A new ECG algorithm for the localization of accessory pathways using only the polarity of the QRS complex

A new algorithm is proposed for localization of accessory atrioventricular pathways by use of a 12-lead electrocardiogram (ECG). The polarity of the QRS complex in leads III, V₁, and V₂ from 102 patients with Wolff-Parkinson-White syndrome with manifested preexcitation who underwent successful radiofrequency catheter ablation was analyzed. Accessory pathways on the right side of the heart were localized to three regions around the tricuspid annulus, and left-sided pathways were localized to two regions around the mitral valve annulus. In 42 of 46 patients (91%) with left posterolateral accessory pathways, a common characteristic of the ECG was a positive QRS complex in leads III and V₁ (sensitivity 91%, specificity 95%). Of 19 patients with left inferior paraseptal or inferior accessory pathways, 16 (84%) had a negative QRS complex in lead III and a positive QRS complex in lead V₁ (sensitivity 84%, specificity 98%). All six patients with right anterosuperior paraseptal accessory pathways had a positive QRS complex in lead III but a negative QRS complex in lead V₁ (sensitivity 100%, specificity 97%). The 25 patients with right inferior paraseptal or inferior accessory pathways had a negative or isodiphasic QRS complex in leads III and V₁, but the QRS complex was positive in lead V₂ in 21 (84%) of these patients (sensitivity 84%, specificity 100%). Finally, five of the six patients (83%) with right anterior accessory pathways had a negative QRS complex in leads III, V₁, and V₂ (sensitivity 83%, specificity 96%). With the algorithm, the localization of accessory pathways was thus identified in 90 of the 102 patients (88%).     

12-Kanal-Elektrokardiogramm

The surface electrocardiogram (ECG) is an important diagnostic tool for the diagnosis of arrhythmias and acute coronary syndrome. Supraventricular tachycardias (SVT) are paroxysmal tachycardias as are sinus tachycardia, atrial tachycardia, AV nodal reentry tachycardia, and tachycardia due to accessory pathways. All SVT are characterized by a ventricular heart rate >100/min and small QRS complexes (QRS width <0.12 s) during tachycardia. It is important to analyze the relation between P wave and QRS complex to look for an electrical alternans as a leading finding for an accessory pathway. Wide QRS complex tachycardias (QRS width ≥ 0.12 s) occur in SVT with aberrant conduction and SVT with bundle branch block or ventricular tachycardia (VT). In broad complex tachycardias, AV dissociation, negative or positive concordant pattern in V₁–V₆, a notch in V₁ and QR complexes in V₆ in tachycardias with left bundle branch block morphologies are findings indicating VT. In addition, an R/S relation <1 in V₆ favors VT when right bundle branch block tachycardia morphologies are present. By analyzing the surface ECG in the right way with a systematic approach, the specificity and sensitivity of correctly identifying a SVT or VT can be raised by >95%. The 12-lead surface ECG allows the coronary culprit lesion to be located in 97% due to determination of the 12-lead ST segment deviation score.     

Specific Electrocardiographic Features of Manifest Coronary Vein Posteroseptal Accessory Pathways

Coronary Vein Accessory Pathways. Introduction: Some posteroseptal accessory pathways (APs) can be successfully ablated by radiofrequency current only from inside the coronary sinus (CS) or its branches, because of an absolute or relatively epicardial location. The aim of this study was to identify ECG features of manifest posteroseptal APs requiring ablation in the CS or the middle cardiac veins (MCVs). Methods and Results: One hundred seventeen consecutive patients with manifest posteroseptal APs successfully ablated: (1) ≥ 1 cm deep inside the MCV (group MCV: n = 13); (2) inside the CS, including the area adjacent to the MCV ostium (group CS: n = 10); (3) at the right (group R: n = 60); or (4) the left posteroseptal endocardial region (group L: n = 34) were included. We reviewed delta wave polarity (initial 40 msec) and QRS morphology during sinus rhythm and atrial pacing as well as electrogram characteristics in these patients. The local target site electrogram in groups MCV and CS was characterized by a longer atrial to ventricular electrogram interval, suggesting a longer course of the pathway and more frequent recording of a presumptive AP potential compared to the group ablated at the right or left endocardium. The most sensitive ECG feature for group CS or group MCV was a negative delta wave in lead II in sinus rhythm (87%), but specificity (79%) and positive predictive value (50%) were relatively low. A steep positive delta wave in aVR during maximal preexcitation possessed the highest specificity and positive predictive value (98% and 88%, sensitivity 61%) which increased to 99% and 91%, respectively, when combined with a deep S wave in V₆ (R wave ≤ S wave). Conclusion: These data suggest that posteroseptal APs ablated inside the coronary venous system have highly specific features, including the combination of a steep positive delta wave in lead aVR and a deep S wave in lead V₆ (R wave ≤ S wave) during maximal preexcitation. The highest sensitivity is provided by a negative delta wave in lead II. These findings may be helpful for anticipating and planning an epicardial ablation strategy.     

