Risk Factors for Thromboembolic and Bleeding Events in Patients After the Fontan Operation (Insights from the National Database of Health Insurance Claims of Japan).

Risk stratification of thromboembolic events (TEs) and bleeding events is important for the appropriate selection of thromboprophylaxis in patients after the Fontan operation. Therefore, we clarified the risk factors for TEs and bleeding events in patients after the Fontan operation using the National Database of Health Insurance Claims and Specific Health Checkups of Japan. We conducted a retrospective cohort study including 2,515 patients who underwent the Fontan operation between June 2011 and September 2019. The end points were TEs and bleeding events within 1 year of the Fontan operation analysis. We analyzed the risk factors for these end points using a multivariate analysis. In total, 1,903 patients were included in the analysis. The median age at the time of the Fontan operation was 3 (1 to 22) years, and 1,067 patients (56%) were male. The incidence rates of TEs and bleeding events were 12% and 11%, respectively. Age (odds ratio [OR] 1.1 per 1 year older, p <0.05) was an independent risk factor for TEs. Thromboprophylaxis with aspirin after the Fontan operation significantly reduced TEs (OR 0.3, p <0.05). A history of postoperative hemorrhage (OR 1.5, p <0.05) and the use of a potassium channel blocker (OR 2.1, p <0.05) were independent risk factors for bleeding events. In conclusion, aspirin was found to reduce the risk of TEs within 1 year of the Fontan operation. The results of this study will be useful in selecting effective and safe thromboprophylaxis in patients after the Fontan operation.

"Half-uncovered technique" to secure larger stents for postoperative pulmonary vein stenosis.

Although larger stent placement could be effective for pulmonary vein stenosis, stents extrusion tends to occur due to caliber narrowing, small landing area, and the slippery nature. We placed stents with diameter ≧8 mm for four stenotic lesions using the "half-uncovered technique". All stents were precisely placed and successfully resolved the stenosis. This technique allows us to avoid extrusion and to perform safe and effective dilatation when placing larger stents for pulmonary vein stenosis.

Loss-of-function mutations in cardiac ryanodine receptor channel cause various types of arrhythmias including long QT syndrome.

AIMS: Gain-of-function mutations in RYR2, encoding the cardiac ryanodine receptor channel (RyR2), cause catecholaminergic polymorphic ventricular tachycardia (CPVT). Whereas, genotype-phenotype correlations of loss-of-function mutations remains unknown, due to a small number of analysed mutations. In this study, we aimed to investigate their genotype-phenotype correlations in patients with loss-of-function RYR2 mutations. METHODS AND RESULTS: We performed targeted gene sequencing for 710 probands younger than 16-year-old with inherited primary arrhythmia syndromes (IPAS). RYR2 mutations were identified in 63 probands, and 3 probands displayed clinical features different from CPVT. A proband with p.E4146D developed ventricular fibrillation (VF) and QT prolongation whereas that with p.S4168P showed QT prolongation and bradycardia. Another proband with p.S4938F showed short-coupled variant of torsade de pointes (scTdP). To evaluate the functional alterations in these three mutant RyR2s and p.K4594Q previously reported in a long QT syndrome (LQTS), we measured Ca2+ signals in HEK293 cells and HL-1 cardiomyocytes as well as Ca2+-dependent [3H]ryanodine binding. All mutant RyR2s demonstrated a reduced Ca2+ release, an increased endoplasmic reticulum Ca2+, and a reduced [3H]ryanodine binding, indicating loss-of-functions. In HL-1 cells, the exogenous expression of S4168P and K4594Q reduced amplitude of Ca2+ transients without inducing Ca2+ waves, whereas that of E4146D and S4938F evoked frequent localized Ca2+ waves. CONCLUSION: Loss-of-function RYR2 mutations may be implicated in various types of arrhythmias including LQTS, VF, and scTdP, depending on alteration of the channel activity. Search of RYR2 mutations in IPAS patients clinically different from CPVT will be a useful strategy to effectively discover loss-of-function RYR2 mutations.

Static balloon atrial septostomy in Japan in shortage of standard balloon septostomy catheter.

