Saito Kazuyoshi

Reports regarding coronavirus disease 2019 (COVID-19) with Fontan circulation are limited. Most studies indicate a relatively good clinical outcome in which SARS-CoV-2 infection is abated; however, COVID-19 can still cause severe pneumonia, and some studies report circulatory breakdown associated with acute respiratory distress syndrome in patients with Fontan circulation. We present the case of a 32-year-old Japanese woman with right isomerism and a single right ventricle who had undergone a fenestrated extracardiac total cavopulmonary connection (Fontan operation), atrioventricular valve replacement, and pacemaker implantation. Despite receiving three doses of the severe acute respiratory syndrome coronavirus 2 mRNA vaccine, the patient contracted COVID-19 and presented with pneumonia. Although her symptoms were mild, the patient was classified as high-risk based on the European Society of Cardiology risk stratification guidelines for COVID-19 in patients with adult congenital heart disease and was admitted to the hospital. Initially, the patient received only symptomatic treatment. However, 2 days later, the patient's COVID-19 condition worsened to moderate grade level II (SpO2 ≤93%, oxygen demand), with SpO2 dropping from 95% to 88% on room air. Treatment with remdesivir and dexamethasone following Japanese treatment protocols resulted in clinical improvement and discharge without hemodynamic complications. COVID-19 pneumonia risks disrupting Fontan circulation in affected patients. This case illustrates the importance of prompt risk stratification using anatomical and physical evaluation and adherence to treatment guidelines in the management of patients with Fontan circulation and COVID-19.

UNLABELLED: As an alternative to implantable cardioverter defibrillators, the wearable cardioverter defibrillator (WCD; LifeVest®, Asahi KASEI Zoll Medical Co., Tokyo, Japan) is the only noninvasive cardioverter defibrillator available that can be worn directly on the skin. The first consensus statement on WCD use in Japan was published in 2014, and, similar to guidelines in other countries, its recommendations focus on adult patients. Pediatric cases involving WCD remain limited, and appropriate indications for its use in children are yet to be established. Here, we report the first pediatric case in Japan where WCD monitored a patient and delivered an appropriate shock to terminate a life-threatening ventricular tachycardia and ventricular fibrillation episode. During this time, the patient was recovering from takotsubo cardiomyopathy, presumably associated with refeeding syndrome secondary to Crohn's disease. No inappropriate shocks were delivered during the three-month monitoring period, and the WCD use was deemed safe. The continuous monitoring function of WCD aided in understanding the patient's conditions. Following treatment, the patient has recovered from Crohn's disease and his cardiac function has stabilized, and he has not experienced neurological sequelae or heart failure symptoms since. This case highlights the potential of WCD use in pediatric patients. LEARNING OBJECTIVE: The wearable cardioverter defibrillator (WCD; LifeVest®) is the only noninvasive cardioverter defibrillator available. However, current guidelines around the world primarily focus on adult patients. Cases of pediatric patients who are rescued by an appropriate shock by WCD are still limited and many aspects, such as device set-up, effectiveness, and risks require further study. This case supports that WCD in children can be safe and effective, demonstrating its potential to protect against ventricular tachycardia and ventricular fibrillation and prevent sudden cardiac death.

UNLABELLED: Propionic acidemia (PA) is a known cause of secondary dilated cardiomyopathy (DCM). However, little is known about how diet and heart failure treatment impact long-term cardiac outcomes in adult PA patients. We report the successful treatment of metabolic disease and secondary DCM-associated heart failure in a 20-year-old male patient with neonatal-onset PA and intellectual disability. At age 19 years, echocardiography had revealed DCM without impaired cardiac contractility. At age 20 years, he developed heart failure, presumably from a common cold infection, and was hospitalized. Acute heart failure treatment improved his symptoms, leading to discharge, but they worsened again, necessitating re-admission. He then was discharged only after successfully adding carvedilol and pimobendan to his medication. Six weeks later, however, he developed hyperammonemia with elevated serum propionyl carnitine and decreased free carnitine levels. He received acute phase treatment for this metabolic crisis and his diet therapy was readjusted, including by reducing natural protein. In the following 5 years, while continuing and slightly adapting heart failure medication and dietary regimens, the patient's cardiac function stably improved and his diuretic dose could be reduced. Our findings support that careful diet therapy and modulation of heart failure medication can improve cardiac function in PA patients with DCM. LEARNING OBJECTIVE: Neonatal-onset propionic acidemia (PA) tends to be the most severe form of PA and life-threatening metabolic disease. Even if the impact of the disease can be ameliorated by adapting the diet, later in life these patients often develop symptoms such as intellectual disability, metabolic crises, and dilated cardiomyopathy (DCM), as observed in this case. This case demonstrates that heart failure medication and dietary therapy can help protect against metabolic disease and DCM-associated heart failure in an adult patient with neonatal-onset PA.

Left ventricular noncompaction (LVNC), also called noncompaction cardiomyopathy (NCM), is a myocardial disease that affects children and adults. Morphological features of LVNC include a noncompacted spongiform myocardium due to the presence of excessive trabeculations and deep recesses between prominent trabeculae. Incidence and prevalence rates of this disease remain contentious due to varying clinical phenotypes, ranging from an asymptomatic phenotype to fulminant heart failure, cardiac dysrhythmias, and sudden death. There is a strong genetic component associated with LVNC, and nearly half of pediatric LVNC patients harbor an identifiable genetic mutation. Recent studies have identified LVNC-associated mutations in genes involved in intercellular trafficking and cytoskeletal integrity, in addition to well-known mutations causing abnormal cardiac embryogenesis. Currently, the diagnosis is based on symptoms, as well as various diagnostic criteria, including echocardiography, electrocardiograms, and cardiac magnetic resonance imaging. Meanwhile, clinical management is primarily focused on the prevention of complications, such as heart failure, thromboembolic events, life-threatening arrhythmias, and stroke. Continued research is focusing on the genetic etiology, the development of gold-standard diagnostic criteria, and evidence-based treatment guidelines across all age groups. This review article will highlight the genotype-phenotype relationship within pediatric LVNC patients and assess the latest discoveries in genetic and molecular research aimed at improving their diagnostic and therapeutic management.