Conventional Electrocardiogram in Arrhythmogenic Right Ventricular Dysplasia-Cardiomyopathy and Idiopathic Right Ventricular Outflow Tract Tachycardia

Objective: Arrhythmogenic right ventricular dysplasia up to now is a rare cardiomyopathic entity with certain difficulties in clinical definition of diagnostic criteria. In 42 patients with major and minor criteria of arrhythmogenic right ventricular dysplasia and 25 patients with idiopathic ventricular arrhythmia, the role of conventional ECG in the diagnosis of arrhythmogenic right ventricular dysplasia was reevaluated. Methods: In standard 12-lead ECG, QRS duration was measured in limb lead D₁, and in V₁-V₆. A ratio of the sum of right (V₂+ V₃) and left (V₄+ V₅) was calculated. T wave inversions, Epsilon wave, and mechanisms of advancing right bundle branch block were analyzed. Results: In 39 out of 42 patients (93%) with the diagnosis of arrhythmogenic right ventricular dysplasia, a ratio of right and left precordial QRS duration of >1.2, a maximum right precordial QRS duration of > 100 ms in 10 cases (26%) and >110 ms in 29 cases (74%) could be found. Incomplete right bundle branch block with right precordial T inversions was found in one case. The ECG in two patients revealed a precordial R/S transition in V₁ or V₂; in all other cases, R/S transition was localized in V₃ or V₄. R peak time was normal (< 0.04 s) in all cases, a “notching” or “slurring” of the S wave was striking in 16 cases. T wave inversions were found in 27 cases and definite Epsilon wave in only one case. Although incomplete right bundle branch block and certain preforms could also be disclosed in four patients with idiopathic right ventricular outflow tract (RVOT) tachycardia, localized right precordial QRS prolongation could be excluded in all but one of these cases. Localized right precordial QRS duration prolongation in one case was probably due to a rotation of the heart with a precordial R/S transition between V₁ and V₂. Conclusion: Localized right precordial QRS prolongation in a normal precordial R/S transition: (a) seems to be the most important aspect of arrhythmogenic right ventricular dysplasia at conventional ECG, with a sensitivity of 93% and a specificity of 96% in order to distinguish idiopathic RVOT tachycardia; (b) can appear with (64%) or without (36%) secondary T wave inversions; and (c) is due to a “parietal” block sparing the specialized conducting system.     

Regelm??ige Tachykardien mit breitem Kammerkomplex

Differential diagnosis of regular tachycardia with broad QRS complex can be challenging in daily practice. There are four different arrhythmias that have to be taken into account when being confronted with a broad QRS complex tachycardia: (1) ventricular tachycardia (VT); (2) supraventricular tachycardia (SVT) with bundle branch block (BBB); (3) SVT with AV conduction over an accessory AV pathway; (4) paced ventricular rhythm. Due to potentially fatal consequences, the correct diagnosis is important in view of both the acute treatment and the long-term therapy. Since SVT with accessory conduction is rare and a paced ventricular rhythm can be identified easily by stimulation artifacts, in most cases, a VT has to be differentiated from an SVT with BBB. Several ECG criteria can be helpful: (1) QRS complex duration > 140 ms in right BBB tachycardia or > 160 ms in left BBB tachycardia; (2) ventricular fusion beats; (3)“Northwest” QRS axis; (4) ventriculoatrial dissociation; (5) absence of an RS complex or RS interval > 100 ms in leads V₁-V₆; (6) a positive or negative concordant R wave progression pattern in leads V₁-V₆; (7) absence of an initial R wave or an S wave in lead V₁ in right BBB tachycardia; (8) absence of an R wave or an R/S ratio < 1 in lead V₆ in right BBB tachycardia; (9) absence or delay of the initial negative forces in lead V₁ in left BBB pattern (R wave duration > 30 ms in V₁; interval between onset of R wave and Nadir of S wave > 60 ms in V₁); (10) presence of Q wave. Any of these variables favor VT. However, none of the criteria has both a sufficient sensitivity and specificity when utilized on its own. Therefore, various diagnostic algorithms have been proposed using a number of the above criteria consecutively. By doing so, the specificity and sensitivity of correctly identifying a VT or an SVT with BBB can be raised to > 95%.     

