Limited Relationship Between Echocardiographic Measures and Electrocardiographic Markers of Left Ventricular Size in Healthy Children.

Pediatric ECG standards have been defined without echocardiographic confirmation of normal anatomy. The Pediatric Heart Network Normal Echocardiogram Z-score Project provides a racially diverse group of healthy children with normal echocardiograms. We hypothesized that ECG and echocardiographic measures of left ventricular (LV) dimensions are sufficiently correlated in healthy children to imply a clinically meaningful relationship. This was a secondary analysis of a previously described cohort including 2170 digital ECGs. The relationship between 6 ECG measures associated with LV size were analyzed with LV Mass (LVMass-z) and left ventricular end-diastolic volume (LVEDV-z) along with 11 additional parameters. Pearson or Spearman correlations were calculated for the 78 ECG-echocardiographic pairs with regression analyses assessing the variance in ECG measures explained by variation in LV dimensions and demographic variables. ECG/echocardiographic measurement correlations were significant and concordant in 41/78 (53%), though many were significant and discordant (13/78). Of the 6 ECG parameters, 5 correlated in the clinically predicted direction for LV Mass-z and LVEDV-z. Even when statistically significant, correlations were weak (0.05-0.24). R2 was higher for demographic variables than for echocardiographic measures or body surface area in all pairs, but remained weak (R2 ≤ 0.17). In a large cohort of healthy children, there was a positive association between echocardiographic measures of LV size and ECG measures of LVH. These correlations were weak and dependent on factors other than echocardiographic or patient derived variables. Thus, our data support deemphasizing the use of solitary, traditional measurement-based ECG markers traditionally thought to be characteristic of LVH as standalone indications for further cardiac evaluation of LVH in children and adolescents.

Current State of Cardiac Implantable Electronic Device Remote Monitoring in Pediatrics and Congenital Heart Disease: A PACES-Sponsored Quality Improvement Initiative.

Cardiac implantable electronic device (CIED) remote transmissions are an integral part of longitudinal follow-up in pediatric and adult congenital heart disease (ACHD) patients. To evaluate baseline CIED remote monitoring (RM) data among pediatric and ACHD centers prior to implementation of a Pediatric and Congenital Electrophysiology  Society (PACES)-sponsored quality improvement (QI) project. This is a cross-sectional study of baseline CIED RM. Centers self-reported baseline data: individual center RM compliance was defined as high if there was > 80% achievement and low if < 50%. A total of 22 pediatric centers in the USA and Australia submitted baseline data. Non-physicians were responsible for management of the RM program in most centers: registered nurse (36%), advanced practice provider (27%), combination (23%), and third party (9%). Fifteen centers (68%) reported that > 80% of their CIED patients are enrolled in RM and only two centers reported < 50% participation. 36% reported high compliance of device transmission within 14 days of implant and 77% of centers reported high compliance of CIED patients enrolled in RM. The number of centers achieving high compliance differed by device type: 36% for pacemakers, 50% for ICDs, and 55% for Implantable Cardiac Monitors (ICM). All centers reported at least 50% adherence to recommended follow-up for PM and ICD, with 23% low compliance rate for ICMs. Based on this cross-sectional survey of pediatric and ACHD centers, compliance with CIED RM is sub-optimal. The PACES-sponsored QI initiative will provide resources and support to participating centers and repeat data will be evaluated after PDSA cycles.

Influence of CYP2D6 genetic variation on adverse events with propafenone in the pediatric and young adult population.

Propafenone is an antiarrhythmic drug metabolized primarily by cytochrome P450 2D6 (CYP2D6). In adults, propafenone adverse events (AEs) are associated with CYP2D6 poor metabolizer status; however, pediatric data are lacking. Subjects were tested for 10 CYP2D6 allelic variants and copy number status, and activity scores assigned to each genotype. Seventy-six individuals (median 0.3 [range 0-26] years old) were included. Propafenone AEs occurred in 29 (38%); 14 (18%) required drug discontinuation due to AE. The most common AEs were QRS (n = 10) and QTc (n = 6) prolongation. Those with AEs were older at the time of propafenone initiation (1.58 [0.13-9.92] vs. 0.20 [0.08-2.01] years old; p = 0.042). CYP2D6 activity scores were not associated with presence of an AE (odds ratio [OR] 0.48 [0.22-1.03]; p = 0.055) but with the total number of AE (ß1  = -0.31 [-0.60, -0.03]; p = 0.029), systemic AEs (OR 0.33 [0.13-0.88]; p = 0.022), and drug discontinuation for systemic AEs (OR 0.28 [0.09-0.83]; p = 0.017). Awareness of CYP2D6 activity score and patient age may aid in determining an individual's risk for an AE with propafenone administration.

