Heart transplant remains an important treatment option for end-stage heart failure in children who have failed maximum medical management. Although the outcome of heart transplant has significantly improved due to advances in perioperative management and immunosuppression, commonly, it is not a permanent solution. We still encounter multiple problems in managing these patients before and after transplant, not only with hemodynamic derangement, but also with functional deterioration of multiple organ systems. Shortage of donor hearts in association with wait-list mortality remains a major ongoing problem, especially for infants. Importantly, transplant for patients with congenital heart disease has unique challenges, including complexity of surgical reconstruction, coagulation abnormalities, allosensitization, and specific problems related to single ventricular palliation. Even after successful transplant, chronic complications emerge as inevitable challenges, including rejection, infection, allograft vasculopathy, lymphoproliferative disorders, and renal dysfunction. Here, we review the current status of pediatric heart transplant in the United States and discuss ongoing major problems frequently encountered with this special life-saving treatment modality. Underlying mechanisms of these complications are reviewed in conjunction with potential management strategies.

Percutaneous pulmonary valve implantation (PPVI), introduced two years before transcutaneous aortic valve implantation (TAVI) is one of the most successful recent improvements in catheter interventional treatment of patients with congenital heart disease and dysfunction of the right ventricular outflow tract (RVOT). At adolescence, many patients with complex cardiac lesions involving the RVOT have experienced several open heart surgeries. Repeated open heart operations are associated with significant morbidity and even mortality. The Melody^® valve was initially introduced to expand the life time of a biological valve in the RVOT and hence to reduce the total number of open heart surgeries during a patients life time. The advent of the Sapien^® valve now enables treatment of RVOT’s as large as 31 mm in diameter and even patients with so called “native” right ventricular outflow tracts (without a biological valved conduit) are amenable to treatment with a percutaneous valve. PPVI is safe and effective and patients can be discharged home after a few days in the hospital. Coronary occlusion and conduit rupture are the major hazards of the intervention. Long-term data on valve durability now show similar results in comparison to surgical valve implantation with less morbidity for the patients. Currently new self expanding valves are tested, which could enhance the possibility for patient selection. This review describes current practice, adds own experience, lessons learned and gives an outline on future developments in PPVI.

In-body tissue architecture (IBTA), based on an encapsulation reaction, can produce autologous implantable tissues with desired shape, thickness, and robustness by simply embedding designed molds into subcutaneous pouches for 2 months. Tubular vascular grafts (biotubes), sheet-like patches (biosheets), or valved conduits (biovalves) have been developed for cardiovascular implants. Upon implantation, vascular, myocardial, or valvular tissues were regenerated within several months with high reliability. IBTA first demonstrated evidence of growth potential of biotubes when implanted using a beagle juvenile model. In this review article, we provide an overview of our recent IBTA-based work for pediatric cardiovascular surgery.

Background: Composition of materials can be determined by dual-energy computed tomography (CT), which we used to analyze coronary arterial calcifications following Kawasaki disease (KD) using effective atomic number (EAN).

Methods and Results: We studied coronary calcifications measuring more than 1 mm in 11 post-KD patients. Age of KD onset ranged from under 1 year to 6 years old (median, 3), while age at imaging ranged from 15 to 45 years (median, 36). We reframed the field of view as 6.0 cm images and randomly placed 3 regions of interest (ROI) 0.7 mm in diameter within each calcification. We calculated averages and displayed histograms of distributions of median, minimal, and maximal EANs, and correlated medians with clinical variables. Medians averaged 13.27±0.83; minima, 12.80±0.93; and maxima, 13.59±0.72. The median was similar to that for atherosclerotic coronary arterial calcifications. EANs in KD differed significantly, according to age at KD onset.

Conclusions: Compositions of coronary arterial calcifications following KD resembled those in atherosclerosis, irrespective of additional factors. Clinical coronary events in KD should be assessed carefully, including characteristics of related arterial calcifications.

Background: We previously reported that radiofrequency catheter ablation (RFCA) is effective for obtaining a complete recovery from Wolff-Parkinson-White (WPW) syndrome. Since few reports have addressed the outcomes after RFCA in children with atrioventricular nodal reentrant tachycardia (AVNRT), we evaluated the clinical features after RFCA to treat such children.

Methods: Between 1993 and 2001, RFCA was performed for AVNRT in 71 patients in our institute. We recently sent a questionnaire survey to 51 affected children and obtained replies from 23. We analyzed the replies in terms of the patient age, gender, body mass index, history of medication before RFCA, congenital heart disease, abolition of echo or one echo after RFCA, type of AVNRT, and repeat ablation.

Results: Twelve of the 23 (52%) respondents experienced palpitations after RFCA (Group A). Seven patients in this group (30%) sought a medical evaluation at a hospital after the procedure; this amounted to 58% of the patients in Group A. Among the 11 patients without palpitations after the procedure (Group B), none visited a hospital for an evaluation. Twenty-two respondents (96%) were satisfied with the effectiveness of the treatment. There was a statistically significant difference between the 2 groups with regard to the percentage of patients who received medication prior to RFCA (A, 58%; B, 17%).

Conclusions: Approximately half of the patients with AVNRT experienced palpitations after RFCA even though most patients were satisfied with the treatment. In this study, the cause of palpitations was usually not disclosed; however, palpitations after RFCA were more common in patients with a history of medication. We have to create a system such as the patients can be re-examined long after the RFCA.

