Catheter Intervention for Flow Regulatory Clips on Palliative Shunts and Conduits in Patients with Congenital Heart Disease.

Catheter intervention (CI) for a Blalock-Taussig shunt (BTS) or a ventricle-to-pulmonary artery conduit (VPC) is often required after a palliative surgery for congenital heart disease. Flow regulatory clips help improve interstage mortality; their use necessitates CIs to prevent cyanosis. To study the CI outcomes in patients who underwent palliative surgery with either BTSs or VPCs with flow regulatory clips. This single-center retrospective study evaluated demographic characteristics and interventional outcomes of 49 consecutive pediatric patients who required CI for BTS (BTS group) or VPC (VPC group) between January 2008 and September 2018. Overall, 34 and 18 procedures were performed in the BTS and VPC groups, respectively. Moreover, 19/32 (59.3%) and 12/17 (70.1%) patients from the BTS and VPC groups had flow regulatory clips, respectively. All clips were unclipped successfully; one patient in each group underwent staged unclipping. A higher proportion of "clipped patients" underwent CI due to desaturation [clipped vs. non-clipped: BTS, 10/20 (50.0%) vs. 3/14 (21.4%), p = 0.092; VPC, 9/13 (69.2%) vs. 1/5 (20.0%), p = 0.060]. Most clipped patients successfully progressed to the next stage [BTS, 19/20 (95.0%); VPC, 12/13 (92.3%)]. Severe adverse events (SAEs) were more frequent in the VPC group than in the BTS group [3/13 (23.1%) vs. 0/20 (0%), p = 0.024]. Two patients developed an atrioventricular block (requiring an atropine infusion), while one died due to pulmonary overcirculation. While the indication of CI was cyanosis for a higher proportion of clipped patients, all clips were unclipped successfully. The incidence of CI-related SAEs was higher in the VPC group than in the BTS group.

Angiographic diagnosis for accurate assessment of congenital porto-systemic shunt and extrahepatic portal vein obstruction in children.

BACKGROUND: Congenital porto-systemic shunt (CPSS) is a rare disease and can cause fatal complications. Accurate angiographic assessment is mandatory for proper treatment. Although technically difficult, we developed assessment techniques and assessed their accuracy. One technique came from evaluating patients with extrahepatic portal vein obstruction (EHPVO). METHODS: We conducted a single center retrospective study to evaluate the efficacy of angiographic diagnostic procedure for the assessment of CPSS and EHPVO, and its impact on patients' subsequent interventions and clinical course. Eight patients with CPSS and two patients with EHPVO who underwent diagnostic angiography were included. Assessment of the intrahepatic portal vein was performed in all patients. The route of the shunt, and portal vein pressure under shunt occlusion, were also evaluated for patients with CPSS. Evaluation was first attempted with a balloon angiographic catheter (standard method). Three additional techniques were performed as needed: (i) direct wedge-catheter injection without balloon inflation, (ii) use of occlusion balloon in two patients, and (iii) hybrid angiography with sheath placement directly into the superior mesenteric vein. RESULTS: The standard method was sufficient in four patients. On the other hand, all three techniques were required in two patients each. One lost contact during follow up, but all other patients underwent optimal intervention. There were no complications related to the angiographic procedure. CONCLUSIONS: Use of direct wedge-catheter injection without balloon inflation, occlusion balloon, and hybrid catheterization improved the diagnostic yield in patients with CPSS or EHPVO.

High accessory pathway conductivity blocks antegrade conduction in Wolff-Parkinson-White syndrome: A simulation study.

BACKGROUND: Wolff-Parkinson-White (WPW) syndrome is characterized by an anomalous accessory pathway (AP) that connects the atrium and ventricles, which can cause abnormal myocardial excitation and cardiac arrhythmias. The morphological and electrophysiological details of the AP remain unclear. The size and conductivity of the AP may affect conduction and WPW syndrome symptoms. METHODS: To clarify this issue, we performed computer simulations of antegrade AP conduction using a simplified wall model. We focused on the bundle size of the AP and myocardial electrical conductivity during antegrade conduction (from the atrium to the ventricle). RESULTS: We found that a thick AP and high ventricular conductivity promoted antegrade conduction, whereas a thin AP is unable to deliver the transmembrane current required for electric conduction. High ventricular conductivity amplifies transmembrane current. These findings suggest the involvement of a source-sink mechanism. Furthermore, we found that high AP conductivity blocked antegrade conduction. As AP conductivity increased, sustained outward transmembrane currents were observed. This finding suggests the involvement of an electrotonic effect. CONCLUSIONS: The findings of our theoretical simulation suggest that AP size, ventricular conductivity, and AP conductivity affect antegrade conduction through different mechanisms. Our findings provide new insights into the morphological and electrophysiological details of the AP.