BACKGROUND: The supply of Rashkind balloon atrial septostomy (BAS) catheters (Medtronic, Minneapolis, MN, USA) has suddenly been discontinued in the world due to its recall. Consequently, Japan fell into a critical shortage of standard BAS catheters. Although the use of static BAS is off-label in Japan, its importance is increasing in such a situation. A nationwide survey of static BAS is needed in such a critical period. METHODS: A questionnaire survey was conducted among centers in Japan regarding BAS performed between October 1, 2020, and December 15, 2020, while the supply of Rashkind BAS catheter was discontinued. RESULTS: We received answers from 70 of the 90 centers, for a response rate of 78%. In this survey, 25 patients who underwent static BAS were enrolled, and a total of 47 BAS procedures were performed. Median age and weight at static BAS were 10 days of life and 3001 g, respectively. The most common diagnosis was transposition of the great arteries without pulmonary stenosis and hypoplastic left heart syndrome and its variants, with 8 cases each. The most frequently used balloon diameter was 10 mm (13 balloons), followed by 12 mm (10 balloons), and 3 cases required double-balloon techniques. The 3-point scale of the efficacy of static BAS rated by physicians were 10 excellent, 15 good, and 0 poor, respectively. Complications included cardiac tamponade during the procedure in 1 patient and the need for Rashkind BAS later in 2 patients. Comparing the share of static BAS in all transcatheter atrial septostomy, its share in the current survey (28/53) is significantly higher compared to the annual registry data in 2018 (86/304) (p < 0.01). CONCLUSIONS: This survey shows that static BAS is widely performed in Japan and is effective and safe. Static BAS cases have increased significantly due to a shortage of standard BAS catheters.

Use of the novel curved GOKU balloon catheter for acute-angled lesions in palliative surgery for congenital heart disease: comparison with a conventional straight balloon.

Obstruction develops commonly at the acute-angled portion of the vessels following palliative surgery, such as systemic-pulmonary shunt (SP shunt), right ventricle-to-pulmonary artery shunt (RV-PA shunt) in the Norwood-Sano procedure for hypoplastic left heart syndrome, and cavopulmonary (Glenn) anastomosis. Although balloon angioplasty is a treatment option, dilation with existing straight balloons is sometimes ineffective and technically complicated because of balloon slippage and target vessel distortion. In this study, we investigated the effectiveness of a curved GOKU balloon catheter for balloon angioplasty in postoperative acute-angled lesions associated with palliative surgery for congenital heart disease. We reviewed patients who underwent balloon angioplasty for angled lesions complicated by SP shunt, RV-PA shunt, or Glenn anastomosis, using the novel curved GOKU or a conventional balloon catheter, such as a Sterling balloon catheter. We evaluated patients' backgrounds, balloon specifications, target lesion anatomical features and angles, and short-term outcomes. We evaluated 45 procedures in 18 patients. A curved GOKU was used in 20 procedures, and a Sterling balloon in 25 procedures. The angulation of the lesions at maximum balloon inflation was significantly smaller using a curved GOKU vs a Sterling balloon [70-120 (mean ± standard deviation, 97 ± 40) degrees vs 110-180 (149 ± 46) degrees, respectively; p < 0.001], while the original angle was similar between the groups. Patients' short-term outcomes with the curved GOKU were excellent, with a significantly better percent increase in minimum lumen diameter of 0-220% (92% ± 66%) vs 0-46% (18% ± 15%) with the Sterling balloon (p < 00.1) and with less frequent balloon slippage. The curved GOKU was more effective in balloon angioplasty for acute-angled lesions compared with a conventional straight balloon, likely because of better conformability to the lesion angle and slip resistance.

Percutaneous pulmonary artery debanding.

BACKGROUND: There is a paucity of data on palliative or total percutaneous pulmonary artery debanding (p-debanding), particularly with use of a stent. METHODS: Twelve p-debandings in eight patients were included in this study. Age at pulmonary artery banding (PAB) ranged from 3 days to 1 year (median, 13 days), while p-debanding was performed at 2-157 (7) months. The body weight at the p-debanding ranged from 3.2 to 22.2 (7.3) kg. We chose the balloon diameter of 30-50% to the circumference of the band for palliative, and larger than 50% for total p-debanding, respectively. In either way, the balloon diameter did not exceed 1.5 times the reference vessel diameter. Stent was implanted for palliative p-debanding in 2 patients. RESULTS: 1. The circumference of the band ranged from 16 to 23 (20) mm, while the balloon diameter ranged from 20-60 (40)% to that, where larger than 50% was used for 2 procedures intended total p-debanding. 2. PAB diameter increased from 2.5-4.7 (3.0) mm to 2.8-9.5 (4.5) mm (p<0.01), however, there was no significant change in the diameter in 2 procedures. In one patient, p-debanding was the definitive treatment associated with spontaneous near closure of muscular ventricular septal defect, in another patient of congenitally corrected transposition of the great arteries, severely depressed left ventricular ejection fraction was recovered following p-debanding. 3. Arterial oxygen saturation (SaO2) increased from 64-97 (80)% to 66-95 (90)% (p<0.01), while in 10 procedures of 6 patients where the indication of p-debanding was hypoxia, SaO2 increased in 8 procedures. There was no significant pulmonary hypertension following p-debanding. CONCLUSION: Palliative or total p-debanding using balloon and/or stenting is generally feasible and effective. A balloon diameter 35-50% to the band circumference in palliative, and more than 50% in total p-debanding, while in either way less than 1.5 times the reference vessel diameter, is safe.

