Arnold L. Fenrich

Cisapride-induced long QT interval

A 2-month-old infant with gastroesophageal reflux was treated with cisapride. Bradycardia developed and an electrocardiogram revealed 2:1 atrioventricular conduction and a prolonged QT interval. After cessation of cisapride therapy, both the rhythm and the QT interval returned to normal. Prolonged QT interval during treatment with cisapride may occur in children as in adults.

Innovative techniques for placement of implantable cardioverter- defibrillator leads in patients with limited venous access to the heart

Background: Because of venous occlusion, intracardiac shunting, previous surgery, or small size placement of implantable cardioverter‐defibrillator (ICD) leads may not be possible using traditional methods. The purpose of this study was to evaluate and describe innovative methods of placing ICD leads.

The use of implantable cardioverter-defibrillators in pediatric patients awaiting heart transplantation

BACKGROUND This multicenter study evaluated experience with implantable cardioverter defibrillators (ICD) as a bridge to orthotopic heart transplantation (OHT) in children. METHODS The application of ICD therapy continues to expand in pediatric populations, due in part to improved technology and new indications, including the prevention of sudden death while awaiting OHT. METHODS We performed a retrospective review of ICD databases at 9 pediatric transplant centers. RESULTS Twenty-eight patients (16 males) underwent implantation or had a preexisting ICD while awaiting OHT between 1990 and 2002. The median age at implant was 14.3 years (11 months to 21 years) with a median weight of 49 kg (11.7-88 kg). Diagnoses included cardiomyopathy (n=22), and congenital heart disease (n=6). Indications for ICD implantation included ventricular tachycardia/fibrillation (n=23), syncope (n=5), aborted sudden death with no documentation of rhythm disturbance (n=5), ventricular ectopy (n=1), and poor function (n=5). Of the 28 ICDs, 23 were implanted by a transvenous approach and 5 by epicardial route. There were 55 defibrillator discharges in 17 patients, 47 (85%) of which (in 13 patients) were appropriate. The 8 inappropriate discharges (in 6 patients) were triggered by sinus tachycardia, inappropriate sensing, and atrial flutter. The mean time from implantation to first appropriate shock was 6.9 months (1 day to 2.6 years). Twenty-one patients underwent transplantation during the study period, whereas 2 died while awaiting a donor. Morbidity included a lead fracture, 3 episodes of electromechanical dissociation, and 1 episode of electrical storm. CONCLUSIONS ICD implantation represents an effective bridge to transplantation in pediatric patients. The complication rate is low, with inappropriate device discharge due primarily to sinus tachycardia or atrial flutter. There is a high incidence of appropriate ICD therapy for malignant ventricular arrhythmias in this highly selected group of patients.

Intravenous amiodarone for life-threatening tachyarrhythmias in children and young adults

OBJECTIVES The purpose of this study was to evaluate the efficacy of intravenous amiodarone in young patients. BACKGROUND Oral amiodarone therapy has proved useful for problematic arrhythmias in children, but its pharmacokinetics with the oral route preclude its use in several acute settings. METHODS Intravenous amiodarone was administered in 1-mg/kg body weight aliquots followed by continuous infusion to patients with potentially life-threatening tachyarrhythmias that had not been abolished by standard therapies. RESULTS Ten patients (mean age 6.8 years) received intravenous amiodarone: for ventricular tachycardia in seven patients and for atrial tachycardia, junctional tachycardia and multiple arrhythmias in one patient each. Surgery for congenital heart defects had been performed previously in six patients. Two patients had a hamartoma causing ventricular tachycardia. Six of 10 patients had complete resolution of arrhythmia with intravenous amiodarone: 4 of 7 with ventricular tachycardia, 1 of 1 with atrial tachycardia and 1 of 1 with postoperative junctional ectopic tachycardia. Intravenous amiodarone was not successful in the two patients with a hamartoma but slowed ventricular tachycardia in one, allowing successful surgical cure. Average drug load at the time of effect was 4.8 mg/kg body weight. Four patients had transient hypotension during loading, corrected with volume or low dose calcium. Intravenous infusion of amiodarone, 10 mg/kg per day, continued an average of 3 days. Four of 10 patients died, all of nonarrhythmic causes not attributable to intravenous amiodarone. CONCLUSIONS Intravenous amiodarone was well tolerated in this small series of patients. Postoperative ventricular tachycardia was responsive to intravenous amiodarone in 80% (8 of 10) of the patients (95% confidence interval 40% to 99%). Use of this drug in acute, postoperative tachyarrhythmias may be lifesaving in some patients when standard intravenous therapies fail.

Flecainide and amiodarone : combined therapy for refractory tachyarrhythmias in infancy

Objectives.: This study assessed the safety and efficacy of combined flecainide and amiodarone therapy in controlling refractory tachyarrhythmias in infants.Background.: Single-drug as well as stan...

Congenital complete atrioventricular block.

Congenital complete atrioventricular block is found in 1 of 22,000 live births. Over time, it has become apparent that these patients represent not a single distinct disease process, but several processes with the common manifestation of atrioventricular block. The evaluation of these patients to determine their risk of sudden death and need for pacing is not well defined.

