Kin-Shing Lun

Analysis of indications for surgical closure of subarterial ventricular septal defect without associated aortic cusp prolapse and aortic regurgitation

Subarterial ventricular septal defect (VSD) is relatively common in Orientals. We reviewed the outcome of 214 patients (137 males) who were followed for 8.6 +/- 5.2 years (range 0.1 to 24.3) and addressed the issue regarding the necessity and optimum timing of closing subarterial defects before development of aortic valve deformities. Demographic data, transthoracic and transesophageal echocardiographic findings, cardiac catheterization results, and operative findings were reviewed. Kaplan-Meier actuarial analysis was performed to assess the development of aortic valve complications over time. Seventy-five patients with heart failure and pulmonary hypertension underwent surgical closure of VSD at the age of 2.4 +/- 2.9 years. No patient had aortic cusp prolapse before operation and none developed aortic cusp prolapse or aortic regurgitation (AR) on follow-up. In contrast, of the 139 asymptomatic patients managed conservatively, 102 (73%) developed aortic cusp prolapse, 78% of whom (80 of 102) developed AR. The prevalence of aortic cusp prolapse and AR at 1, 5, 10, and 15 years old was 8%, 30%, 64%, and 83%, and 3%, 24%, 45%, and 64%, respectively. Significant prolapse or AR prompted surgical closure of VSD with (n = 22) or without (n = 26) valvoplasty in 48 of 102 patients (47%). The size of the VSD was significantly larger in patients with heart failure (9.6 +/- 3.3 mm) or aortic cusp prolapse (11.7 +/- 4.1 mm) compared with those without heart failure (4.5 +/- 1.4 mm, p <0.001). All patients with aortic cusp prolapse and all but 1 with heart failure had a defect size of > or =5 mm. In conclusion, subarterial VSD of > or =5 mm should be closed as early as possible to prevent development of aortic cusp prolapse and AR. Asymptomatic patients with small defects <5 mm could be managed conservatively.

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.

Management of symptomatic congenital tracheal stenosis in neonates and infants by slide tracheoplasty: a 7-year single institution experience.

OBJECTIVE Congenital tracheal stenosis (CTS) is rare. When it presents early in life, its management can be challenging. Of the surgical techniques that have been devised to correct long-segment CTS, slide tracheoplasty (ST) appears to be superior. We present our 7-year-experience of ST for the treatment of symptomatic CTS in neonates and infants. METHODS The hospital records of all 14 neonates and infants who underwent ST between 2001 and 2008 at our hospital were retrieved. Patient characteristics, trachea morphology, co-existing anomalies, operative procedures, techniques, outcomes and clinical courses were reviewed. RESULTS Patients underwent ST at age 4 days to 22 months (median: 2.4 months). Five (36%) required intermittent ventilator support prior to surgery. All ST was done under cardiopulmonary bypass. The associated cardiovascular anomalies in 10 infants (71%) were also corrected at the same operation. All survived the initial surgical procedures. The in-hospital mortality for the group was 14.3%. The median periods of postoperative intensive care unit and hospital stay of the 12 children, who were successfully extubated within 7 postoperative days, were 9 days (range: 6-28 days) and 28 days (range: 14-375 days), respectively. Follow-up of all 12 midterm survivors was complete, ranging from 5 months to 5.6 years (median: 40 months). A total of four patients had been found to have tracheobronchial malacia postoperatively and were managed with stenting. Of the remaining 10 survivors who had no residual or recurrent airway problems, and no cardiovascular residuum or sequela, two had gross developmental delay. CONCLUSIONS In the management of symptomatic infants with CTS, our limited experience suggests that meticulously performed ST together with vigilant pre- and postoperative care can provide satisfactory short and midterm solution to the airway problem. Some incidental residual clinical problems appear to be unavoidable.

Identification of novel FBN1 and TGFBR2 mutations in 65 probands with Marfan syndrome or Marfan-like phenotypes†

Marfan syndrome is an autosomal dominant connective tissue disorder, and mutations in the FBN1 and TGFBR2 genes have been identified in probands with MFS and related phenotypes. Using DHPLC and sequencing, we studied the mutation spectrum in 65 probands with Marfan syndrome and related phenotypes. A total of 24 mutations in FBN1 were identified, of which 19 (nine missense, six frameshift, two nonsense and two affecting splice junctions) were novel. In the remaining 41 probands, six were identified to have novel TGFBR2 mutations (one frameshift and five missense mutations). All novel mutations found in this study were confirmed to be absent in 50 unrelated normal individuals of the same ethnic background. In probands who fulfilled the Ghent criteria (n = 16), mutations in FBN1 were found in 81% of cases. None of those with TGFBR2 mutations fulfilled the Ghent criteria. Novel missense mutations of unknown significance were classified according to the latest ACMG guidelines and their likelihood to be causative was evaluated.