Comparison of optimal scalar electrocardiographic,orthogonal electrocardiographic and vectorcardiographic criteria for diagnosing inferior and anterior myocardial infarction

A scalar electrocardiogram (ECG), orthogonal ECG and vectorcardiogram (VCG) were recorded in 46 normal persons, 38 patients with inferior myocardial infarction (MI) and 22 patients with anterior MI proved at cardiac catheterization. The diagnostic information provided by the scalar ECG, orthogonal ECG and VCG was quantitatively analyzed and the optimal criteria for diagnosing inferior and anterior MI exhibited by each method were identified. The optimal scalar electrocardlographic, orthogonal electrocardiographic and vectorcardiographic criteria, respectively, are: For inferior MI: initial superior duration in lead aVF >30 ms (sensitivity 63%, specificity 100%), superior/inferior amplitude ratio in lead Y ≥0.2 (sensitivity 63%, specificity 96%), initial superior duration >29 ms or initial superior distance >0.4 mV in the frontal plane loop (sensitivity 68%, specificity 100%). For anterior MI: initial anterior duration in lead V₂ <20 ms or initial anterior duration in lead V₃ < 25 ms (sensitivity 91%, specificity 100%), anterior/posterior duration ratio in lead Z <0.3 (sensitivity 73%, specificity 98%), initial anterior duration <15 ms in the transverse plane loop (sensitivity 64%, specificity 98%). There were no significant differences among the performances of the optimal scalar ECG, orthogonal ECG and the VCG for diagnosing inferior MI. However, the performance of the optimal scalar ECG was superior to that of the optimal orthogonal ECG and the optimal VCG for diagnosing anterior MI (chi-square = 5.20, p <0.02 and chi-square = 7.14, p >0.01, respectively).     

Ventricular activation during ventricular endocardial pacing: I. Electrocardiographic patterns related to the site of pacing

The QRS configuration produced by pacing at multiple left ventricular endocardial sites was evaluated in eight patients with (group 1) and six patients without (group 2) left ventricular wall motion abnormalities. Pacing was performed at a total of 122 sites, 4 to 13 sites in each patient. The QRS configuration resulting from apical pacing locations was compared with that at basal, septal to lateral and inferior to superior locations. Significant differences in QRS configuration during pacing from apical and basal locations were observed in electrocardiographic leads I, V₁, V₂ and V₆ (probability [p] < 0.01). Specifically, a QS pattern in leads I, V₂ and V₆ was more characteristic of an apical pacing location (p < 0.001), and a monophasic R wave in leads V₁ and V₂ was more characteristic of a basal pacing location (p < 0.01). Significant differences in leads V₁ and V₂ were observed when septal and lateral pacing sites were compared (p < 0.001). A monophasic R wave in leads V₁ and V₂ was more characteristic of a lateral pacing location (p < 0.01); a QS complex in lead V₂ was more characteristic of a septal pacing location (p < 0.001). Pacing at superior sites usually produced an inferior axis and vice versa (p < 0.001). The electrocardiographic patterns produced by pacing at similar sites in patients in group 1 were less consistent than those in patients in group 2. The QRS complex during ventricular pacing was wider in patients in group 1 (159 ± 30 ms) than in patients in group 2 (132 ± 18 ms) (p < 0.001).It is concluded that the QRS configuration recorded with 12 lead electrocardiography during endocardial pacing can help locate the region of the pacing site in patients with and without organic heart disease, although precise localization is not possible.     

