Journal of Electrocardiology

Dispersed measures of dispersed repolarization and depolarization: Scalars, vectors, angles, maps, and prospects for improved clinical utility

Pentti M. Rautaharju — 2010-07-01

This invited overview addresses recent trends in electrocardiographic (ECG) research as mirrored in the publications in the present issue of the Journal of Electrocardiography and related communications in other recent issues of the journal. A common denominator and the central focus of these communications is dispersed repolarization, continuing a long tradition in ECG research with seemingly intensified fervor. Dispersed repolarization has emerged as one of the hot recent controversies in cardiology with intense debates about issues such as is there a significant transmural repolarization gradient, or is there an apicobasal repolarization gradient. With the availability of more accurate independent standards for evaluation of the extent and severity of myocardial ischemia, the slow phase of repolarization (ST segment) continues to occupy a prominent role in ECG research, with improved detection and quantifying of acute ischemic injury as the major challenge of the mission. Fragmented QRS, Q waves, R and S wave notches, high-frequency components, and the traditional “bites” and “slurs” in QRS loop are among the familiar QRS counterparts of dispersed depolarization. Recent ECG communications in this journal have evaluated side-by-side with dispersion of repolarization the utility of some of these parameters of fragmented depolarization for detecting old myocardial infarction (MI) and quantifying infarct volume with newer cardiac imaging procedures as an ECG-independent standard. This brief overview of these recent trends opened up like a kaleidoscopic panorama of the microcosm of contemporary electrocardiography.

Factors influencing and significance of ST-segment deviation in lead aVR in acute inferior wall ST-elevation myocardial infarction

Zhan Zhong-qun, Kjell C. Nikus — 2010-04-09

Without doubt, ST-segment changes in lead aVR in acute ST-segment elevation myocardial infarction (STEMI) are of great significance for predicting the culprit artery, even the location of the culprit lesion within the infarct-related artery (IRA), and for risk stratification. ST-segment elevation in aVR has been associated with left main or 3-vessel disease and with adverse outcome. The typical electrocardiographic (ECG) finding in cases with preserved flow through the left main is widespread ST-segment depression maximally in leads V4 through V6 with inverted T waves and ST-segment elevation in lead aVR. ST-segment elevation in aVR with less elevation in V1 proved to be an important predictor of total or subtotal left main obstruction in patients admitted within 12 hours from the onset of acute myocardial infarction. Several studies demonstrated that ST-segment elevation in aVR is valuable for distinguishing proximal from distal lesions in the left anterior descending coronary artery (LAD) in anterior wall STEMI. However, in inferior wall STEMI, the value of lead aVR is less well understood. In this article, we propose explanations for some seemingly contradictory findings related to the significance of ST-segment changes in lead aVR in previous publications. Our statements are supplemented by .

Ventricular fibrillation during the use of an electric shaver?

2009-12-04

The spatial QRS-T angle in the Frank vectorcardiogram: accuracy of estimates derived from the 12-lead electrocardiogram

2010-04-26

Abstract: Background and Purpose: The spatial QRS-T angle (SA), a predictor of sudden cardiac death, is a vectorcardiographic variable. Gold standard vertorcardiograms (VCGs) are recorded by using the Frank electrode positions. However, with the commonly available 12-lead ECG, VCGs must be synthesized by matrix multiplication (inverse Dower matrix/Kors matrix). Alternatively, Rautaharju proposed a method to calculate SA directly from the 12-lead ECG. Neither spatial angles computed by using the inverse Dower matrix (SA-D) nor by using the Kors matrix (SA-K) or by using Rautaharju's method (SA-R) have been validated with regard to the spatial angles as directly measured in the Frank VCG (SA-F). Our present study aimed to perform this essential validation.Methods: We analyzed SAs in 1220 simultaneously recorded 12-lead ECGs and VCGs, in all data, in SA-F-based tertiles, and after stratification according to pathology or sex.Results: Linear regression of SA-K, SA-D, and SA-R on SA-F yielded offsets of 0.01°, 20.3°, and 28.3° and slopes of 0.96, 0.86, and 0.79, respectively. The bias of SA-K with respect to SA-F (mean ± SD, −3.2° ± 13.9°) was significantly (P < .001) smaller than the bias of both SA-D and SA-R with respect to SA-F (8.0° ± 18.6° and 9.8° ± 24.6°, respectively); tertile analysis showed a much more homogeneous behavior of the bias in SA-K than of both the bias in SA-D and in SA-R. In pathologic ECGs, there was no significant bias in SA-K; bias in men and women did not differ.Conclusion: SA-K resembled SA-F best. In general, when there is no specific reason either to synthesize VCGs with the inverse Dower matrix or to calculate the spatial QRS-T angle with Rautaharju's method, it seems prudent to use the Kors matrix.