Impact of obesity on post-operative arrhythmias after congenital heart surgery in children and young adults.

BACKGROUND: Obesity increases the risk of post-operative arrhythmias in adults undergoing cardiac surgery, but little is known regarding the impact of obesity on post-operative arrhythmias after CHD surgery. METHODS: Patients undergoing CHD surgery from 2007 to 2019 were prospectively enrolled in the parent study. Telemetry was assessed daily, with documentation of all arrhythmias. Patients aged 2-20 years were categorised by body mass index percentile for age and sex (underweight <5, normal 5-85, overweight 85-95, and obese >95). Patients aged >20 years were categorised using absolute body mass index. We investigated the impact of body mass index category on arrhythmias using univariate and multivariate analysis. RESULTS: There were 1250 operative cases: 12% underweight, 65% normal weight, 12% overweight, and 11% obese. Post-operative arrhythmias were observed in 38%. Body mass index was significantly higher in those with arrhythmias (18.8 versus 17.8, p = 0.003). There was a linear relationship between body mass index category and incidence of arrhythmias: underweight 33%, normal 38%, overweight 42%, and obese 45% (p = 0.017 for trend). In multivariate analysis, body mass index category was independently associated with post-operative arrhythmias (p = 0.021), with odds ratio 1.64 in obese patients as compared to normal-weight patients (p = 0.036). In addition, aortic cross-clamp time (OR 1.007, p = 0.002) and maximal vasoactive-inotropic score in the first 48 hours (OR 1.03, p = 0.04) were associated with post-operative arrhythmias. CONCLUSION: Body mass index is independently associated with incidence of post-operative arrhythmias in children after CHD surgery.

Assessment of dynamic cardiac repolarization and contractility in patients with hypertrophic cardiomyopathy.

AIMS: Arrhythmia mechanisms in hypertrophic cardiomyopathy remain uncertain. Preclinical models suggest hypertrophic cardiomyopathy-linked mutations perturb sarcomere length-dependent activation, alter cardiac repolarization in rate-dependent fashion and potentiate triggered electrical activity. This study was designed to assess rate-dependence of clinical surrogates of contractility and repolarization in humans with hypertrophic cardiomyopathy. METHODS: All participants had a cardiac implantable device capable of atrial pacing. Cases had clinical diagnosis of hypertrophic cardiomyopathy, controls were age-matched. Continuous electrocardiogram and blood pressure were recorded during and immediately after 30 second pacing trains delivered at increasing rates. RESULTS: Nine hypertrophic cardiomyopathy patients and 10 controls were enrolled (47% female, median 55 years), with similar baseline QRS duration, QT interval and blood pressure. Median septal thickness in hypertrophic cardiomyopathy patients was 18mm; 33% of hypertrophic cardiomyopathy patients had peak sub-aortic velocity >50mmHg. Ventricular ectopy occurred during or immediately after pacing trains in 4/9 hypertrophic cardiomyopathy patients and 0/10 controls (P = 0.03). During delivery of steady rate pacing across a range of cycle lengths, the QT-RR relationship was not statistically different between HCM and control groups; no differences were seen in subgroup analysis of patients with or without intact AV node conduction. Similarly, there was no difference between groups in the QT interval of the first post-pause recovery beat after pacing trains. No statistically significant differences were seen in surrogate measures for cardiac contractility. CONCLUSION: Rapid pacing trains triggered ventricular ectopy in hypertrophic cardiomyopathy patients, but not controls. This finding aligns with pre-clinical descriptions of excessive cardiomyocyte calcium loading during rapid pacing, increased post-pause sarcoplasmic reticulum calcium release, and subsequent calcium-triggered activity. Normal contractility at all diastolic intervals argues against clinical significance of altered length-dependent myofilament activation.

Catheter ablation of orthodromic reciprocating tachycardia and atrioventricular nodal reentrant tachycardia in children with hypoplastic left heart syndrome.