Diagnostic Significance of a Small Q Wave in Precordial Leads V2 or V3

Background: An abnormal Q wave is usually defined as an initial depression of the QRS complex having a duration of ≥40 ms and amplitude exceeding 25% of the following R wave in any contiguous leads on the 12‐lead electrocardiogram (ECG). However, much smaller Q waves are sometimes recorded on the ECG. This study investigated the diagnostic value of the small Q wave recorded in precordial leads V₂ or V₃ on the ECG. Methods: We investigated 807 consecutive patients who underwent coronary angiography. A small Q wave was defined as any negative deflection preceding the R wave in V₂ or V₃ with <40‐ms duration and <0.5‐mV amplitude, with or without a small (<0.1‐mV) slurred, spiky fragmented initial QRS deflection before the Q wave (early fragmentation). ECG and coronary angiographic findings were analyzed. Results: The small Q wave was present in 87 patients. Multiple logistic regression analysis revealed that presence of a small Q wave was a strong independent predictor of any coronary artery stenosis or left anterior descending artery (LAD) stenosis (odds ratio = 2.706, 2.902; P < 0.001, < 0.001, respectively). Conclusion: A small Q wave (<40‐ms duration and <0.5‐mV amplitude) in V₂ or V₃ with or without early fragmentation significantly predicted the presence of CAD and, especially, significant stenosis in the LAD. Ann Noninvasive Electrocardiol 2010;15(2):116–123     

La onda R prominente en V1 pero no en V2 es un signo específico de infarto transmural lateral grande

Introduction and objectives

In the absence of right ventricular hypertrophy or bundle-branch block, a prominent R wave in V₁ or V₂ is considered to reflect a lateral myocardial infarction. We investigated the differences in infarct location, size and transmural extent between patients with prominent R wave in V₁ and those with prominent R wave in V₂.

Methods

We studied 50 patients with a previous first infarction involving left ventricular inferior and/or lateral wall at contrast-enhanced magnetic resonance.

Results

A prominent R wave in V₁ was present in 8 patients (16%), in V₂ in 23 (46%). At magnetic resonance, the infarction involved the inferior wall in 11 patients (22%), the lateral wall in 6 (12%), and both walls in 33 patients (66%). The sensitivity of a prominent R wave in V₁ in detecting a lateral infarction was low (17.9%), while the specificity was high (90.9%). The sensitivity and specificity of a prominent R wave in V₂ were 46.2% and 54.5%, respectively. In patients with a prominent R wave in V₁, infarct size and lateral and transmural extent were greater than in patients without this pattern (P<.005, <.001, and <.05, respectively); conversely, infarct size and transmural extent in the inferior wall and in its basal-posterior segment were not significantly different. In patients with a prominent R wave in V₂, infarct size, lateral and transmural extent were not different from patients without this pattern.

Conclusions

Only a prominent R wave in V₁ is a specific sign of large and transmural lateral infarction.Full English text available from:www.revespcardiol.org     

T wave “humps” as a potential electrocardiographic marker of the long QT syndrome

