Medications used to manage supraventricular tachycardia in the infant a North American survey.

Supraventricular tachycardia is the most common pediatric arrhythmia, but there is no consensus and little evidence to guide its treatment. We sent a questionnaire to pediatric cardiologists in North America to assess the current practice pattern. Of 1534 surveys mailed, 352 (23%) were returned and 295 (19%) had complete data for analysis. In the acute setting, 11 different medications were chosen. The most commonly used in the infant without preexcitation were digoxin (42%), procainamide (21%), esmolol (13%), propranolol (10%), and amiodarone (8%). In the infant with preexcitation, propranolol (34%), procainamide (23%), esmolol (17%), amiodarone (11%), and digoxin (6%) were used. In the chronic setting, 8 different medications were chosen. The most commonly used in this scenario were digoxin (52%), propranolol (33%), amiodarone (4%), and sotalol (3%). In the infant with preexcitation, propranolol (70%), amiodarone (6%), digoxin (6%), atenolol (6%), and flecainide (5%) were used. Medication choices were influenced by additional electrophysiology training and preexcitation. Digoxin was used less in the setting of preexcitation. There are no comparative trials to explain the different medication choices. Although a number of medications may be efficacious, a randomized clinical trial is needed to offer further guidance.

Andersen-Tawil syndrome: prospective cohort analysis and expansion of the phenotype.

Andersen-Tawil syndrome (ATS) is an autosomal dominant multisystem disorder characterized by developmental, cardiac, and neuromuscular abnormalities. Approximately 70% of patients have mutations in KCNJ2, resulting in dysfunction of the inward-rectifying potassium channel Kir2.1. Variable expression complicates the diagnosis of ATS, which in many cases, is not made until years after the first recognized symptom. To better define the distinctive clinical features of ATS and facilitate earlier diagnosis, we conducted a prospective, standardized evaluation of 10 subjects with confirmed KCNJ2 mutations. Detailed anthropometric, neurological, and cardiac evaluations were performed. Using this approach, we identified novel skeletal and dental findings and proposed additional diagnostic criteria for ATS dysmorphology.

Radiofrequency ablation for supraventricular tachycardia in children < or =15 kg is safe and effective.

Risks associated with radiofrequency ablation (RFA) have been reported to be increased in children < or =15 kg. We sought to compare the safety and efficacy of RFA in children <15 kg with those between 15.1 and 20 kg. Clinical, electrophysiologic, and RFA data for all patients < or =20 kg who underwent RFA for supraventricular tachycardia between January 1994 and January 2003 were reviewed. Patients were divided into those < or =15 kg (group 1, n = 25) and those between 15.1 and 20 kg (group 2, n = 44). The two groups differed significantly in age and weight by design (group 1: mean weight, 11.9 +/- 3.0 kg; age, 2.8 +/- 1.9 years; group 2: weight, 18.0 +/- 1.5 kg; age, 5.1 +/- 1.1 years). There were no significant differences in other baseline characteristics except for incidence of structural heart disease (28% group 1 vs 7% group 2, p < 0.01). No significant differences in mechanism of tachycardia, arrhythmia cycle length, number of total and brief RFA applications, total RFA time, average and maximum RFA temperatures, total procedure duration, short-term success rate (96% group 1 vs 86% group 2, p = 0.17), long-term success rate (91% group 1 vs 89% group 2, p = 0.76), or major complications (8.0% group 1 vs 2.3% group 2, p = 0.39) were found. There were no procedure-related deaths in either group. These data suggest that, in two large volume electrophysiology centers, the procedural risks and outcomes of RFA are similar between patients weighing less than 15 kg and those between 15.1 and 20 kg.

Successful pediatric stenting of a nonthrombotic coronary occlusion as a complication of radiofrequency catheter ablation.

This is a case of a right coronary artery occlusion complicating a RF catheter ablation of a posteroseptal accessory connection in an 8-year-old boy. After multiple balloon angioplasty attempts in the occluded vessel, only transient patency was achieved. The occlusion was successfully treated with placement of an intracoronary stent.

Intra-atrial conduction block along the mitral valve annulus during accessory pathway ablation: evidence for a left atrial "isthmus".

