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Biomedical subjects

Christopher S Snyder

Publications and source records attributed to Christopher S Snyder.

5 recordsLinked to original sources
PubMed2003

Frequency of recurrence among infants with supraventricular tachycardia and comparison of recurrence rates among those with and without preexcitation and among those with and without response to digoxin and/or propranolol therapy.

Approximately 60% of children with supraventricular tachycardia (SVT) develop their initial episode by 1 year of age. Despite resolution in most of these patients by 1 year, approximately 30% of the SVT will recur. We performed a retrospective review of all patients <1 year of age with SVT between January 1984 and December 2000. Recurrence was defined as documented SVT at >1 year of age. Patients were divided into: (1) a first line (FL) group (controlled with digoxin and/or propranolol) and (2) a second line (SL) group (requiring additional antiarrhythmics). The groups were divided based on the presence of preexcitation. The FL group included 116 patients, 20 of whom (17%) had Wolff-Parkinson-White (WPW) syndrome. The SL group included 34 patients, 21 of whom (62%) had WPW (p <0.001). Recurrence of SVT occurred in 32 patients (28%) in the FL group and in 23 patients (68%) in the SL group (p <0.001). SVT recurred in 36 of 41 patients (88%) with WPW compared with 19 of 109 patients (17%) without WPW syndrome (p <0.001). Logistic regression analysis demonstrated that the presence of WPW syndrome was associated with a 29-fold higher odds of SVT recurrence (p <0.001), and that patients with WPW syndrome were more likely to require additional antiarrhythmic therapy (p <0.001). Thus, patients with WPW syndrome who had SVT at <1 year of age have 29-fold higher odds of recurrence at >1 year of age versus those patients with preexcitation. These patients are also more likely to require additional antiarrhythmic therapy to control SVT. Furthermore, children with WPW syndrome who are refractory to treatment with digoxin and/or propranolol are at increased risk of SVT recurrence.

Age of Onset↗
PubMed2002

Flecainide and sotalol: a new combination therapy for refractory supraventricular tachycardia in children <1 year of age.

OBJECTIVES: The goal of this study was to assess the efficacy and safety of the combination therapy of flecainide and sotalol for the treatment of refractory supraventricular tachycardia (SVT) in children <1 year of age. BACKGROUND: Supraventricular tachycardia in infants can be refractory to single-drug as well as standard combination medical therapy. Radiofrequency ablation (RFA) is the definitive treatment of refractory SVT; however, interventional therapy poses a high risk of morbidity and mortality in this age group. METHODS: A retrospective review was performed identifying infants who required flecainide and sotalol to control refractory SVT. Patient age, previous drug therapy, duration of treatment, flecainide levels and corrected QT intervals were recorded; 24 h Holter monitoring was utilized to gauge efficacy of treatment. Efficacy was defined as suppression of SVT to no more than rare nonsustained episodes or slowing of SVT to a clinically tolerable rate. RESULTS: Ten patients (median age: 29 days, range: 1 to 241 days) failed at least two antiarrhythmic agents including either flecainide or sotalol as single agents before initiating combination therapy. Efficacy was achieved in all patients. The failure rate for therapy was reduced from 100% to 0% (95% confidence interval: 0% to 26%). The median doses used were: flecainide 100 mg/m(2)/day (range: 40 to 150 mg/m(2)/day) and sotalol 175 mg/m(2)/day (range: 100 to 250 mg/m(2)/day). Median duration of therapy was 16 months (range: 5 to 35 months). No proarrhythmia occurred. CONCLUSIONS: The combination of flecainide and sotalol can safely and effectively control refractory SVT and may obviate the need for RFA in children <1 year.

Anti-Arrhythmia Agents↗
PubMed2002

Intraoperative radiofrequency ablation of the atrium: effectiveness for treatment of supraventricular tachycardia in congenital heart surgery.

BACKGROUND: Supraventricular tachycardia (SVT) is common in surgical patients with congenital heart disease. Ablation and maze operations have been shown to be effective in treating SVT, but these procedures can be complex and time-consuming because of variable anatomy and a thickened right atrium. To simplify and shorten these procedures, we used a long, flexible radiofrequency probe capable of producing long ablation lines quickly and effectively. We report the initial results with this procedure. METHODS: Six patients aged 6 weeks to 40 years with refractory SVT were referred for reoperation for repair of complex congenital heart disease (transposition of the great vessels, Ebstein's anomaly, single ventricle, tetralogy of fallot). Intraoperative radiofrequency ablation was performed in the right atrium for refractory SVT as an adjunct to surgical reconstruction (redo Fontan, right atrial reduction plasty, right ventricular outflow tract reconstruction, tricuspid repair). Lesions were made with a radiofrequency probe using temperatures of 70 degrees C for 60 seconds. Lesions were placed between the coronary sinus and the tricuspid valve, between the tricuspid valve and the inferior vena cava, between the atrial septal defect and the superior and inferior vena cava in patients with intraatrial reentry tachycardia/atrial flutter, and at the location of the accessory pathway in a patient with Wolff-Parkinson-White syndrome. The long, flexible probe has multiple independently controlled segments allowing ablation lesions that conform to the atrial morphology. RESULTS: An average of five intraoperative radiofrequency ablation lesions per patient were made. Average time for ablation was 14 minutes. With up to 25 months' follow-up, 5 patients are in sinus rhythm, and 1 is in a paced atrial rhythm. The patient with Wolff-Parkinson-White syndrome showed no preexcitation after operation. No complications resulting from intraoperative radiofrequency ablation were encountered. CONCLUSIONS: Intraoperative radiofrequency ablation in the atrium is a safe, effective, and expeditious procedure for control of SVT in patients undergoing reoperation for congenital heart disease with refractory SVT.

Adolescent↗
PubMed2002

Sinus node dysfunction associated with lithium therapy in a child.

Lithium salts have been used extensively in both adults and children during the last 30 years, for the treatment of a variety of psychiatric conditions, including bipolar disorder The cardiac side effects of lithium in adult patients have been well described. However, to the best of our knowledge, there are no reports of lithium-induced cardiac side effects in pediatric patients. We describe the case of a 9-year-old boy who developed cardiac toxicity while receiving long-term lithium therapy.

Child↗