Normal Ventricular and Regional Blood Flow Volumes and Native T1 Values in Healthy Japanese Children Obtained from Comprehensive Cardiovascular Magnetic Resonance Imaging.

Age-related mean and reference ranges for ventricular volumes and mass, regional blood flow measurements, and T1 values using cardiovascular magnetic resonance (CMR) imaging are yet to be established for the pediatric population. Especially in infants and toddlers, no consistent flow volume sets or T1 values have been reported. The purpose of this study was to determine the relevant normal values.Twenty-three children (aged 0.1-15.3 years) without cardiovascular diseases were included. Comprehensive CMR imaging including cine, 2-dimensional phase-contrast, and native T1 mapping, were performed. Ventricular volumes and masses, 11 sets of regional blood flow volumes, and myocardial and liver T1 values were measured. All intraclass correlation coefficient values were > 0.94, except for the right ventricular mass (0.744), myocardial (0.868) and liver T1 values (0.895), reflecting good to excellent agreement between rates.Regression analysis showed an exponential relationship between body surface area (BSA) and ventricular volumes, mass, and regional blood flow volumes (normal value = a*BSAb). Left ventricular myocardial T1 values were regressed on linear regression with age (normal value = -7.39*age + 1091), and hepatic T1 values were regressed on a quadratic function of age (normal value = 0.923*age2 -18.012*age + 613).Comparison of the 2 different methods for the same physical quantities by Bland-Altman plot showed no difference except that the right ventricular stroke volume was 1.5 mL larger than the main pulmonary trunk flow volume.This study provides the normal values for comprehensive CMR imaging in Japanese children.

Ultrahigh density atrio-ventricular dual-chamber mapping as a next generation tool for ablation of accessory pathways.

INTRODUCTION: Detailed three-dimensional (3D) mapping has been useful for effective radiofrequency catheter ablation. The Rhythmia system can create atrio-ventricular dual-chamber mapping, which reveals the atrial and ventricular potentials all at once in the same map. The aim of this study was to investigate the utility of mapping the atrium and ventricle simultaneously with a high-density 3D mapping system for the ablation of accessory pathways (AP). METHODS: From July 2015 to August 2020, 111 patients underwent ablation of APs. Dual-chamber maps were created in 50 patients (median age 15 [10-54], 32 male [64.0%]), while 61 patients underwent radiofrequency (RF) ablation with conventional single-chamber 3D maps. The background characteristics and procedural details were compared between the dual-chamber mapping group and the conventional single-chamber mapping group. RESULTS: The number of RF applications (median [IQR]; 1.0 [1.0-3.0] vs. 3.0 [1.0-6.0], p = .0023), RF time (median [IQR], s; 9.2 [2.0-95.7] vs. 95.6 [4.1-248.7], p = .0107), and RF energy (median [IQR], J; 248.4 [58.7-3328.2] vs. 2867.6 [134.2-7728.4], p = .0115) were significantly lower in the dual-chamber group. The fluoroscopy time (median [IQR], min; 19.9 [14.2-26.1] vs. 26.5 [17.7-43.4], p = .0025) and fluoroscopy dose (median [IQR], mGy; 52.5 [31.3-146.0] vs. 119.0 [43.7-213.5], p = .0249) were also significantly lower in the dual-chamber than single-chamber mapping group. CONCLUSION: The dual-chamber mapping was useful for ablating accessory pathways and reducing the number of RF applications, total RF energy, and radiation exposure as compared with traditional mapping techniques.

Late recovery of the cardiopulmonary exercise capacity after transcatheter amplatzer device closures for atrial septal defects in adults.

Transcatheter atrial septal defect (ASD) closures using an Amplatzer Septal Occluder (ASO) have been widely performed. Compared to children, we sometimes experience late recovery of exercise performance in adult patients. Our study aimed to evaluate the change in the cardiopulmonary exercise capacity in asymptomatic or mildly symptomatic adult patients after a transcatheter ASD closure using an ASO. The subjects consisted of 29 patients (age 39.5 ± 13.6 years) that underwent cardiopulmonary exercise testing (CPX) before, 3, 6, and 12 months after a transcatheter secundum ASD closure using an ASO. The peak oxygen consumption (peak VO2), anaerobic threshold (AT), and slope of the correlation between the ventilation and carbon dioxide production (VE/VCO2 slope) were evaluated. We also evaluated the left-ventricular end-diastolic diameter (LVEDD), right-ventricular end-diastolic dimension (RVEDD) by echocardiography, and hemodynamic values by cardiac catheterization before the ASO procedure. The peak VO2 did not show any improvement 3 months after the ASO procedure; however, a significant improvement was displayed 6 and 12 months (baseline: 23.4 ± 6.3, 3 months: 23.6 ± 6.4, 6 months: 25.1 ± 5.6, 12 months: 26.4 ± 5.3 mL/kg/min; p < 0.001) after the ASO. The LVEDD (before: 38.1 ± 3.6, 3 months: 43.4 ± 3.4 mm; p < 0.001) and RVEDD (before: 33.6 ± 5.3, 3 months: 26.3 ± 2.6 mm; p < 0.001) on echocardiography quickly improved 3 months after the ASO. Although the LVEDD and RVEDD normalized 3 months after the ASO, the peak VO2 still decreased; however, the peak VO2 improved to almost a normal range 6 months after the ASO.

