Transcatheter balloon angioplasty aims to promote vascular remodeling through temporary dissection in the vascular wall and approach the larger diameter of the targeted vessel. Transcatheter balloon angioplasty is indicated for postoperative vascular stenosis associated with congenital heart diseases, and the identification of the stenotic lesion depends upon the pressure gradient and anatomy. Stenotic lesions involved thickened, atrophic, hypoplastic, compressed, and stiff lesions, and balloon angioplasty is the most effective for thickened lesions. Stent implantation or surgical repair rather than balloon angioplasty is expected to be effective in other types of stenotic lesions. High-pressure balloons are basically used for balloon angioplasty, and ultrahigh-pressure balloons may be chosen to treat the stiff stenotic lesions. The optimal balloon diameter is determined according to the narrowest and adjusted vessel diameters. Then, the sizes of the sheath, guiding catheter, and guide wire are determined according to the balloon catheter and body size. The risks for transcatheter balloon angioplasty are stratified according to the duration after the last surgical intervention, presence of artificial material, interference to the surrounding tissue, and influence on hemodynamic alteration during the procedure. Additional procedures are performed stepwise, including the introduction of the guidewire, delivery of a balloon catheter, inflation of the balloon at the stenotic lesion, and assessments of hemodynamic and anatomical results. Placing a guidewire at the appropriate position is important for a successful procedure. When the procedure is performed through right heart structures, maintaining stable hemodynamics during the procedure is critical. The disappearance of the balloon waist is the criterion for the completion of treatment. Hemodynamic and anatomical alterations across the target lesion are assessed after the withdrawal of the balloon catheter. As transcatheter balloon angioplasty for congenital heart disease targets various lesions, individual planning and experience for procedures are necessary.

In Japan, Amplatzer™ duct occluder I (ADO I), Amplatzer™ duct occluder II (ADO II), and Amplatzer Piccolo occluder™ (Piccolo) were included in insurance in 2009, 2019, and 2020 respectively. Since then, the occlusion of patent ductus arteriosus (PDA) using coils has become less common. However, knowledge and information about the anatomy and pathophysiology of PDA are very important for catheter interventions for PDA using other devices. Moreover, experiences of PDA coil occlusion have provided information related to catheter interventions using coils for other vessels. We describe our knowledge and experience and provide tips to improve PDA coil occlusion, focusing on 1) indications for PDA coil occlusion in the device era, 2) anatomy and pathophysiology of PDA, 3) performances of coils when deployed in the PDA, 4) complications of PDA coil occlusion, and 5) procedures useful for the closure of moderate or severe PDA.

Coil embolization of collateral vessels is one of the most common catheter interventions. Owing to variations in the target vessels and the coils used, catheter interventionists should have a wide range of knowledge and skills. This paper describes our approach to coil embolization of collateral vessels with case presentations.

Eosinophilic myocarditis (EMC) is a myocardial disease with a benign prognosis, for which patients are successfully treated by the early administration of steroids. To date, no studies have reported the occurrence of myasthenia gravis (MG) during tapering of the steroid dose. A 3-year-old girl was admitted to our hospital with pallor and in respiratory distress, which were not associated with an antecedent infection. Echocardiography displayed depression of the wall motion. We suspected EMC because of eosinophilia and increased cardiac enzymes after the initial steroid therapy, so steroid treatment was restarted. The cardiac wall motion improved thereafter, with a decrease in peripheral blood eosinophilic count. After discharge from our hospital, she developed gait difficulty with muscle weakness and right blepharoptosis, and after detailed examination, she was diagnosed with MG. She was treated with immunosuppressants in addition to steroids, and her MG symptoms disappeared. Thus, it is important to administer steroids at the early phase when EMC was suspected. MG related to an immunological mechanism may occur because immunity is involved in the onset of EMC. This case suggests attending to neurological symptoms during tapering of the steroid dose.

Myocarditis is a known adverse reaction against messenger RNA (mRNA) coronavirus disease 2019 (COVID-19) vaccines, but the method for the diagnosis of postvaccination myocarditis has not been established. We report a child case of postvaccination myocarditis, which was diagnosed by abnormal blood test results alone. The patient was a previously healthy 13-year-old boy who received the second dose of mRNA COVID-19 vaccine (BNT162b2). Two days after vaccination, he experienced chest pain. He was taken to the hospital on the same day, but no abnormal physical findings were noted. Electrocardiogram and echocardiogram were both normal, but cardiac enzymes were elevated. We diagnosed him with postvaccination myocarditis. The symptoms and elevation of cardiac enzymes improved with no medical treatment. Throughout the disease course, only abnormal blood test values were noted on the acute phase; therefore, the diagnosis could not be confirmed. The incidence of postvaccination myocarditis is expected to increase with the increase in the vaccinations to younger age groups and additional vaccinations. To estimate the exact frequency and long-term prognosis of postvaccination myocarditis, accumulation of cases through proactive investigation, including blood tests, are desirable.

Echocardiographic evaluation of the morphology and blood flow of multiple muscular ventricular septal defects (VSDs) can be difficult. Cardiac phase-contrast magnetic resonance imaging (PC-MRI) visualizes blood flow at any cross-section. We used phase-contrast imaging to visualize multiple muscular VSDs (mVSDs) and perimembranous VSD (pmVSDs) using en face imaging in a 1-year-old boy complicated with mitral stenosis (MS). Multiple VSDs were identified, and blood flow through each defect was evaluated. The pulmonary-to-systemic flow ratio (Qp/Qs) was 2.05. The breakdown of shunt flow was 76.4％ for the pmVSD and 13.4％ for the largest mVSD near the right ventricular outflow tract (RVOT). During surgery, we released the MS and closed the pmVSD. Then, we approached the RVOT and closed the largest mVSD and the nearby minor defect. A slight residual shunt was found postoperatively, and the Qp/Qs was 1.05. En face imaging with cardiac PC-MRI for multiple VSDs helps identify the foramen’s location and estimate the shunt volume, thus assisting in preoperative evaluation.

Congenital right atrial appendage aneurysm is a rare heart disease, with only a few dozen cases worldwide since the report by Morrow et al. in 1968. Complications include arrhythmia, thromboembolism, palpitation, and dyspnea. Appropriate diagnosis and treatment are important, but guidelines are not yet established. The patient’s mother was referred to our hospital at 29 weeks of gestation for enlarged right atrium. Fetal echocardiography revealed a 14.2×7.9 mm (0.7 cm²) aneurysm, which was diagnosed as congenital right atrial aneurysm. Based on the aneurysm size at diagnosis (＜20×13 mm, ＜2 cm²), it was decided that the patient could be followed-up without treatment, and the baby was born without complications. At birth, the aneurysm size was 22×11 mm (1.7 cm²), and the ratio of the aneurysm size to the right atrium was unchanged from the fetal period. The patient is now nearing 1 year old without any complications. We think that the aneurysm size can guide the follow-up of congenital right atrial appendage aneurysms.