At the 6th World Symposium on Pulmonary Hypertension (WSPH) held in Nice in 2018, PH classification was updated. A major change in the classification was that PH and pulmonary arterial hypertension (PAH) were defined as mean pulmonary arterial pressure of ＞20 mmHg. Additionally “Calcium channel blocker responder for long period” was added to PAH classification. Furthermore, the subgroup “PAH with overt features of venous/capillaries (PVOD/PCH) involvement” was added to the updated PAH classification. This manuscript provides an outline of the Nice PH Classification 2018 and reviews the relationship between the genetic basis and clinical presentation of PAH and the difficulty of treating childhood PAH. In addition, it describes the author’s own research in this field.

There is a close relationship between the pulmonary and systemic circulations (i.e., cardiopulmonary interaction) in patients with congenital heart diseases. Consequently, a deep understanding of respiratory and cardiac physiology is mandatory. Every patient has different hemodynamics even if they have the same diagnosis, thereby necessitating individualized therapy. Cardiac intensive care is the subspecialty of pediatric cardiology in which acutely ill patients receive care. A requirement of such intensive care is to maintain the balance between oxygen demand and oxygen consumption: to control demand, you can adjust body temperature and use sedatives, muscle relaxants, and artificial ventilation and to control oxygen supply, you can adjust inotropes, vasodilators, and ratio of pulmonary to systemic blood flow. These cardiorespiratory principles are essentially the same before and after corrective surgery. Additionally, neurological, infectious, and nutritional issues are relevant; therefore, cardiac intensivists must be familiar with both cardiac and non-cardiac issues.

Bis-diamine was administered at a dose of 200 mg/kg to 40 pregnant rats on the 9th and 10th days of gestation. Following cervical dislocation of the rats on the 21st day, the fetuses were delivered by cesarean section and were frozen immediately in acetone cooled to −76°C with dry ice. Each frozen fetal thorax was cut transversely and the sectioned surface was serially photographed with a stereoscopic microscope (Wild Photomacroscope) at intervals of 500 µm. Of the 330 fetuses, 46 had tetralogy of Fallot and absent pulmonary valve (TF/APV).

In those with TF/APV, a large aorta was overriding a large ventricular septal defect. The right ventricular infundibulum was minimally stenotic, and the pulmonary valve was absent with a small residual ridge on the valve ring. The pulmonary arteries (PAs) were generally enlarged, particularly at the right and left pulmonary hilar regions, and compressed and obstructed the adjacent trachea and bronchi. The diameter of the enlarged PAs was equal to or as much as twice the diameter of the aorta. In normal fetuses, the diameter of the right and left PAs was half the aortic diameter. The bronchial obstruction in TF/APV extended peripherally. Pericardial and pleural effusions were mildly increased. Both ventricles were mildly enlarged. The thymus was either hypoplastic or absent. These pictures show wide-spread obstruction of the fetal trachea and bronchi in TF/APV.

Background: Noncompaction cardiomyopathy is characterized by a left ventricle with a prominent trabecular meshwork. The clinical courses of the growing number of pediatric cases with noncompaction cardiomyopathy remain only partially elucidated.

Methods: We enrolled patients with cardiomyopathies from the database of Specific Pediatric Chronic Diseases in Japan. Questionnaires were sent to institutions throughout Japan to obtain details about the diagnosis, management, and prognosis of these patients.

Results: We enrolled 1,360 patients and obtained clinical data for 470, among whom 46 had noncompaction cardiomyopathy (29 males, 17 females; median age: 0.3 years). Among these patients, 22 displayed symptoms at diagnosis, 4 were detected by school medical screening, and 2 were detected by infant medical screening. Symptomatically, 27 patients had heart failure, 9 had arrhythmia, and 1 had embolism, and almost all the patients received medical therapy (e.g., inotropes, diuretics, antiplatelets, anticoagulants, vasodilators, or β-blockers). Based on the school-life guidance and management in Japan, patients were classified as follows: E-sports club activities allowed (19.5%), E-sports club activities prohibited (13.0%), D (23.9%), C (4.3%), and B (2.1%).