Electrocardiogram interference by a neurostimulator

2010-04-12

When deriving the spatial QRS-T angle from the 12-lead electrocardiogram, which transform is more Frank: regression or inverse Dower?

Daniel L. Cortez, Todd T. Schlegel — 2010-05-13

Abstract: Introduction: Our primary objective was to ascertain which commonly used 12-to-Frank-lead transformation yields spatial QRS-T angle values closest to those obtained from simultaneously collected true Frank-lead recordings.Materials and Methods: Simultaneous 12-lead and Frank XYZ-lead recordings were analyzed for 100 postmyocardial infarction patients and 50 controls. Relative agreement, with true Frank-lead results, of 12-to-Frank-lead–transformed results for the spatial QRS-T angle using Kors' regression versus inverse Dower was assessed via analysis of variance, Lin's concordance, and Bland-Altman plots.Results: Spatial QRS-T angles from the true Frank leads were not significantly different than those derived from the Kors' regression-related transformation but were significantly smaller than those derived from the inverse Dower-related transformation (P < .001). Independent of method, spatial mean QRS-T angles were also always significantly larger than spatial “maximum” (“peaks”) QRS-T angles.Discussion: Spatial QRS-T angles are best approximated by regression-related transforms. Spatial mean and spatial “peaks” QRS-T angles should not be used interchangeably.

Prediction of cardiovascular death and myocardial infarction by the QRS-T angle and T vector loop morphology after angioplasty in stable angina pectoris: an 8-year follow-up

Aigars Rubulis, Lennart Bergfeldt, Lars Rydén, Jens Jensen — 2010-07-01

Abstract: Reliable cardiovascular (CV) risk assessment by a noninvasive tool would be of great value for CV event prevention.The present study consists of 187 coronary artery disease patients with 8 years of follow-up. Eight vectorcardiographic parameters characterizing different aspects of ventricular repolarization were analyzed at baseline: (1) the ST-segment (ST-VM), (2) the T vector angles (QRS-T angle, Televation, and Tazimuth), (3) the T vector loop morphology (Tavplan and Teigenvalue), and (4) Tarea and Tpeak-end. Cardiovascular death, myocardial infarction (MI), and repeated revascularization were traced via national registries.There were 16 CV deaths and 19 MIs; 89 patients remained free from CV events and revascularization. Ventricular repolarization parameters independently predicted CV death (widened QRS-T angle) and new MI (increased Tavplan) during follow-up.CV mortality was associated with increased divergence between depolarization and repolarization waves (widened QRS-T angle). Increased Tavplan, presumably reflecting heterogeneous repolarization, predicted future MI, which is a novel finding.

The Selvester QRS Score is more accurate than Q waves and fragmented QRS complexes using the Mason-Likar configuration in estimating infarct volume in patients with ischemic cardiomyopathy

2010-04-09

Abstract: Infarct volume independently predicts cardiovascular events. Fragmented QRS complexes (fQRS) may complement Q waves for identifying infarction; however, their utility in advanced coronary disease is unknown. We tested whether fQRS could improve the electrocardiographic prediction of infarct volume by positron emission tomography in 138 patients with ischemic cardiomyopathy (ejection fraction, 0.27 ± 0.09). Indices of infarction (pathologic Q waves, fQRS, and Selvester QRS Score) were analyzed by blinded observers. In patients with QRS duration less than 120 milliseconds, number of leads with pathologic Q waves (mean, 1.6 ± 1.7) correlated weakly with infarct volume (r = 0.30, P < .05). Adding fQRS increased the number of affected leads (3.6 ± 2.5), but the significant correlation with infarct volume was lost (r = 0.02, P = .10). Selvester Score was the most accurate (mean, 5.9 ± 4.9 points; r = 0.49; P < .001). Fragmented QRS was not predictive of infarct size in patients with QRS duration of at least 120 milliseconds (r = 0.02, P = .19). Thus, in ischemic cardiomyopathy, consideration of fQRS complexes does not improve Q wave prediction of infarct volume; but Selvester Score was more accurate.

