Analysis of T wave changes by activation recovery interval in patients with atrial septal defect

School electrocardiography screening program prompts the detection of otherwise unrecognized atrial septal defect in children in Japan

Background

Atrial septal defect (ASD) is a congenital heart disease that often presents without symptoms or murmurs. If left untreated, children with ASD can develop comorbidities in adulthood. In Japan, school electrocardiography (ECG) screening has been implemented for all 1st, 7th, and 10th graders. However, the impact of this program in detecting children with ASD is unknown.

Methods

This is a retrospective study that analyzed consecutive patients with ASD who underwent catheterization for surgical or catheter closure at ≤18 years of age during 2009-2019 at a tertiary referral center in Japan.

Results

Of the overall 116 patients with ASD (median age: 3.0 years of age at diagnosis and 8.9 years at catheterization), 43 (37%) were prompted by the ECG screening (Screening group), while the remaining 73 (63%) were by other findings (Non-screening group). Of the 49 patients diagnosed at ≥6 years of age, 43 (88%) were prompted by the ECG screening, with the 3 corresponding peaks of the number of patients at diagnosis. Compared with the non-screening group, the screening group exhibited similar levels of hemodynamic parameters but had a lower proportion of audible heart murmur, which were mainly prompted by the health care and health checkups in infancy or preschool period. Patients positive for a composite parameter (rsR' type of iRBBB, inverted T in V4, or ST depression in the aVF lead) accounted for 79% of the screening group at catheterization, each of which was correlated with hemodynamic parameters in the overall patients.

Conclusions

The present study shows that school ECG screening detects otherwise unrecognized ASD, which prompted the diagnosis of the majority of patients at school age and >one-third of overall patients in Japan. These findings suggest that ECG screening program could be an effective strategy for detecting hemodynamically significant ASD in students, who are asymptomatic and murmurless.

Chronological T-wave alternation before and after the onset of arrhythmogenic right ventricular cardiomyopathy

Identification of arrhythmogenic right ventricular cardiomyopathy (ARVC) during childhood is challenging due to the lack of specific ECG manifestation. We report chronological ECG alteration before several years of the ARVC onset in two affected children. Their ECG at the age of 6 years was almost normal for their age, and their chronological ECGs exhibited inversion of T wave in inferior leads, which are typical for ARVC, developed at younger age than that in precordial leads. In addition, the leftmost T‐wave inversion in the precordial lead shifted toward the left in our patients, which is a sharp contrast to its physiological transition.

Impact of the T-wave characteristics on distinguishing arrhythmogenic right ventricular cardiomyopathy from healthy children

BACKGROUND

T-wave inversion (TWI) is not considered useful for diagnosing pediatric arrhythmogenic right ventricular cardiomyopathy (ARVC), because right precordial TWI in ARVC resembles a normal juvenile pattern.

OBJECTIVES

The aims of this study were to clarify the electrocardiographic (ECG) characteristics of pediatric ARVC to distinguish those patients from healthy children.

METHODS

Between 1979 and 2017, 11 ARVC patients under 18 years old were registered and compared with school screening ECGs from 48,401 healthy children.

RESULTS

The mean age at the first arrhythmic event or diagnosis was 13.3 ± 4.7 years. Nine patients were asymptomatic initially and were found by ECG screening, but 6 developed severe symptoms during the follow-up. Healthy children had a normal juvenile pattern, while ARVC children, especially symptomatic patients, had a significant tendency to have inferior and anterior TWI. The phenomenon of T-wave discontinuity (TWD) in which the TWI became deeper from V1 to V3 and suddenly turned positive in V5 was significantly more frequent in ARVC (60%) than healthy children (0.55%). Anterior TWI and TWD were also significantly more frequent in those who developed severe symptoms. The sensitivity and specificity of TWD were 60% (95% CI, 31-83%), and 99% (95% CI, 99-99%) to distinguish ARVC from healthy children, as well as 100% (95% CI, 71-100%) and 80% (95% CI, 51-80%), respectively, to predict severe symptoms in the future.

CONCLUSIONS

The ECG is useful to distinguish ARVC children, even in the early phase. Anterior TWI and TWD could detect ARVC children and to predict the possible serious conditions.

Electrical remodeling after percutaneous atrial septal defect closure in pediatric and adult patients

BACKGROUND

Several studies have reported changes in electrocardiographic variables after atrial septal defect (ASD) closure. However no temporal electro-and vectorcardiographic changes have been described from acute to long-term follow-up at different ages. We aimed to study electrical remodeling after percutaneous ASD closure in pediatric and adult patients.

METHODS

ECGs of 69 children and 75 adults (median age 6 [IQR 4-11] years and 45 [IQR 33-54] years, respectively) were retrospectively selected before percutaneous ASD closure and at acute (1-7 days), intermediate (4-14 weeks) and late (6-18 months) follow-up. Apart from electrocardiographic variables, spatial QRS-T angle and ventricular gradient (VG) were derived from mathematically-synthesized vectorcardiograms.