Propranolol Attenuates Late Sodium Current in a Long QT Syndrome Type 3-Human Induced Pluripotent Stem Cell Model.

BACKGROUND: Long QT syndrome type 3 (LQT3) is caused by gain-of-function mutations in the SCN5A gene, which encodes the α subunit of the cardiac voltage-gated sodium channel. LQT3 patients present bradycardia and lethal arrhythmias during rest or sleep. Further, the efficacy of ß-blockers, the drug used for their treatment, is uncertain. Recently, a large multicenter LQT3 cohort study demonstrated that ß-blocker therapy reduced the risk of life-threatening cardiac events in female patients; however, the detailed mechanism of action remains unclear. OBJECTIVES: This study aimed to establish LQT3-human induced pluripotent stem cells (hiPSCs) and to investigate the effect of propranolol in this model. METHOD: An hiPSCs cell line was established from peripheral blood mononuclear cells of a boy with LQT3 carrying the SCN5A-N1774D mutation. He had suffered from repetitive torsades de pointes (TdPs) with QT prolongation since birth (QTc 680 ms), which were effectively treated with propranolol, as it suppressed lethal arrhythmias. Furthermore, hiPSCs were differentiated into cardiomyocytes (CMs), on which electrophysiological functional assays were performed using the patch-clamp method. RESULTS: N1774D-hiPSC-CMs exhibited significantly prolonged action potential durations (APDs) in comparison to those of the control cells (N1774D: 440 ± 37 ms vs. control: 272 ± 22 ms; at 1 Hz pacing; p < 0.01). Furthermore, N1774D-hiPSC-CMs presented gain-of-function features: a hyperpolarized shift of steady-state activation and increased late sodium current compared to those of the control cells. 5 µM propranolol shortened APDs and inhibited late sodium current in N1774D-hiPSC-CMs, but did not significantly affect in the control cells. In addition, even in the presence of intrapipette guanosine diphosphate ßs (GDPßs), an inhibitor of G proteins, propranolol reduced late sodium current in N1774D cells. Therefore, these results suggested a unique inhibitory effect of propranolol on late sodium current unrelated to ß-adrenergic receptor block in N1774D-hiPSC-CMs. CONCLUSION: We successfully recapitulated the clinical phenotype of LQT3 using patient-derived hiPSC-CMs and determined that the mechanism, by which propranolol inhibited the late sodium current, was independent of ß-adrenergic receptor signaling pathway.

Successful transcatheter closure of coronary artery fistula in a patient with anomalous aortic origin of the left main coronary artery from the right aortic sinus.

Transcatheter closure is an established method to treat coronary artery fistula (CAF). We present transcatheter closure in a 6-year-old girl with CAF and anomalous aortic origin of the left main coronary artery from the right aortic sinus. The CAF originated from the left coronary artery (LCA), coursed through the interventricular septum (intraseptal course) with prominent dilation, and drained into the right ventricular outflow tract. She underwent transcatheter closure and was in a stable condition at the 3-year follow-up with regression of the dilated portion of the intraseptal-type LCA. Hence, transcatheter closure of CAF is feasible in patients with anomalous origins of coronary arteries. .

Quinidine therapy and therapeutic drug monitoring in four patients with KCNT1 mutations.

Several recent studies have reported potassium sodium-activated channel subfamily T member 1 (KCNT1) mutations in epilepsy patients on quinidine therapy. The efficacy and safety of quinidine for epilepsy treatment, however, remains controversial. We herein report the cases of four patients with KCNT1 mutations treated with quinidine. A reduction in seizures of more than 50% after quinidine treatment was observed in one patient with epilepsy of infancy with migrating focal seizures (EIMFS), whereas two patients with EIMFS and one with focal epilepsy did not achieve apparent seizure reduction. The relationship between quinidine dose and serum quinidine concentration was inconsistent, particularly at high quinidine doses. One patient with EIMFS developed ventricular tachycardia the day after an increase in quinidine dose from 114 to 126 mg/kg/day. The serum trough quinidine concentration and the corrected QT interval (QTc) before arrhythmia onset were 2.4 µg/ml and 420 ms, respectively, and peak serum quinidine concentration after arrhythmia onset was 9.4 µg/ml. Another patient with EIMFS showed aberrant intraventricular conduction with a quinidine dose of 74.5 mg/kg/day and a serum trough concentration of 3.2 µg/ml. Given that serum quinidine levels may elevate sharply after a dose increase, careful monitoring of electrocardiographs and serum concentrations is required. Based on a review of previous reports and our experience with this case, quinidine should be considered as a promising drug for patients with EIMFS harbouring KCNT1 mutations, however, its efficacy remains controversial due to the limited number of cases, and more information on optimal serum concentrations and appropriate titration methods is required.

