Antiarrhythmic Treatment Duration and Tachycardia Recurrence in Infants with Supraventricular Tachycardia.

We sought to assess the effect of a shorter medication treatment course (up to 4-6 months of age) on the recurrence of infantile supraventricular tachycardia (SVT). This was a retrospective review of infants with SVT diagnosed at age 0-12 months at Rady Children's Hospital (2010-2017). Infants with structural congenital heart disease, automatic tachycardias, atrial flutter, or lack of follow-up data were excluded. Seventy-four infants met criteria. Median age at diagnosis was 6 days (IQR 0-21 days); 28.4% presented with fetal tachycardia. Median gestational age was 38.4 weeks (IQR 36-40), 30% were preterm. Median age at medication discontinuation was 6.7 months (IQR 4.6-9.8). Therapy was stopped at younger age in patients managed by pediatric electrophysiologist (vs. general pediatric cardiologist): 4.9 vs. 8.6 months (p = 0.03). Thirty-eight patients (51.4%) were treated for < 6 months; 32.4% for 6-12 months, and 16.2% for > 12 months. SVT recurrence was similar for these groups: 13.2% vs. 16.7%, and 33.3%, respectively, (p = 0.27). Most patients with recurrence required emergency care, though none had significant adverse outcomes. Infants with SVT and structurally normal cardiac anatomy, who remain recurrence free on a single agent, have no increased risk of recurrence with shorter treatment courses of 4-6 months, compared to traditional treatment duration of 6-12 months.

Dexmedetomidine-related atrial standstill and loss of capture in a pediatric patient after congenital heart surgery.

OBJECTIVE: Dexmedetomidine (DEX; Precedex) is an alpha-2 adrenergic receptor agonist that produces anxiolysis and sleep-like sedation without narcosis or respiratory depression and has relatively few cardiovascular side effects. Given its favorable sedative properties combined with its limited effects on hemodynamic and respiratory function, it is widely used in pediatric intensive care and anesthesia settings. DESIGN: Case report. SETTING: Pediatric intensive care unit. PATIENT: A three-yr-old girl was admitted after mitral valve replacement for persistent severe mitral insufficiency. Her prior history was significant for tetralogy of Fallot which was repaired at nine months of age. A year later the patient developed mitral and tricuspid valve insufficiency and subsequently underwent mitral and tricuspid valve repair, pulmonary valve replacement, and a maze procedure (the latter was performed for persistent atrial flutter). Following that operation she developed sinus node dysfunction and had a permanent epicardial dual-chamber pacemaker implanted. Due to remaining severe mitral insufficiency the patient had increasing pulmonary symptoms, necessitating the most recent surgery to replace her mitral valve. INTERVENTIONS: On postoperative day two the patient was hemodynamically stable and weaning off mechanical ventilation. Tracheal extubation was anticipated to occur within the next 24 hrs. A DEX infusion of 0.6 mcg/kg/hr was initiated. A pacemaker interrogation performed on postoperative day three, 21 hrs after the initiation of DEX, revealed unsuccessful atrial capture. MEASUREMENTS AND MAIN RESULTS: Dexmedetomidine was subsequently discontinued and the patient's pacemaker was reinterrogated. The interrogation findings were similar to those seen prior to the initiation of DEX. CONCLUSION: As a result of these findings, caution is warranted in the administration of DEX to patients with predisposing conduction abnormalities and patients who are pacemaker-dependent.

Surgical approaches to epicardial pacemaker placement: does pocket location affect lead survival?

Permanent cardiac pacing in pediatric patients presents challenges related to small patient size, complex anatomy, electrophysiologic abnormalities, and limited access to cardiac chambers. Epicardial pacing currently remains the conventional technique for infants and patients with complex congenital heart disease. Pacemaker lead failure is the major source of failure for such epicardial systems. The authors hypothesized that a retrocostal surgical approach would reduce the rate of lead failure due to fracture compared with the more traditional subrectus and subxiphoid approaches. To evaluate this hypothesis, a retrospective chart review analyzed patients with epicardial pacemaker systems implanted or followed at Rady Children's Hospital San Diego between January 1980 and May 2007. The study cohort consisted of 219 patients and a total of 620 leads with epicardial pacemakers. Among these patients, 84% had structural congenital heart disease, and 45% were younger than 3 years at time of the first implantation. The estimated lead survival was 93% at 2 years and 83% at 5 years. The majority of leads failed due to pacing problems (54%), followed by lead fracture (31%) and sensing problems (14%). When lead failure was adjusted for length of follow-up period, no significant differences in the rates of failure by pocket location were found.