INTRODUCTION: We observed a change in the atrial activation sequence during radiofrequency (RF) energy application in patients undergoing left accessory pathway (AP) ablation. This occurred without damage to the AP and in the absence of a second AP or alternative arrhythmia mechanism. We hypothesized that block in a left atrial "isthmus" of tissue between the mitral annulus and a left inferior pulmonary vein was responsible for these findings. METHODS AND RESULTS: Electrophysiologic studies of 159 patients who underwent RF ablation of a left free-wall AP from 1995 to 1999 were reviewed. All studies with intra-atrial conduction block resulting from RF energy delivery were identified. Fluoroscopic catheter positions were reviewed. Intra-atrial conduction block was observed following RF delivery in 11 cases (6.9%). This was evidenced by a sudden change in retrograde left atrial activation sequence despite persistent and unaffected pathway conduction. In six patients, reversal of eccentric atrial excitation during orthodromic reciprocating tachycardia falsely suggested the presence of a second (septal) AP. A multipolar coronary sinus catheter in two patients directly demonstrated conduction block along the mitral annulus during tachycardia. CONCLUSION: An isthmus of conductive tissue is present in the low lateral left atrium of some individuals. Awareness of this structure may avoid misinterpretation of the electrogram during left AP ablation and may be useful in future therapies of atypical atrial flutter and fibrillation.

Radiofrequency catheter ablation of left-sided accessory pathways in pediatric patients.

In many cases, radiofrequency catheter ablation has replaced the long-term use of antiarrhythmic medication for symptomatic tachycardia, and has all but eliminated arrhythmia surgery. The most common substrate for radiofrequency catheter ablation in pediatric patients is atrioventricular (AV) reentry tachycardia due to a concealed or manifest accessory pathway. Accessory pathways are distributed unevenly along the right and left atrioventricular valve annuli, and left-sided accessory pathways are most common. Although some centers advocate an abbreviated diagnostic and mapping approach to both concealed and manifest left-sided accessory pathways, most still use a complete electrophysiological evaluation and complex catheter manipulation for mapping, followed by the application of radiofrequency energy. Left-sided accessory pathways may be approached from the transatrial approach, the retrograde aortic approach, or less commonly from within the coronary sinus. Each approach has proven to be associated with success, but also with a distinct set of risks. Possibly because left-sided accessory pathways are most common, catheter ablation of this substrate has proven highly successful and has the lowest risk of recurrence. However, recent data also suggest that this substrate is associated with greater risk of complications than of right-sided accessory pathways or pathways located in the posteroseptal region. The following report reviews some of the recently described diagnostic and mapping techniques, success rates, risks and follow-up data in pediatric patients undergoing radiofrequency catheter ablation of left-sided accessory pathways.

An unusual cause of severe cyanosis in infancy.

An infant presented with cyanosis due to a diaphragmatic Morgagni hernia compromising right ventricular diastolic filling and resulting in right-to-left atrial-level shunting as demonstrated by contrast echocardiography. There was complete resolution of cyanosis after repair of the hernia.

Amiodarone is safe and highly effective therapy for supraventricular tachycardia in infants.

BACKGROUND: The clinical effectiveness of amiodarone must be weighed against the likelihood of adverse effects. Adverse effects are less common in children than in adults, yet there have been no large studies assessing the efficacy and safety of amiodarone in the first 9 months of life. We sought to assess the safety and efficacy of amiodarone as primary therapy for supraventricular tachycardia in infancy. METHODS: We evaluated the clinical course of 50 consecutive infants and neonates (1.0+/-1.5 months, 35 male) treated with amiodarone for supraventricular tachyarrhythmias between July 1994 and July 1999. At presentation, congenital heart disease, congestive heart failure, or ventricular dysfunction were present in 24%, 36%, and 44% of the infants, respectively. Infants received a 7- to 10-day load of amiodarone at either 10 or 20 mg/kg/d. If this failed to control the arrhythmia, oral propranolol (2 mg/kg/d) was added. Patients were followed up for 16.0+/-13.0 months, and antiarrhythmic drugs were discontinued as tolerated. RESULTS: Rhythm control was achieved in all patients. Of the 34 patients who have reached 1 year of age, 23 (68%) have remained free of arrhythmia, despite discontinuation of propranolol and amiodarone. Growth and development remained normal for age. Higher loading doses of amiodarone were associated with an increase in the corrected QT interval, but no proarrhythmia was seen. There were no side effects necessitating drug withdrawal. CONCLUSIONS: Amiodarone is an effective and safe therapy for tachycardia control in infancy.

What is the yield of screening echocardiography in pediatric syncope?