Safety and Efficacy of Radiofrequency Catheter Ablation for Tachyarrhythmia in Children Weighing Less Than 10 kg.

An increasing number of children are undergoing radiofrequency catheter ablation (RFCA) for tachyarrhythmia. However, infants and toddlers undergoing RFCA are often resistant to medication or need to eliminate arrhythmia substrate, and the risks of RFCA complications are still high in infants and toddlers. From April 2008 and December 2016, 285 children who underwent radiofrequency catheter ablation (RFCA) were stratified according to body weight (group A, less than 10 kg, n = 22; group B, over 10 kg, n = 263) and the clinical features of RFCA were retrospectively reviewed in these groups. Indications for RFCA included drug-refractory tachyarrhythmia or symptomatic tachycardia and tachycardia-induced cardiomyopathy. The acute success rate in this group was 90.9%, with a relatively low recurrence rate (15.0%) after 7.0 ± 1.6 years follow-up. We performed RFCA using only 2-4 catheters in all cases. Major complications included complete right bundle branch block in one patient. No significant differences in rates of success, recurrence, or complications were noted between children weighing less and more than 10 kg. RFCA is safe and efficacious for tachyarrhythmia even in patients weighing less than 10 kg.

Study design for control of HEART rate in inFant and child tachyarrhythmia with heart failure Using Landiolol (HEARTFUL): A prospective, multicenter, uncontrolled clinical trial.

BACKGROUND: Persistent tachycardia in pediatric patients after congenital heart surgery further deteriorates their hemodynamic condition, and may become fatal. Therefore, immediate control of the tachycardia is mandatory in these patients. For this purpose, quick-acting, short-acting, titratable intravenous agents are required. However, there are no agents with such characteristics among the drugs approved for control of pediatric arrhythmias in Japan, and thus novel and effective medications for these patients are awaited. Landiolol, an ultrashort-acting ß-blocker, was approved in 2013 for tachyarrhythmias in adult patients with heart failure. However, its efficacy and safety in pediatric patients remain unclear. The aim of this prospective, multicenter, open-label phase IIb/III study is to investigate the efficacy and safety of landiolol in pediatric patients with tachyarrhythmias as well as heart failure. METHODS: Eligible patients are aged ≥ 3 months and <15 years, and have tachyarrhythmia (atrial fibrillation, atrial flutter, supraventricular tachycardia) as well as heart failure. The primary endpoint of the study is ≥20% reduction from baseline heart rate or return to normal sinus rhythm within 2h after starting intravenous administration of landiolol. Patients will receive intravenous infusion of landiolol, starting at 1µg/kg/min. The dose will be increased by 1µg/kg/min every 15-20min until the tachycardia rate has decreased by >20% or tachycardia has terminated, and the dose will then be maintained or further increased depending on the patient's condition. The study was started in April 2015 and will end within a few years. CONCLUSIONS: The study was designed and designated the "HEARTFUL study" in the hope of establishing a basis for control of HEART rate in inFant and child tachyarrhythmia Using Landiolol in children with heart failure.

Inherited catecholaminergic polymorphic ventricular tachycardia due to RYR2 mutation.

We report the case of an 11-year-old boy who was diagnosed with catecholaminergic polymorphic ventricular tachycardia (CPVT). The patient had a medical history of three episodes of syncope. The last episode was cardiac arrest while swimming. After resuscitation using automated external defibrillator, he was placed under cerebral hypothermia, examined for long QT syndrome, and underwent insertion of implantable cardioverter defibrillator. He was subsequently discharged from hospital without any adverse sequelae. The patient was diagnosed with CPVT after detection of ryanodine receptor 2 mutation. His father also carried the same mutation, although he did not have any symptoms nor did he have a history of syncope. We propose that CPVT should be included in the differential diagnosis in children with recurrent episodes of syncope.

Current trends in use of implantable cardioverter defibrillators and cardiac resynchronization therapy with a pacemaker or defibrillator in Japanese pediatric patients: results from a nationwide questionnaire survey.

