Larry A. Rhodes

Transcatheter ablation of ectopic atrial tachycardia in young patients using radiofrequency current.

BackgroundEctopic atrial tachycardia (EAT) is a reversible cause of cardiomyopathy but may be quite difficult to control with conventional therapy. Transcatheter ablation with radiofrequency current was tested as an alternative to medical or surgical treatment of this condition Methods and ResultsTwelve young patients (aged 10 months to 19 years) with drug-resistant EAT were treated with direct transcatheter ablation of the ectopic focus using radiofrequency (RF) energy. All had depressed left ventricular contractility by echocardiographic criteria, involving shortening fractions of 10–26% (median, 20%; normal, 28–35%). The EAT was mapped to the left atrium in seven cases and to the right atrium in five. Local atrial activation at the ectopic site preceded the onset of the surface P wave by 20–60 msec (median, 42 msec). Tachycardia terminated 0.5–13.0 seconds (median, 2.0 seconds) into a successful RF application. The ablation effectively eliminated EAT in 11 of 12 patients (92%), all of whom were discharged in sinus rhythm without medications after a median hospital stay of 48 hours. Ablation was unsuccessful in one patient with diffuse dysplasia of the anterior right atrium, who eventually did well after surgical resection of abnormal atrial tissue. Transient depression of sinus node function was noted in one patient who had successful ablation of an EAT focus in close proximity to the sinus node, although normal sinus node function returned within 72 hours. No other complications were encountered. During follow-up (3–21 months; median, 13 months), one patient had recurrence of a slower and less-sustained EAT that was successfully eliminated at a second ablation session. All others remained in sinus rhythm, and all 12 subjects recovered normal ventricular function ConclusionsRF ablation appears to be a safe and effective therapeutic option for drug-resistant ectopic atrial tachycardia and may be the preferred first-line therapy for those patients with depressed ventricular function.

Predictors of survival in neonates with critical aortic stenosis.

BackgroundFailure of infants with critical aortic stenosis to survive after adequate valvotomy despite a left ventricular size that appears to be adequate indicates that additional preoperative anatomic features may contribute to mortality. Methods and ResultsDiscriminant analysis was used to determine which of several echocardiographically measured left heart structures were independent predictors of survival after valvotomy for neonatal critical aortic stenosis. It was possible to predict outcome after classic valvotomy (two-ventricle-type repair) with 95% accuracy based on mitral valve area, long-axis dimension of the left ventricle relative to the long-axis dimension of the heart, diameter of the aortic root, and body surface area. Left ventricular volume was not a major determinant in this study, in part because patients who had initial valvotomy had been preselected in favor of an adequately sized left ventricle. Patients with multiple small left ventricular structures were found to have significantly improved survival after initial Norwood operation. In contrast, balloon valvotomy with subsequent Norwood procedure was usually unsuccessful. ConclusionsThe adverse effects of small inflow, outflow, and/or cavity size of the left ventricle are cumulative. The accuracy of prediction of outcome based only on preoperative anatomy indicates that adequacy of valvotomy is not generally a limiting factor for survival in this group of patients. It is possible to identify subjects whose chance of survival is better after a Norwood procedure rather than valvotomy, even if left ventricular volume is not critically small.

Permanent Epicardial Pacing in Pediatric Patients Seventeen Years of Experience and 1200 Outpatient Visits

Background—The purpose of this study was to evaluate the long-term outcome of all pediatric epicardial pacing leads. Methods and Results—All epicardial leads and 1239 outpatient visits between January 1, 1983, and June 30, 2000, were retrospectively reviewed. Pacing and sensing thresholds were reviewed at implant, at 1 month, and at subsequent 6-month intervals. Lead failure was defined as the need for replacement or abandonment due to pacing or sensing problems, lead fracture, or phrenic/muscle stimulation. A total of 123 patients underwent 207 epicardial lead (60 atrial/147 ventricular, 40% steroid) implantations (median age at implant was 4.1 years [range 1 day to 21 years]). Congenital heart disease was present in 103 (84%) of the patients. Epicardial leads were followed for 29 months (range 1 to 207 months). The 1-, 2-, and 5-year lead survival was 96%, 90%, and 74%, respectively. Compared with conventional epicardial leads, both atrial and ventricular steroid leads had better stimulation thresholds 1 month after implantation; however, only ventricular steroid leads had improved chronic pacing thresholds (at 2 years: for steroid leads, 1.9 &mgr;J [from 0.26 to 16 &mgr;J]; for nonsteroid leads, 4.7 &mgr;J [from 0.6 to 25 &mgr;J];P <0.01). Ventricular sensing was significantly better in steroid leads 1 month after lead implantation (at 2 years: for steroid leads, 8 mV [from 4 to 31 mV]; for nonsteroid leads, 4 mV [from 0.7 to 10 mV];P <0.01). Neither congenital heart disease, lead implantation with a concomitant cardiac operation, age or weight at implantation, nor the chamber paced was predictive of lead failure. Conclusions—Steroid epicardial leads demonstrated relatively stable acute and chronic pacing and sensing thresholds. In this evaluation of >200 epicardial leads, lead survival was good, with steroid-eluting leads demonstrating results similar to those found with historical conventional endocardial leads.

