Congenitally corrected transposition of the great arteries (CCTGA) is characterized by atrioventricular and ventriculoarterial discordance. Because of double discordance, the circulation is physiologically corrected, but the morphologic right ventricle supports systemic circulation, and 90% of patients have associated cardiac anomalies. The clinical presentation is influenced by the presence of associated anomalies. Since progressive systemic right ventricular failure and tricuspid regurgitation occur by the fourth decade in many patients with CCTGA, early intervention is recommended. The unique anatomy of CCTGA is malalignment between the atrial septum and the inlet part of the ventricular septum. This produces a gap into which is deeply wedged the pulmonary out flow tract and the abnormal course of atrioventricular conduction tissue. The aorta is usually anterior and to the left. Laboratory investigations including chest radiograph, electrocardiogram, echocardiography, MRI, and MDCT, reflect these morphological characteristics. Echocardiography is the imaging modality that provides the most accurate diagnostic assessment of CCTGA. It permits the identification of the basic anatomy by sequential segmental analysis as well as of associated anomalies. The role of echocardiography to evaluate the systemic right ventricular function is to be elucidated.
Congenitally corrected transposition of the great arteries (ccTGA) has two major cardiac malformations, including atrio-ventricular discordance, together with ventriculo-arterial discordance. One of the biventricular repair (BVR) for ccTGA is “functional repair”, such as closure of ventricular septal defect, repair or reconstruction of pulmonary pathway, and/or tricuspid valve replacement or repair, in which the anatomical right ventricle is used as systemic ventricle. Another type of BVR is “double switch operation”, which consists of an atrial switch and an arterial switch or a ventriculo-arterial switch (Rastelli type procedure), so the anatomical left ventricle is used as systemic ventricle. Although, results of these surgeries have much improved more recently, the long term precise outcomes are still unidentified and controversial, especially concerning with indication and some optional procedures of double switch.
In congenital corrected transposition of the great arteries, tricuspid regurgitation, systemic right ventricular failure, supraventricular tachy-arrhythmias, atrioventricular block can happen with age. Conventional repair such as tricuspid valve replacement and/or extra-conduit repair and/or ventricular septal defect closure, or anatomical repair (double switch operation) can be performed during childhood or in adults as initial surgery. Similar complications will occur even after repair. Prevention and management of arrhythmias, cardiac failure and infective endocarditis are necessary during follow-up. The incidence of reoperation in conventional repair is higher than anatomical repair. In patients with anatomical repair especially using the Jatene procedure, the reoperation and mortality rates are low comparing with conventional repair.
Holter recording is the most efficacious cardiac examination during routine daily activities and in the nighttime to detect different cardiac abnormalities such as arrhythmias, ischemia, disturbance of the cardiac autonomic nerve activities, and to evaluate the symptoms such as palpitation, atypical angina, or syncope. To improve the electrical signal quality, the adequate attachment of the electrodes to the cleaned skin is required. When the cardiac events occur rarely, cardiac event recorders are indicated. Two types of event recorders are available: Loop recorders which can save the electrical abnormalities for 30 sec to 60 sec prior to pressing the recording button (presymptom recording). The other is an event monitor without loop memory. When symptoms occur, the patient presses a button to start the recording (patient activation). Now, many Holter ECG softwares are available such as Lorenz plot, Winkle plot, 3D expression of ST-segments displacement, heart rate variability, heart rate turbulence, QT interval, microvolt T-wave alternans and SAECG late potentials. However, standard data about HRV, HRT, QT dynamics, and TWA in infants and children are not established.
A new concept and definition for metabolic syndrome pronounced in 2005 in Japan elucidated the importance of abdominal obesity and insulin resistance. Until then, treatment and research for obesity might be a minor and an unsolved field in both internal medicine and pediatrics. Especially in pediatrics, we were educated and we also sent messages based on personal experience and/or information because of the paucity of evidence. Are the following messages true for recent Japanese children and adolescents? 1. Childhood and adolescent obesity has been increasing. 2. Childhood obesity will disappear after entering school. 3. Do not worry about mild obesity. 4. Childhood obesity is mainly associated with maternal obesity. 5. There is no concern about metabolic syndrome in pediatrics. 6. It is difficult to treat obesity in both the adult and pediatric population. The author presents the current status and strategies for obesity and metabolic syndrome based on the recently obtained evidences in pediatric population.