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).

Left ventricular noncompaction in children.

OBJECTIVE Left ventricular noncompaction (LVNC) is an uncommon type of cardiomyopathy in children. We sought to determine the clinical presentations and outcomes of children diagnosed to have LVNC. DESIGN The case records of children diagnosed to have LVNC between 1999 and 2007 were reviewed. The diagnosis was based on echocardiographic finding of a thick noncompacted myocardium layer characterized by a trabecular meshwork with deep endomyocardial spaces. RESULTS Ten patients (seven males) were diagnosed to have LVNC at a median age of 2 years (range, 7 days to 12 years). Seven patients had isolated LVNC while three had associated structural congenital heart diseases. The right ventricle was also involved in two patients. Clinical presentations included congestive heart failure in eight patients, asymptomatic heart murmur in one, and syncope with exercise intolerance in one. At presentation, cardiomegaly was found in nine patients, electrocardiographic abnormalities in nine, and impaired LV contraction in six. Eight patients received anti-heart failure medications. Three patients died at a median of 1.5 years after diagnosis, two died suddenly of unknown causes, and one of heart failure. The seven surviving patients were followed up for a median of 2 years (range, 2 months to 3 years). Three patients developed cardiac arrhythmias. The LV function improved in three patients and worsened in one on follow-up. None of the patients developed thromboembolic complications. CONCLUSIONS Left ventricular noncompaction in children is a heterogeneous condition. Long-term follow-up for development of progressive LV dysfunction and cardiac arrhythmias is indicated.

Impact of Right Ventricular Pacing on Three-Dimensional Global Left Ventricular Dyssynchrony in Children and Young Adults With Congenital and Acquired Heart Block Associated With Congenital Heart Disease

The aim of this study was to determine the effect of long-term right ventricular pacing on left ventricular (LV) mechanical dyssynchrony in children and young adults with congenital and acquired heart block. Eighteen patients aged 19 +/- 7 years with congenital heart block (group I), 9 aged 21 +/- 11 years with acquired heart block after congenital heart surgery (group II), and 15 healthy control subjects (group III) were studied. The LV volumes, ejection fractions, and systolic dyssynchrony index (SDI) values, as determined using 3-dimensional echocardiography, were compared among groups. Groups I (6.68 +/- 2.44%) and II (9.43 +/- 4.44%) had significantly greater SDI values than group III (3.88 +/- 0.63%) (p = 0.011 and p <0.001, respectively). The prevalence of LV mechanical dyssynchrony (SDI >5.14%, mean + 2 SDs of controls) in groups I and II was 72% and 67%, respectively. In 27 patients with right ventricular pacing, LV SDI values were correlated negatively with the LV ejection fractions (r = -0.74, p <0.001). The times to minimum regional volume were significantly longer in lateral, posterior, and inferior segments in group I and septal and inferior segments in group II compared to those in group III (p <0.05). Compared to patients without LV dyssynchrony, patients with LV dyssynchrony had lower LV ejection fractions (p <0.001), had shorter RR intervals (p <0.001), and tended to have dual-chamber pacing (p = 0.088) but had similar durations of pacing, QRS durations, and positions of pacing wires (epicardial vs endocardial). In conclusion, permanent right ventricular pacing in childhood has a negative effect on LV systolic function through the induction of mechanical dyssynchrony, the magnitude and pattern of which differ between congenital and acquired heart block.

NGS identifies TAZ mutation in a family with X-linked dilated cardiomyopathy

We reported a family with two male siblings affected with infantile dilated cardiomyopathy (DCM). Extensive evaluation failed to identify the underlying cause for the DCM. Next generation sequencing (NGS) with targeted enrichment identified a hemizygous variant c.718G>C (p.Gly240Arg) in the TAZ gene. This variant has been reported in three other families with X linked infantile DCM and is therefore likely pathogenic. NGS allows efficient screening of a large number of uncommon genes in complex disorders like DCM, in which there is substantial genetic and phenotypic heterogeneity. The identification of TAZ mutation has major impact on their medical care as the surveillance needs to be expanded to cover for the Barth syndrome, a severe metabolic phenotype also caused by TAZ mutation, in addition to DCM.

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.

Cardiovascular symptoms and signs in evaluating cardiac murmurs in children

Background: The aim of the present study was to determine the usefulness of cardiovascular symptoms and signs in the recognition of significant congenital heart lesions that required surgical or catheter interventions in different pediatric age groups.