Use of Intravenous Amiodarone for Postoperative Junctional Ectopic Tachycardia in Children

To assess the efficacy and safety of intravenous (IV) amiodarone for the treatment of postoperative junctional ectopic tachycardia (JET) in children, we retrospectively reviewed 11 patients treated with IV amiodarone for JET between 1/92 and 2/00. Data included heart rate and hemodynamics pre- and post-amiodarone, drug dosage, duration of therapy, and effect. Success was defined as reversion to sinus rhythm or slowing to a hemodynamically stable rate. The mean heart rate prior to amiodarone was 203 bpm, and the mean systolic blood pressure was 64 mmHg. Mean IV amiodarone loading dose was 8.2 ± 4.0 mg/kg, followed by an infusion in 7 patients at a dose of 12.9 ± 3.9 mg/kg/day for a duration of 74.3 ± 46.9 hours. At 1 hour post-load, mean heart rate was 147 bpm and mean systolic blood pressure was 88 mmHg for the group. Three patients were in sinus rhythm, 4 in intermittent sinus rhythm with accelerated junctional rhythm, and 4 patients solely accelerated junctional rhythm. Control of JET persisted in 9 patients. Of the two patients requiring additional treatment, both had received a 5 mg/kg load and neither was on an infusion. Five patients were paced at some point following amiodarone: four to improve hemodynamics and one for late sinus bradycardia. Side effects included hypotension with loading (1) and late sinus bradycardia (1). One patient was discharged on oral amiodarone. Intravenous amiodarone given in doses of 10 mg/kg in two 5 mg/kg increments, followed by an infusion of 10–15 mg/kg/day for 48–72 hours, appears to be safe and effective for postoperative JET in patients who fail conventional therapy or who are hemodynamically unstable. Long-term oral therapy is usually not necessary.

Stent dilation of superior vena cava and innominate vein obstructions permits transvenous pacing lead implantation.

The purpose of this study was to assess the feasibility of stent dilation of venous obstructions/occlusions to permit transvenous pacing lead implantation. Innominate vein or superior vena cava (SVC) obstruction may preclude the implantation of transvenous pacing leads. Patients with d‐transposition of the great arteries, after a Mustard or Senning procedure, and children with previously placed transvenous pacing leads are at higher risk for this vascular complication. From May 1993 to January 1996, eight pediatric patients who underwent transvenous pacing lead implantation or replacement were found to have significant innominate vein or SVC obstruction or occlusion. Utilizing in‐travascular stents, a combined interventional and electrophysiological approach was used to relieve the venous obstruction and to permit implantation of a new transvenous pacing lead. Two patients had complete SVC occlusion requiring puncture through the obstruction with a transseptal needle. Vessel recanalization was achieved with balloon dilation and stent implantation. The remaining six patients had severe venous obstruction with a mean minimum diameter of 3.1 ± 3.3 mm. The mean pressure gradient across the obstructed veins was 8.6 ± 7.3 mmHg. Following implantation of 15 Palmaz P308 stents in eight vessels, the mean diameter increased to 14.2 ± 1.9 mm and the mean pressure gradient across the stented vessels decreased to 1.0 ± 2.0 mmHg, A transvenous pacing lead was implanted successfully through the stent (s) immediately or 6–8 weeks later. Innominate vein and SVC obstruction can be safely and effectively relieved with intravascular stents and permit immediate or subsequent transvenous pacing lead implantation.

Persistence of ventricular arrhythmia after resolution of occult myocarditis in children and young adults.

OBJECTIVES We sought to examine whether resolution of occult myocarditis in children with associated ventricular arrhythmia correlated with the presence of arrhythmia at late follow-up. BACKGROUND Complex ventricular arrhythmias have been documented in children with myocarditis. Therapy is aimed at controlling the arrhythmia and any associated ventricular dysfunction. However, no reported studies have documented whether resolution of myocarditis in children is associated with resolution of the associated arrhythmias. METHODS We performed a retrospective analysis of 12 patients (mean age 12 years) with myocarditis. Ambulatory electrocardiographic (Holter) monitors were reviewed for ventricular arrhythmias at presentation and follow-up. Patients were assigned to Group I if they received corticosteroids in addition to any antiarrhythmic agents and to Group II if they did not receive steroids. Follow-up endomyocardial biopsy was performed in some patients, and results were analyzed in relation to the presence of arrhythmias at follow-up. RESULTS Eleven patients had ventricular tachycardia, and one had multiform couplets. Corticosteroids were given to seven patients (Group I). Follow-up biopsy was performed in seven patients (six received steroids), with resolution of inflammation in all; four of the seven still had ventricular arrhythmias but with improved control. Of the five patients without follow-up biopsy, three had persistent arrhythmia. Absence of inflammation at follow-up biopsy did not correlate with loss of ventricular arrhythmias, and there was no difference between Group I and II patients with respect to resolution of arrhythmia (Fisher exact test, p = 0.70, power 11%). CONCLUSIONS Complex ventricular arrhythmias persist after apparent resolution of occult myocarditis in children. Although these arrhythmias are easier to control after such resolution, the patients may require long-term antiarrhythmic therapy.

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.