Risk factors for development of ventricular tachycardia in patients with ventricular premature contraction with a structurally normal heart.

BACKGROUND: We examined risk factors for development of ventricular tachycardia (VT) in pediatric patients with ventricular premature contractions (VPCs) and a structurally normal heart. METHODS: The subjects were 81 844 first graders and 88 244 seventh graders of Kagoshima City School-based cardiovascular screening (SCV-screening) between 2001 and 2015. We retrospectively reviewed the clinical data of students who were diagnosed as having VPC. RESULTS: Ventricular premature contractions were observed in 134 first graders (0.16%) and 270 seventh graders (0.31%). On the screening electrocardiograms (ECGs), 43 patients (11%) showed bi-/trigemini, three patients (0.7%) showed a couplet, and one patient showed VT. We obtained 166 patients' follow-up information and evaluated 59 patients (36%) as improved, 97 patients (58%) as no change, and 10 patients (6%) as worsened (couplets, five; triplets, two; VT, three). We assumed that these worsened patients have risk factors for development of VT. Comparing the findings of SCV-screening ECGs of risk patients with the others, a significant difference was observed only in the number of VPCs (per 10 seconds) (mean ± SD; 4.3 ± 2.6 vs 1.8 ± 1.4, P < .0001). A logistic regression analysis revealed that the number of VPCs was significant (P < .001, odds ratio; 2.01, 95% confidence intervals; 1.46-2.93). Receiver operating characteristics analysis showed an adequate cut-off number of three VPCs for the risk, the sensitivity was 89% and the specificity was 77%. CONCLUSIONS: Of the patients with VPC and a structurally normal heart, a few patients developed VT. Careful observation is important in patients who had three or more VPCs on SCV-screening ECG.

Probability of diagnosing long QT syndrome in children and adolescents according to the criteria of the HRS/EHRA/APHRS expert consensus statement.

AIMS: The present study aimed to determine the probability of diagnosing long QT syndrome (LQTS) in children and adolescents based on the HRS/EHRA/APHRS criteria for LQTS. We used data of a school-based electrocardiographic screening programme in Japan. METHODS AND RESULTS: The total numbers of subjects who participated in the screening programme between 2008 and 2013 in Kagoshima, Japan, were 33 051 first- and 34 751 seventh-grade students, aged 6 and 12 years, respectively. The screening process consisted of three steps of examination: the first screening, and the second and third examinations. Among the total subjects, 32 982 first graders (99.8% of the total) and 34 572 seventh graders (99.5% of the total) participated in the first screening. After the first, second, and third screening or examinations, the programme determined 10 first and 32 seventh graders as having a high probability of LQTS according to the HRS/EHRA/APHRS criteria for LQTS. The probability of diagnosing LQTS by the screening programme was 1:3298 (0.30/1000) and 1:1080 (0.93/1000) in first and seventh graders, respectively. During the study periods, three subjects of 7th graders were already diagnosed as having LQTS at the first grade. Therefore, the overall probability of diagnosing LQTS was 1:3298 (95% confidence interval, 1:2036 to 1:8673) and 1:988 (95% confidence interval, 1:742 to 1:1477) in first and seventh graders, respectively. CONCLUSION: This study shows important data on the probability of diagnosing LQTS as ∼1:3300 in subjects aged 6 years and 1:1000 in those aged 12 years based on the HRS/EHRA/APHRS criteria.

Fatal systemic air embolism in a neonate with absent aortic valve.

A 32-year-old pregnant woman was referred at 33 weeks' gestation for prenatal ultrasound demonstrating fetal hydrops due to absent aortic valve with free aortic valve insufficiency. Elective caesarian section at 34 week's gestation was performed. Surgical intervention was planned immediately after labor at which time mitral valve closure and atrial septostomy using cardiopulmonary bypass would be performed. However, before insertion of the cannula for cardiopulmonary bypass, a gush of air from the right atrium was noted. The surgical procedure was abandoned because systemic air embolism was suspected. The child died 2 h after birth. Autopsy showed absent aortic valve with closed foramen ovale and left-ventricular hypertrophy. Microscopic findings showed pulmonary and systemic lymphangiectasis, which caused the introduction of air into systemic venous system by way of lymphatic duct just after birth.

Impact and issues of detecting fetal congenital heart defects in Kyushu, Japan.

AIM: To determine the current status of fetal CHD screening in our region and to establish a CHD screening system in Japan. MATERIAL AND METHODS: Subjects were 168 fetuses prenatally-diagnosed with CHD at four referral centers in Japan from 2003 to 2007. Subjects were divided into two groups: group A (n = 84) included cases without extracardiac sonographic abnormalities and known risk factors for CHD and group B (n = 84) included those with extracardiac sonographic abnormalities or risk factors. The diagnostics and outcomes between the groups were analyzed. RESULTS: There were more cases of single ventricle and restrictive ductus arteriosus and fewer cases of ventricular septal defect and double outlet right ventricle in group A than in group B (P < 0.05). In group A, the most frequent referral reason was an abnormal four-chamber view. In group B, 37 cases had chromosomal anomalies. The mortality rates in group B were higher than those in group A (P < 0.05). There were no differences in mortality rates between fetuses without chromosomal anomalies in group B and group A. CONCLUSION: Prenatally-diagnosed CHD were mostly limited to those cases with obvious abnormalities in the four-chamber view or those with chromosomal anomalies. Prenatal detection of CHD is useful for the prediction of outcomes.

Mutation of junctophilin type 2 associated with hypertrophic cardiomyopathy.

Junctophilin subtypes, designated as JPH1 approximately 4, are protein components of junctional complexes and play essential roles in cellular Ca2+ signaling in excitable cells. Knockout mice lacking the cardiac-type Jph2 die of embryonic cardiac arrest, and the mutant cardiac myocytes exhibit impaired formation of peripheral couplings and arrhythmic Ca2+ signaling caused by functional uncoupling between dihydropyridine and ryanodine receptor channels. Based on these observations, we hypothesized that mutations of JPH2 could cause human genetic cardiac diseases. Among 195 Japanese patients (148 index cases and 47 affected family members) with hypertrophic cardiomyopathy (HCM), two heterozygous nonsynonymous nucleotide transitions, G505S and R436C, were newly found in JPH2. When Fisher's exact test was used to compare index cases with HCM to unrelated Japanese healthy controls in the frequencies of mutant alleles, only the G505S mutation showed statistical significance (4/296 HCM patients and 0/472 control individuals, P=0.022). This result was still significant after Bonferroni's correction for multiple comparisons (P=0.044). To the best of our knowledge, this is the first report on JPH2 mutation associated with HCM.