Mi Kyoung Song

Clinical Characteristics and Prognostic Factors of Primary Pulmonary Vein Stenosis or Atresia in Children

BACKGROUND Primary pulmonary vein stenosis or atresia (PVS/A) is a rare entity with a high mortality rate. The aim of this study was to elucidate the clinical characteristics, progression, and prognostic factors of primary PVS/A in children. METHODS We reviewed the medical records of patients who had primary PVS/A with normally connected pulmonary veins (PVs) at five pediatric cardiology centers in Korea between 1995 and 2010. RESULTS A total of 34 cases were identified. The median age at diagnosis was 12.0 months. During the follow-up period (median, 18 months; range, 2 to 185 months), PVS/A progressed to previously uninvolved veins in 9 patients. Surgical interventions were performed on 29 patients (venoplasty on 25 and pneumonectomy on 4). Nineteen of the patients who underwent venoplasty had restenosis after a median of 2 months. The sutureless technique did not reduce the rate of restenosis, progression of the disease to previously uninvolved PVs, or mortality rate. The mortality rate was 46.7%, the median age of death was 10.8 months, and the median interval between diagnosis and death was 3.0 months. In univariate analysis, predictors of death included involvement of at least three PVs, bilateral PV involvement, infancy-onset PVS/A, restenosis after surgery, and progression to previously uninvolved PVs. In multivariate analysis, significant risk factors for death were involvement of at least three PVs (hazard ratio, 8.8; p < 0.0001) and progression to uninvolved PVs (hazard ratio, 4.2; p = 0.014). CONCLUSIONS Primary PVS/A may carry a significant risk of recurrent and progressive PV obstruction or death even after surgical venoplasty.

Intra-atrial reentrant tachycardia in adult patients after Fontan operation

BACKGROUND Atrial tachyarrhythmia is a major late complication in adult Fontan patients. This study examined the clinical features and risk factors of late intra-atrial reentrant tachyarrhythmia (IART) in adult patients after Fontan surgery and the mid-term outcome of Fontan conversion with or without antiarrhythmic surgery in these patients. METHODS We conducted a retrospective study on adult patients who were born before 1994 and survived at least 3 months after a Fontan operation at Seoul National University Childrens Hospital. RESULTS We followed 160 patients over 20.9 ± 4.1 years. Sustained atrial tachycardia was identified in 51 patients, and IART was found in 41, appearing a mean 13.6 years after surgery. By the 25 year follow-up, 40% had developed IART. The incidence of IART significantly increased over time. Patients with an atriopulmonary connection (APC) (n=65) had significantly longer follow-up duration and higher incidence of IART than patients with a lateral tunnel (n=86) or extracardiac conduit Fontan (n=9). On multivariate analysis, APC, sinus node dysfunction, and nonsustained atrial tachycardia were found to be significantly associated with IART. Twenty-four patients with IART underwent Fontan conversion. Over the follow-up period, IART severity scores in the 22 patients who survived after Fontan conversion decreased significantly, and New York Heart Association functional class significantly improved. On multivariate analysis, protein losing enteropathy and ventricular dysfunction were found to be significant risk factors for mortality. CONCLUSIONS IART was common in adult Fontan patients, and Fontan conversion with or without antiarrhythmic surgery and pacemaker placement helped to control it.

Application of Multigene Panel Sequencing in Patients with Prolonged Rate-corrected QT Interval and No Pathogenic Variants Detected in KCNQ1, KCNH2, and SCN5A

Long QT syndrome (LQTS) is an inherited cardiac disease characterized by a prolonged heart rate-corrected QT (QTc) interval. We investigated the genetic causes in patients with prolonged QTc intervals who were negative for pathogenic variants in three major LQTS-related genes (KCNQ1, KCNH2, and SCN5A). Molecular genetic testing was performed using a panel including 13 LQTS-related genes and 67 additional genes implicated in other cardiac diseases. Overall, putative genetic causes of prolonged QTc interval were identified in three of the 30 patients (10%). Among the LQTS-related genes, we detected a previously reported pathogenic variant, CACNA1C c.1552C>T, responsible for cardiac-only Timothy syndrome. Among the genes related to other cardiac diseases, a likely pathogenic variant, RYR2 c.11995A>G, was identified in a patient with catecholaminergic polymorphic ventricular tachycardia. Another patient who developed dilated cardiomyopathy with prolonged QTc interval was found to carry a likely pathogenic variant, TAZ c.718G>A, associated with infantile dilated cardiomyopathy. Comprehensive screening of genetic variants using multigene panel sequencing enables detection of genetic variants with a possible involvement in QTc interval prolongation, thus uncovering unknown molecular mechanisms underlying LQTS.