INTRODUCTION: Experience with catheter ablation of orthodromic reciprocating tachycardia (ORT) and atrioventricular nodal reentrant tachycardia (AVNRT) in young children with hypoplastic left heart syndrome (HLHS) is limited. We report the feasibility, safety, and outcomes of catheter ablation of ORT and AVNRT in children with HLHS. METHODS AND RESULTS: This was a retrospective review of patients with HLHS who underwent catheter ablation for reentrant supraventricular tachycardias (excluding atrial tachycardias) between 2005 and 2017 at a single center. Descriptive data including demographics, clinical history, procedural data, and outcomes were recorded. Ten children with HLHS underwent eleven catheter ablation procedures. Median age and weight at ablation were 2.7 years (range: 0.1-10.5) and 11.4 kg (range: 3.6-30.4), respectively. Tachycardia mechanism was AVNRT in four, ORT in five (two with preexcitation), and both in one. Acute procedural success was 100% and there was no spontaneous recurrence of tachycardia orpreexcitationin median 92 months (range: 21-175 months) follow-up. Five patients underwent subsequent EP studies at catheterization (intracardiac) or after surgery (via epicardial wires): three were noninducible, one after AVNRT ablation had inducible atrial tachycardia, and one after initial ORT ablation had inducible ORT at fenestration closure and underwent successful repeat ablation. Thus, long-term freedom from clinical tachycardia was 100% and from inducible AVNRT or ORT was 80%. CONCLUSION: Transcatheter ablation for ORT and AVNRT in children with HLHS can be performed with excellent acute and long-term success without major complications.

Type 8 long QT syndrome: pathogenic variants in CACNA1C-encoded Cav1.2 cluster in STAC protein binding site.

AIMS: Pathogenic gain-of-function variants in CACAN1C cause type-8 long QT syndrome (LQT8). We sought to describe the electrocardiographic features in LQT8 and utilize molecular modelling to gain mechanistic insights into its genetic culprits. METHODS AND RESULTS: Rare variants in CACNA1C were identified from genetic testing laboratories. Treating physicians provided clinical information. Variant pathogenicity was independently assessed according to recent guidelines. Pathogenic (P) and likely pathogenic (LP) variants were mapped onto a 3D modelled structure of the Cav1.2 protein. Nine P/LP variants, identified in 23 patients from 19 families with non-syndromic LQTS were identified. Six variants, found in 79% of families, clustered to a 4-residue section in the cytosolic II-III loop region which forms a region capable of binding STAC SH3 domains. Therefore, variants may affect binding of SH3-domain containing proteins. Arrhythmic events occurred in similar proportions of patients with II-III loop variants and with other P/LP variants (53% vs. 48%, P = 0.41) despite shorter QTc intervals (477 ± 31 ms vs. 515 ± 37 ms, P = 0.03). A history of sudden death was reported only in families with II-III loop variants (60% vs. 0%, P = 0.03). The predominant T-wave morphology was a late peaking T wave with a steep descending limb. Exercise testing demonstrated QTc prolongation on standing and at 4 min recovery after exercise. CONCLUSION: The majority of P/LP variants in patients with CACNA1C-mediated LQT8 cluster in an SH3-binding domain of the cytosolic II-III loop. This represents a 'mutation hotspot' in LQT8. A late-peaking T wave with a steep descending limb and QT prolongation on exercise are commonly seen.

What have we learned in the last 20 years? A comparison of a modern era pediatric and congenital catheter ablation registry to previous pediatric ablation registries.

BACKGROUND: Since the onset of pediatric catheter ablation, the pediatric electrophysiology community has reported outcomes via various registries (PAPCA [Prospective Assessment After Pediatric Cardiac Ablation], PCAR [Pediatric Catheter Ablation Registry]). Most recently, a modern era pediatric and congenital ablation registry (MAP-IT [Multicenter Pediatric and Congenital EP Quality Initiative]) was developed for eventual incorporation into the National Cardiovascular Data Registry (NCDR) IMPACT (Improving Pediatric and Adult Congenital Treatment) registry. OBJECTIVE: The purpose of this study was to describe initial findings from the MAP-IT pilot registry and to compare these findings to earlier registries. METHODS: Before entering the NCDR IMPACT registry, MAP-IT was active at 12 centers (11 in the United States) between October 2014 and April 2016. All electrophysiological studies for patients younger than 21 years and for patients of all ages with structural congenital heart disease were included. We compared the acute success, fluoroscopy and procedural times, and frequency of complications between MAP-IT and the earlier registries. RESULTS: Acute success rates have improved from the initial PCAR registry for both accessory and slow pathway substrates. Both fluoroscopy and procedural times have significantly decreased across the time periods (fluoroscopy time 47.6 ± 40 minutes to 7.0 ± 9.2 minutes; P <.001; procedural time 257 ± 157 minutes to 166 ± 84 minutes; P <.001). CONCLUSION: Acute success rates and fluoroscopy and procedural times in pediatric ablation all have improved over the last 25 years.