Diagnostic value of body surface potential mapping in assessment of the coronary artery lesion after angina pectoris and without repolarization changes on the electrocardiogram

2010-04-09

Abstract: Background: The body surface potential mapping (BSPM) method is sensitive in detecting minor electrical potential abnormalities, but its diagnostic value is unclear in detection and localization of significant coronary artery lesion (CAL) in patients after angina pectoris and without ischemic electrocardiogram abnormalities at the time of the BSPM record.Methods and Results: Characteristic features and quantitative parameters of the isopotential maps during the depolarization were evaluated and compared with the result of coronary angiography in 228 patients (164 males; age, 61.6 ± 9.5 years). Twenty-three of them had their first angina, but the others had a history of earlier angina, unstable angina, non–ST-elevation infarction. Fifty-nine healthy subjects (32 males; age, 53.3 ± 12.2 years) served as control. The diagnostic power was high in detection of CAL among patients with previous ischemic events, but it was low in first angina. The accuracy of the CAL localization by multiple regression was different: at 90% specificity level, the sensitivity was near 80% for right/posterior descending CAL and slightly more than 60% for left anterior descending CAL but only 19% for first marginal/first diagonal CAL.Conclusions: The BSPM changes during the depolarization could well indicate CAL only after previous ischemic events. Sensitivity and specificity of the CAL localization depended on the extension and location of the underlying myocardium damage.

Bradycardia?

2010-05-10

Electrocautery-induced artifactual ST-segment depression in a patient with coronary artery disease

Amit Jain, Jeetinder Kaur Makkar, Kishore Mangal — 2010-04-22

We read, with great interest, a case of interference in electrocardiogram (ECG) with electrocautery mimicking ST-segment depression described by Ketchey et al, as we recently encountered a situation where intraoperative electrocautery-induced ST-segment changes created an alarming situation.

Electrophysiologic, ischemic, inflammatory, genetic, and neurogenic factors in the etiology of atrial fibrillation

Galen S. Wagner — 2010-07-01

In this issue, the Journal of Electrocardiology features a mini-symposium on some of the broad spectrum of factors that may facilitate development of atrial fibrillation. The combination of the diagnostic modalities of Doppler Echocardiography and standard Electrocardiography presented in the studies by Pekdemir et al of Inonu University in Malayta Turkey and Pala et al of Istanbul provide the capability to noninvasively measure left atrial electromechanical delay in the presence of mitral valve and left ventricular pathology. Increased resistance to blood flow at the atrioventricular valve or ventricular levels can increase atrial “afterload” and stress this crucial, but perhaps fragile, link between atrial electrical and mechanical physiology.

Assessment of atrial conduction time by tissue Doppler echocardiography and P-wave dispersion in patients with mitral annulus calcification

2010-04-09

Abstract: The aim of our study was to investigate atrial conduction time in patients with mitral annulus calcification (MAC) using P-wave dispersion (PWD) and electromechanical coupling measured with the surface electrocardiogram and the tissue Doppler echocardiography. Fifty-nine patients with MAC and 43 control subjects underwent resting the surface electrocardiogram and tissue Doppler echocardiography. The difference between the maximum (Pmax) and minimum P-wave durations was calculated and defined as PWD. Interatrial and intraatrial electromechanical delays were measured with tissue Doppler echocardiography. Both Pmax and PWD were higher in patients with MAC compared with controls (111.4 ± 15.8 vs 97.3 ± 18.8 milliseconds; P < .0001 and 46.4 ± 14.6 vs 31.4 ± 13.1 milliseconds; P < .0001, respectively). Both interatrial and intraatrial conduction time were also delayed in patients with MAC compared with controls (29.8 ± 13.3 vs 17.6 ± 12.5 milliseconds; P < .0001; 9.4 ± 5.1 vs 6.8 ± 4.0 milliseconds; P < .008, respectively). Left atrial (LA) diameter was significantly higher in patients with MAC compared with controls (35.4 ± 5.0 mm vs 32.3 ± 4.2 mm; P < .001). The LA diameter correlated significantly with both interatrial conduction times and PWD (r = 0.56; P < .0001 and r = 0.47; P < .0001, respectively). There is a delay in both intraatrial and interatrial electromechanical coupling intervals in patients with MAC.

