Clinical and genetic profile of congenital long QT syndrome in Hong Kong: a 20-year experience in paediatrics.

INTRODUCTION: Congenital long QT syndrome (LQTS) is a genetically transmitted cardiac channelopathy that can lead to sudden cardiac death. This study aimed to report the clinical and genetic characteristics of all young patients diagnosed with LQTS in the only tertiary paediatric cardiology centre in Hong Kong. METHODS: This is a retrospective review of all paediatric and young adult patients diagnosed at our centre with LQTS from January 1997 to December 2016. The diagnosis of LQTS was established with a corrected QT interval (QTc) ≥480 ms, Schwartz score of >3 points, or the presence of a pathogenic mutation. RESULTS: Fifty-nine patients (33 males) from 52 families were included, with a mean age of 8.17 years (range, 0.00-16.95 years) at presentation. Five patients had concomitant congenital heart diseases. The mean follow-up duration was 5.33 ± 4.65 years. The mean QTc in the cohort was 504 ± 47 ms. They presented with syncope and convulsion (49%), cardiac arrest (10%), bradycardia and neonatal atrioventricular block (12%). Fifteen (25%) patients were asymptomatic at diagnosis. Thirty-eight (64.4%) patients were confirmed to have a pathogenic mutation for LQTS genes. Forty-five (76.3%) patients received beta blocker therapy. Thirteen (22.0%) patients required implantable cardioverter defibrillator. There was no mortality in the study period. The 1-, 5-, and 10-year breakthrough cardiac event-free rates were 93.0%, 80.7%, and 72.6%, respectively. CONCLUSION: Identification of the disorder, administration of beta blockers, and lifestyle modification can prevent subsequent cardiac events in LQTS. Genotyping in patients with LQTS is essential in guiding medical therapy and improving prognosis.

Clinical and genetic profile of catecholaminergic polymorphic ventricular tachycardia in Hong Kong Chinese children.

OBJECTIVE: To report our experience in the management of catecholaminergic polymorphic ventricular tachycardia in Hong Kong Chinese children. METHODS: This case series study was conducted in a tertiary paediatric cardiology centre in Hong Kong. All paediatric patients diagnosed at our centre with catecholaminergic polymorphic ventricular tachycardia from January 2008 to October 2014 were included. RESULTS: Ten patients (five females and five males) were identified. The mean age at presentation and at diagnosis were 11.0 (standard deviation, 2.9) years and 12.5 (2.8) years, respectively. The mean delay time from first presentation to diagnosis was 1.5 (standard deviation, 1.3) years. They presented with recurrent syncope and six patients had a history of aborted cardiac arrest. Four patients were initially misdiagnosed to have epilepsy. Catecholaminergic polymorphic ventricular tachycardia was diagnosed by electrocardiogram at cardiac arrest (n=2), or provocation test, either by catecholamine infusion test (n=6) or exercise test (n=2). Mutations of the RyR2 gene were confirmed in six patients. Nine patients were commenced on beta-blockers after diagnosis. Despite medications, three patients developed aborted or resuscitated cardiac arrest (n=2) and syncope (n=1). Left cardiac sympathetic denervation was performed in five patients and an implantable cardioverter defibrillator was implanted in another. There was no mortality during follow-up. CONCLUSIONS: Catecholaminergic polymorphic ventricular tachycardia should be considered in children who present with recurrent syncope during exercise or emotional stress. Despite beta-blocker treatment, recurrent ventricular arrhythmias occur and may result in cardiac arrest.

A newborn with a 790 kb chromosome 17p13.3 microduplication presenting with aortic stenosis, microcephaly and dysmorphic facial features - is cardiac assessment necessary for all patients with 17p13.3 microduplication?

While deletion of chromosome 17p13.3 (encompassing PAFAH1B1 and YWHAE genes) is known to result in Miller-Dieker syndrome (OMIM 247200), 17p13.3 microduplication gives rise to a condition commonly associated with developmental delay and autism spectrum disorder. We report a Chinese newborn presenting with dysmorphic features, microcephaly and valvar aortic stenosis, who was confirmed to have a 790 kb microduplication in chromosome 17p13.3 by array comparative genomic hybridization (aCGH). The patient passed away at 4 months of age with presumably life-threatening event associated with his cardiac condition. From literature review, congenital heart diseases of various kinds were identified in up to 20% of patients with 17p13.3 microduplication. We propose cardiac assessment should be part of the comprehensive evaluation of these patients.

Transcatheter ablation of atrioventricular junctional re-entrant tachycardia in children and adolescents in Hong Kong: comparison of cryothermal with radiofrequency energy.

OBJECTIVE: To compare the outcome of cryothermal and radiofrequency energy transcatheter ablation of atrioventricular junctional re-entrant tachycardia in children and adolescents. DESIGN: Case series with internal comparison. SETTING: Two hospitals in Hong Kong. PATIENTS: Consecutive transcatheter ablation procedures for atrioventricular junctional re-entrant tachycardia in children and adolescents in our unit from August 2000 to September 2008 were retrospectively reviewed. Radiofrequency ablation was performed from August 2000 to June 2005, and cryoablation from July 2005 to September 2008. MAIN OUTCOME MEASURES: Demographic data, outcome and procedural details. RESULTS: Thirty-eight procedures were reviewed. The radiofrequency ablation group (n=20) and cryoablation group (n=18) had similar demographic characteristics, except that there were more patients with congenital heart disease in the latter group (P=0.03). Acute procedural success rate was 100% in both groups. One patient from the radiofrequency ablation group had recurrence of atrioventricular junctional re-entrant tachycardia. The frequency of post-ablation persistent heart block was higher in the radiofrequency ablation than cryoablation group (10% vs 0%, P=0.17), but this difference was not statistically significant. A shorter fluoroscopy time was noted in the cryoablation group (31 ± 13 vs 38 ± 18 minutes; P=0.03). CONCLUSIONS: Transcatheter cryoablation for atrioventricular junctional re-entrant tachycardia in children and adolescents is as effective as radiofrequency ablation over the medium term. It has an excellent safety profile in terms of avoiding heart block.