Background: The clinical outcomes of pediatric patients with bicuspid aortic valve (BAV) are unclear. The aim of this study was to explore the short and mid-term outcomes and the risk of the progression of valve dysfunction.

Methods: We evaluated the fusion type of cusps and the valve dysfunction of 34 of 80 patients (6 of 30 screened infants and 28 of 50 outpatients) with BAV by echocardiography, from January 2009 to May 2016.

Results: Among 34 BAV patients without any complications, right- noncoronary cusp (R-N) fusion was the most common (62%) finding, followed by left-noncoronary cusp (L-N) fusion (32%). The progression of aortic regurgitation (AR) was observed in 6 patients (R-N, n=3; L-R, n=3). In contrast, AS progressed in one patient and improved in 6 patients. However, AR remained mild in most cases (76%) and progressed to a moderate or severe state in a few patients (19%) who were 8–20 years of age.

Conclusions: With the exception of cases involving infants with severe AS, AS remained unchanged, while AR mildly progressed in a pediatric population with BAV. It appears that the progression to a moderate or severe degree of AR typically occurs at 8 to 20 years of age.

Background: The tetralogy of Fallot (TOF) is comprised of an anterior deviation of the septal insertion of the cardiac infundibular septum that leads to four detrimental morphological features which include a narrowing of the right ventricular outflow tract. A precise morphology of the frontal architecture of the affected right ventricular outflow tract has not yet been described even though its reconstruction is a critical part of TOF repair. We hypothesized that blood flow through this tract narrowed from behind by an anteriorly deviated infundibular septum causes an anterior prominence compared to the normal heart.

Methods: 51 cases of TOF versus 34 control cases of isolated ventricular septal defect (VSD) without pulmonary hypertension were reviewed by applying a geometric method to clarify cardiac morphology. We analyzed each triangle (AOP) and compared the data between the TOF and control groups, but our hypothesis was disproven as the TOF anterior faces were not anteriorly prominent.

Results: Several angles were shortened on analysis. However, after geometric comparison of triangle AOP between groups, we found only very small visible differences in the overall shapes of the triangles. The relative heights of anterior prominence of the right ventricular outflow tract were nearly the same in both groups.

Conclusions: An anteriorly deviated infundibular septum has no relationship with the anterior wall of the right ventricular outflow tract and that surgeons should expand the anterior wall of the right ventricular outflow tract forward to conform to the deviated infundibular septum during TOF repair to restore normal blood flow.

Background: Hypertrophic cardiomyopathy (HCM) is a major cause of sudden death in children in the school setting; however, more students with HCM are being successfully resuscitated due to the increased spread and accessibility of basic life support systems. Therefore, the prognosis for students with HCM who experience cardiac events at school is in a transitional period whereby the chances of survival are gradually improving. The present study aimed to determine the outcomes of cardiac events arising in children with HCM and the effects of automated external defibrillators (AED) applied under school supervision.

Methods: We retrospectively studied case reports of cardiac events occurring in schoolchildren with HCM submitted to the Mutual Aid System in Japan between 2004 and 2011.

Results: Among 44 children with HCM who experienced sudden cardiac events at school, 29 died and 15 survived following resuscitation. An AED was applied to 14 of the survivors and one individual already had an implantable cardioverter defibrillator (ICD) surgically inserted. There was a prevalence of males in both the survivor and non-survivor groups. Among children with HCM who experienced cardiac events in kindergarten, primary school, junior high school (JHS) and high school (HS), only those in the latter two levels of education tended to recover from cardiac events. The ratios (%) of victims and survivors that had been pre-diagnosed with HCM prior to the onset of cardiac events in the JHS and HS groups were 48% and 20%, respectively. Cardiac events occurred most frequently during exercise in both the survivor and non-survivor groups.

Conclusions: The numbers of individuals diagnosed with HCM who are successfully resuscitated after cardiac arrest while under school supervision has significantly improved in Japan since 2007. This can be attributed to the growing availability of AEDs and ICDs—both of which are essential solutions to prevent sudden cardiac death due to HCM in schoolchildren.

Background: In many cases of congenital cyanotic heart disease with stenosis or atresia of the main pulmonary artery, the ascending aorta is enlarged. This narrows the retroaortic space, making corrective surgery difficult. To overcome this problem, we devised an aortic extension technique using autologous aortic tissues.

Methods: Between 2005 and 2013, we performed the aortic extension technique on five patients, including four with a functional single ventricle and one with pulmonary atresia and a ventricular septal defect. Operative data, prognosis, and pre- to postoperative changes in aortic diameter, which were obtained using aortic angiography, were examined and compared.

Results: The mean patient age at the time of surgery was 18.2±7.6 months (range, from 7 months to 2 years), and the mean body weight was 8.4±0.9 (range, 7.1–10.0) kg. For all patients, aortic extension was performed in approximately 30 min. The preoperative ratio of the maximum to peripheral diameter of the ascending aorta was 1.64±0.22, and this significantly reduced to 1.01±0.36 postoperatively. Thus, enlargement of the retroaortic space was achieved. The patients progressed well, with no stenosis or re-enlargement being observed for over 53.8±38.3 (range, 32–130) months postoperatively.

Conclusions: This aortic extension procedure uses only autologous aortic tissues to simultaneously reduce the aortic diameter while extending the aorta. Because growth is also expected, our method appears to be a useful surgical procedure for reconstructing the large central pulmonary artery and decompressing the bronchus by sufficiently enlarging the retroaortic space.