Objectives. This study attempted to determine the prevalence and electrocardiographic (ECG) lead distribution of T wave “humps” (T2, after an initial T wave peak, T1) among families with long QT syndrome and control subjects.Background. T wave abnormalities have been suggested as another facet of familial long QT syndrome, in addition to prolongation of the rate-corrected QT interval (QTc), that might aid in the diagnosis of affected subjects.Methods. The ECGs from 254 members of 13 families with long QT syndrome (each with two to four generations of affected members) and from 2,948 healthy control subjects (age ≥ 16 years, QTc interval 0.39 to 0.46 s) were collected and analyzed. Tracings from familes with long QT syndrome were read without knowledge of QTc interval or family member status (210 blood relatives and 44 spouses).Results. We found that T2 was present in 53%, 27% and 5% of blood relatives with a “prolonged” (≥ 0.47 s), “borderline” (0.42 to 0.46 s) and “normal” (≤0.41 s) QTc interval, respectively (p < 0.0001), but in only 5% and 0% of spouses with a borderline and normal QTc interval, respectively (p = 0.06 vs. blood relatives). Among blood relatives with T2, the mean [±SD] maximal T1T2 interval was 0.10 ± 0.03 s and correlated with the QTc interval (p < 0.01); a completely distinct U wave was seen in 23%. T2 was confined to leads V₂and V₃in 10%, whereas V₄, V₅, V₆or a limb lead was involved in 90% of blood relatives with T2. Among blood rotatives with a borderline QTc interval, 50% of those with versus 20% of those without major symptoms manifested T2 in at least one left precordial or limb lead (p = 0.05). A T2 amplitude > 1 mm (grade III) was observed, respectively, in 19%, 6% and 0% of blood relatives with a prolonged, borderline and normal QTc interval with T2 in at least one left precordial or limb lead. Among the 2,948 control subjects, 0.6% exhibited T2 confined to leads V₂and V₃, and 0.9% had T2 involving one or more left precordial lead (but none of the limb leads). Among 37 asymptomatic adult blood relatives with QTc intervals 0.42 to 0.46 s, T2 was found in left precordial or limb leads in 9 (24%; 5 with limb lead involvement) versus only 1.9% of control subjects with a borderline QTc interval (p < 0.0001).Conclusions. These findings are consistent with the hypothesis that in families with long QT syndrome, T wave humps involving left precordial or (especially) limb leads, even among asymptomatic blood relatives with a borderline QTc interval, suggest the presence of the long QT syndrome trait.     

12-Kanal-Elektrokardiogramm bei Kindern und Jugendlichen

The surface electrocardiogram (ECG) is an important diagnostic tool in general medicine, for children, adolescents and adults. Although technical aspects of ECG recordings are similar in young and old patients, there are some age-specific differences between children and adults. The QRS axis shifts from right to left at several stages during childhood. The heart rate decreases from 140/min (newborns) to 130/min (young children) to 75/min (adolescents). First and second degree atrioventricular (AV) blocks (I and II type Wenckebach) are frequent in children. Duration of the QRS is age-dependent as is the R peak amplitude. The ST-segment elevation is relatively frequent in children and is normal up to 0.1 mV. Negative T waves diminish with age and QTc times are also age-dependent. Supraventricular tachycardia (SVT) is characterized by small QRS complexes (QRS width <?0.12 s) during tachycardia. It is important to analyze the relationship between the p wave and QRS complex and to look for electrical alternans as a leading finding for an accessory pathway. Wide QRS complex tachycardia (QRS width ≥?0.12 s) occurs in SVT with aberrant conduction, SVT with bundle branch block or ventricular tachycardia (VT). In broad complex tachycardia, AV dissociation, negative or positive concordant pattern in V₁–V₆, a notch in V₁ and qR complexes in V₆ in tachycardia with left bundle branch block morphologies are findings indicating VT. In addition, an R/S relationship in V₆ favors VT when right bundle branch block tachycardia morphologies are present. By analyzing the surface ECG in the correct way with a systematic approach, a specificity and sensitivity of correctly identifying SVT or VT of over 95?% can be achieved.     

Preferred left ventricular lead position for upgrade from right ventricular pacing to cardiac resynchronization therapy

Introduction

Cardiac resynchronization therapy (CRT) is well-established for treating symptomatic heart failure with electrical dyssynchrony. The left ventricular (LV) lead position is recommended at LV posterolateral to lateral sites in patients with left bundle branch block; however, its preferred region remains unclear in patients being upgraded from right ventricular (RV) apical pacing to CRT. This study aimed to identify the preferred LV lead position for upgrading conventional RV apical pacing to CRT.

Methods

We used electrode catheters positioned at the RV apex and LV anterolateral and posterolateral sites via the coronary sinus (CS) branches to measure the ratio of activation time to QRS duration from the RV apex to the LV anterolateral and posterolateral sites during RV apical pacing. Simultaneous biventricular pacing was performed at the RV apex and each LV site, and the differences in QRS duration and LV dP/dt_max from those of RV apical pacing were measured.

Results

Thirty-seven patients with anterolateral and posterolateral LV CS branches were included. During RV apical pacing, the average ratio of activation time to QRS duration was higher at the LV anterolateral site than at the LV posterolateral site (0.90 ± 0.06 vs. 0.71 ± 0.11, p < .001). The decreasing ratio of QRS duration and the increasing ratio of LV dP/dt_max were higher at the LV anterolateral site than at the posterolateral site (45.7 ± 18.0% vs. 32.0 ± 17.6%, p < .001; 12.7 ± 2.9% vs. 3.7 ± 8.2%, p < .001, respectively) during biventricular pacing compared with RV apical pacing.