BACKGROUND: In Japan, the use of implantable cardioverter defibrillators (ICDs), cardiac resynchronization therapy with a biventricular pacemaker (CRTP) and CRT with a defibrillator (CRTD) in children has not been studied statistically, and dual-chamber (DDD) pacemakers are still used for pediatric CRT because of current government regulations. METHODS AND RESULTS: Data were obtained from 15 children's and 74 general hospitals through a questionnaire survey regarding the aforementioned therapies performed before 2012 in Japanese children (<16 years old). ICD, CRT with DDD, CRTP and CRTD were used in 64 (42%), 47 (31%), 34 (22%) and 7 (5%), respectively, of all cases reported (n=152). Among all CRTP and CRT-DDD cases (n=81), the use of DDD accounted for 41% in general hospitals vs. 89% in children's hospitals, and CRT-DDD and CRTP were effective in 67 cases (83%). Of 64 ICD cases, appropriate shocks were experienced in 28 cases (44%), and inappropriate shocks in 19 cases (29%). Additionally, data from the Japan Arrhythmia Device Industry Association obtained for overall device usage analysis revealed that CRTP was more commonly used in children than in adults. CONCLUSIONS: There is an increasing need for pediatric device therapy, especially CRTP. However, many children's hospitals were still using DDD pacemakers in 2012. Although the demand for device therapy in children may be small, it is indispensable in pediatric cardiology.

Electrophysiologic studies and radiofrequency catheter ablation of ectopic atrial tachycardia in children.

Ectopic atrial tachycardia (EAT) often resists medical therapy, making radiofrequency catheter ablation (RFCA) the preferred treatment. This study reviewed the records of 35 patients who underwent electrophysiologic studies (EPS) and 39 RFCA procedures for EAT during a 10-year period. Of the 35 patients, 10 (28%) presented with decreased ventricular function and tachycardia-induced cardiomyopathy (TIC). The EAT originated on the right atrial side in 19 patients (54%) and on the left atrial side in the remaining 16 patients (46%). The right atrial sites included the right atrial appendage (RAA) (n = 9, 25%), the tricuspid annulus (n = 7, 20%), and the crista terminalis (n = 3). The left atrial sites included the left atrial appendage (LAA) (n = 6, 17%), the pulmonary veins (n = 5, 14%), the mitral annulus (n = 3), and the posterior wall of the left atrium (n = 2). The mechanism of all EAT probably is automaticity. All EATs could be abolished using RFCA. Follow-up data were available for all patients 2 to 8 years after RFCA. All 35 patients remained recurrence free, and ventricular function improved for all 10 patients with TIC. The origin of EAT in children differed from its origin in adults. The authors conclude that RFCA is a safe and effective treatment option for children with refractory EAT and should be considered early in the course of their illness.

Successful catheter ablation of reentrant junctional tachycardia in a patient with asplenia syndrome before total cavo-pulmonary connection.

Asplenia syndrome is commonly associated with complex structural cardiac malformations, and junctional tachycardia (JT), which may compromise hemodynamic status, has been reported in association with asplenia syndrome.(1) We report successful radiofrequency catheter ablation of reentrant JT in a patient with asplenia syndrome.

Thrombocytosis at an early stage of respiratory tract viral infection.

AIM: To determine whether thrombocytosis, a platelet count of more than 500 x 10(9)/l, occurs at an early stage of respiratory tract viral infection. METHODS: The medical records of 345 patients with respiratory syncytial virus (RSV), influenza, measles, adenovirus or human herpes virus 6 infections were retrospectively reviewed. RESULTS: The mean platelet count was significantly higher in RSV patients than in patients with other respiratory infections. Among the 29 patients with thrombocytosis, 24 (82.8%) had RSV infection. CONCLUSION: When thrombocytosis is positive at an early stage of respiratory tract infection, RSV should be taken into account as a causative agent.

Stachyflin and acetylstachyflin, novel anti-influenza A virus substances, produced by Stachybotrys sp. RF-7260. I. Isolation, structure elucidation and biological activities.

Two novel compounds, stachyflin and acetylstachyflin, have been isolated by solid-state fermentation of Stachybotrys sp. RF-7260. The structures of both metabolites, determined by detailed NMR analyses and X-ray crystallographic analysis, are novel with a pentacyclic moiety including cis-fused decalin. The absolute stereochemistry of stachyflins was determined by circular dichroism analysis. Stachyflin showed antiviral activity against influenza A virus (H1N1) in vitro with an IC50 value of 0.003 microM. Acetylstachyflin was about 77-fold less active than stachyflin.