Assessment of atrial electromechanical delay by tissue Doppler echocardiography in patients with nonischemic dilated cardiomyopathy

2009-12-25

Abstract: Background: Atrial electromechanical delay (AEMD) calculated from tissue Doppler imaging (TDI) echocardiography can be an alternative to invasive electrophysiologic studies. We investigated whether the AEMD obtained from TDI is prolonged in patients with nonischemic dilated cardiomyopathy (DCM).Methods: Fifty-five patients with nonischemic DCM (23 men/32 women; age, 43.9 ± 14.8 years) and 55 controls (20 men/35 women; age, 41.3 ± 13.4 years) were included in this study. Atrial electromechanical delay (the time interval from the onset of P wave on electrocardiogram to the beginning of late diastolic wave [Am wave] on TDI) was calculated from the lateral and septal mitral annulus, and lateral tricuspid annulus (PA lateral, PA septum, and PA tricuspid, respectively). P-wave dispersion was calculated from the 12-lead electrocardiogram.Results: PA lateral and PA septum duration were significantly longer in patients with nonischemic DCM than the controls (78.4 ± 19.7 versus 53.8 ± 6.6 and 55.2 ± 16.3 versus 40.5 ± 6.2, P < .0001 for both; respectively). However, PA tricuspid duration was statistically similar between the 2 groups (36.4 ± 10.9 versus 37.2 ± 5.7, P ≥ .05). P-wave dispersion was significantly higher in nonischemic DCM patients than the controls (53.0 ± 14.4 versus 37.5 ± 5.5, P < .0001). PA lateral was correlated with the left atrial maximal volume (r = 0.64, P < .0001), P-wave dispersion (r = 0.65, P < .0001), and log B-type natriuretic peptide (NT proBNP) (r = 0.63, P < .0001). There was a statistically significant and negative correlation between the PA lateral and left ventricular ejection fraction (r = −0.63, P < .0001) and E-wave deceleration time (r = −0.34, P < .0001). Multivariate analysis revealed that left atrial maximal volume and log NT proBNP were the independent predictors of PA lateral (P < .0001 and P = .003, respectively).Conclusion: The AEMD was significantly prolonged in patients with nonischemic DCM. Left atrial enlargement and log NT proBNP were the independent predictors of this prolongation.

Do baseline atrial electrocardiographic and infarction patterns predict new-onset atrial fibrillation after ST-elevation myocardial infarction? Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction Trial

2010-05-05

Abstract: Background: Atrial infarction reportedly occurs in 0.7% to 52% of ST-elevation myocardial infarctions (STEMIs), up to two thirds of whom develop atrial fibrillation and flutter (AF). Prospective validation of electrocardiographic atrial infarction patterns is lacking. Hence, in STEMI patients treated with primary percutaneous coronary intervention, we examined whether baseline atrial electrocardiographic changes or atrial infarction patterns predicted new AF or mortality.Methods: Within the Assessment of Pexelizumab in Acute Myocardial Infarction trial, a nested case-control study was conducted. Patients with new AF were matched 1:1 with controls, and baseline atrial electrocardiographic variables were examined.Results: Abnormal P wave morphology (Liu minor criterion for atrial infarction) was significantly associated with new AF (adjusted odds ratio, 1.68; 1.03-2.73). This was also independently associated with 90-day mortality in the overall case-control cohort (adjusted hazard rate, 1.90; 1.04-3.46) and among patient with new-onset AF (adjusted hazard rate, 2.43; 1.22-4.84).Conclusions: Abnormal P wave morphology significantly predicted new AF and 90-day mortality in STEMI patients.