Conclusion

The LV anterolateral site is the preferred LV lead position in patients being upgraded from conventional RV apical pacing to CRT.     

Lead I R‐wave amplitude to distinguish ventricular arrhythmias with lead V3 transition originating from the left versus right ventricular outflow tract

BackgroundThe electrophysiology algorithm for localizing left or right origins of outflow tract ventricular arrhythmias (OT‐VAs) with lead V₃ transition still needs further investigation in clinical practice.HypothesisLead I R‐wave amplitude is effective in distinguishing the left or right origin of OT‐VAs with lead V₃ transition.MethodsWe measured lead I R‐wave amplitude in 82 OT‐VA patients with lead V₃ transition and a positive complex in lead I who underwent successful catheter ablation from the right ventricular outflow tract (RVOT) and left ventricular outflow tract (LVOT). The optimal R‐wave threshold was identified, compared with the V₂S/V₃R index, transitional zone (TZ) index, and V₂ transition ratio, and validated in a prospective cohort study.ResultsLead I R‐wave amplitude for LVOT origins was significantly higher than that for RVOT origins (0.55 ± 0.13 vs. 0.32 ± 0.15 mV; p < .001). The area under the curve (AUC) for lead I R‐wave amplitude as assessed by receiver operating characteristic (ROC) analysis was 0.926, with a cutoff value of ≥0.45 predicting LVOT origin with 92.9% sensitivity and 88.2% specificity, superior to the V₂S/V₃R index, TZ index, and V₂ transition ratio. VAs in the LVOT group mainly originated from the right coronary cusp (RCC) and left and right coronary cusp junction (L‐RCC). In the prospective study, lead I R‐wave amplitude identified the LVOT origin with 92.3% accuracy.ConclusionLead I R‐wave amplitude provides a useful and simple criterion to identify RCC or L‐RCC origin in OT‐VAs with lead V₃ transition.     

不同心电图特征对特发性室性期前收缩右室流出道起源部位诊断价值比较

目的 比较体表心电图鉴别右室流出道室性期前收缩具体起源点的诊断价值。 方法 分析经射频导管消融治疗室性期前收缩靶点明确为右室流出道的139例患者（其中右室流出道间隔部起源的111例,游离壁起源的28例）的体表心电图特点,以室性期前收缩时Ⅰ导联主波形态、QRS波时限、胸前导联移行及下壁三肢体导联有无顿挫进行分析,评估其对鉴别右室流出道室性期前收缩具体起源点的准确性。 结果 以室性期前收缩的QRS波宽度≥140 ms判断为右室流出道游离壁起源的灵敏度为86%,特异度为58%;以下壁三肢体导联均有顿挫或切迹判断为游离壁起源的灵敏度为64%,特异度为91%;以Ⅰ导联主波向上判断游离壁起源的灵敏度为86%,特异度为73%。 结论 I导联主波方向及下壁三肢体导联有无顿挫能对鉴别游离壁还是间隔起源有较大实用价值。     

Specificity of the wide QRS complex tachycardia algorithms in recipients of cardiac resynchronization therapy

BackgroundWe assessed the specificity of wide QRS complex tachycardia (WCT) differentiating algorithms in patients with preexistent left bundle branch block (LBBB) and heart failure.MethodsThree hundred fourteen patients with resynchronization devices were retrospectively screened. electrocardiograms with supraventricular LBBB rhythm were used as a surrogate for supraventricular tachycardia QRS morphology. The Pava lead II criterion, ventricular activation velocity ratio (Vi/Vt) ratio in V₂, Vereckei aVR, Brugada, Griffith, and Bayesian algorithms were investigated.ResultsThe WCT algorithms had a lower specificity (33%-69%) in patients with LBBB than in general WCT populations. The Pava lead II criterion and Brugada algorithm had higher specificity than other algorithms (P < .05). Several of the single criteria (absence of an RS complex in V₁ through V₆, initial R wave in aVR, Vi/Vt < 1 in V₂) had specificities of 92% to 99%.ConclusionsIn patients with heart failure and LBBB, an electrocardiographic diagnosis of ventricular tachycardia should be based on selected, specific criteria rather than on WCT algorithms.     

