Cardiac crises: Cardiac arrhythmias and cardiomyopathy during TANGO2 deficiency related metabolic crises.

BACKGROUND: TANGO2 deficiency disorder (TDD) is an autosomal recessive disease associated with metabolic crisis, lethal cardiac arrhythmias, and cardiomyopathy. Data regarding treatment, management, and outcomes of cardiac manifestations of TDD are lacking. OBJECTIVE: The purpose of this study was to describe TDD-related cardiac crises. METHODS: Retrospective multicenter chart review was made of TDD patients admitted with cardiac crises, defined as development of ventricular tachycardia (VT), cardiomyopathy, or cardiac arrest during metabolic crises. RESULTS: Twenty-seven children were admitted for 43 cardiac crises (median age 6.4 years; interquartile range [IQR] 2.4-9.8 years) at 14 centers. During crisis, QTc prolongation occurred in all (median 547 ms; IQR 504-600 ms) and a type I Brugada pattern in 8 (26%). Arrhythmias included VT in 21 (78%), supraventricular tachycardia in 3 (11%), and heart block in 1 (4%). Nineteen patients (70%) developed cardiomyopathy, and 20 (74%) experienced a cardiac arrest. There were 10 deaths (37%), 6 related to arrhythmias. In 5 patients, recalcitrant VT occurred despite use of antiarrhythmic drugs. In 6 patients, arrhythmias were controlled after extracorporeal membrane oxygenation (ECMO) support; 5 of these patients survived. Among 10 patients who survived VT without ECMO, successful treatment included intravenous magnesium, isoproterenol, and atrial pacing in multiple cases and verapamil in 1 patient. Initiation of feeds seemed to decrease VT events. CONCLUSION: TDD-related cardiac crises are associated with a high risk of arrhythmias, cardiomyopathy, cardiac arrest, and death. Although further studies are needed, early recognition and appropriate treatment are critical. Acutely, intravenous magnesium, isoproterenol, atrial pacing, and ECMO as a last resort seem to be the best current treatment options, and early initiation of feeds may prevent VT events.

Implantable Cardioverter-defibrillators in Adult Congenital Heart Disease.

With improved surgical techniques and medical therapies, many patients who are born with complex congenital heart defects are now living well into adulthood. As these patients age, an increasingly common cause of mortality is sudden cardiac death (SCD) from ventricular tachyarrhythmias. The implantable cardioverter-defibrillator (ICD) is a therapy with the ability to prevent some of these deaths; however, there are many diagnostic and technical challenges that remain in the congenital heart disease (CHD) population. We performed a literature review, searching PubMed for articles that examined the role of ICDs in CHD. We herein present the evidence for when to place an ICD in CHD patients, stratified by subtype as relevant. Then, we discuss the technical challenges and complications that are unique to this patient population. We conclude that, despite active work in the area, more research is needed given the small event rates and clinical variability within CHD populations.

Catheter Ablation to Treat Supraventricular Arrhythmia in Children and Adults With Congenital Heart Disease: What We Know and Where We Are Going.

BACKGROUND: Catheter ablation has been used to manage supraventricular arrhythmia in children since 1990. This article reviews the history of catheter ablation used to treat arrhythmia in children and discusses new frontiers in the field. We also address ablation in adult patients with a history of congenital heart disease (CHD) that was diagnosed and initially treated in childhood. METHODS: We conducted an evidence-based literature review to gather available data on ablation for supraventricular tachycardia in children and adult patients with CHD. RESULTS: Ablations can be performed safely and effectively in children. Complication rates are higher in children <4 years and <15 kg. In one study, the overall success rate of radiofrequency ablation in pediatrics was 95.7%, with the highest success rate in left free wall pathways (97.8%). Recurrence was higher in septal pathways. Cryoablation has been reported to have a 93% acute success rate for atrioventricular (AV) nodal reentrant tachycardia and septal pathways with no risk of AV block and a 5%-9% risk of recurrence. Three-dimensional mapping, intracardiac echocardiography, remote magnetic navigation, and irrigated catheter ablation are new technologies used to treat pediatric and adult patients with CHD. The population of adult patients with CHD is growing, and these patients are at particularly high risk for arrhythmia. A paucity of data is available on ablation in adult patients with CHD. CONCLUSION: Electrophysiology for pediatric and adult patients with CHD is a rapidly growing and progressing field. We benefit from continuous development of ablation techniques for adults with structurally normal hearts and have the unique challenge and responsibility to ensure the safe and effective application of these techniques in the vulnerable population of pediatric and adult patients with CHD.

Arrhythmias in children with ventricular assist devices.