The Complexity of Pediatric Multifocal Atrial Tachycardia and Its Prognostic Factors

Background and Objectives Multifocal atrial tachycardia (MAT), in general, has a favorable outcome. However, there are insufficient data regarding MAT in a pediatric population. This study sought to determine the clinical course of MAT and identify potential prognostic factors. Methods The medical records of MAT patients from 1997–2015 were reviewed. The arrhythmia control rate and factors for unfavorable outcomes were assessed and compared to those in the literature. Results Of the 33 included patients (19 boys and 14 girls), 27 were infants less than 1 year of age. The median age at diagnosis was 1.7 months (range, 0 day to 14 years). Fourteen (42%) patients had structural heart disease. Eight (24%) patients had lung disease and 6 (18%) had a syndromic diagnosis belonging to RASopathy. Two patients developed polymorphic ventricular tachycardia, in whom genetic analysis confirmed the presence of the RyR2 mutation several years later. MAT was controlled in 26 patients (84%) within 3.9 months (median; range, 16 days–18.4 years) using an average of 2.4 medications. There were 3 cases of cardiopulmonary mortality. The arrhythmia control rate was higher in the infant group (85%) than in the non-infant group (67%), although this trend was not statistically significant. There was a significantly lower rate of unfavorable outcomes in the idiopathic infant group (n=11) than in the other groups (p=0.008). Considering the findings of previous studies, the mortality rate was significantly higher in patients with structural heart disease than in patients without (21% vs. 5%, p=0.01). Conclusions MAT usually affects infants and has a favorable prognosis, particularly in the idiopathic infant group. However, in the presence of other comorbidities, MAT may have a variable clinical course.

A stepwise approach to conduit puncture for electrophysiological procedures in patients with Fontan circulation

Aims In patients with Fontan circulation, the conduit may be punctured for electrophysiological procedures. We evaluated the feasibility and safety of a stepwise approach to conduit puncture in adults who have undergone Fontan operation. Methods and results We included 13 consecutive patients with lateral tunnel or extracardiac conduit Fontan circulation [median age (interquartile range), 24.0 (16.0-25.0) years; seven men] who had undergone electrophysiological procedures. We performed a stepwise approach to conduit puncture: 1st, Brockenbrough needle; 2nd, Brockenbrough needle with snare; 3rd, extra-steep Brockenbrough needle with/without snare; 4th radiofrequency transseptal needle with/without snare; 5th, wiring through the puncture; 6th, conduit dilation with angioplasty balloon; 7th, non-compliant or cutting balloon; and 8th, Inoue dilator. In 12 patients, conduit puncture was successful. In two, one, and two patients with a lateral tunnel made of the pericardium or right atrial wall, conduit puncture was performed by steps 1st, 2nd, and 4th, respectively. In one, three, two, and one patient with the Goretex lateral tunnel or extracardiac conduit, conduit puncture was performed by steps 1st, 6th, 7th, and 8th, respectively. Puncture time was significantly longer in patients with Goretex conduits than with pericardial conduits [62.0 (50.0-120.0) and 11.5 (10.0-14.8) min, respectively; P < 0.001]. A snare was necessary in patients with angles ≤ 35° between the conduit wall and vertical line. Conclusion A stepwise conduit puncture approach is feasible and safe in patients with lateral tunnel and extracardiac conduit Fontan circulation. Goretex conduit puncture was more difficult than pericardial conduit puncture.

Successful Feasibility Human Trial of a New Self-Expandable Percutaneous Pulmonary Valve (Pulsta Valve) Implantation Using Knitted Nitinol Wire Backbone and Trileaflet α-Gal–Free Porcine Pericardial Valve in the Native Right Ventricular Outflow Tract

Background— Self-expandable percutaneous pulmonary valve implantation (PPVI) for native right ventricular outflow tract lesions is still in the clinical trial phase. The aim of this study is to present the result of feasibility study of a novel self-expandable knitted nitinol wire stent mounted with a treated trileaflet &agr;-Gal–free porcine pericardial valve for PPVI. Methods and Results— A feasibility study using Pulsta valve (TaeWoong Medical Co, Gyeonggi-do, South Korea) was designed for patients with severe pulmonary regurgitation in the native right ventricular outflow tract, and 6-month follow-up outcomes were reviewed. Ten tetralogy of Fallot patients were enrolled. Before PPVI, severe pulmonary regurgitation (mean pulmonary regurgitation fraction, 45.5%±7.2%; range, 34.9%–56%) and enlarged right ventricular volume (mean indexed right ventricular end-diastolic volume, 176.7±14.3 mL/m2; range, 158.9–205.9 mL/m2) were present. The median age at PPVI was 21.7±6.5 years (range, 13–36 years). Five patients were successfully implanted with 28 mm and the other 5 with 26 mm valves loaded on the 18F delivery cable. No significant periprocedural complications were noted in any patient. At the 6-month follow-up, indexed right ventricular end-diastolic volume was dramatically decreased to 126.3±20.3 mL/m2 (range, 99–164.2 mL/m2), and the mean value of peak instantaneous pressure gradient between the right ventricle and the pulmonary artery decreased from 6.8±3.5 mm Hg (range, 2–12 mm Hg) before PPVI to 5.7±6.7 mm Hg (range, 2–12 mm Hg) without significant pulmonary regurgitation. There was no adverse event associated with the valve. Conclusions— A feasibility study of the Pulsta valve for native right ventricular outflow tract lesions was completed successfully with planned Pulsta valve implantation and demonstrated good short-term effectiveness without serious adverse events. Clinical Trial Registration— URL: https://www.clinicaltrials.gov. Unique identifier: NCT02555319.