NASPE expert consensus conference: Radiofrequency catheter ablation in children with and without congenital heart disease. Report of the writing committee

A Consensus Conference on Pediatric Radiofrequency Catheter Ablation took place at the 21 Annual Scientific Sessions of the North American Society of Pacing and Electrophysiology (NASPE). The participants included health professionals from the pediatric and adult electrophysiological communities, and involved physicians, nurses, and other allied professionals. This statement attempts to coalesce the information presented and is directed to all health professionals who are involved in the care of pediatric patients undergoing ablation. In an attempt to write such a document, the editors must try to represent what they believed was the general consensus of opinion amongst the participants. As generally understood in the medical world, “consensus” does not indicate complete harmony within a group but a substantial degree of agreement. It is hoped that the information presented falls within that definition and will serve as a foundation on which to build toward in the future. Even as this document was being prepared, new technologies were introduced that may expand the indications and possibly the type of personnel and training necessary to perform these procedures. It will be interesting to look back on this statement of the current state-of-the art over the next 5–10 years and see if some of the recommendations stand the test of time. As is true of many documents, only in retrospect can a judgement be made on the strength of what is stated in this statement. The goal of the Consensus Conference was to bring together pediatric and adult practitioners in electrophysiology for an all day discussion of catheter ablation in children and in patients with congenital heart disease (CHD). The organizers believed that, in choosing topics for discussion, the development of indications for catheter ablation should flow naturally from what is known concerning the natural history of the arrhythmias in question in the pediatric population and from the latest information available concerning outcomes from these procedures. Therefore, the initial part of this statement deals with the natural history issues of specific arrhythmias in children with and without CHD. Issues of radiation exposure and animal models of toxicity due to radiofrequency (RF) application are noted followed by outcomes and complications of RF ablation for various arrhythmias. Indications for ablation are then discussed. It is important to realize that these indications as presented are not necessarily “written in stone” and do not take the place of a “Policy Statement.” Rather, as mentioned above, this represents a general sense of agreement within the community of pediatric and adult electrophysiologists . The second half of the conference then dealt with the “nuts and bolts” of performing these proNASPE POSITION STATEMENT

Postoperative junctional ectopic tachycardia in children : Incidence, risk factors, and treatment

BACKGROUND Junctional ectopic tachycardia (JET) occurs commonly after pediatric cardiac operation. The cause of JET is thought to be the result of an injury to the conduction system during the procedure and may be perpetuated by hemodynamic disturbances or postoperative electrolyte disturbances, namely hypomagnesemia. The purpose of this study was to determine perioperative risk factors for the development of JET. METHODS Telemetry for each patient admitted to the cardiac intensive care unit from December 1997 through November 1998 for postoperative cardiac surgical care was examined daily for postoperative JET. A nested case-cohort analysis of 33 patients who experienced JET from 594 consecutively monitored patients who underwent cardiac operation was performed. Univariate and multivariate analyses were conducted to determine factors associated with the occurrence of JET. RESULTS The age range of patients with JET was 1 day to 10.5 years (median, 1.8 months). Univariate analysis revealed that dopamine or milrinone use postoperatively, longer cardiopulmonary bypass times, and younger age were associated with JET. Multivariate modeling elicited that dopamine use postoperatively (odds ratio, 6.2; p = 0.01) and age less than 6 months (odds ratio, 4.0; p = 0.02) were associated with JET. Only 13 (39%) of the patients with JET received therapeutic interventions. CONCLUSIONS Junctional ectopic tachycardia occurred in 33 (5.6%) of 594 patients who underwent cardiac operation during the study period. Postoperative dopamine use and younger age were associated with JET. It may be speculated that dopamine should be discontinued in the presence of postoperative JET.

