In cases of secondary cardiomyopathies, it is crucial to distinguish between background diseases, such as metabolic and neuromuscular diseases, that are often seen in children. The age at onset varies according to the cause and is important for the differential diagnosis. This review discusses the diagnosis and pathogenesis of cardiomyopathy associated with Fabry disease, Pompe disease, Danon disease, mitochondrial disease, RAS/MAPK syndrome (RASopathies), and Duchenne/Becker muscular dystrophy, which often occur in children and adults in transition. We also discuss the role of myocardial biopsy in the identification of secondary cardiomyopathies.

Noonan syndrome (NS), first described by Dr. Jacqueline Noonan in 1963, is an autosomal dominant congenital anomaly syndrome. It is characterized by unique facial features, heart disease, and short stature. Patients with NS require comprehensive medical treatment for a variety of systemic symptoms. Genetic analyses have recently revealed that Costello syndrome and cardiofaciocutaneous syndrome, which share many clinical similarities with NS, are caused by abnormalities in the RAS/MAPK intracellular signaling pathway. Collectively, these syndromes and other NS-associated disorders are now referred to as RAS/MAPK syndromes or RASopathies. This review provides basic knowledge on 25 NS-associated disorders and RAS/MAPK syndromes with which pediatric cardiologists should be familiar.

Due to improved long-term prognosis for patients with congenital heart disease (CHD), more women with CHD, including those who have undergone surgical repair or palliation for cyanotic heart disease, reach reproductive age and wish to become pregnant. Such women have a high risk of perinatal cardiovascular events, including heart failure and arrhythmia, because of the substantial changes in maternal hemodynamics. This trend is particularly pronounced in women with cyanotic heart disease, even after surgery, and there is a wide range of pathological factors that must be considered, including the underlying disease, surgical technique, presence or absence of residual lesions, and comorbidities. Therefore, to reduce the risk to mother and child, perinatal medical care tailored to each woman’s condition and severity is necessary. Furthermore, changes in women’s lifestyles have led to advanced maternal age, so the risk of obstetric complications requires greater consideration. Preconception counseling and perinatal management by a specialized medical care team are essential in high-risk cases.

Fetal cardiac function is assessed using ultrasonography with both fetal-specific and pediatric/adult echocardiographic parameters. Recently, the cardiovascular profile score, a composite index of these parameters, has been introduced for comprehensive assessment. Recent evidence also indicates that various conditions, including fetal growth restriction and gestational diabetes, influence fetal cardiac function. Alterations in fetal cardiac function are linked to the Developmental Origins of Health and Disease (DOHaD) hypothesis.

Cardiovascular magnetic resonance imaging (CMR) for basic cardiac function and hemodynamic evaluation is contrast-free, radiation-free, and noninvasive. Thus, imaging can be repeated over time, making it extremely suitable for use in the pediatric cardiovascular field, where ultrasonography observation becomes more difficult as the child grows. CMR is performed using a combination of various imaging and evaluation methods. This study describes cardiac function evaluation using cine magnetic resonance imaging (MRI), from the basic method of cine MRI to post-imaging analysis and reading, including basic and more advanced methods that are still in the research stage. Cine MRI, the most basic type of CMR, provides information on not only cardiac function by analyzing ventricular wall motion but also on various other aspects of cardiovascular function, such as anatomical morphology, including epicardial large blood vessels, and blood flow. Conversely, a disadvantage of CMR is the long imaging time. However, technological innovations are being developed to shorten the imaging time, and these are also discussed.

Midventricular obstruction (MVO) is a risk factor for sudden cardiac death in patient with hypertrophic cardiomyopathy (HCM). Report of MVO in children are rare. Thus the clinical picture is unclear, and no established management approaches exist. Here, we report asymptomatic HCM with MVO diagnosed with exercise stress echocardiography in a 15-year-old boy. The resting echocardiogram showed progressive myocardial hypertrophy in the middle ventricular septum, and the exercise stress echocardiogram showed a severe pressure gradient in the same area. Due to the exercise stress echocardiography findings, beta blocker treatment was initiated and exercise was restricted. Exercise stress echocardiography may be useful for the early detection of significant MVO in childhood cases of asymptomatic hypertrophic cardiomyopathy.

The importance of palliative care for patients with chronic heart failure is well-known. However, few studies on this topic have been reported in the pediatric field. Here, we present an 8-year-old girl diagnosed with a single ventricle who underwent the Glenn operation in infancy. She was hospitalized due to worsening heart failure. Because she was unresponsive to heart failure treatment, palliative care was indicated. We used the integrated palliative care outcome scale (IPOS) to perform a palliative care assessment. This provided an opportunity for the patient and her parents to express their feelings. We conducted multiple assessments to evaluate the effectiveness of therapeutic intervention. The scoring of some assessment items concerning physical, psychological, and spiritual issues differed among the patient, parents, and medical staff. For physical pain, the evaluation score of the medical staff was notably higher than that of the patient. This case study suggests that palliative care assessments using the IPOS are useful for medical staff to understand the needs of pediatric patients and their parents, although the patient’s background and personality must be taken into account when interpreting the self-assessment. To improve the palliative care system for pediatric heart failure from various perspectives, it is important to inform patients of their condition and assist them in decision-making, and the IPOS has the potential to support this.