Congenital heart defects (CHD) result from abnormal morphogenesis of the embryonic cardiovascular system and usually involve defects in specific structural components of the developing heart and vessels. Decades of research in molecular embryology have suggested that multiple distinct cell lineages give rise to the cardiovascular system. Neural crest cells (NCC) are pluripotent cells that delaminate from the dorsal neural tube and migrate widely throughout the body as mesenchymal cells. A subregion of the cranial NCC originating between the otocyst and somite 3 is called the “cardiac NCC” that migrate into the third, fourth, and sixth pharyngeal arches and the cardiac outflow tract. They contribute to the remodeling of the six pairs of bilaterally symmetric pharyngeal arch arteries that eventually results in formation of the aortic arch system. In addition, they also form the septum of the outflow tract that divides the embryonic single truncus arteriosus into the aortic and the pulmonary trunk. Recently, a new population of myocardial precursor cells in pharyngeal mesoderm anterior to the early heart tube was discovered and named the “second heart field (SHF)“. Reciprocal signaling between cardiac NCC and cells originated from the SHF are essential for the development of the outflow tract and the aortic arch system. Discovery of the SHF has provided important implications for the interpretation of the cardiac outflow tract development and new insights into the morphogenesis of CHD.
The blood of the coronary arteries is perfused differently from other organs mainly because of myocardial diastole, and it is particularly remarkable in the left coronary arteries. Furthermore, the coronary circulation can be autoregulated, but it is controlled by coronary peripheral vascular resistance, tissue pressure in the diastolic myocardium, and myocardium contractility. Imaging modalities cannot evaluate complex coronary hemodynamics, and thus indexes such as coronary flow pattern, time-averaged peak flow velocity (APV), coronary flow reserve (CFR), myocardial fractional flow reserve (FFRmyo), shear stress, and peripheral vascular resistance are useful. Giant coronary aneurysms and significant stenosis-related lesions become problematic in coronary artery lesions of Kawasaki disease. Coronary flow is turbulent and APV, CFR, and shear stress decrease, whereas peripheral vascular resistance increases in giant coronary aneurysms that are not complicated with significant stenosis-related lesions and in the distal parts of giant coronary aneurysms. Flow is also turbulent and APV, CFR, FFRmyo, and shear stress significantly decrease and peripheral artery resistance increases in the distal part of significant stenotic lesions. Both of these conditions mean that the endothelium of blood vessels becomes disordered and could adversely affect later vascular remodeling.
Purpose: We assess whether cardiac catheterization and a biopsy is needed for registration of cardiac transplantation in a pediatric patient of dilated cardiomyopathy through our female case of dilated cardiomyopathy with onset at age 4 months. Case: She needed ongoing intravenous inotropic support since 19 months. In response to her application for cardiac transplantation, the Japanese circulation society requested cardiac catheterization to rule out an anomalous origin of the left coronary artery from the pulmonary artery to accurately calculate pulmonary vascular resistance and to perform a cardiac biopsy to rule out metabolic disease as a cause of the cardiomyopathy. Because cardiac catheterization and a biopsy carried a considerable risk in this situation, we explained using video files of ultrasound cardiography to clearly show the normal origin of the left coronary artery. Tricuspid regurgitation showed almost normal right ventricular pressure under elevated left atrial pressure, not indicating the elevated pulmonary vascular resistance over exclusion criteria. No family history, no carnitine deficiency, normal hepatic and renal function, and no mental retardation did not indicate cardiomyopathy secondary to metabolic disease. Although these non-invasive assessments seemed to meet Japanese guidance for pediatric heart transplantation, cardiac catheterization and a biopsy had been requested until the end of her life. Conclusion: We believe it is not absolutely necessary for the decision on the indication of pediatric cardiac transplantation if a non-invasive modality provided high-quality evidence. Instead, future refinement of the guidance is absolutely necessary to optimally guide the clinicians' and reviewers' evaluation process.
Although the incidence of atrioventricular reentry tachycardia (AVRT) using the right anteroseptal accessory pathway is low, the risk of atrioventricular block by radiofrequency catheter ablation (RFCA) of right anteroseptal accessory pathway is high. A 10-month-old infant with narrow QRS tachycardia was noted to have narrow QRS tachycardia at 280 bpm when she was referred to a general pediatrician for fever. The tachycardia was refractory to ATP and verapamil injection, per os administration of flecainide and bisoprolol, and frequent cardioversion and intravenous infusion of amiodarone were required. She was referred to our hospital for RFCA. An electrophysiological study (EPS) was performed, and the earliest ventriculoatrial (V-A) conduction was demonstrated near the His bundle electrogram, and retrograde conduction did not demonstrate decreased conduction properties. The atrial electrogram revealed a reset phenomenon by a single extra ventricular stimulus during tachycardia. From these results, AVRT using a right anteroseptal accessory pathway near the compact atrioventricular node was suspected. V-A conduction disappeared easily with catheter-induced mechanical trauma (bumping) at the earliest atrial activation site. We performed a low energy test application of radiofrequency energy at the earliest atrial activation site where the His potential was recorded. A junction rhythm appeared during radiofrequency applications. V-A conduction did not recur after catheter-induced mechanical trauma, so we applied radiofrequency application at the site. V-A conduction was completely eliminated, and it was impossible to induce AVRT. After RFCA, there were no abnormalities of atrioventricular node function. In infants with small cardiac dimensions, radiofrequency catheter ablation was possible and useful for a right anteroseptal accessory pathway.