RESULTS

In both pediatric and adult patients, the heart rate decreased immediately post-closure, which persisted to late follow-up. The P-wave amplitude also decreased acutely post-closure, but remained unchanged at later follow-up. The PQ duration shortened immediately in children and at intermediate follow-up in adults. The QRS duration and QTc interval decreased at intermediate-term follow-up in both children and adults. In both groups the spatial QRS-T angle decreased at late follow-up. The VG magnitude increased at intermediate follow-up in children and at late follow-up in adults, after an initial decrease in children.

CONCLUSION

In both pediatric and adult ASD patients, electrocardiographic changes mainly occurred directly after ASD closure except for shortening of QRS duration and QTc interval, which occurred at later follow-up. Adults also showed late changes in PQ duration. At 6-to-18 month post-closure, the spatial QRS-T angle decreased, reflecting increased electrocardiographic concordance. The initial acute decrease in VG in children, which was followed by a significant increase, may be the effect of action potential duration dynamics directly after percutaneous ASD closure.

Prolonged repolarization in atrial septal defect: An example of mechanoelectrical feedback due to right ventricular volume overload

BACKGROUND

Prolonged corrected QT (QTc) intervals are frequently observed in children before atrial septal defect (ASD) closure in our department.

OBJECTIVE

The aim of the study was to assess the effect of long-term right ventricular volume overload on repolarization.

METHODS

QRS, QT, and JT intervals were measured manually in leads II and V5 of a standard 12-lead electrocardiogram in 45 children with an isolated ASD a day before and at least 6 months after ASD closure. QT intervals were corrected for heart rate using the Bazett, Fridericia, Framingham, and Hodges formulas. Each QTc interval calculated using the Bazett formula was compared to sex- and age-matched normal values.

RESULTS

Individual QTc intervals shortened significantly (P < .001) using all correction formulas, whereas the QRS duration did not change. The prevalence of prolonged QTc interval decreased from 22.2% to 2.2% after shunt closure (P = .007).

CONCLUSION

The QTc interval shortens significantly after the closure of a hemodynamically relevant ASD in childhood. This phenomenon is independent of the used QT correction formula and may reflect a mechanoelectrical feedback associated with right ventricular volume overload.

Relationship between electrocardiographic signs and shunt volume in atrial septal defect

BACKGROUND

The aim of this study was to determine whether electrocardiographic signs correlate with hemodynamics and the magnitude of the intracardiac shunt in children with ostium secundum atrial septal defects (ASD).

METHODS

A total of 100 ASD patients (median age, 6 years 4 months; 54 girls) underwent cardiac catheterization between August 1980 and April 2010. We retrospectively investigated the relationship between electrocardiographic signs and the pulmonary/systemic blood flow ratio (Qp/Qs) in these patients. We also compared 63 postoperative electrocardiograms with those recorded before surgery.

RESULTS

The mean Qp/Qs ratio of the 100 patients was 2.46 ± 0.81 (range, 1.1-5.0). The Qp/Qs ratio in patients with and without right bundle branch block (RBBB) was 2.57 ± 0.82 (n = 73) and 2.15 ± 0.72 (n = 27), respectively (P = 0.016). The Qp/Qs ratio in patients with and without isolated negative T-wave was 2.85 ± 0.87 (n = 38) and 2.22 ± 0.68 (n = 62), respectively (P = 0.0003). None of the patients with low Qp/Qs ratio (Qp/Qs ratio ≤ 1.5) had both RBBB and isolated negative T-wave. The prevalence of these two signs decreased from 73.0% (n = 46) and 36.5% (n = 23) to 15.9% (n = 10) and 15.9% (n = 10) after surgical repair, respectively.

CONCLUSIONS

RBBB and isolated negative T-wave in the precordial leads are well correlated with high Qp/Qs ratio in ASD patients.

Hypertrophic cardiomyopathy: electrical abnormalities detected by the extended-length ECG and their relation to syncope

BACKGROUND

Ventricular repolarization abnormalities can represent a trigger for lethal arrhythmias in hypertrophic cardiomyopathy (HCM). We sought to assess whether multiparametric computerized surface ECG analysis identifies repolarization abnormalities in HCM patients, and whether this approach allows identification of patients with syncope.

METHODS

In 28 HCM patients and 102 healthy subjects (14 and 51 males, mean age 44 +/- 15 and 41 +/- 14 years, respectively), 8-lead ECG (I, II, V1-V6) was recorded for 5 min, acquired in digital format and analyzed. Heart-rate corrected QT (QTc) and T wave complexity index (TWCc), QT dispersion, activation-recovery interval (ARI) and its dispersion, signal duration in the terminal portion of the filtered QRS at 25 Hz (LAS(25 Hz)) were analyzed among other parameters.

