Efficacy and safety of amiodarone in infants.
Explore the source record for details and available documents.
Amiodarone↗
Biomedical subjects
P C Gillette
Publications and source records attributed to P C Gillette.
Prospective study of the electrocardiographic effects of imipramine in children.
Because imipramine and desipramine have been implicated in sudden death in children, noninvasive electrophysiologic data were accumulated in 25 patients. Two children were excluded on the basis of resting electrocardiographic and Holter abnormalities. The remaining 23 patients received imipramine to a maximum dose of 5 mg/kg or a serum level of 150 to 250 ng/ml. Consistent but clinically insignificant resting electrocardiographic changes occurred during treatment. Ambulatory electrocardiographic monitoring may be useful when one is assessing the cardiovascular risks of imipramine therapy.
Adolescent↗
Automatic atrial and junctional tachycardias in the pediatric patient: strategies for diagnosis and management.
Unlike supraventricular arrhythmias secondary to reentry, automatic rhythm disturbances in children are rare and more resistant to standard pharmacological therapy. This article reviews strategies for the diagnosis and management of two of the more common pediatric automatic rhythm disturbances, that is, atrial ectopic tachycardia, and junctional ectopic tachycardia. The place of newer nonpharmacological therapy, such as catheter ablation, in the treatment of these entities is beginning to be explored, yet has not been fully delineated. Despite these limitations, there is enough experience with these difficult tachycardias in the pediatric age group to formulate some strategies for optimal diagnosis and management.
Adolescent↗
Actuarial survival of transvenous pacing leads in a pediatric population.
This study was undertaken to examine the actuarial survival of endocardial pacing leads in a pediatric population. We prospectively followed 148 children and young adults age 4 months to 38 years. Of these, 58 had normal cardiac anatomy and 90 had surgically corrected congenital heart disease. A total of 213 leads were inserted in these patients. Actuarial analysis showed that at 5 years 76.0% of the pacemaker leads were still in use. The reasons for abandonment included death (10), exit block (8), lead fracture (8), adapter malfunction (7), and other including infection, lead migration, and pacemaker malfunction (12). Excluding deaths, an actuarial survival curve was constructed. Stepwise discriminant analysis and independent measures of association showed a significant difference in lead abandonment when the leads placed in the atrium were compared to those placed in the ventricle (30 vs 5; P < 0.0005). Lead insulating material, cardiac anatomy, and/or indication for pacemaker placement had no statistically significant impact on lead survival.
Actuarial Analysis↗
Radiofrequency catheter ablation of an accessory atrioventricular connection in a Fontan patient.
Radiofrequency catheter ablation is fast becoming the procedure of choice for the nonpharmacological treatment of atrioventricular connections that are responsible for debilitating tachycardias. We, herein, present a case of reentrant supraventricular tachycardia secondary to an atrioventricular connection in a Fontan patient that was successfully treated with radiofrequency catheter ablation.
Catheter Ablation↗
Ventricular lead transection and atrial lead damage in a young softball player shortly after the insertion of a permanent pacemaker.
Explore the source record for details and available documents.
Child↗
The long QT syndrome in children. An international study of 287 patients.