Right Pulmonary Vein Atresia in a Mildly Symptomatic Boy: Comprehensive Analysis of Flow Dynamics Using Non-contrast-enhanced 4D Flow MR Imaging.

We present multimodal imaging in the rare case of isolated unilateral pulmonary vein atresia in a 6 year-old boy, including analysis of hemodynamics by magnetic resonance acquisition technique of time-resolved three-dimensional phase contrast imaging (4D flow magnetic resonance imaging). This novel imaging method enables the quantification and especially comprehensive visualization of blood flow patterns, even in complex congenital anomalies which abducted detailed assessment so far, and therefore constitutes a promising alternative to conventional vascular imaging techniques.

A de novo gain-of-function KCND3 mutation in early repolarization syndrome.

BACKGROUND: Early repolarization syndrome (ERS) is characterized by J-point elevation on electrocardiograms and ventricular fibrillation (VF). Early repolarization arises from augmentation of the transmural electrical gradient in the cardiac action potential; therefore, the transient outward potassium current (Ito) has been regarded as a key candidate current for elucidating the mechanism of ERS. KCND3 encoding Kv4.3, an α-subunit of the Ito channel, is considered as one of target genes. OBJECTIVE: The purpose of this study was to search for novel KCND3 mutations associated with ERS and to clarify the pathogenesis. METHODS: We performed genetic screening for 11 unrelated probands with ERS and analyzed the electrophysiological properties of detected mutations by patch-clamp methods. RESULTS: A novel de novo KCND3 heterozygous mutation, Gly306Ala (c.917g>c), was found in 1 proband. The proband was a 12-year-old boy, who suffered VF storm and showed significant J-point elevation in multiple leads. Intravenous isoproterenol and subsequent administration of quinidine were effective in preventing VF recurrence and restored the J-point elevation. In electrophysiological analysis, cultured cells expressing mutant Kv4.3 showed significantly increased current densities, slow inactivation, and slow recovery from inactivation compared to wild type. Extracellular application of quinidine significantly restored the inactivation time course in mutant Kv4.3. A simulation study confirmed the relationship between the novel KCND3 mutation and early repolarization on electrocardiograms. CONCLUSION: A novel KCND3 heterozygous mutation was found to be associated with ERS. The pathogenesis can be explained by the increased Ito. Genetic screening for KCND3 could be useful for understanding the pathogenesis and selecting effective treatment.

Plasma Exchange Downregulates Activated Monocytes and Restores Regulatory T Cells in Kawasaki Disease.

In Kawasaki disease (KD), the effect of plasma exchange (PE) on immune cells has not been fully elucidated. Therefore, we examined the changes in the number of CD14+ CD16+ activated monocytes, regulatory T (Treg ), and T-helper type 17 (Th17) cells in KD patients treated with PE. The percentage of total monocytes and subclasses of lymphocytes, including CD4+ and CD8+ T cells, and CD19+ B cells, showed no significant difference before and after PE. However, the percentage of CD14+ CD16+ monocytes in total leukocytes decreased significantly after PE (1.1% ± 1.5% vs. 2.1% ± 2.3%, P < 0.05). Furthermore, while the percentage of Th17 cells in CD4+ T cells did not change, the percentage of Treg cells in CD4+ T cells increased significantly after PE (11.1% ± 5.1% vs. 8.0% ± 4.4%, P < 0.05). Therefore, PE downregulates activated monocytes and upregulates Treg cells toward normal levels and thus attenuates inflammation in KD.

Electrical storm in an infant with short-coupled variant of torsade de pointes.

A 10-month-old infant experienced cardiac arrest caused by ventricular fibrillation (VF). His electrocardiogram (ECG) at rest was within the normal range. Amiodarone was indispensable due to its refractoriness to defibrillation. After implantable cardioverter defibrillator (ICD) implantation, ICD shock was delivered. ICD recordings documented VF and ventricular tachycardia (VT) triggered by premature ventricular contractions with an extremely short coupling interval (240 ms), which were controlled by verapamil. To the best of our knowledge, our case is the first infant with ScTdP. As the electrical storm with ScTdP occurs unpredictably, it can be a cause of sudden infant death syndrome.