Catheter ablation of accessory atrioventricular pathways in young patients: Use of long vascular sheaths, the transseptal approach and a retrograde left posterior parallel approach

OBJECTIVES This study retrospectively assesses the technical aspects of the catheter techniques used to ablate 83 accessory atrioventricular (AV) pathways during 88 procedures in 71 pediatric and adult patients (median age 14 years, range 1 month to 55 years). A number of catheter approaches and techniques evolved that may have improved success and shortened procedure times. BACKGROUND Radiofrequency catheter ablation of accessory AV pathways can be highly successful. However, the technical difficulty of many of the procedures is masked by the success rate. METHODS Left free wall, right free wall and septal accessory pathways were ablated with a variety of approaches. RESULTS Left free wall pathways were ablated successfully by using a standard retrograde approach through the aortic valve in only 10 (24%) of 43 cases. The remaining 33 (76%) required an approach that was either retrograde through the mitral valve (2 of 33), transseptal (21 of 33) or retrograde where the catheter was advanced behind the posterior mitral leaflet at the point of mitral-aortic continuity, so that the catheter course was parallel rather than perpendicular to the mitral anulus (10 of 33). Nineteen of 20 septal pathways were ablated successfully by using either the parallel approach (2 of 29), a transseptal approach (2 of 19), ablation within the coronary sinus or one of its veins (8 of 19) or ablation on the atrial side of the tricuspid valve (7 of 19). Fifteen of 20 right free wall pathways were ablated successfully with a variety of approaches on both the atrial and the ventricular side of the tricuspid valve. Long vascular sheaths were judged to contribute directly to success in 33 (43%) of 77 pathways. The overall success rate has been 93% (77 of 83 pathways), with 100% success for left free wall (43 of 43), 75% for right free wall (15 of 20) and 95% for septal pathways (19 of 20). CONCLUSIONS Thus, successful ablation of accessory AV pathways in a mixed group of pediatric and adult patients appears to benefit from a wide range of vascular and catheter approaches.

Benefits and potential risks of atrial antitachycardia pacing after repair of congenital heart disease.

Atrial reentry tachycardia is common after surgical repair of congenital heart disease. The arrhythmia is often difficult to treat and is occasionally life‐threatening. This study reports experience with atrial antitachycardia (AAIT mode) pacing for the management of atrial reentry tachycardia, with emphasis on the risks and benefits of automatic pacing therapy. Eighteen patients (2–32 years of age) with a variety of congenital heart lesions underwent atrial antitachycardia pacemaker placement for recurrent atrial tachycardia that was amenable to pace termination prior to the implantation procedure. An appropriate antitachycardia program was determined by repeated induction and termination of atrial tachycardia using the noninvasive programmed stimulation mode of the pacemaker. Over 4–30 months of follow‐up, 6 patients had 189 episodes of tachycardia successfully converted with AAI‐T pacing, 4 patients had 8 episodes of tachycardia detected hut not successfully converted, and 8 patients had no episodes of tachycardia with antibradycardia pacing alone. The number of patients receiving pharmacological therapy other than digoxin or beta blockade fell from 12 to 6, Two subjects died suddenly, 1 while wearing a Holter monitor. In both, tachycardia was detected and pace cardioversion attempted. Conclusions: Atrial antitachyardia pacing is a useful tool in the management of patients with congenital heart disease and atrial arrhythmias; however, in selected cases, it may not prevent and may even exacerbate the lethal complications of the tachycardia. Antitachycardia function evaluation is recommended under varying levels of autonomic stress prior to institution of automatic therapy.

