Faculty Bibliography

The management of complete heart block in premature low birth-weight infants, particularly those with hydrops fetalis, is challenging. We report emergent implantation of permanent epicardial pacemakers in the first 48 hours of life in two premature infants (one with hydrops fetalis) with birth weights of 1,400 grams and 1,000 grams.

Background:Radiofrequency catheter ablation of atrioventricular nodal reentrant tachycardia (AVNRT) has proven to be an effective therapy in the pediatric population. However, concerns of inadvertent permanent AV nodal block have resulted in many pediatric programs adopting cryoablation as their primary ablation approach for AVNRT. Methods:A retrospective analysis of the results of pediatric radiofrequency catheter ablation at a single institution over the most recent 5 years (January 2004 through December 2008) was performed. Acute, intermediate, and long-term success, along with the incidence of AV block, were determined. Results:There were 65 patients with a mean age of 12.1 +/- 5.2 years and weight of 46.5 +/- 17.3 kg who underwent radiofrequency catheter ablation for AVNRT. There was 100% acute success with no recurrences at a mean follow up of 32.5 months. Although two patients had a brief second-degree AV block, there was no permanent AV block of any degree. Conclusions:The safety and efficacy of radiofrequency catheter ablation for pediatric AVNRT demonstrated in this study support its continued application and should not be abandoned as a method of treatment. (PACE 2009; 1-5)

We report the technique of transatrial delivery of the Medtronic 3830 SelectSecure lead (Medtronic Inc., Minneapolis, MN, USA) for right ventricular endocardial pacing in two young adults with congenital heart disease who had multiple pacing lead failures and superior vena cava occlusion. The deflectable catheter delivery system used to position the SelectSecure lead provided the opportunity to map the right ventricular endocardial surface and determine the best available pacing site. At midterm follow-up, both systems are functioning well. (PACE 2009; e1-e3)

Intravenous administration of amiodarone has recently been recommended for use during pediatric resuscitation of pediatric patients with ventricular fibrillation or pulseless ventricular tachycardia. We present two pediatric patients who received amiodarone for polymorphic ventricular tachycardia, although they were ultimately determined to have congenital long QT syndrome. Amiodarone is contraindicated in this setting and may have exacerbated the ventricular arrhythmia

BACKGROUND: Catheter ablation of right free-wall (RFW) accessory pathways continues to be associated with lower success and higher recurrence rates compared with other pathway locations. Reliably identifying the precise location of RFW accessory pathways often contributes to the difficulty in ablating these pathways. Improved localization of RFW accessory pathways has been described utilizing multielectrode right coronary artery (RCA) catheterization. This approach has not been widely adopted, in part due to concerns of prolonged catheter placement within the RCA. We describe the technique of creating a 3-D electroanatomic map of the right atrioventricular groove, limiting the duration of a microcatheter within the RCA, to facilitate ablation of RFW accessory pathways. METHODS AND RESULTS: Following intracardiac identification of a RFW accessory pathway, an octapolar microcatheter was placed in the RCA. A 3-D electroanatomic map of the RCA was created during retrograde accessory pathway conduction using ventricular pacing. Immediately following creation of the map, the RCA catheter was removed. Endocardial mapping and ablation of the RFW accessory pathway was performed using the RCA electroanatomic map as a guide. This technique was used in four pediatric patients. The microcatheter was within the RCA for less than 1 min in all patients. Radiofrequency catheter ablation of the RFW accessory pathways were successfully performed with two lesions. There were no complications or recurrences at follow-up. CONCLUSIONS: The creation of a 3-D electroanantomic map of the RCA effectively localizes RFW accessory pathways and facilitates successful ablation. This technique minimizes the duration of RCA instrumentation

Patients undergoing congenital heart surgery may occasionally require additional surgical procedures in the form of tracheostomy and gastrostomy. These procedures are often performed in an attempt to diminish hospital morbidity and length of stay. We reviewed the Web-based medical records of all patients undergoing congenital heart surgery at Miami Children's Hospital from February 2002 through August 2007. Patients who were deemed preterm and had undergone closure of a patent ductus arteriosis were eliminated. The records of all other patients were queried for the terms gastrostomy, g-tube, Nissan, fundal plication, tracheostomy, or tracheotomy. Patients' medical records in which these terms appeared in any portion were completely reviewed. There were 1660 congenital heart operations performed in the study period. There were 592 operations performed on patients whose age ranged from 1 month to 1 year and 441 neonatal operations. Mortality was 2%. Median postoperative stay was 8 days (range, 1-191 days), 12 days for neonates (range, 3-142 days), and 19 days for neonates undergoing RACHS-1 category 6 operations (range, 4-142 days). Tracheostomies were performed in four patients (0.2%). Gastrostomies were performed on eight patients (0.4%), representing 0.8% of patients <1 year of age, 1.4% of neonates, and 2.4% of patients undergoing RACHS-1 category 6 operations. The rate of patients undergoing either tracheostomy or gastrostomy after congenital heart surgery at our institution was quite low. Avoidance of either of these two procedures was achieved without increased morbidity or length of stay. The rate at which these procedures need to be performed may reflect the magnitude of the patients' lifetime trauma related to their underlying condition and acute and total surgical experiences