Correction to: Outcomes of plasma exchange for severe dilated cardiomyopathy in children.

In original publication of the article, some of the co-author's names were not included. The correct author group is published in this article.

Infliximab regulates monocytes and regulatory T cells in Kawasaki disease.

BACKGROUND: The effect of infliximab (IFX) on immune cells has not been fully reported in Kawasaki disease (KD). To investigate the mechanism of IFX in KD, we examined changes in the abundance of CD14+ CD16+ activated monocytes, regulatory T cells (Treg ) cells, and T-helper type 17 (Th17) cells following treatment with IFX. METHODS: We collected peripheral blood from patients with i.v. immunoglobulin (IVIG)-resistant KD and analyzed absolute CD14+ CD16+ monocyte, Treg (CD4+ CD25+ FOXP3+ ) and Th17 cell (CD4+ IL-17A+ ) counts on flow cytometry. We also measured changes in serum soluble interleukin (IL)-2 receptor (IL-2R), IL-6, and tumor necrosis factor (TNF)-α on enzyme-linked immunosorbent assay. RESULTS: Treg cells and Th17 cells significantly increased after IFX treatment compared with baseline (126 ± 85 cells/µL vs 62 ± 53 cells/µL, P < 0.01; 100 ± 111 cells/µL vs 28 ± 27 cells/µL, P < 0.05, respectively). In contrast, in a subgroup of patients with CD14+ CD16+ monocytes above the normal range before IFX, the CD14+ CD16+ monocytes significantly decreased following IFX treatment (72 ± 51 cells/µL vs 242 ± 156 cells/µL, P < 0.05).. Serum TNF-α did not change, but soluble IL-2R and IL-6 decreased after IFX treatment. CONCLUSION: IFX could downregulate activated monocytes and upregulate Treg cells towards the normal range. IFX treatment thus contributes to the process of attenuating inflammation in KD.

Plasma exchange for the patients with dilated cardiomyopathy in children is safe and effective in improving both cardiac function and daily activities.

Autoantibodies against cardiac proteins play an important role in the development of dilated cardiomyopathy (DCM). The efficacy and safety of apheresis such as immunoadsorption (IA) or plasma exchange (PE) to remove such antibodies have been reported in adult DCM patients. However, apheresis for pediatric DCM has not been performed because of technical difficulty due to relatively low blood volume and instability of hemodynamics. As we have experiences of preforming apheresis on hemodynamically unstable children, we have preformed ten courses of PE on seven child DCM patients including both patients in chronic and acute phase to assess the safety and efficacy to PE. Under general anesthesia, the patients were administered PE three times during 3 days as 1 course. Simultaneously, continuous hemodiafiltration (CHDF) was performed in series with the PE circuit to stabilize hemodynamic status and to minimize the adverse effects of PE. The changes in LVEF, CTR, mBP, the dosage of furosemide and NYHA were assessed before and after the procedure of PE. There were no severe adverse effects such as systemic bleeding or refractory hypotension due to apheresis. Echocardiography showed that mean baseline LVEF was 24.3 ± 7.8%. Mean LVEF significantly increased 1 week after PE to 30.5 ± 12.5%. CTR significantly decreased after PE. Mean BP significantly increased 1 month after PE (54.5 ± 10.7 to 60.7 ± 9.8 mmHg). NYHA improved after PE significantly (NYHA; 3.4 ± 1.1 to 2.5 ± 1.1). PE is safe and effective in improving both cardiac function and daily activities.

Outcomes of plasma exchange for severe dilated cardiomyopathy in children.

Antimyocardial autoantibodies are a cause of dilated cardiomyopathy (DCM). Immunoabsorption therapy for eliminating autoantibodies can improve cardiac function in adult DCM. The purpose of this study was to investigate the indication and efficacy of plasma exchange in children with DCM and their outcomes. We performed a single-center, retrospective study in children with DCM who had received plasma exchange (PE). Six patients in various degrees of heart failure (three patients in acute exacerbation phase, one patient in early phase, and two patients in chronic phase) received PE. The effects of first PE were that the left ventricular ejection fraction (LVEF) and New York Heart Association (NYHA) functional class were transiently increased in five of six patients (83 %) and in four of five patients (80 %), respectively. The median duration of improved cardiac function after first PE was 8 months. PE was performed a total of two times in two patients and three times in one patient. The effect of repeated PE was attenuated when compared with first PE. Improved LVEF and NYHA functional class were observed in two of four courses (50 %) and in one of four courses (25 %), respectively. The median duration of improved cardiac function was 1 month. PE can transiently improve cardiac function and clinical symptoms of DCM in children. PE may be an additional therapeutic option in children with refractory DCM. However, PE should only be considered as a bridge to ventricular assist device implantation or heart transplantation.