Arrhythmias and intracardiac conduction after the arterial switch operation

UNLABELLED Intraatrial baffling procedures such as the Mustard or Senning repair of transposition of the great arteries have been associated with a high incidence of cardiac arrhythmias. These abnormalities are thought to arise from trauma to the sinus node and atrial muscle during the procedure. In the arterial switch operation, there is little intraatrial manipulation other than the repair of the atrial septal defect. In theory, rhythm disturbances after the arterial switch operation should be less prevalent. From January 1, 1983, to December 31, 1990, 390 patients (230 with intact ventricular septum and 160 with a coexisting ventricular septal defect) underwent an arterial switch operation. Electrocardiograms and 24-hour Holter monitor studies were obtained in the 364 survivors at hospital discharge and during follow-up. Limited intracardiac electrophysiologic studies were performed 6 to 12 months after the operation. RESULTS Atrioventricular node function was preserved in most patients; seven patients (2%) had first-degree, two (0.7%) second-degree, and five (1.7%) had complete atrioventricular block (all with coexisting ventricular septal defect). All five patients with complete heart block received a permanent pacemaker. In those patients not having a permanent pacemaker, sinus rhythm was present in 96% on the surface electrocardiogram and 99% during 24-hour Holter monitor studies (1 month to 8.5 years, mean 2.1 years after the operation). Intracardiac electrophysiologic studies (n = 158) demonstrated normal corrected sinus node recovery times and AH intervals in 97% of patients. Atrial ectopy was present in 152 of 172 (81%) patients, with the majority (64%) of patients having only occasional premature beats without repetitive forms. Ventricular ectopy was a frequent finding during 24-hour monitoring. At hospital discharge 70% had ventricular ectopy; these values fell to 57% (in patients with intact ventricular septum) and 30% (in patients with a coexisting ventricular septal defect) at follow-up. In the early postoperative period, there were 25 episodes of supraventricular tachycardia (14 of which required therapy), 6 episodes of junctional ectopic tachycardia, and 9 episodes of ventricular tachycardia. The incidence of supraventricular tachycardia had fallen to 5% at follow-up, with no atrial flutter or fibrillation noted. Three patients had ventricular tachycardia on follow-up Holter studies. In summary, our results confirm the theoretical advantages of anatomic correction over atrial level correction of transposition of the great arteries with respect to preservation of sinus node function and low incidence of clinically significant tachyarrhythmias.

The Incidence of Arrhythmias in a Pediatric Cardiac Intensive Care Unit

A pediatric cardiac intensive care unit (CICU) manages critically ill children and adults with congenital or acquired heart disease. These patients are at increased risk for arrhythmias. The purpose of this study was to prospectively evaluate the incidence of arrhythmias in a pediatric CICU patient population. All patients admitted to the CICU at the Cardiac Center at The Childrens Hospital of Philadelphia between December 1, 1997, and November 30, 1998, were evaluated prospectively from CICU admission to hospital discharge via full disclosure telemetry reviewed every 24 hours. Arrhythmias reviewed included nonsustained and sustained ventricular tachycardia (VT), nonsustained and sustained supraventricular tachycardia (SVT), atrial flutter and fibrillation, junctional ectopic tachycardia, and complete heart block. We reviewed 789 admissions consisting of 629 patients (age range, 1 day–45.5 years; median, 8.1 months). Hospital stay ranged from 1 to 155 days (total of 8116 patient days). Surgical interventions (n = 602) included 482 utilizing cardiopulmonary bypass. During the study period, there were 44 deaths [44/629 patients (7.0%)], none of which were directly attributable to a primary arrhythmia. The operative mortality was 5.1%. Overall, 29.0% of admissions had one or more arrhythmias the most common arrhythmia was nonsustained VT (18.0% of admissions), followed by nonsustained SVT (12.9% of admissions). Patients admitted to a pediatric CICU have a high incidence of arrhythmias, most likely associated with their underlying pathophysiology and to the breadth of medical and surgical interventions conducted.

Long follow-up (to 43 years) of ventricular septal defect with audible aortic regurgitation

From 1946 to March 1989, 92 patients (33 women and 59 men) were seen with ventricular septal defect (VSD) and audible aortic regurgitation (AR). The VSD was subcristal in 62 patients, subpulmonary in 21 and unknown in the remaining 9. The median age of onset of AR was 5.3 years. The risk of developing AR was 2.5 times greater in those with a subpulmonary VSD. The aortic valve was tricuspid in 90% and bicuspid in 10%. Prolapse was seen in 90% of those with subcristal VSD and in all with subpulmonary VSD. Pulmonary stenosis was seen in 46% of the patients with gradients ranging from 10 to 55 mm Hg. The incidence of infective endocarditis was 15 episodes/1,000 patient years. Among 20 patients followed medically, for 297 patient years, 1 died (1959) and most have been stable, including 2 followed for greater than 30 years. In the 72 patients operated on, there were 15 perioperative and 5 late deaths. Operations consisted of VSD closure alone in 7, VSD closure and valvuloplasty in 50 and VSD closure and aortic valve replacement in the other 15. Valvuloplasty was more effective in those operated on under age 10 compared to those older than 15 years (46 vs 14%). The durability of the valvuloplasty was 76% at 12 years and 51% at 18 years.