OBJECTIVE: Temporary pacing wires have been associated with serious postoperative complications. Recommendations for their routine use after open heart surgery are decades old, and may not reflect current surgical techniques and outcomes. METHODS: The electronic web-enabled medical records of all patients undergoing congenital cardiac surgery from February, 2002, through December, 2005, were reviewed, excluding patients undergoing implantation of pacemakers as a primary procedure, or those undergoing ligation of a patent arterial duct. RESULTS: There were 1193 surgical procedures performed, 1041 with cardiopulmonary bypass. Median age of the patients was 5.8 months, with a range from 0 days to 54 years, weighing 6.2 kilograms, with a range from 1 to 114 kilograms. Mortality prior to discharge was 2.5%, and median postoperative stay was 6 days. No deaths were attributed to arrhythmias. Temporary pacing wires were placed 14 times (1.2%). Indications for placement included sinus nodal dysfunction in 8 patients, preoperative in 4 and intraoperative in 4, high degree atrioventricular block in 4 patients, and intraoperative atrial flutter in 2 patients. Of these patients, 4 (0.3%) eventually underwent permanent implantation of a pacemaker, 2 for persistent sinus nodal dysfunction, and 2 for persistent atrioventricular block. Postoperative junctional ectopic tachycardia requiring antiarrhythmic therapy occurred in 9 patients (0.8%). All recovered without incident, and none were treated with temporary pacing. CONCLUSIONS: The diminished risk of unexpected postoperative arrhythmias in the current era alleviates the necessity for routine placement of temporary pacing wires. Those institutions with experienced surgical and cardiac critical care teams may be able to predict the need for temporary pacing wires preoperatively or intraoperatively

The reproducible induction of supraventricular tachycardia (SVT) during electrophysiological study is critical for the diagnosis of atrioventricular nodal reentry tachycardia (AVNRT), and for determining a therapeutic endpoint for catheter ablation. In the sedated state, there are patients with reentry SVT due to AVNRT who are not inducible at electrophysiological study. This article reports on the empiric slow pathway modification for AVNRT in six pediatric patients (age 6-17, mean 13.3 years) with documented, recurrent, paroxysmal SVT in the setting of a structurally normal heart who were not inducible at electrophysiological study. Atrial and ventricular burst and extrastimulus pacing at multiple drive cycle lengths were performed in the baseline state, during an isuprel infusion, and during isuprel elimination. Single AV nodal (AVN) echo beats were present in all patients, while classic dual AVN physiology was present in three of six patients. Radiofrequency energy was administered in the right posteroseptal AV groove resulting in accelerated junctional rhythm in five of six patients. Postablation testing demonstrated the elimination of echo beats in four patients, while dual AVN physiology and echo beats persisted in two patients. At follow-up (22-49 months, mean 29.5 months), all patients are asymptomatic without recurrence of SVT and are not taking any antiarrhythmic medication. In selected patients, empiric slow pathway modification may be offered as a potential cure in children with recurrent paroxysmal SVT who are not inducible at electrophysiological study. Elimination of slow pathway conduction may serve as a surrogate endpoint, though is not necessary for long-term success

Isoproterenol (ISO) testing following radiofrequency catheter ablation (RFCA) of accessory pathways (APs) in children is often performed to assess efficacy. However, its role in postablative testing for this indication has not been previously studied. In view of a recent national shortage of ISO, this study reviewed the results of ISO testing in pediatric patients after acutely successful RFCA to evaluate its role in postablative testing. Seventy patients (median age 13.0 years, range 2.8-24 years) underwent acutely successful RFCA for APs. If AP conduction was not present and tachycardia was not inducible with programmed stimulation 30 minutes following RFCA, repeat testing was performed during continuous infusion ISO. ISO infusion resulted in the induction of arrhythmias in 3 (4%) of 70 patients that required further ablative therapy. None of these patients had inducible arrhythmias or AP conduction during postablative testing without ISO infusion. One patient, with the permanent form of junctional reciprocating tachycardia (PJRT), had persistence of AP conduction requiring further RFCA applications. Two patients had inducible AV nodal reentrant tachycardia (AVNRT) that was treated with slow pathway modification. At a median follow-up of 7.3 months, two (3%) patients had recurrence of tachycardia. These patients did not have inducible tachycardia, AP conduction, or dual AVN physiology with ISO testing. Although ISO may improve AP conduction in patients with PJRT and uncover AVNRT, these results suggest that ISO testing after an apparently successful AP ablation may not be necessary to confirm acute success. In addition, lack of AP conduction on ISO did not rule out the possibility of medium-term recurrence

The management of ventricular arrhythmias in adults with congenital heart disease is becoming increasingly more important. Ventricular arrhythmias are associated with a number of congenital heart defects (particularly tetralogy of Fallot), and sudden death. A number of invasive and noninvasive methods have been applied to identify those patients at risk, although indications and the prognostic value of these tests are unclear. Treatment of ventricular arrhythmias in this population include antiarrhythmic medications, catheter ablation, surgery, and implantable cardiac defibrillators