Association of Shunt Type With Arrhythmias After Norwood Procedure.

BACKGROUND: Transplant-free survival for single right ventricle (RV) lesions remains less than 70% at 3 years. Arrhythmia burden, influence of shunt type at Norwood procedure (RV-to-pulmonary artery shunt [RVPAS] versus Blalock-Taussig shunt [BTS]), and implications for mortality risk are not well defined. METHODS: The authors performed a single-center retrospective analysis of patients with single RV lesions enrolled in a prospective study of arrhythmias after congenital heart surgery. RESULTS: Fifty-eight patients received a RVPAS and 62 received a BTS, with a median follow-up of 773 days. Overall arrhythmia incidence was 78%, two-thirds of which prompted intervention. Among all types of arrhythmias, only ventricular arrhythmias (VAs) differed by shunt type, which were more common in patients receiving an RVPAS (29% RVPAS versus 14% BTS; p = 0.049). The majority of VAs were transient (69% less than 1 minute), and typically occurred early post-Norwood procedure (median 12 days). No additional variables were associated with development of VAs. Shunt type did not influence transplant-free survival. Within the entire cohort, there was a trend toward increased mortality with prior history of VA (odds ratio, 2.90; 95% confidence interval, 0.99 to 8.90; p = 0.052). For interstage survivors to Glenn palliation, any VA associated with a 14-fold increased risk of death or transplant (hazard ratio, 14.00; 95% confidence interval, 3.66 to 53.40; p < .001). No other tachyarrhythmia or bradyarrhythmia was associated with mortality. CONCLUSIONS: In this cohort with single RV lesions and prospective rhythm surveillance, patients receiving an RVPAS at Norwood surgery had an increased incidence of VAs compared with patients with a BTS. VAs correlated with late mortality in patients who survived the interstage period.

Serial assessment of accessory pathway antegrade conduction in children.

There is limited longitudinal data on accessory pathway (AP) antegrade conduction throughout childhood, with implications for risk stratification. Ten patients underwent serial electrophysiology study (EPS) with assessment of fastest 1:1 AP conduction. The median age at first and follow-up EPS was 0 (median 4 days) and 53 months. Median fastest 1:1 AP conduction was 255 ms at initial EPS and 275 ms at follow-up (P=0.24). The interval of time between studies had no influence on stability over time, nor was there any appreciable effect following changes in retrograde AP conduction. In conclusion, no patient displayed any marked shortening of 1:1 AP conduction over time.

Association between perioperative dexmedetomidine and arrhythmias after surgery for congenital heart disease.

BACKGROUND: Dexmedetomidine is commonly used after congenital heart surgery and may be associated with a decreased incidence of postoperative tachyarrhythmias. Using a large cohort of patients undergoing congenital heart surgery, we examined for an association between dexmedetomidine use in the immediate postoperative period and subsequent arrhythmia development. METHODS AND RESULTS: A total of 1593 surgical procedures for congenital heart disease were performed. Dexmedetomidine was administered in the immediate postoperative period after 468 (29%) surgical procedures. When compared with 1125 controls, the group receiving dexmedetomidine demonstrated significantly fewer tachyarrhythmias (29% versus 38%; P<0.001), tachyarrhythmias receiving intervention (14% versus 23%; P<0.001), bradyarrhythmias (18% versus 22%; P=0.03), and bradyarrhythmias receiving intervention (12% versus 16%; P=0.04). After propensity score matching with 468 controls, the arrhythmia incidence between groups became similar: tachyarrhythmias (29% versus 31%; P=0.66), tachyarrhythmias receiving intervention (14% versus 17%; P=0.16), bradyarrhythmias (18% versus 15%; P=0.44), and bradyarrhythmias receiving intervention (12% versus 9%; P=0.17). After excluding controls exposed to dexmedetomidine at a later time in the hospitalization, dexmedetomidine was associated with increased odds of bradyarrhythmias receiving intervention (odds ratio, 2.18; 95% confidence interval, 1.02-4.65). Furthermore, there was a dose-dependent increase in the odds of bradyarrhythmias (odds ratio, 1.04; 95% confidence interval, 1.01-1.07) and bradyarrhythmias receiving intervention (odds ratio, 1.05; 95% confidence interval, 1.01-1.08). CONCLUSIONS: Although dexmedetomidine exposure in the immediate postoperative period is not associated with a clinically meaningful difference in the incidence of tachyarrhythmias after congenital heart surgery, it may be associated with increased odds of bradyarrhythmias.