OBJECTIVE: To determine the yield of screening echocardiography in the evaluation of pediatric syncope. DESIGN: All patients diagnosed with syncope from January 1993 to January 1999 were identified and their records were reviewed for age, weight, sex, year of presentation, personal and family history, physical examination, and cardiac diagnostic testing. Cardiac defects were identified by reviewing echocardiograms and reports. RESULTS: The 480 patients (268 females) ranged in age from 1.5 to 18.0 years old and ranged in weight from 10.3 to 113.6 kg. Final diagnoses included noncardiac causes in 458, long QT syndrome in 14, arrhythmias in 6, and cardiomyopathy in 2. An abnormal history, physical examination, or electrocardiogram identified 21 of the 22 patients with a cardiac cause of syncope. Of the 322 (67%) echocardiograms performed, abnormalities were detected in 37. These abnormalities included 26 minor valve anomalies, 7 hemodynamically insignificant shunt lesions, 2 mildly decreased left ventricular shortening fractions, and 2 cardiomyopathies. Only the 2 cardiomyopathies were considered to be potential causes of syncope, and in both cases, the electrocardiogram was markedly abnormal. A similar percentage of echocardiograms were ordered during the first and last 3 years of the study (61% vs 71%). CONCLUSION: History, physical examination, and electrocardiography provide a screening protocol that allows the identification of a cardiac cause of syncope in the overwhelming majority of pediatric patients. In the absence of a positive screen result, the echocardiogram does not contribute to the evaluation of syncope in children. We speculate that primary care providers and pediatric cardiologists continue to use echocardiography because of the paucity of data regarding its value in pediatric syncope. However, this study shows little benefit of screening echocardiography and should discourage its routine use.

Spontaneous resolution of ventricular arrhythmias with left bundle branch block morphology and abnormal endomyocardial biopsy.

Four children presenting with ventricular tachycardia with a left bundle branch block morphology were evaluated and found to have structurally normal hearts but abnormal endomyocardial biopsies. All four children had spontaneous resolution of their ventricular rhythm abnormalities during follow-up.

Supraventricular tachycardia in infancy: evaluation, management, and follow-up.

BACKGROUND: Supraventricular tachycardia (SVT) occurs frequently in infancy. However, some infants have no recurrences after the initial presentation of SVT, and approximately 30% of infants lose SVT inducibility by 1 year of age. OBJECTIVE: To determine whether features at presentation, tachycardia characteristics, or data from an esophageal electrophysiology (EP) study could predict which infants will not require antiarrhythmic medication and which infants will not have inducible SVT at 1 year. DESIGN: Clinical and tachycardia characteristics at presentation of SVT and data obtained from an esophageal EP study were evaluated prospectively. Patients were followed up for 1 year, and an esophageal EP study was performed to evaluate for continued SVT inducibility. SETTING: Primary Children's Medical Center is a tertiary care hospital affiliated with the University of Utah that provides primary care to local patients and is a referral center for a 4-state region. PATIENTS: All infants aged 3 months or younger who presented with SVT between August 1995 and October 1997 were evaluated. INTERVENTIONS: An esophageal EP study was performed at diagnosis and at 1 year. RESULTS: The SVT was controlled in all 33 infants. At the initial esophageal EP study, the mechanism of SVT was atrioventricular node reentry in 5 patients (15%) and orthodromic reciprocating tachycardia via an accessory atrioventricular connection in 28 patients (85%). One infant was lost to follow-up, 5 never required medication, 11 had SVT controlled with propranolol hydrochloride, 10 had SVT controlled with amiodarone, and 6 required more than 1 medication. Of the 21 patients who have reached 1 year of age, 16 (76%) were not taking any medication and were free of SVT at the time of follow-up. All 16 patients without clinical SVT have undergone a follow-up esophageal EP study, and 11 of 16 had inducible SVT on esophageal EP study. Thus, of the 21 one-year-old patients, 5 (24%) no longer had clinical or inducible SVT. CONCLUSIONS: Control of SVT was possible in all patients. Clinical episodes of SVT were uncommon after discharge, yet most still had inducible SVT at 1 year of age. No data at presentation or initial esophageal EP study were predictive of the clinical course or of continued SVT.

Usefulness of echocardiography for detection of coronary artery thrombi in patients with Kawasaki disease.

To evaluate the role of echocardiography for predicting and accurately detecting thrombi in patients with abnormal coronary arteries after Kawasaki disease, we reviewed the echocardiograms of 40 consecutive patients and compared echocardiographic findings with angiographic findings when available. Patients with Kawasaki disease who had coronary artery aneurysms > or =5 mm had significantly greater multivessel involvement, thrombi, and persistent coronary abnormalities than those with diameters <5 mm.