Hemangioma of the diaphragm presenting with cardiac tamponade.

We report a rare form of presentation of diaphragmatic hemangioma in a neonate. The patient presented with pericardial effusion and cardiac tamponade, requiring tapping of the pericardial effusion and subsequent en-bloc resection of the hemangioma with diaphragmatic reconstruction.

Fate of the unligated vertical vein after repair of supracardiac anomalous pulmonary venous connection.

OBJECTIVE: To determine the fate of the unligated vertical vein after repair of isolated supracardiac total anomalous pulmonary venous connection (TAPVC). METHODS: We reviewed the outcome of 28 patients who were diagnosed to have isolated supracardiac TAPVC and determined the fate of the unligated vertical vein. RESULTS: Of the 28 patients, four died before surgery. The remaining 24 patients underwent surgical correction of TAPVC with (n = 5) or without (n = 19) ligation of vertical vein at a median age of 20 days (range: 1-574 days). There were no significant differences in age, weight, presence of pulmonary venous obstruction, need for preoperative inotropic and ventilatory support, cardiopulmonary bypass duration, postoperative pulmonary hypertensive crisis and requirement of peritoneal dialysis between patients with and those without vertical vein ligation. The in-hospital surgical mortality was 50% (12/24), with 83% (10/12) of deaths occurring before 1990. Patients who died after surgery were significantly younger (median age: 5.5 days vs 37 days, P = 0.005), lighter (3.3 +/- 0.5 kg vs 3.9 +/- 0.6 kg, P = 0.016), more likely to have pulmonary venous obstruction preoperatively (75% vs 12%, P = 0.039) and have undergone surgery before 1990 (83% vs 33%, P = 0.036). The 12 survivors were followed up for a median of 4.7 years (range: 2.3-18.1 years), 10 of whom had their vertical vein unligated. The vertical vein remained patent in five (50%) patients, while stenosis of pulmonary venous anastomosis was only present in one patient. Of these five patients, three had subsequently undergone surgical ligation of the vertical vein to eliminate a large left-to-right shunt. CONCLUSIONS: Patency of the unligated vertical vein is common after the repair of supracardiac TAPVC, even in the absence of pulmonary venous obstruction. The degree of left-to-right shunt through the patent vertical vein may be so significant as to warrant surgical ligation.

Evolution of the management approach for pulmonary atresia with intact ventricular septum.

OBJECTIVE: To review the evolution of the management approach for pulmonary atresia with intact ventricular septum (PAIVS) in the past two decades and to assess its impact on patient outcomes. DESIGN AND PATIENTS: Retrospective review of the management and outcomes of 94 patients (55 male patients) with PAIVS diagnosed between July 1980 and August 2003. SETTINGS: Tertiary paediatric cardiac centre. RESULTS: Seven patients died before interventions. Of the remaining 87 patients who underwent intervention at a median age of 9 days (from 1 day to 2 years), 12 had right ventricular outflow tract reconstruction (RVOTR), 42 had closed pulmonary valvotomy (CPV), and 15 had laser assisted valvotomy with balloon valvoplasty. A systemic-pulmonary shunt was inserted in 18 patients, six of whom had subsequent RVOTR (n = 4) or laser assisted valvotomy (n = 2). Since 1990, catheter intervention accounted for 38% (17 of 45) of the right ventricular outflow procedures. The mean (SEM) freedom from reintervention was 93 (7)%, 71 (12)%, and 57 (13)% after RVOTR, 75 (7)%, 40 (8)%, and 14 (6)% after CPV, and 54 (13)%, 24 (12)%, and 16 (10)% after laser assisted valvotomy at one month, six months, and one year, respectively (RVOTR versus CPV, p < 0.001; RVOTR versus laser assisted valvotomy, p = 0.001). Low cardiac output syndrome was significantly less common after catheter intervention than after RVOTR (0% v 44%, p = 0.003) or CPV (0% v 29%, p = 0.01). The overall mean (SEM) survival was 77 (5)% and 70 (5)% at one and five years, respectively, and the overall mortality was 33% (29 of 87). There were no significant differences in survival between the three groups. CONCLUSIONS: Multiple interventions are often required in the treatment algorithm of PAIVS. The shift towards increased use of the transcatheter approach has reduced the occurrence of postprocedural low cardiac output syndrome.

Ventricular aneurysm complicating neonatal coxsackie B4 myocarditis.

A premature neonate suffered from disseminated Coxsackie B4 infection. Myocarditis and a coexisting persistent ductus arteriosus became complicated with recurrent atrial tachycardia and severe heart failure. She survived with satisfactory cardiac function. Ventricular aneurysm was detected on follow-up echocardiography.

Facial nerve palsy and Kawasaki disease.

We report on a case of facial nerve palsy associated with Kawasaki disease in a 2-year-old boy. Facial nerve palsy is one of the rare neurological manifestations of Kawasaki disease. Twenty-seven other cases that have been reported in the literature are reviewed. There is a high incidence of coronary artery aneurysm (52%) and a female predilection in patients with Kawasaki disease. The facial palsy associated with the disease is self-limiting. Recovery is spontaneous in surviving patients, although the use of intravenous immunoglobulin may be able to hasten the recovery.