Diagnostic value of P-waves in children with idiopathic restrictive cardiomyopathy.

Restrictive cardiomyopathy (RCM) is a rare myocardial disease with an impaired diastolic function and poor prognosis. Almost all RCM patients are reported to have abnormal P-waves due to atrial overloading. This study aimed to reveal the characteristics of the P-waves in RCM patients and to suggest the diagnostic index of RCM in children with a 12-lead electrocardiogram (ECG). We retrospectively investigated 17 ECGs of children with idiopathic RCM during the initial visit at 15 institutes in Japan between 1979 and 2013. The RCM group was divided into four groups based on the age (elementary school [ES] and junior high school [JHS] students) and inception of the diagnosis (abnormal ECG on school-heart-screening [e-RCM] and some cardiovascular symptoms [s-RCM]), the ES/e-RCM (n = 5), ES/s-RCM (n = 4), JHS/e-RCM (n = 4), and JHS/s-RCM (n = 4) groups. As an aged-match control group, school-heart-screening ECGs of 1st-grade ES students (16,770 students) and 1st-grade JHS students (18,126 students) from Kagoshima in 2016 were adopted. For a comparison between the groups, we used the effect size "Hedge's g" by calculating the mean and standard deviation of the two groups. An effect size of 0.8 (or above) had an overlap of 53% (or less). The effect sizes of the sum of the absolute values of the forward and backward amplitudes in lead V1 (P1 + P2 V1) was the largest, and the ES/e-RCM, ES/s-RCM, JHS/e-RCM, and JHS/s-RCM were 15.8, 22.1, 9.4, and 10.3, respectively. A P1 + P2 V1 > 200 µV was able to rule in all RCM patients, thus, we proposed 200 µV as the cutoff value for screening purposes. In conclusion, the P1 + P2 V1 in the school-heart-screening may be useful for detecting asymptomatic or early-stage RCM in school-age children.

Efficacy of a Subcutaneous Implantable Cardioverter Defibrillator in a Child with Early Repolarization Syndrome.

An early repolarization (ER) pattern or J waves are considered to be a benign finding observed in the healthy population, however, it has been pointed out that the ER pattern seen in the inferolateral leads could be an independent risk factor for fatal arrhythmias. We present a pediatric case in which early repolarization syndrome (ERS) was suspected due to the presence of ER or J waves in the inferior leads, which eventually disappeared after the administration of pilsicainide. During the follow-up period, several fatal ventricular arrhythmias were recorded after implantation of a subcutaneous implantable cardiac defibrillator (S-ICD). This report describes the efficacy of S-ICDs in a child with an ER pattern after aborted sudden cardiac death.

Successful Percutaneous Thrombectomy of the Left Pulmonary Artery in a Neonate After a Patent Ductus Arteriosus Clipping.

We report a neonate with a successful percutaneous thrombectomy of a total thrombotic occlusion of the left pulmonary artery (LPA) after a surgical clipping for a patent ductus arteriosus (PDA). We suspected the compression of the LPA by the clipping and postoperative hemodynamic instability caused the LPA obstruction. After the surgical removal of the PDA clip and division of the PDA, we could safely retrieve the LPA thrombus with a non-hydrodynamic thrombectomy catheter for coronary arteries.

Successful Ablation of Atrial Tachycardia Originating from Inside the Single Atrium and Conduit After a Fontan Operation.

An 18-year-old male who had a past medical history of an intracardiac total cavopulmonary connection (TCPC) operation was referred to our hospital for radiofrequency catheter ablation (RFCA) of supraventricular tachycardia (SVT). Two types of SVTs were induced, and 3-dimensional (3D) maps were created using an ultra-high-density 3-dimensional mapping system (Rhythmia). The earliest atrial activation site (EAAS) of SVT1 was at the superior part of the conduit, and the EAAS of SVT2 was at the inferior part of the single atrium (SA). The SVTs were terminated by energy deliveries to the EAAS from the conduit in SVT1 and from inside the single atrium in SVT2. Detailed maps of the SVTs were important to understand the mechanisms of the SVTs. The Rhythmia system was useful for the detailed mapping of complex arrhythmias. The use of Rhythmia in patients after a TCPC is difficult, because puncturing the TCPC conduit and proceeding and manipulating the Orion catheter via a narrow puncture hole are difficult. We were the first to succeed in ablating two atrial tachycardias (ATs) originating from the inside and outside of the conduit after a TCPC operation by using an ultra-high-density 3-dimensional mapping system.