Novel methodology for the detection of exercise-induced myocardial wall motion abnormalities by surface electrocardiogram during exercise test

Background

We investigated whether ischemia-induced wall motion abnormalities during exercise test modify electrical vector variation.

Methods

We performed treadmill exercise test and thallium 201 scintigraphy in 150 normotensives. Beat-to-beat change of direction of S wave in V₁ (reference lead) was compared with that of R wave in V₅ and aVF, representative of anterior and inferior walls, respectively. The percentage of neighboring QRS couples where S wave in V₁ and R wave in V₅ or aVF change toward the same direction (increase or decrease) constitutes V1-V5 and V1-aVF indexes.

Results

V1-V5 and V1-aVF indexes were significantly decreased in subjects with reversible anterior or inferior ischemia, respectively. A decrease in V1-V5 index ≥0.14 defines those with anterior wall ischemia (sensitivity, 100%; specificity, 75.5%), whereas a decrease in V1-aVF index ≥0.05 defines those with inferior wall ischemia (sensitivity, 92.3%; specificity, 61.5%).

Conclusions

These novel electrocardiographic exercise test indexes improved significantly their sensitivities.     

Differences in ST-elevation and T-wave amplitudes do not reliably differentiate takotsubo cardiomyopathy from acute anterior myocardial infarction

BackgroundPrevious efforts to distinguish acute anterior ST-elevation myocardial infarction (anterior-STEMI) from various forms of takotsubo cardiomyopathy (TTC) by electrocardiography (ECG) have produced differing results.MethodsWe performed a retrospective comparison of acute ECGs between 48 apical and 9 mid-ventricular TTC patients, with 96 anterior-STEMI patients. ECG was recorded in acute phase (< 24 h from onset of pain), and analyzed for ST-changes, negative T-waves, abnormal Q-waves and QT-interval duration. Time from onset of pain to ECG was gathered from patient records.ResultsAnterior-STEMI patients had ST-elevation in lead V₁ more frequently than apical (70% vs 15%, p < 0.0001) or mid-ventricular TTC patients (70% vs 0%, p < 0.0001), and higher ST-elevation amplitudes in leads V₂–V₅ (p < 0.02). Lack of ST-elevation in lead V₁ and ST-elevation amplitude < 2 mm in lead V₂ distinguished TTC from anterior-STEMI patients with 63% sensitivity and 93% specificity, with 79% predictive value.ConclusionsIn patients with anterior ST-elevation and acute chest pain, lack of ST-elevation in lead V₁ and ST-elevation amplitude < 2 mm in lead V₂ suggests a TTC diagnosis. However, this criterion is not reliable enough in clinical practice to distinguish between TTC and anterior-STEMI patients.     

Electrocardiographs criteria for the diagnosis of anterior myocardial infarction: Importance of the duration of precordial R waves

A systematic evaluation of a large number of electrocardiographic (ECG) variables that might be useful for diagnosing anterior myocardial infarction (MI) is reported. Previous anterior MI was shown to be present or absent by cardiac catheterization in 199 patients. The best discriminator between cases and noncases of anterior MI in most patients is the presence of a Q wave of any magnitude or an initial R wave < 20 ms in lead V₂. In patients with ECG evidence of associated left ventricular or type C right ventricular enlargement, the more stringent criterion of a Q wave of any magnitude in lead V₂ yielded the optimal combination of sensitivity and specificity for diagnosing anterior MI. The diagnostic performance of the proposed criteria for anterior MI is superior to that of more traditional criteria that use measurements of the absolute and relative amplitudes of precordial R waves.     