The development of a pseudo-chamber after balloon pulmonary angioplasty: long-term complications of balloon pulmonary angioplasty.

We experienced a rare complication where extravasation developed a pseudo-chamber long after the balloon pulmonary angioplasty for supravalvular pulmonary stenosis. A 3-month-old girl was diagnosed with an anomalous origin of the left coronary artery from the pulmonary artery. She underwent the Takeuchi procedure at 10 months of age. During the follow-up, the supravalvular pulmonary stenosis deteriorated, and was treated by balloon pulmonary angioplasty with the double balloon technique catheter at 6 years of age. Angiography at the main pulmonary artery showed a small amount of extravasation contrast medium after the procedure. Follow-up echocardiography showed a diminished extravasation hemorrhage. Twelve years later, right ventricular enlargement due to pulmonary regurgitation had been observed on echocardiography. In addition, abnormal echo free space was detected at the left posterior of the left atrium. Enhanced computed tomography clearly demonstrated there was an orifice and extent of the pseudo-chamber. Surgical findings revealed a large tear just distal to the coronary tunnel. We speculated that extravasation blood was limited in the perivascular area early after the procedure but eventually reached the non-adhesive oblique pericardial sinus with age. Consequently, pulmonary to oblique pericardial sinus communication was established and looked like a pseudo-chamber long after the procedure. In conclusion, even if extravasation seems to be limited immediately after the balloon pulmonary angioplasty, it could expand for non-adhesive space and could develop a huge blood space like chamber. Long-term careful observation should be necessary for extravasation of pulmonary artery even with surgical adhesion.

Benefits of Balloon-Dilatable Bilateral Pulmonary Artery Banding in Patients With Hypoplastic Left Heart Syndrome and Other Complex Cardiac Anomalies.

OBJECTIVES: The purpose of this study was to evaluate the potential of balloon-dilatable bilateral pulmonary artery banding (b-PAB) and its impact on the configuration of the pulmonary artery (PA). BACKGROUND: We have previously used balloon-dilatable b-PAB as first-stage palliation for patients with hypoplastic left heart syndrome (HLHS) and other complex cardiac anomalies. METHODS: Two pliable tapes were placed around each branch of the PA and tightened with 7-0 polypropylene sutures in a manner that allowed for the subsequent adjustment of PA diameters. We retrospectively examined the adjustability of PA diameters by balloon dilation and the need for surgical PA angioplasty at later stages. RESULTS: From January 2010 to October 2013, we performed b-PAB in 8 patients, including 3 borderline cases between biventricular repair (BVR) and univentricular repair (UVR). The b-PAB procedures were performed at a median age of 6.5 days (range, 2-10 days). Balloon dilations were performed in 10 lesions in 4 patients. All of the procedures were performed safely. Two patients reached definite BVR. The remaining 6 patients underwent open palliative procedures with univentricular physiologies that resulted in 2 deaths unrelated to the initial b-PAB. In all but 1 of the patients, the PA configuration was properly maintained and did not require surgical pulmonary angioplasty. CONCLUSIONS: Balloon-dilatable b-PAB can be performed safely and prevents PA distortion at later stages. This technique should be considered for patients with complex cardiac anomalies if uncertainty exists regarding the optimal surgical strategy (BVR or UVR) in early infancy.

Co-occurrence of hypertrophic cardiomyopathy and myeloproliferative disorder in a neonate with Noonan syndrome carrying Thr73Ile mutation in PTPN11.

Most cases of Noonan syndrome (NS) result from mutations in one of the RAS-MAPK signaling genes, including PTPN11, SOS1, KRAS, NRAS, RAF1, BRAF, SHOC2, MEK1 (MAP2K1), and CBL. Cardiovascular diseases of varying severity, such as pulmonary stenosis and hypertrophic cardiomyopathy (HCM), are common in NS patients. RAF1 mutations are most frequent in NS with HCM, while PTPN11 mutations are also well known. Thr73Ile is a gain-of-function mutation of PTPN11, which has been highly associated with juvenile myelomonocytic leukemia and NS/myeloproliferative disease (MPD), but has not previously been reported in HCM. Here, we report a Japanese female infant with NS carrying the PTPN11 T73I mutation with NS/MPD, complete atrio-ventricular septal defect, and rapidly progressive HCM. No other HCM-related mutations were detected in PTPN11, RAF1, KRAS, BRAF, and SHOC2. This patient provides additional information regarding the genotype-phenotype correlation for PTPN11 T73I mutation in NS.