Platelet glycoprotein IIb/IIIa receptor blockade therapy for large coronary aneurysms and thrombi in Kawasaki disease.

A 4-month-old girl with Kawasaki disease, large coronary artery aneurysms, and coronary thrombi was treated with standard therapy followed by abciximab, a platelet glycoprotein IIb/IIIa antagonist, in addition to standard heparin and warfarin sodium anticoagulation and low-dose aspirin. She did not develop evidence of ischemia, had no complications from the therapy, and showed resolution of the aneurysms and thrombi after 6 wk of therapy.

Echocardiographic-guided internal jugular venous cannulation in children with heart disease.

OBJECTIVE: To determine if cannulation of the internal jugular vein (IJV) with echocardiographic guidance increases the success and decreases the complications of the procedure when performed in children with heart disease. DESIGN: Twenty-five consecutive pediatric patients with heart disease who underwent IJV cannulation with echocardiographic guidance between September 1986 and March 1992. SETTING: University hospital referral center serving a four-state area. PATIENTS AND OTHER PARTICIPANTS: Ambulatory patients were admitted for this procedure and then discharged at its completion; others included hospitalized patients. All patients were between the ages of 6 weeks and 21.8 years. All patients underwent IJV cannulation performed by a member of the Pediatric Cardiology Division at the University of Minnesota, Minneapolis. All patients either underwent heart transplant, and IJV access was obtained to perform an endomyocardial biopsy or had congenital heart disease, and the IJV was cannulated to perform a heart catheterization. Written consent was obtained either from the patient, if 18 years of age or older, or a parent or legal guardian. INTERVENTION: Cannulation of the IJV using echocardiographic guidance. MAIN OUTCOME MEASURES: Would IJV cannulation with echocardiographic guidance improve safety and diminish complications of the procedure when performed in pediatric patients with heart disease? We compared the results of our evaluation with published results in which echocardiographic guidance was not used. RESULTS: Cannulation of the IJV with echocardiographic guidance was performed successfully on 138 occasions in 25 pediatric patients. There were no lasting complications and no deaths using this method of venous access. CONCLUSIONS: As in the adult population, IJV cannulation with the assistance of echocardiography increases the success of the procedure and decreases the number of complications. Furthermore, echocardiographic guidance allows for repeated IJV cannulation in pediatric patients, regardless of age.

Cytomegalovirus colitis in a pediatric heart transplant patient.

Cytomegalovirus colitis is one of the sequelae of cytomegalovirus infection in transplant patients and can be associated with severe consequences. This case details the clinical, radiographic, and laboratory features of this infection in a child after heart transplantation where early recognition and treatment resulted in complete resolution of the disease.

Therapeutic and diagnostic utility of adenosine during tachycardia evaluation in children.

Adenosine has become the drug of choice for termination of regular, normal QRS tachycardia. Initial studies in adult and pediatric patients have shown that the drug is effective for tachycardias using the atrioventricular (AV) node as an integral part of the tachycardia circuit and has few serious side effects. Experience with adenosine administration in children was reviewed to examine the diagnostic and therapeutic usefulness, effective dose, and adverse effects of adenosine. Adenosine was administered to 38 children during 50 separate electrophysiologic evaluations. Eleven patients had structural or acquired heart disease. Tachycardia mechanisms included orthodromic-reciprocating tachycardia using an accessory AV connection (23 patients), primary atrial tachycardia (6 patients), AV node reentrant tachycardia (3 patients), ventricular tachycardia (2 patients), postoperative junctional tachycardia (1 patient), and antidromic-reciprocating tachycardia (1 patient). Adenosine successfully terminated 51 of 53 episodes (96%) of tachycardia using the AV node, 5 of 10 primary atrial tachycardias, 1 of 1 junctional tachycardia, and 1 of 3 ventricular tachycardias. Reinitiation of tachycardia was seen after 16 of 58 successful terminations (28%), reducing the effectiveness to 39 of 53 (74%) for tachycardia requiring the AV node. Average effective dose was 132 micrograms/kg, range 50 to 250 micrograms/kg, and was slightly higher for peripheral (147 micrograms/kg) than for central (120 micrograms/kg) administration. Significant complications occurred in 4 of 38 patients, including atrial fibrillation, accelerated ventricular tachycardia, apnea, and 1 minute of asystole. Although adenosine is useful therapeutically and diagnostically in children with tachycardia, its effectiveness is limited by tachycardia reinitiation and adverse effects. Higher doses may be required for peripheral intravenous administration.