A New Electrocardiographic Algorithm Using Retrograde P Waves for Differentiating Atrioventricular Node Reentrant Tachycardia From Atrioventricular Reciprocating Tachycardia Mediated by Concealed Accessory Pathway

Objectives. The purpose of this study was to use an electrocardiographic (ECG) algorithm, derived from the results of radiofrequency ablation, to discriminate atrioventricular node reentrant tachycardia (AVNRT) from atrioventricular reciprocating tachycardia (AVRT) and to localize a concealed accessory pathway, prospectively.Background. Information about ECG criteria for differentiating AVNRT from AVRT is limited and has not been confirmed by surgical or catheter ablation.Methods. Four hundred six ECGs (obtained from 406 different patients) that demonstrated narrow QRS complex (<0.12 s) supraventricular tachycardia with an RP′ interval less than the P′R interval or pseudo r′ wave in lead V₁or pseudo S wave in inferior leads, or both, were examined, and the results were confirmed by radiofrequency catheter ablation. The initial 226 ECGs were analyzed to develop a stepwise algorithm, and the subsequent 180 ECGs were prospectively evaluated by the new algorithm.Results. The presence of a pseudo r′ wave in lead V₁or a pseudo S wave in leads II, III, aVF indicated anterior-type AVNRT with an accuracy of 100%. With the difference of RP′ intervals in leads V₁and III >20 ms, posterior-type AVNRT could be differentiated from AVRT utilizing a posteroseptal pathway with a sensitivity of 71% (95% confidence interval [CI] 55% to 89%), a specificity of 87% (95% CI 67% to 97%) and a positive predictive value of 75% (95% CI 56% to 91%). According to the polarity of retrograde P waves in leads V₁, II, III, aVF and I during AVRT, the concealed accessory pathway could be localized to one of the nine regions on the atrioventricular annuli with an accuracy of 75% (for a right midseptal pathway) to 93.8% (for a left posterior pathway). Overall, the new algorithm had an accuracy of 97.8% in discriminating AVNRT from AVRT and 88.1% in localizing a concealed accessory pathway, prospectively. Prediction was incorrect in only 15 patients (9.1%).Conclusions. The new ECG algorithm derived from the analysis of retrograde P waves during tachycardia could provide a criterion for differential diagnosis between AVNRT and AVRT and for predicting the location of concealed accessory pathways.(J Am Coll Cardiol 1997;29:394–402)     

Electrocardiographic diagnosis of left ventricular hypertrophy by the time-voltage integral of the QRS complex

Objectives. This study was conducted to test the hypothesis that the time-voltage integral of the QRS complex can improve the electrocardiographic (ECG) identification of left ventricular hypertrophy.Background. Standard ECG criteria have exhibited poor sensitivity for left ventricular hypertrophy at acceptable levels of specificity. However, left ventricular mass may be more closely related to the time-voltage integral of the summed left ventricular dipole than to QRS duration or voltages used in standard ECG criteria.Methods. Standard 12-lead ECGs, orthogonal lead signal-averaged ECGs and echocardiograms were obtained in 62 male control subjects without left ventricular hypertrophy and 51 men with left ventricular hypertrophy defined by echocardiographic criteria (indexed left ventricular mass >125 g/m²). Voltage of the QRS complex was integrated over the total QRS duration in leads X, Y and Z to calculate the time-voltage integral of each orthogonal lead, of the maximal spatial vector complex and of the horizontal, frontal and sagittal plane vector complexes.Results. At matched specificity of 99%, the 73% (37 of 51) sensitivity of the time-voltage integral of the vector QMS complex in the horizontal plane was significantly greater than the 10% sensitivity of the Romhilt-Estes point score, the 16% sensitivity of QRS duration alone, the 22% sensitivity of Cornell voltage, the 33% sensitivity of the 12-lead sum of QRS voltage and the 37% sensitivity of Sokolow-Lyon voltage (each p < 0.001). Sensitivity of the horizontal plane time-voltage integral was also greater than the 10% to 51% sensitivity of the time-voltage integral calculated in the individual X, Y or Z leads (p < 0.01 to < 0.001), the 18% and 35% sensitivity of the time-voltage integrals of the frontal and sagittal plane vectors (p < 0.001) and the 49% sensitivity of the time-voltage integral of the maximal spatial vector complex calculated from all three orthogonal leads (p < 0.001). Comparison of receiver operating characteristic curves confirmed that the superior performance of the horizontal plane time-voltage integral relative to standard and other signal-averaged criteria was independent of partition value selection.Conclusions. These findings suggest that use of the time-voltage integral of the QRS complex, a method that can be readily implemented on commercially available computerized ECG systems, can improve the accuracy of ECG methods for the identification of left ventricular hypertrophy.