Permanent junctional reciprocating tachycardia in children: a multicenter experience.

BACKGROUND: Permanent junctional reciprocating tachycardia (PJRT) is an uncommon form of supraventricular tachycardia in children. Treatment of this arrhythmia has been considered difficult because of a high medication failure rate and risk of cardiomyopathy. Outcomes in the current era of interventional treatment with catheter ablation have not been published. OBJECTIVE: To describe the presentation and clinical course of PJRT in children. METHODS: This is a retrospective review of 194 pediatric patients with PJRT managed at 11 institutions between January 2000 and December 2010. RESULTS: The median age at diagnosis was 3.2 months, including 110 infants (57%; aged <1 year). PJRT was incessant in 47%. The ratio of RP interval to cycle length was higher with incessant than with nonincessant tachycardia. Tachycardia-induced cardiomyopathy was observed in 18%. Antiarrhythmic medications were used for initial management in 76%, while catheter ablation was used initially in only 10%. Medications achieved complete resolution in 23% with clinical benefit in an additional 47%. Overall, 140 patients underwent 175 catheter ablation procedures with a success rate of 90%. There were complications in 9% with no major complications reported. Patients were followed for a median of 45.1 months. Regardless of treatment modality, normal sinus rhythm was present in 90% at last follow-up. Spontaneous resolution occurred in 12% of the patients. CONCLUSION: PJRT in children is frequently incessant at the time of diagnosis and may be associated with tachycardia-induced cardiomyopathy. Antiarrhythmic medications result in complete control in few patients. Catheter ablation is effective, and serious complications are rare.

The Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT) Initiative-rationale and design: report from the pediatric and congenital electrophysiology society's MAP-IT taskforce.

Multicenter clinical registries are increasingly recognized as valuable tools for establishing benchmarks, facilitating patient-centered quality improvement and research. In 2010, the Pediatric and Congenital Electrophysiology Society convened a taskforce of its members to design, construct, and implement a clinical registry known as the Multicenter Pediatric and Adult Congenital EP Quality (MAP-IT) Initiative. The present aim of the MAP-IT Initiative is to create an infrastructure by which we can measurably improve patient-centered outcomes and reduce complications associated with electrophysiology studies and catheter ablation in pediatric and congenital heart disease patients. The purpose of this writing is to report the progress to date from three of the four subcommittees of the MAP-IT taskforce. Specifically, we present our initial set of key data elements and definitions, recommended database table structure, and considerations regarding wide-scale implementation of the registry. Development of a risk/complexity score for use in the MAP-IT registry is presented in a separate companion manuscript. It is our intent that these manuscripts will serve to introduce the electrophysiology and pediatric cardiology community to the MAP-IT initiative and provide a rationale for its design and recommended implementation strategy.

Prospective evaluation of defibrillation threshold and postshock rhythm in young ICD recipients.

BACKGROUND: Adaptation of implantable cardioverter defibrillator (ICD) systems to the needs of pediatric and congenital heart patients is problematic due to constraints of vascular and thoracic anatomy. An improved understanding of the defibrillation energy and postshock pacing requirements in such patients may help direct more tailored ICD therapy. We describe the first prospective evaluation of defibrillation threshold (DFT) and postshock rhythm in this population. METHODS: We prospectively studied patients ≤ 60 kg at time of ICD intervention. DFTs were obtained using a binary search protocol with three VF inductions. Postshock pacing was programmed using a stepwise protocol, lowering the rate prior to each VF induction. RESULTS: Twenty patients were enrolled: 11 had channelopathy, five congenital heart disease, and four cardiomyopathy. The median age was 16 years, median weight 48 kg. Twelve patients had a transvenous high-voltage coil; eight had pericardial +/- subcutaneous coil(s). Median DFT was 7 J (range 3-31 J); 19/20 patients had DFT ≤ 15 J and all patients <25 kg had DFT ≤ 9 J (n = 6). There was no difference in DFT between patients with transvenous versus pericardial +/- subcutaneous coils (median 7 J vs 6 J, P = 0.59). No patient with normal atrioventricular conduction prior to defibrillation required postshock pacing (n = 16). There were no adverse events. CONCLUSIONS: These data suggest that many pediatric ICD patients have low DFTs and adequate postshock escape rhythm. This may help determine appropriate parameters for future design of pediatric-specific ICDs.

