictive value of 71% to predict a proximal LAD lesion. Surprisingly, ECG or angiographic signs of lesion proximality were not associated with worse outcome at 30 day or 2.7 year follow-up. CONCLUSIONS: The site of occlusion in the LAD could be reliably predicted by 12-lead ECG in patients with acute anterior MI. The prognostic significance of the level of occlusion in the LAD in the modern era of acute ST-elevation MI treatment should be reassessed.