Epicardial Intraoperative Three-Dimensional Mapping of Wolff-Parkinson-White Syndrome in a Child With Ebstein's Anomaly.

Catheter ablation of arrhythmias in small patients has inherent significant risk because of the patient, catheter, and lesion size. Heart block, perforation, and coronary damage may occur. This report shows adaptation of a three-dimensional electroanatomic mapping system for intraoperative use in a small patient with Ebstein's anomaly who was undergoing a cone procedure and a bidirectional Glenn procedure. Use of this technique gave clear identification of the epicardial insertion points of two accessory pathways causing Wolff-Parkinson-White syndrome and resistant episodes of supraventricular tachycardia. Successful three-dimensional mapping and cryoablation were performed with a short procedure time and no complications. The patient remains without preexcitation or arrhythmia 6 months postoperatively.

Improved growth and developmental activity post tracheostomy in preterm infants with severe BPD.

OBJECTIVES: To examine growth, sedation needs, and participation in developmental activities before and after tracheostomy among infants with severe bronchopulmonary dysplasia. METHODS: Retrospective analysis of infants born at <32 weeks' gestation or birth weights <1500 g with severe BPD who underwent tracheostomy placement between January 1, 2010 and December 31, 2016 in a quaternary referral newborn and infant intensive care unit. Changes in growth parameters and frequency/type of participation in physical therapy sessions performed during the 4-weeks before tracheostomy and 4-weeks after the first tracheostomy tube change were compared. RESULTS: A total of 72 patient were included in the study. Average weekly gain in weight, length, and head circumference were significantly higher during the 4-week period after compared to before tracheostomy. The most significant change occurred for linear growth (0.71 ± 0.40 cm/wk pre vs 0.97 ± 0.48 cm/wk pre, P < 0.001). Median Z score improved for weight (pre -1.42 [-3,10, -0.33] vs post -0.91 [-2.7, 0.27], P < 0.001), length (pre -3.07 [-4.39, -1.31] vs post -1.95 [-3.83, -0.93], P < 0.001) and weight-to-length ratio (pre 1.66 [0.58, 2.55] vs post 1.32 [0.17, 2.2], P = 0.02). Participation in developmental therapies significantly improved post tracheostomy (pre vs post: 5.2 ± 2.9 vs 8.7 ± 4.3 sessions performed over 4 weeks, P < 0.0001). Physical therapy sessions more often promoted developmental skill acquisition after tracheostomy compared to facilitating physiologic stability before tracheostomy. Daily sedation requirements decreased post tracheostomy. CONCLUSIONS: Tracheostomy was associated with improved proportional growth and increased participation in activities promoting developmental skill acquisition and reduced daily sedation requirements in preterm infants with severe BPD.

Genotype Positive Long QT Syndrome in Patients With Coexisting Congenital Heart Disease.

Congenital long QT syndrome (LQTS) is characterized by QT prolongation with predisposition to life-threatening arrhythmia. There have been sporadic reports of LQTS coexisting with more common forms of congenital heart disease (CHD). However, the diagnosis of LQTS when CHD is present may be confounded by several common variables including postoperative electromechanical factors predisposing to ventricular arrhythmia, intrinsic, and postoperative QRS abnormalities. This report documents a single-center experience with patients who have both genetically confirmed LQTS and CHD to examine their modes of presentation and factors associated with making the diagnosis of LQTS in this patient population, as well as potential confounding variables that may mask or delay both LQTS diagnosis and initiation of therapy. A retrospective review was performed of subjects with confirmed LQTS and associated CHD from 1999 to January 2017. Genetic analysis was performed predominantly using commercially available panel testing. A chart review included detailed analysis of electrocardiograms, 24-hour 3-lead rhythm monitors and exercise stress test tracings as well as the genetic test reports. QT intervals were measured using Bazett's formula. Eleven patients were identified. Four patients had LQTS type 1, 6 had LQTS type 2, and 1 had a disease-associated mutation in KCNQ1 and a variant of unknown significance in KCNH2 gene. Two patients had positive cascade screening. Arrhythmia presentations of the LQTS were at both extremes of the cohort age range (in-utero and midchildhood age). There was a seeming overrepresentation of conotruncal anomalies and/or arch anomalies, with 7 of the 11 patients. In conclusion, the diagnosis of LQTS may be challenging in the setting of CHD (a prolonged ST segment may be helpful), and high index of suspicion is required. The overall incidence of LQTS in CHD appears extremely rare, but the diagnosis and true incidence may be masked by confounding electrocardiogrpahic findings and other variables common in CHD.