BACKGROUND: The Pediatric Electrophysiology Society studied children with the long QT syndrome (LQTS) to describe the features of LQTS in patients less than 21 years old, define potential "low-risk" and "high-risk" subpopulations, and determine optimal treatment. METHODS AND RESULTS: Patients less than 21 years old were included if either QTc was more than 0.44; they had unexplained syncope, seizures, or cardiac arrest preceded by emotion or exercise; or family history of LQTS. We found 287 patients from 26 centers in seven countries. Mean +/- SD age at presentation was 6.8 +/- 5.6; 9% presented with cardiac arrest, 26% with syncope, and 10% with seizures. Of those with symptoms, 67% had symptoms related to exercise. Family history was positive for long QT interval in 39% and for sudden death in 31%. Hearing loss was present in 4.5%. A normal QTc was present in 6%, and QTc of more than 0.60 was in 13%. Atrioventricular block occurred in 5%, but 13 of 15 patients had second-degree atrioventricular block (2:1), and only two of 287 had complete atrioventricular block. Ventricular arrhythmias were found on 16% of initial routine ECGs: 4% uniform premature ventricular contractions, 5% multiform premature ventricular contractions, 1% monomorphic ventricular tachycardia, and 6% torsade de pointes. Overall, treatment was effective for symptoms in 76% and for ventricular arrhythmias in 60%. There was no difference between propranolol and other beta-blockers in effective treatment. Left stellectomy was performed in nine patients, and defibrillators were implanted in four; no sudden death occurred in these 13 patients. In follow-up (duration, 5.0 +/- 4 years; age, 10.9 +/- 6.3 years), 5% had cardiac arrest, 4% had syncope, and 1% had seizures. The two multivariate predictors of symptoms at follow-up were symptoms at presentation and propranolol failure. Sudden death occurred in 8%; multivariate predictors of sudden death were length of QTc at presentation of more than 0.60 and medication noncompliance. CONCLUSIONS: The appearance of 2:1 atrioventricular block, multiform premature ventricular contractions, and torsade de pointes are relatively more common in children with LQTS than other children and should raise the index of suspicion for LQTS. Because 9% of patients presented with cardiac arrest and no preceding symptoms, perhaps prophylactic treatment in asymptomatic children is indicated. Asymptomatic patients with normal QTc and positive family history may be a low-risk group. Patients with QTc of more than 0.60 are at particularly high risk for sudden death, and if treatment is not effective, consideration should be given to cardiac sympathetic denervation, pacemaker implantation, and perhaps implantation of a defibrillator.
Adrenergic beta-Antagonists↗
Prophylactic treatment of swine with bretylium for experimental cardiac catheterization.
We evaluated a cryothermic ablation catheter for potential use in treating supraventricular tachycardia by cardiac catheterization in miniature swine. Cardiac catheterization was performed on anesthetized miniature swine by using multiple catheters that were inserted bilaterally by either percutaneous or cutdown techniques into the femoral veins. We performed electrophysiologic tests according to standard atrial and ventricular electrical stimulation protocols. Manipulation of catheters in the tricuspid valve area and right ventricle was an essential part of the study. During an initial study of five swine, catheter manipulation produced sustained and nonsustained ventricular tachycardia and ventricular fibrillation. To prevent arrhythmias, bretylium (5 mg/kg) was administered intravenously 10 minutes before catheter manipulation and repeated every 30 minutes throughout the procedure. Since the use of bretylium was instituted, there have been no cases of ventricular fibrillation in a series of 20 animals. We determined that bretylium is effective in the suppression of ventricular arrhythmias in swine undergoing cardiac catheterization.
Animals↗
Radiofrequency catheter ablation of incessant, medically resistant supraventricular tachycardia in infants and small children.
OBJECTIVES: This study retrospectively evaluates initial experience with radiofrequency catheter ablation in a group of seven infants and small children with a history of incessant, medically resistant supraventricular tachycardia. METHODS: Before attempted catheter ablation, all patients had had unsuccessful conventional medical therapy (with digoxin or propranolol, or both) and, in addition, each continued to have daily episodes of supraventricular tachycardia while taking amiodarone or a class IC antiarrhythmic agent alone or in combination. The average patient age was 10 months (range 1 to 27) and the average patient weight was 6 kg (range 3 to 13). Electrophysiologic diagnosis included reentrant supraventricular tachycardia in six patients and atrial ectopic tachycardia in one patient. RESULTS: These seven patients underwent a total of nine catheter ablation procedures. The atrial approach to ablation was employed in eight of the nine procedures. Overall, radiofrequency catheter ablation was totally successful in five of the seven patients, partially successful in one patient and unsuccessful in the remaining patient. The combination of radiofrequency catheter ablation and surgical ablation was successful in controlling tachycardia in all patients; with at least 5 months of follow-up study, no patient has had a recurrence of supraventricular tachycardia or reappearance of a delta wave. CONCLUSIONS: Surgical ablation of arrhythmogenic substrates in the pediatric age group, although rarely indicated, has been found in the past to be safe and effective. Our initial experience with radiofrequency catheter ablation in infants and small children demonstrates that this procedure is a promising nonpharmacologic therapeutic alternative to surgical ablation.
Catheter Ablation↗
Successful treatment of medically refractory ventricular fibrillation with emergency cardiopulmonary bypass in an adolescent with corrected complex congenital heart disease.
