Clinical presentation and course of long QT syndrome in Thai children.

BACKGROUND: Congenital long QT syndrome (LQTS) is a genetically transmitted cardiac channelopathy that can lead to lethal arrhythmia and sudden cardiac death in healthy young people. The clinical characteristics of LQTS are variable and depend on the subtype of long QT syndrome, which differ among populations. This single hospital-based case review study examined the clinical presentation of long QT syndrome and the outcomes of its treatment in 20 Thai children at King Chulalongkorn Memorial Hospital in Bangkok, Thailand. METHODS: Inpatient and outpatient records of children (aged 0-14 years) diagnosed with long QT syndrome from January 1, 1998, to September 30, 2013, were retrospectively reviewed. Presentation at diagnosis, treatments, and clinical courses were collected and analyzed. In the 20 subjects, total Schwartz scores totaled 5.2±0.9 points, and mean age at diagnosis was 7.6±4.4 years (range, 1 day-13.8 years). The patients were assigned to one of 3 groups based on trigger events: 50% of patients had events at rest (sleep or at rest), 35% experienced adrenergic-mediated events (e.g., stress, exercise, startle), and 15% were asymptomatic. Excluding the 3 patients who died at first presentation, 100% of patients received a beta blocker, and 47.1% were treated with an automatic implantable cardioverter-defibrillator (AICD). RESULTS: At follow-up (median=959 days; range, 1-4170 days), 4 patients (20%) were known to have died, 3 of whom died shortly after the diagnosis. Among patients who survived the initial event, 52.9% (9 of 17) experienced cardiac events (appropriate AICD shock, death, and/or syncope) during the follow-up period. The mean duration from diagnosis to cardiac event was 1420±759 days (range, 497-2499 days). CONCLUSIONS: All 20 patients with LQTS were mostly symptomatic at presentation. Owing to the geographical region and ethnicity of the Thai population, we conclude that the ratio of patients who develop cardiac symptoms at rest or during sleep might be higher than in other Asian countries.

Balloon pulmonary valvuloplasty in tetralogy of Fallot: effects on growth of pulmonary annulus and transannular patch.

BACKGROUND: Balloon pulmonary valvuloplasty and its benefit on the growth of pulmonary annulus and pulmonary artery in tetralogy of Fallot (TOF) patients remains controversial. The purpose ofthe present study was to determine the growth of pulmonary valve annulus and pulmonary artery and to evaluate the need of transannular patch during total surgical correction in patients with tetralogy of Fallot (TOF) after balloon pulmonary valvuloplasty. MATERIAL AND METHOD: Fifty-one severely hypoxic TOF patients, who underwent balloon dilatation ofpulmonary valve, were included in the present study. The clinical outcomes, oxygen saturation, and echocardiographic parameters before and after balloon dilatation were analyzed. RESULTS: There were 33 males and 18females. The mean age was 3 years 5 months old (range, I month-15 years 8 months old). The mean oxygen saturation increasedfrom 73.9 +/- 9.1 to 84.8 +/- 6.7% immediately after the procedure (p-value < 0.05). There was no serious procedural-related complication. At the mean follow-up period of 2 years and 4 months, the mean Z-score of pulmonary annulus size increased from -2.56 SD to -1.87 SD (p-value < 0.05) and the right pulmonary artery size from -0.29 SD to + 0.46 SD (p-value < 0.05). Thirty-seven patients (66.1%) underwent corrective surgery. Pulmonary transannular patch was performed in 11 of37 patients (29.7%). CONCLUSION: Pulmonary valve dilatation in patients with TOF is safe. It promotes the growth ofthe pulmonary valve annulus and pulmonary artery and may decrease the need of transannular patch at the time of surgical correction.

Transcatheter closure of patent ductus arteriosus with a self-expanding platinum-coated nitinol device.

BACKGROUND: An occluding device for closure of patent ductus arteriosus (PDA) was developed from meshed nitinol wires coated with platinum for prevention of nickel release after implantation. OBJECTIVES: Our purpose was to assess the immediate and short-term results of transcatheter PDA closure with this device. METHODS: Sixty patients (13 males and 47 females) underwent catheter-based PDA closure. The age ranged from 9 months to 65 years, with a median age of 4 years. The weight ranged from 4.2-65 kg, with a median of 15.2 kg. The mean PDA diameter at the narrowest segment was 4.7 +/- 2.2 mm, with a range of 2.0-15.1 mm. Eighteen cases had serial blood samples for serum nickel analysis taken before and at 1, 3 and 30 days after device implantation. RESULTS: The devices were successfully deployed in all 60 patients. There were no serious procedural complications. Color Doppler demonstrated complete occlusion rate of 78.3%, 90.0% and 100% at 1 day, 1 month and 1 year after implantation, respectively. There was no statistical difference in serum nickel concentrations between pre- and post-implantation. CONCLUSION: Transcatheter PDA closure using a platinum-coated nitinol device can be performed safely and successfully. There was no evidence of nickel release or nickel reaction after device implantation. This device model may be an alternative for PDA closure, especially in patients with potential nickel allergy.

Self-expanding nanoplatinum-coated nitinol devices for atrial septal defect and patent ductus arteriosus closure: a swine model.

OBJECTIVES: Our purpose was to evaluate self-expanding nanoplatinum-coated nitinol devices for transcatheter closure of atrial septal defects and patent ductus arteriosus in a swine model. The devices were braided from platinum-activated nitinol wires and filled with polyester to enhance thrombogenicity. The platinum activation of the nitinol wires was carried out with the help of Nanofusion technology. The coating of platinum covers the exposed surface of the nitinol wires and prevents the release of nickel into the blood stream after the implantation of the device but does not affect its shape memory, which makes the device self-expanding after it is loaded from the catheter. METHODS AND RESULTS: Atrial septal defects were created in 12 piglets by balloon dilation of the patent foramen ovale. The size of the device was selected on the basis of the diameter of the balloon and the size of the defect, measured by transthoracic echocardiography. The devices were successfully deployed in all 12 piglets under fluoroscopic study. Transthoracic color Doppler echocardiograms showed complete closure of the atrial septal defect within 15 minutes of device implantation. Twelve patent ductus arteriosus closure devices were deployed in the right or left subclavian arteries in 10 piglets. Angiograms showed complete occlusion of the subclavian arteries within a few minutes of device deployment. In the atrial septal defect cases, the autopsy findings showed complete organizing fibrin thrombus formation and complete neo-endothelialization on the outer surface of the devices within one week and six weeks of implantation, respectively. CONCLUSION: The use of self-expanding nanoplatinum-coated nitinol devices for the transcatheter closure of atrial septal defects and patent ductus arteriosus is feasible. The excellent occlusion result and complete neo-endothelialization of the devices in the swine model is an indication of the potential of these devices in human application.