Improvement in Dyssynchrony with Pharmacological Ablation of Right-Sided Accessory Pathway-Induced Cardiomyopathy in Infants.

Right-sided accessary pathways in patients with Wolff-Parkinson-White (WPW) syndrome may cause cardiac dyssynchrony and dilated cardiomyopathy, with a characteristic septal shape, irrespective of any supraventricular tachycardia episodes. We report on two infants (13 and 5 months), whose right-sided accessary pathway-induced dilated cardiomyopathy was successfully treated by flecainide for the first time. After the flecainide administration, an abnormal aneurysmal dilation of the basal interventricular septum was almost restored to normal, and the decreased ejection fraction recovered. Flecainide use may be an important therapeutic option for this entity to avoid catheter ablation during infancy.

Efficacy of SubcutAneous implantable cardioVErter-defibrillators in ≤18 year-old CHILDREN: SAVE-CHILDREN registry.

BACKGROUND: In adult patients, subcutaneous implantable cardioverter defibrillators (S-ICDs) have been reported to be non-inferior to transvenous ICDs with respect to the incidence of device-related complications and inappropriate shocks. Only a few reports have investigated the efficacy of S-ICDs in the pediatric field. This study aimed to investigate the utility and safety of S-ICDs in patients ≤18 years old. METHODS: This study was a multicenter, observational, retrospective study on S-ICD implantations. Patients <18 years old who underwent S-ICD implantations were enrolled. The detailed data on the device implantations and eligibility tests, incidence of appropriate- and inappropriate shocks, and follow-up data were assessed. RESULTS: A total of 62 patients were enrolled from 30 centers. The patients ranged in age from 3 to 18 (median 14 years old [IQR 11.0-16.0 years]). During a median follow up of 27 months (13.3-35.8), a total of 16 patients (26.2%) received appropriate shocks and 13 (21.3%) received inappropriate shocks. The common causes of the inappropriate shocks were sinus tachycardia (n = 4, 30.8%) and T-wave oversensing (n = 4, 30.8%). In spite of the physical growth, the number of suitable sensing vectors did not change during the follow up. No one had any lead fractures or device infections in the chronic phase. CONCLUSIONS: Our study suggested that S-ICDs can prevent sudden cardiac death in the pediatric population with a low incidence of lead complications or device infections. The number of suitable sensing vectors did not change during the patients' growth.

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.

Hepatocyte growth factor predicts failure of Fontan circulation.

AIMS: This study aimed to assess the value of the hepatocyte growth factor (HGF) as an independent predictor of a Fontan circulation failure. METHODS AND RESULTS: This retrospective case-control study included 34 consecutive patients (19 men and 15 women) who underwent a post-operative cardiac catheterization after a Fontan operation at the Saitama Medical University International Medical Center between April 2017 and December 2019. We divided the patients into two groups according to the HGF level: HGF < 0.4 ng/mL (n = 20, normal HGF group) and HGF ≥ 0.4 ng/mL (n = 14, elevated HGF group). The age at the time of the cardiac catheterization was 59.3 ± 7.9 months. The range of the duration between the Fontan operation and the cardiac catheterization was 37.5 ± 7.9 months. The age (P = 0.417), gender (P = 0.08), morphology of the functional ventricle (P = 0.99), presence or closure of the Fontan fenestration (P = 0.704), and rate of medication use (angiotensin-converting enzyme inhibitors or angiotensin II receptor blockers) (P = 0.99) were equivalent between the two groups. Laboratory parameters including the brain natriuretic peptide level (P = 0.085), serum creatinine level (P = 0.27), and aspartate aminotransferase level (P = 0.235) were similar between the two groups. The elevated HGF group had a higher C-reactive protein level than the normal HGF group (0.42 ± 0.14 and 0.05 ± 0.01 mg/dL, P = 0.005). The elevated HGF group had a higher central venous pressure (CVP) level than the normal HGF group (13.4 ± 0.7 and 9.7 ± 0.4 mmHg, P < 0.0001), and the HGF was positively correlated with the CVP (P = 0.0004, r2  = 0.33). The SvO2 level was significantly lower in the elevated HGF group than in the normal HGF group (61.9 ± 2.3% and 75.0 ± 1.2%, P < 0.0001), and the HGF was negatively correlated with the SvO2 (P < 0.0001, r2  = 0.65). Of the 34 patients, six underwent catheter interventions. Patients who underwent catheter interventions had a higher HGF level than those who did not (0.44 ± 0.03 and 0.37 ± 0.01 ng/mL, P = 0.032). The receiver operating characteristic curve created for the discrimination of a catheter intervention revealed that an HGF value of >0.405 ng/mL could detect the need for a catheter intervention with 75.0% sensitivity and 83.3% specificity. A multivariable regression analysis showed that an elevated HGF was an independent predictor of an elevated CVP (ß-coefficient 21.2, SE 5.5, P = 0.0005) and decreased SvO2 (ß-coefficient -92.9, SE 12.4, P < 0.0001). CONCLUSIONS: The HGF is an independent predictor of a failure of a Fontan circulation. The HGF is an indicator for an additional catheter intervention after a Fontan operation.