BACKGROUND: Children with decompensated heart failure are at high risk for arrhythmias, and ventricular assist device placement is becoming a more common treatment strategy. The impact of ventricular assist devices on arrhythmias and how arrhythmias affect the clinical course of this population are not well described. METHODS AND RESULTS: A single-centre retrospective analysis of children receiving a ventricular assist device between 1998 and 2011 was performed. In all, 45 patients received 56 ventricular assist devices. The median age at initial placement was 13 years (interquartile range 6-15). The median duration of support was 10 days (range 2-260). The aetiology of heart failure included cardiomyopathy, transplant rejection, myocarditis, and congenital heart disease. In all, 32 patients (71%) had an arrhythmia; 19 patients (42%) had an arrhythmia before ventricular assist device and eight patients (18%) developed new arrhythmias on ventricular assist device. Ventricular tachycardia was most common (25/32, 78%). There was no correlation between arrhythmia and risk of death or transplantation (p=0.14). Of the 15 patients who weaned from ventricular assist device, post-ventricular assist device arrhythmias occurred in nine (60%), with five (33%) having their first arrhythmia after weaning. Patients with ventricular dysfunction after ventricular assist device were more likely to have arrhythmias (p<0.02). CONCLUSIONS: Arrhythmias, especially ventricular, are common in children requiring ventricular assist device. They frequently persist for those able to wean from ventricular assist device.

Limited utility of exercise stress tests in the evaluation of children with chest pain.

OBJECTIVES: The objective of this study was to assess the utility of the exercise stress test (EST) in pediatric patients without previously diagnosed heart disease who present with chest pain and to correlate EST results with echocardiographic findings. DESIGN: Retrospective chart review over a 14-month period. SETTING: Cardiology clinic at an academic children's hospital. PATIENTS: Two hundred three pediatric patients who presented to a pediatric cardiologist and had an EST for chest pain. OUTCOME MEASURES: Correlate EST results with echocardiographic findings and the patient's ultimate diagnosis. METHODS: Retrospective review of patients who presented to cardiology clinic for chest pain, analysis of medical records, EST, echocardiograms, and other downstream testing. RESULTS: Of 433 patients who presented to a pediatric cardiologist for chest pain, 203 (47%) had an EST performed. One hundred seventy-six (87%) patients did not have a prior diagnosis of congenital heart disease and made up our study population. Mean age was 13.2 ± 3 years. Of the patients who had an EST, 139 (79%) had chest pain with exercise. Echocardiography was performed in 124 (70%) of the patients who had an EST. Of patients undergoing echocardiography, 17/124 (14%) had abnormalities, but none of the abnormalities found were thought to contribute to the patients' chest pain. There were only four (2%) abnormal EST, and none were thought to be diagnostic for the patients' symptoms of chest pain. The most common diagnoses were musculoskeletal chest pain in 34 patients (19%) and reactive airway disease in 27 patients (15%). CONCLUSION: In children referred to pediatric cardiology clinic for chest pain, EST has a low yield in identifying cardiac abnormalities.

Magnetic versus manual catheter navigation for ablation of free wall accessory pathways in children.

BACKGROUND: Transcatheter ablation of accessory pathway (AP)-mediated tachycardia is routinely performed in children. Little data exist regarding the use of magnetic navigation (MN) and its potential benefits for ablation of AP-mediated tachycardia in this population. METHODS AND RESULTS: We performed a retrospective review of prospectively gathered data in children undergoing radiofrequency ablation at our institution since the installation of MN (Stereotaxis Inc, St. Louis, MO) in March 2009. The efficacy and safety between an MN-guided approach and standard manual techniques for mapping and ablation of AP-mediated tachycardia were compared. During the 26-month study period, 145 patients underwent radiofrequency ablation for AP-mediated tachycardia. Seventy-three patients were ablated with MN and 72 with a standard manual approach. There were no significant differences in demographic factors between the 2 groups with a mean cohort age of 13.1±4.0 years. Acute success rates were equivalent with 68 of 73 (93.2%) patients in the MN group being successfully ablated versus 68 of 72 (94.4%) patients in the manual group (P=0.889). During a median follow-up of 21.4 months, there were no recurrences in the MN group and 2 recurrences in the manual group (P=0.388). There were no differences in time to effect, number of lesions delivered, or average ablation power. There was also no difference in total procedure time, but fluoroscopy time was significantly reduced in the MN group at 14.0 (interquartile range, 3.8-23.9) minutes compared with the manual group at 28.1 (interquartile range, 15.3-47.3) minutes (P<0.001). There were no complications in either group. CONCLUSIONS: MN is a safe and effective approach to ablate AP-mediated tachycardia in children.