Intraoperative Three-Dimensional Mapping of Supraventricular Tachycardia in a Young Fontan Patient.

Preoperative tachycardia is uncommon before an initial Fontan procedure. Catheter intervention can risk complications in small patients. A patient with fetal tachycardia and double inlet left ventricle underwent Norwood and bidirectional Glenn procedures. She had persistent tachycardia. A three-dimensional electroanatomic mapping system was modified for the operative procedure; it was used to identify the arrhythmia substrate and cryoablate an atrioventricular nodal tachycardia. Mapping added 20 minutes to the operation. She is arrhythmia-free and off medication after 4 months. This three-dimensional system was successfully adapted for an intraoperative SVT ablation in this small patient, and it may be useful in other settings.

A Novel Method for Epicardial Defibrillator Lead Placement in Young Children: Coil Between the Great Arteries.

The primary and secondary prevention of sudden cardiac death resulting from malignant arrhythmia, channelopathy, and hypertrophic cardiomyopathy often requires the implantation of automatic internal cardiac defibrillators (AICDs) in the pediatric population. In young patients, the small size of the systemic veins, complex anatomy of congenital heart disease, and body habitus often preclude safe and durable transvenous placement of the AICD coil, requiring innovative methods to circumvent this problem. This report describes the technique used at Rady Children's Hospital San Diego/UCSD for the epicardial placement of an ICD system with a transvenous ICD coil placed between the aorta and pulmonary artery, thereby producing a stable location and excellent coil-to-can vector for successful defibrillation.

Long-term follow-up shows excellent transmural atrial lead performance in patients with complex congenital heart disease.

BACKGROUND: Many patients with congenital heart disease require permanent pacing for rhythm management but cannot undergo transvenous lead placement. In others, epicardial scarring prohibits adequate sensing and pacing thresholds using epicardial leads. This study describes long-term lead performance using a transmural atrial (epicardial to endocardial) pacing approach in patients with congenital heart disease. METHODS AND RESULTS: For transmural atrial (TMA) lead access, a bipolar, steroid-eluting transvenous lead was placed from the epicardium via purse-string incision or atriotomy and affixed to atrial endocardium. Records were reviewed for patient data and acute and long-term lead performance for TMA leads placed 1998 to 2004. Forty-two of 48 TMA leads remain active at last follow-up. Two leads fractured, 4 were functional at >5-year follow-up but no longer active. Freedom from lead failure 98% (95% confidence interval, 86%-100%) at mean follow-up 7.8 years. TMA leads gave excellent sensing and pacing characteristics at implant and chronically. Median acute and chronic sensing thresholds were 3 and 2.8 mV, respectively; median acute and chronic pacing thresholds at 0.5 ms were 0.9 and 0.7 V, respectively. TMA leads performed similarly in Fontan patients. Overdrive pacing for intra-atrial re-entrant tachycardia was successful in 7 of 8 patients. One patient with high baseline risk died of stroke 7 years after implant. No lead-associated thrombi were observed. CONCLUSIONS: TMA pacing leads had excellent longevity, initial, and chronic functional properties and provide an alternative to epicardial leads in patients with congenital heart disease. Patients who cannot receive transvenous leads, have epicardial scarring or have intra-atrial re-entrant tachycardia could benefit most from routine use of this technique.