Effect of periodontitis on susceptibility to atrial fibrillation in an animal model

Guang Yu, Yang Yu, Yi Ning Li, Rong Shu — 2009-12-28

Abstract: Background: Inflammation is implicated in the pathophysiology of atrial fibrillation (AF). Periodontitis causes a general inflammatory response. Whether periodontitis is related to AF is unknown.Objective: The aim of the study was to test the hypothesis that inflammation facilitates AF.Methods: Twenty-two adult mongrel canines of either sex were used for this study. Periodontitis was induced in 12 dogs (periodontitis group) by tying 2-0 silk ligatures at the second premolar of mandibula. Ten healthy dogs were used as controls. Before the ligation procedure and on the day 30, 60, and 90 after ligation, an electrophysiologic evaluation was performed to measure atrial refractoriness and AF inducibility by delivering a single atrial extrastimuli in the high right atrium, atrial septum (AS), and coronary sinus (CS), respectively. Before each electrophysiologic study, blood samples were taken for determining the levels of C-reactive protein (CRP) and tumor necrosis factor-α (TNF-α). Animals were killed after 90 days. The hearts and mandibulae were harvested for morphological study, and the periodontal disease severity was quantiﬁed.Results: Atrial effective refractory period (AERP) shortened, and AF inducibility increased progressively in the periodontitis group. At a drive length of 300 milliseconds, AERP in the CS was 126.7 ± 13.0 milliseconds and 107.5 ± 9.7 milliseconds after 60 and 90 days of ligation, respectively (vs 165.8 ± 10.8 milliseconds at baseline; P < .001). By CS pacing, AF was induced in 5 and 10 of 12 dogs on day 60 and 90 after ligation, respectively (vs 1/12 at baseline; P < .05 and P < .01, respectively). Elevation of CRP and TNF-α occurred after 60 days of ligation (CRP, 13.42 ± 2.21 mg/L vs control, 1.92 ± 0.38 mg/L; P < .001; TNF-α, 9.85 ± 1.72 mg/L vs control, 3.36 ± 0.75 mg/L; P < .001) and reached the peak at the end of the study (CRP, 31.38 ± 2.69 mg/L vs control, 1.99 ± 0.40 mg/L; P < .001; TNF-α, 12.32 ± 1.07 mg/L vs control, 3.24 ± 0.53 mg/L; P < .001). There was a negative correlation between the levels of serum inflammatory factors and AERP values (P < .05). Alveolar bone level decreased in the periodontitis group (P < .001). The long axis (P < .001) of atrial cardiomyocytes including the right atrial appendage (25.50 ± 3.58 μm vs 18.14 ± 3.32 μm), AS (24.78 ± 3.45 μm vs 17.47 ± 2.57 μm), and left atrial appendage (31.90 ± 4.80 μm vs 18.78 ± 2.42 μm) from the periodontitis group was larger than the control group. The short axis of atrial cardiomyocytes was larger than the control group, too (P < .001). Inflammatory cells were more generally found in the atria of the periodontitis group (P < .001). Myolysis affected some atrial cardiomyocytes of the dogs with periodontitis.Conclusion: Periodontitis led to inflammatory responses in the atrial myocardium, which disturbed the structural and electrophysiologic properties of the atrium and facilitated AF.

Epicardial ablation of right pulmonary artery ganglionated plexi for the prevention of atrial fibrillation originating in the pulmonary veins