Ultra-high density mapping of intra-atrial reentrant tachycardia in a patient after a lateral tunnel total cavopulmonary connection.

We report a case of an 18-year-old male with a postsurgical lateral tunnel (LT) total cavopulmonary connection (TCPC) and supraventricular tachycardia (SVT). Patients after an LT TCPC have complicated suture lines and a considerable area of damaged myocardium in the LT, which could become a complex arrhythmogenic substrate of tachycardias. Detailed three-dimensional (3D) mapping of the LT and atrium is important for a successful ablation. In this patient, successful catheter ablation of two types of complex tachycardias was accomplished using an ultra-high density 3D mapping system inside the LT.

Safety and accuracy of the Rhythmia mapping system in pediatric patients.

BACKGROUND: A new mapping system (Rhythmia) using a 64 mini-electrode small basket array (Orion) was developed that enables rapid high-density mapping in a short time. However, there are few reports about the usefulness of this system in pediatric cases. OBJECTIVE: The purpose of this study was to investigate the safety and accuracy of the Rhythmia system and Orion catheter in children. METHODS: Catheter ablation was performed using the Rhythmia system and Orion catheter in 23 patients younger than 20 years (body weight >20 kg) without a past medical history of cardiac disease. Mapping time, number of mapping beats, and number of mapping electrodes were compared for left atrium, right atrium and right ventricular outflow tract. RESULTS: Twenty-three maps of the right atrium were acquired in 12.6 minutes (range 8.9-15.1), consisting of 709 beats (range 492-1163) and 7132 electrograms (range 4618-10,533). Twelve maps of the left atrium were acquired in 12.1 minutes (range 9.8-14.6), consisting of 565 beats (range 446-881) and 6412 electrograms (range 4912-11,402). There were no significant difference in mapping time, accepted beats, and electrograms between the 2 chambers. Manual annotation was needed in 53 of 293,185 electrograms (0.01%) due to far-field ventricular electrogram sensing and artifact. No adverse events occurred in any of the cases. CONCLUSION: The Orion catheter and Rhythmia mapping system were safe and accurate for mapping various arrhythmias in pediatric patients. Detailed geometry and high-resolution activation mapping were acquired without the need for manual reannotation.

The necessity of implantable cardioverter defibrillators in patients with Kearns-Sayre syndrome - systematic review of the articles.

The most common cardiac feature of Kearns-Sayre syndrome (KSS) is atrioventricular block (AVB), and pacemaker implantations (PMIs) are recommended for KSS patients with advanced AVB. However, some KSS patients develop fatal arrhythmias such as polymorphic ventricular tachycardia (PMVT) and ventricular fibrillation (VF) and die suddenly even after PMIs. We report a patient with KSS who developed PMVT, VF, and QT prolongation, and was treated with mexiletine and successfully managed with an implantable cardioverter defibrillator (ICD). We reviewed the literature on arrhythmias in KSS published from 1975 to 2018. There were 112 patients with arrhythmia-associated KSS, 10 died, and 6 died suddenly after the PMI. The first manifestation of an arrhythmia was bundle branch block, then it progressed to AVB, and developed into complete AVB (CAVB) in about half the KSS patients. Ventricular arrhythmias were documented in 12 patients, and 8 were implanted with defibrillators afterwards. One patient after the implantation of a cardiac resynchronization therapy defibrillator (CRT-D) was treated for VF by an appropriate shock. This fact suggested that VF occurred even under proper pacing, and that defibrillators were effective. Pacemakers may suppress early afterdepolarizations (EADs) associated with a QT prolongation due to bradycardia. Similarly, mexiletine may suppress EADs by blocking the late sodium and Ca currents. Ventricular arrhythmias observed under suppression of EADs may be caused by delayed afterdepolarization (DADs) via an increasing intracellular Ca concentration due to mitochondrial dysfunction. Therefore, a PMI alone may not be sufficient to prevent sudden death, and an ICD implantation should be necessary.