RESULTS

Compared to healthy subjects, HCM patients exhibited longer QRS, filtered QRS, QTc and QTd, greater TWCc, minor ARId and LA(25 Hz). QRS duration and maximal septum thickness were linearly correlated (r=0.231 p<0.001). ARId shortening depended on ARI shortening in lead V1 (241 +/- 51 vs. 287 +/- 45, HCM vs. healthy subjects, p<0.0001) and lengthening in V6 (257 +/- 42 vs. 209 +/- 34, HCM vs. healthy subjects, p<0.0001). Significant factors for syncope at Wilks' stepwise discriminant analysis were TWCc, QRSd and LAS(25 Hz) (F=14.394, 10.098 and 9.226, respectively) with 92.3% positive predictive accuracy.

CONCLUSIONS

In HCM, longer QRS and QT intervals are consequences of increased left ventricular mass, while ARI seems to reflect myocardial activation rather than inhomogeneity of recovery. The simultaneous evaluation of TWC, QRSd and LAS(25 Hz), unable by itself to hold a predictive value, yielded high accuracy in predicting cardiogenic syncope.

Resolution of Abnormal Body Surface Maps in Children with Atrial Septal Defect after Intracardiac Repair

INTRODUCTION

The genesis of repolarization abnormalities of ECG waveforms in atrial septal defect (ASD), which typically is characterized by right ventricular (RV) volume overload, has not been explored, particularly in association with postoperative hemodynamic improvement. The aim of this study was to evaluate the effects of reduced RV overload after ASD closure on depolarization and repolarization abnormalities on body surface maps (BSMs).

METHODS AND RESULTS

BSMs of 14 children with ASD were recorded preoperatively and at early postoperative (1-6 months) and late postoperative (>9 months) stages. BSMs of 31 age-matched healthy children were studied as normal controls. Before intracardiac repair, QRS isopotential maps of children with ASD showed delayed RV breakthrough and subsequent rightward enlargement of the positive area with a maximum shifting to the right. Delayed conduction of the RV, particularly at the outflow tract area, was noted. The preoperative QRST isointegral maps exhibited the two-maximum pattern reflecting repolarization abnormality. The delayed appearance of breakthrough and delayed RV conduction on the QRS isopotential maps persisted from the preoperative to the late postoperative stage, whereas the two-maximum pattern on the QRST isointegral maps normalized to the one-dipole pattern at an early stage after repair.

CONCLUSION

Abnormal repolarization parameters in ASD patients showed rapid improvement postoperatively, despite the persistence of depolarization abnormalities. Therefore, the two-maximum pattern on the QRST isointegral maps indicates a primary T wave change due to hemodynamic RV volume overload.

Changes in body surface potential distributions induced by isoproterenol and Na channel blockers in patients with the Brugada syndrome

BACKGROUND

The characteristics of unique ECG findings in the Brugada syndrome have not been well explained.

METHODS

To clarify their characteristics and mechanisms, body surface maps (BSM) were recorded from patients with the Brugada syndrome (13 cases; a mean age of 48 years) before and after administration of isoproterenol (ISP) or Na channel blockers (12 cases).

RESULTS

ST elevation in V1-V3 was decreased by 0.1 mV or more after ISP infusion in 8 of 11 cases and elevated after Na channel blockers in 8 of 12. In ventricular activation time (VAT) isochronal map, delayed conduction was noted on upper anterior chest in 11 and on anterior left chest in two. Delayed conduction areas were decreased by ISP and expanded by Na channel blockers. QRST isointegral map showed normal findings in baseline with minimal changes after ISP or Na channel blockers. Activation recovery interval (ARI) isochronal map showed prolonged area on upper anterior chest in baseline, being reduced by ISP and expanded by Na channel blockers. ARI dispersion (ARI-d), defined as difference between the maximum and minimum value of ARI, was larger in Brugada patients than that of normal subjects in baseline, and decreased after ISP and increased after Na channel blockers.

CONCLUSION

ST elevation in the Brugada syndrome is primarily caused by abnormality in depolarization rather than in repolarization. BSM can provide better information to clarify a mechanism of ECG changes adding its diagnostic value for this unique syndrome.

Computer analysis of multichannel ECG

Multichannel electrocardiography (MECG) is an extension of the conventional electrocardiography that is aimed at refining the non-invasive characterisation of cardiac activity. Body surface mapping is a graphical presentation of cardiac activity as measured from the body surface. Body surface maps can show the distribution of the potential at a selected moment in time or over a specified time interval. A new family of maps, based on the characteristics derived from the complete analysed beat, is described. Some new computer supported methods, which are able to calculate automatically different temporal maps, are proposed. MECG measurements can be seen in this context as a powerful research and clinical tool for improving the resolution of cardiac measurements.