2010-05-26

Abstract: Problem Presented: A novel study of catheter ablation of the right pulmonary artery ganglionated plexi (RPA GP) to reduce atrial fibrillation (AF) originating in the pulmonary veins (PVs) is presented.Studies Undertaken: In 20 dogs, atrial effective refractory periods (AERPs), PVERP, and the dispersion of AERP (dAERP) were measured at baseline during RPA GP stimulation and after ablation. Programmed stimulation and burst stimulation protocols were performed at 4 distal PVs to measure the percentage of AF induced before and after ablation.Results: Stimulation of the RPA GP shortened AERP (116 ± 16 vs 130 ± 10 milliseconds, P < .01) and PVERP (122 ± 14 vs 136 ± 12 milliseconds, P < .01), and increased dAERP (31 ± 6 vs 23 ± 6 milliseconds, P < .01). However, the above indices revealed an adverse change after excision (AERP, 138 ± 7 vs 130 ± 10 milliseconds; PVERP, 146 ± 18 vs 136 ± 12 milliseconds; and dAERP, 19 ± 5 vs 23 ± 6 milliseconds; P < .05). Furthermore, the percentage of AF induced from PVs was significantly reduced with vagosympathetic stimulation (40% vs 90%, P < .01).Conclusions: Ablation of the RPA GP changes the electrophysiologic properties of both the atria and the PVs and decreases AF inducibility arising from the PVs.

Angiotensinogen polymorphisms and acquired atrial fibrillation in Chinese

2009-11-23

Abstract: Genetic predisposition may be underlying the prevalence of acquired atrial fibrillation (AF). We investigated the association between polymorphism in angiotensinogen (AGT) and angiotensin-converting enzyme gene and risk of acquired AF in a pair-matched case-control study conducted in Chinese Hans. We selected 9 single nucleotide polymorphisms (SNPs) in the AGT gene and 3 SNPs in the angiotensin-converting enzyme gene using a tagging-SNP strategy. We observed significant association between tagging-SNP rs699 (M235T), located in exon 2 of the AGT gene, and AF. The AA genotype of rs699 increased the risk of AF by 70% (95% confidence interval, 1.01-2.85; P = .044) under a recessive model (AA vs AG + GG). The significance remained after controlling for covariates age, smoking, body mass index, hypertension, diabetes, and left atrial dimension, with an increased risk of AF by 90% (95% confidence interval, 1.04-3.46; P = .036). We provide evidence that polymorphism in AGT gene may confer predisposition to acquired atrial fibrillation in Chinese Hans.

Articles Appearing in the Next Issue

2010-07-01

Editorial Board

2010-07-01

Journal of Electrocardiology

Dispersed measures of dispersed repolarization and depolarization: Scalars, vectors, angles, maps, and prospects for improved clinical utility

Factors influencing and significance of ST-segment deviation in lead aVR in acute inferior wall ST-elevation myocardial infarction

Ventricular fibrillation during the use of an electric shaver?

The spatial QRS-T angle in the Frank vectorcardiogram: accuracy of estimates derived from the 12-lead electrocardiogram

Electrocardiogram interference by a neurostimulator

When deriving the spatial QRS-T angle from the 12-lead electrocardiogram, which transform is more Frank: regression or inverse Dower?

Prediction of cardiovascular death and myocardial infarction by the QRS-T angle and T vector loop morphology after angioplasty in stable angina pectoris: an 8-year follow-up

The Selvester QRS Score is more accurate than Q waves and fragmented QRS complexes using the Mason-Likar configuration in estimating infarct volume in patients with ischemic cardiomyopathy

Diagnostic value of body surface potential mapping in assessment of the coronary artery lesion after angina pectoris and without repolarization changes on the electrocardiogram

Bradycardia?

Electrocautery-induced artifactual ST-segment depression in a patient with coronary artery disease

Electrophysiologic, ischemic, inflammatory, genetic, and neurogenic factors in the etiology of atrial fibrillation

Assessment of atrial conduction time by tissue Doppler echocardiography and P-wave dispersion in patients with mitral annulus calcification

Assessment of atrial electromechanical delay by tissue Doppler echocardiography in patients with nonischemic dilated cardiomyopathy

Do baseline atrial electrocardiographic and infarction patterns predict new-onset atrial fibrillation after ST-elevation myocardial infarction? Insights from the Assessment of Pexelizumab in Acute Myocardial Infarction Trial

Effect of periodontitis on susceptibility to atrial fibrillation in an animal model

Epicardial ablation of right pulmonary artery ganglionated plexi for the prevention of atrial fibrillation originating in the pulmonary veins

Angiotensinogen polymorphisms and acquired atrial fibrillation in Chinese

Articles Appearing in the Next Issue

Editorial Board

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