Antitachycardia pacing reduces appropriate and inappropriate shocks in children and congenital heart disease patients.

BACKGROUND: Antitachycardia pacing (ATP) can reduce implantable cardioverter-defibrillator shocks, but its use in children and patients with congenital heart disease (CHD) is not well described. OBJECTIVE: To review the efficacy of ATP in children and patients with CHD. METHODS: We reviewed implantable cardioverter-defibrillator therapies in children and patients with CHD (aged 2-52 years) at our institution. Appropriate therapies were defined as those delivered for true ventricular tachycardia (VT) or ventricular fibrillation; other therapies were defined as inappropriate. RESULTS: During a median follow-up of 4 years (range 0.5-15 years), 17 of 79 patients (23%) received appropriate therapy and 14 received ATP for 100 episodes of VT. ATP was highly successful (88%) in terminating VT, and only 10 of 100 episodes required a shock. Shocks were effective in terminating VT/ventricular fibrillation in 21 of 24 episodes (87%). The outcomes of appropriate therapy were similar for ATP and shocks (success 88% vs 87%, failure 9% vs 8%, acceleration 3% vs 4% for ATP and shocks, respectively). Thirty-one patients (39%) received inappropriate therapy. Inappropriate ATP (without subsequent shocks) was delivered to 11 patients for the following: sinus tachycardia (19 episodes in 7 patients) with slowing of the rate after ATP, T-wave oversensing (2 episodes in 2 patients) with loss of oversensing after ATP, and reentrant supraventricular tachycardia (14 episodes in 2 patients) terminated with ventricular ATP. CONCLUSIONS: ATP is highly efficacious for VT in children and patients with CHD. In addition to reducing appropriate shocks, inappropriate shocks due to sinus or supraventricular tachycardia can be significantly reduced with ATP.

System survival of nontransvenous implantable cardioverter-defibrillators compared to transvenous implantable cardioverter-defibrillators in pediatric and congenital heart disease patients.

BACKGROUND: Nontransvenous (NTV) implantable cardioverter-defibrillator (ICD) systems with pericardial and/or subcutaneous coils are used in select pediatric and congenital heart disease patients who are not candidates for transvenous ICD leads. Outcomes with these hybrid configurations are not well understood. OBJECTIVE: The purpose of this study was to compare survival of NTV ICD systems to standard transvenous (TV) ICD systems. METHODS: We conducted a retrospective single-center study in which the TV group was matched to the NTV group 2:1 by type of cardiac disease and implant date. RESULTS: There were 39 patients in the NTV group and 78 matched in the TV group. Compared to the TV group, the NTV group was younger (median 7 vs 20 years) with a smaller body surface area at implant (0.9 vs 1.8 m(2); both P <.001). Median follow-up in the NTV group was 17 months. System survival at 12, 24, and 36 months was 73%, 55%, and 49% in the NTV group versus 91%, 83%, and 76% in the TV group (P = .003). A multivariable Cox proportional hazards model including group, body surface area, and age at implant revealed the NTV group to be an independent predictor of system failure (hazard ratio 2.9, P = .04). Rate of total unanticipated interventions in the NTV group was 18 versus 6 per 1,000 person-months in the TV group. In patients with NTV systems, 23% received appropriate shocks and 18% received inappropriate shocks. CONCLUSION: Survival of ICD systems using NTV defibrillation coils is significantly shorter than with TV ICD systems. Although NTV systems provide protection for this unique subset of patients, more durable options are needed.

Ascending aortic dilation in patients with congenital complete heart block.