Explore the source record for details and available documents.
Adolescent↗
The developmental electrophysiologic effects of moricizine HCl on the canine cardiac Purkinje fiber.
Using standard microelectrode techniques, the developmental cellular electrophysiologic effects of moricizine HCl on adult and neonatal canine Purkinje fibers were studied. Steady state and rate-related changes in the transmembrane action potentials produced by moricizine HCl in both age groups were characterized and compared. Also, the rate of barium-induced abnormal automaticity before and after drug was also investigated in neonatal and adult Purkinje fibers. The major findings of this study are as follows. (1) The steady state and rate-related depressant effects of moricizine HCl on Vmax were similar in both age groups. (2) Moricizine HCl shortened APD90 in the adult fibers to a greater extent than in the neonate. (3) The concentration of moricizine HCl required to significantly reduce the rate of abnormal automaticity was less in the neonate than in the adult. The effect of moricizine HCl on APD90 of individual Purkinje fibers is influenced both by their control APD90 value as well as by maturational factors. It is less clear whether developmental differences in the effects of moricizine HCl on abnormal automaticity are solely a result of differences in control rates of abnormal automaticity between the two age groups.
Action Potentials↗
Adenosine's effectiveness in long RP' re-entrant tachycardia: additional evidence of the decremental qualities of the retrograde limb.
Adenosine's ability to terminate atrioventricular (AV) re-entrant supraventricular tachycardia is well documented. Typically, termination occurs as a consequence of transient conduction block in the atrioventricular node, a tissue with decremental qualities. However, the atrioventricular node is not always the site of action when adenosine is used on the re-entrant types of long RP' tachycardias. These tachycardias are, in part, characterized by the decremental qualities of the retrograde limb of the tachycardia circuit, which, in turn, are typically exemplified by retrograde Wenckebach during ventricular (VVI) pacing during intracardiac electrophysiology studies. This case report involves adenosine's ability to block conduction in the retrograde limb of the permanent form of junctional reciprocating tachycardia to provide further evidence as to the AV "nodelike" decremental qualities of this limb.
Adenosine↗
Subcutaneous lidocaine affects inducibility in programmed electrophysiology testing in children: a follow-up study.
Invasive cardiac electrophysiology testing during cardiac catheterization requires local anesthesia at the point of entry for the catheters. Frequently, lidocaine is employed for this purpose. A prospective study completed in 1990 indicated that subcutaneous administration of lidocaine adversely influenced the inducibility of arrhythmias in pediatric patients. Upon completion of that study, lidocaine concentration was reduced from 1% to 0.5%, and extra caution was taken to avoid deep penetration during administration. A follow-up, prospective study was performed to evaluate inducibility under these changed conditions. Because the depressant effect of lidocaine on inducibility was age- and weight-related, the second study group was required to have statistically indistinguishable age and weight distributions from the first group to eliminate these variables as factors in inducibility. A total of 177 subjects were collected in the second group before a periodic random computer match with the first group produced 99 individuals with the required age and weight distributions. Analysis of the electrophysiology tests in the second study revealed that: (1) incidence of inducibility was higher in the second group (58 of 99 versus 43 of 99, p < 0.05); (2) average lidocaine dose per kilogram was lower (1.8 mg/kg versus 3.28 mg/kg, p < 0.0001); (3) average lidocaine serum concentration was also lower (0.58 micrograms/ml versus 1.47 micrograms/ml, p < 0.0003); (4) in contrast to the first study, neither lidocaine dose nor serum concentration had any effect on inducibility. We conclude that the new procedures for lidocaine administration effectively removed lidocaine as a factor in inducibility.
Adolescent↗
Successful radiofrequency catheter ablation of an atrial ectopic tachycardia in an adolescent.
Explore the source record for details and available documents.
Adolescent↗
Life-threatening postoperative junctional ectopic tachycardia.
Junctional ectopic tachycardia developed in an infant after intraatrial repair of transposition of the great arteries. He failed to respond to medical management and, in moribund condition, underwent His bundle cryoablation. He survived and ultimately did well. Junctional ectopic tachycardia is not uncommon after open heart operations in children and may be lethal. Its genesis, diagnosis, and treatment are now well enough understood to allow successful treatment of nearly all patients.