Conclusions: It is imperative that we continue to survey and assess cases of specific pediatric chronic disease associated with cardiomyopathy for inclusion in the repository.

A 19-year-old male presented with a history of mild muscle weakness, hypoacusis, cleft lip plate, and delayed development since birth. However, a chromosomal analysis had been refrained. At the age of 16 years, a heart murmur was identified for the first time during a school checkup, and aortic valve regurgitation was identified by echocardiography. At that time, he was diagnosed with partial trisomy and monosomy 18 based on G-banding analysis and was then referred to our hospital for comprehensive management of the chromosomal disease and aortic valve insufficiency. The regurgitation gradually progressed, and we performed aortic valve replacement with a mechanical valve. The postoperative course was uneventful, and pathological examination revealed that each leaflet of the aortic valve was thickened and hyalinized mainly around the Arantius body. Alcian blue and periodic acid-Schiff staining also confirmed the myxomatous change around the aortic valve and wall. Hematoxylin–eosin staining confirmed the lengthening, disruption, and effacement of the collagen fiber in aortic media. However, we found no significant macroscopic findings on the aortic wall. Single nucleotide polymorphism and comparative genomic hybridization microarray analysis revealed a deletion only at the long arm of chromosome 18, and the patient was diagnosed with 18q-syndrome. We report the first case of partial monosomy 18 during adolescence requiring cardiovascular surgery and discuss the cardiovascular features of this chromosomal abnormality.

We present a neonatal girl who developed complete atrioventricular block after postnatal cardioversion for fetal ventricular tachyarrhythmia. A pregnant women was referred at 39 gestational weeks due to fetal tachyarrhythmia of 180 bpm and without atrioventricular (AV) dissociation. Subsequently, a baby girl was delivered weighing 3,130 g. Electrocardiography revealed wide QRS tachycardia with left axis deviation, and the esophageal leads revealed a short RP′ duration without AV dissociation. However, AV dissociation was overt after injecting adenosine triphosphate, which suggested ventricular tachycardia. Cardioversion stopped the ventricular tachycardia but led to atrioventricular block with fascicular block (P rate 138 bpm, QRS rate 75 bpm), and the resulting hypotension (32/15 mmHg) was improved by dopamine administration. Echocardiography revealed a left ventricular end-diastolic diameter of 16.8 mm and an ejection fraction of 30％. Serial electrocardiography revealed a second-degree atrioventricular block at 15 hours after birth that reverted to sinus rhythm at day 2 after birth. She was discharged on day 48 after birth. Holter electrocardiographic monitoring did not shown recurrence of either the ventricular tachycardia or the atrioventricular block. The present case was unique because advanced atrioventricular block due to overdrive suppression in the His–Purkinje conduction system followed ventricular tachycardia with ventriculoarterial conduction.

A 7-month-old boy with pulmonary atresia and an intact ventricular septum underwent a bidirectional Glenn operation. Perioperative intubation lasted for 8 hours, and immediately after extubation, the boy presented with severe inspiratory stridor and chest retraction. Diagnosis of bilateral vocal cord paralysis was made based on the findings of flexible laryngoscopy, which revealed vocal cords fixed in the medial position. We speculated that the posterior cricoarytenoid muscle, the only internal laryngeal muscle that opens the vocal cords, was compressed between the tracheal tube and transesophageal echocardiography probe during treatment. The repetitive mechanical compression may have then caused muscle damage that resulted in bilateral vocal cord paralysis. Re-intubation was avoided considering that it would result in further airway damage; therefore, we placed the boy under mild sedation that did not suppress spontaneous breathing. Over the following 4 weeks, the respiratory symptoms gradually alleviated and improvement of vocal cord mobility was confirmed by laryngoscopy. The optimal treatment strategy in cases of vocal cord paralysis is selected according to the clinical presentation. However, evaluation of the underlying pathophysiological mechanisms by laryngoscopy may be vital.