BACKGROUND: The clinical spectrum and underlying pathophysiology of isolated congenital complete heart block (CCHB) remain incompletely understood. Aortic dilation has been anecdotally observed in some children with CCHB, but detailed reports are lacking. OBJECTIVE: This study sought to systematically describe aortic size in children with CCHB and to investigate predictor variables associated with aortic dilation. METHODS: A retrospective review of clinical features and echocardiograms was performed for all patients with CCHB and a structurally normal heart or simple anatomic lesions seen at our center over 22 years. Echocardiographic measurements were assigned z-scores using validated norms. RESULTS: Sixty subjects met inclusion criteria. The median ascending aorta (AsAo) z-score was 2.2 (range -0.6 to 7.2) at first echocardiogram, with 30 of 58 (52%) having a z-score >2 (P <.0001) and 11 of 58 (19%) having a z-score >4. The distribution of aortic root dimensions was nearly normal with a median z-score of 0.4 (range -1.3 to 3.2). Although the AsAo remained dilated at the last echocardiogram (median z = 1.7, range -0.9 to 6.3), the trend toward normalization was significant (P = .002). Maternal autoantibody seropositivity and decreased left ventricular function were associated with AsAo dilation at initial echocardiogram in a multiple logistic regression model controlling for heart rate and indexed stroke volume (odds ratio 15, P = .03, and odds ratio 0.8, P = .02, respectively). CONCLUSION: Potentially clinically significant AsAo dilation, but not aortic root dilation, is present in a large proportion of pediatric patients with isolated CCHB. Maternal autoantibody seropositivity and decreased left ventricular function at initial echocardiogram correlate with this previously unreported finding. This observation may indicate a previously unrecognized consequence of fetal exposure to these autoantibodies.

Effects of G207, a conditionally replication-competent oncolytic herpes simplex virus, on the developing mammalian brain.

Viral oncolytic therapy for malignant brain tumors involves local intratumoral delivery of a genetically engineered virus with tumor cell-specific lytic activity. Promising preliminary results have been achieved in preclinical models with G207, a replication-competent herpes simplex virus type 1 constructed with multiple directed mutations. Although the safety of G207 has been demonstrated in adults, application of viral oncolytic therapy to children with brain tumors has been delayed because of previous lack of data concerning the impact of a replication-competent oncolytic virus on the developing mammalian brain. In this study there was no significant difference in long-term physical development, cognitive performance, or exploratory behaviors between mice that received intracerebral inoculation of G207 or control saline at 4 days of age. However, histological examination and magnetic resonance imaging revealed frequent unilateral ventriculomegaly ipsilateral to the site of injection in only the G207 group. These results suggest that although it is unlikely that G207 will have significant adverse effects on neurodevelopmental outcomes of pediatric patients with brain tumors, an initial study of G207 in children should exclude those patients with tumors in or near the ventricular system as well as patients less than 2 years of age. Furthermore, patients in such a study will need to be closely monitored for the development of hydrocephalus.

Initial treatment of melanoma brain metastases using gamma knife radiosurgery: an evaluation of efficacy and toxicity.

BACKGROUND: Melanoma is the primary malignancy that is most likely to metastasize to the brain. Because such an event carries an almost uniformly poor prognosis, the current study reviewed outcomes and identified associated prognostic indicators for 51 consecutive patients receiving gamma knife (GK) radiosurgery in the initial treatment of 188 intracranial melanoma metastases. METHODS: Data were collected retrospectively from a single-center GK radiosurgery database and from primary patient medical records and radiographs. RESULTS: At presentation, 71% of patients had multiple intracranial metastases, and extracranial metastases were present in 66% of patients. Thirty-two patients (63%) were initially treated with GK radiosurgery alone, whereas the remainder received GK radiosurgery in combination with surgery and/or whole-brain radiotherapy (WBRT). Overall median survival from time of GK radiosurgery was 26 weeks. Subgroup analysis revealed a median survival of 77 weeks for patients presenting with a single lesion, compared with 20 weeks for patients presenting with multiple lesions (P = 0.003). Patients in recursive partitioning analysis (RPA) Class I survived a median of 57 weeks, compared with a median survival of 20 weeks for patients in RPA Class II or III (P = 0.002). Although long-term imaging follow-up revealed that a majority of patients experienced distant brain metastases, multivariate analysis showed that distant metastases occurred significantly sooner in patients with extracranial metastases (P = 0.0004). Addition of initial WBRT had no significant effect on the time to development of new brain metastases (P = 0.13). Local control (crude) was observed in 81% of lesions initially treated with GK. Patients experienced improved or stable symptoms for a median of 37 weeks post-GK radiosurgery. CONCLUSIONS: Survival analyses supported the use of GK radiosurgery in the initial treatment of patients with melanoma brain metastases, with best results occurring in patients presenting with a single lesion.