Atrioventricular Node↗
Atrioventricular pacing in congenital heart disease.
We have attempted to optimize cardiac performance in patients with congenital heart disease requiring artificial pacing by using pacemakers capable of both sensing and pacing both the atrium and the ventricle (DDD). We reviewed our results with 88 patients receiving DDD devices to determine the safety and dependability of these devices in children. Age ranged from 1 hour to 25 years. Endocardial leads were used in 68 patients, whereas epicardial leads were used in 20 patients. Previous cardiac procedures had been done in 30 patients. There were nine deaths but none due to pacemaker malfunction. Endocardial leads functioned better than epicardial leads. Ninety-eight percent of patients with endocardial leads and 62% of patients with epicardial leads were maintained in the DDD mode. Complications were infrequent and all were corrected without long-term sequelae. The DDD mode may offer considerable benefits to children who require artificial pacing. Our data allow us to conclude that most children can be paced safely and dependably in the DDD mode.
Adolescent↗
Cardiomyopathy and myocarditis in children with ventricular ectopic rhythm.
OBJECTIVE: The objective of this study was to evaluate the histologic features of the myocardium in children with abnormal ventricular ectopic rhythm but a structurally normal heart. BACKGROUND: Abnormal ventricular ectopic rhythm in children with a structurally normal heart is an uncommon but serious condition. Previous studies in adults with these findings have shown that approximately 10% have "primary electrical disease" and that 40% to 100% of these have abnormal histologic findings. METHODS: Endomyocardial biopsy samples were obtained prospectively in 33 subjects presenting with ventricular ectopic rhythm but a structurally normal heart by physical examination and noninvasive studies. Biopsy specimens were evaluated for histologic changes consistent with dilated cardiomyopathy or myocarditis and these results were compared with noninvasive and invasive clinical findings. RESULTS: Of the 33 subjects, 16 (48%) had normal myocardial histologic features (Group A), 14 (42%) had changes similar to the histologic features seen with idiopathic dilated cardiomyopathy (Group B) and 3 (9%) had lymphocytic myocarditis (Group C). Presenting clinical symptoms, surface electrocardiograms (ECGs), exercise stress testing and electrophysiologic stimulation tests failed to predict the biopsy results. Twenty-four-hour ambulatory ECGs showed a statistical difference between sustained and nonsustained ventricular tachycardia in Group A versus Group B (p less than 0.007), with Group A having more sustained ventricular tachycardia. Left ventricular function measured by fractional shortening on echocardiography did not differ between groups, but left ventricular end-diastolic dimension was greater in the subjects with abnormal histologic findings (Group B) (p less than 0.03). CONCLUSIONS: These results provide evidence that approximately 50% of children with abnormal ventricular ectopic rhythm but a structurally normal heart may have subclinical cardiomyopathy or unsuspected myocarditis.
Biopsy↗
Surgical management of dysrhythmias in infants and small children.
Surgery for cardiac dysrhythmias is infrequently reported in infants and children as compared with adults. This report reviews 55 infants and small children (age, less than or equal to 5 years) operated on during the interval July 1, 1984 to December 31, 1991 for Wolff-Parkinson-White Syndrome (41), atrioventricular node reentry (two), atrial automatic tachycardia (two), and ventricular tachycardia (nine). Ages ranged from 3 weeks to 71 (mean, 29) months. Associated congenital heart defects were present in five (10%). Indications for surgery included failure of medical therapy, life-threatening dysrhythmias, and more recently, failure of catheter ablation. There were no hospital or late deaths. One patient sustained perioperative central nervous system injury. Surgery was successful in 52 of 55 (94.5%) (Wolff-Parkinson-White, 38/41 (93%); atrioventricular node reentry, 2/2 (100%); atrial automatic tachycardia, 3/3 (100%); ventricular tachycardia, 9/9 (100%). Ventricular function returned to normal in all 12 patients in whom it was abnormal before operation. Thus, surgical ablation is highly successful in the management of various forms of refractory or life-threatening dysrhythmias in infants and small children. Catheter ablation techniques require significant fluoroscopic time, are more difficult in infants, and as yet do not have adequate long-term follow-up. Accordingly, surgery may continue to play a role in this particular group of patients.
Arrhythmias, Cardiac↗