Faculty Bibliography

Background- Ventricular arrhythmia-related sudden cardiac arrest in infants with structurally normal hearts is rare. There have been no previously published reports of infants <3 months of age with ventricular fibrillation in which a primary diagnosis could not be defined. Methods and Results- Retrospective chart review of 3 unrelated infants <2 months of age from 3 different tertiary care centers within the United States and Australia was conducted. All 3 infants survived sudden cardiac arrest secondary to multiple episodes of polymorphic ventricular tachycardia and ventricular fibrillation. Each infant demonstrated unique and transient ECG findings consisting of ST changes and QRS widening before arrhythmia onset, which have not been previously reported. Amiodarone, sedation, sodium channel-blocking agents, and ventricular pacing were effective in suppressing acute events. Despite thorough investigation, including genetic testing, the cause of ventricular arrhythmias in each of these infants remains unclear. Conclusions- This is the first report of idiopathic ventricular fibrillation in young infants preceded by stereotypical transient ECG changes. These findings may represent a new, potentially treatable cause of sudden infant death. Recognition of these prodromal changes may be important in future management and survival of these infants.

BACKGROUND: Implantable cardioverter-defibrillator (ICD) therapy in children and congenital heart disease patients is hampered by poor long-term lead survival. Lead extraction is technically difficult and carries substantial morbidity. We sought to determine the outcomes of ICD leads in pediatric and congenital heart disease patients. METHODS AND RESULTS: The Pediatric Lead Extractability and Survival Evaluation (PLEASE) is a 24-center international registry. Pediatric and congenital heart disease patients with ICD lead implantations from 2005 to 2010 were eligible. Study subjects comprised 878 ICD patients (44% congenital heart disease). Mean+/-SD age at implantation was 18.6+/-9.8 years. Of the 965 total leads, 54% were thin (18 years (P=0.015). The actuarial yearly failure rate was 2.3% for non-Fidelis and 9.1% for Fidelis leads. Extraction was performed on 143 leads (80% thin, 7% expanded polytetrafluoroethylene coated), with lead age as the only independent predictor for advanced extraction techniques. There were 6 major extraction complications (4%) but no procedural mortality. CONCLUSIONS: This study demonstrates that ICD leads in children and congenital heart disease patients have an age-related suboptimal performance, further compounded by a high failure rate of Fidelis leads. Advanced extraction techniques were common and correlated with older lead age. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT00335036.

BACKGROUND: An increasing number of adults with congenital heart disease (CHD) require implantable cardioverter-defibrillators (ICDs), yet little is known about their impact on psychological well-being and sexual function. OBJECTIVE: To assess shock-related anxiety in adults with CHD and its association with depression and sexual function. METHODS: A prospective, multicenter, cross-sectional study was conducted on adult patients with CHD with (ICD(+)) and without (ICD(-)) ICDs. The Florida Shock Anxiety Scale was administered to patients with ICD(+) and the Beck Depression Inventory-II to all patients. Men completed the Sexual Health Inventory for Men, and women completed the Female Sexual Function Index. RESULTS: A total of 180 adults with CHD (ICD(+): n = 70; ICD(-): n = 110; median age 32 years [interquartile range 27-40 years]; 44% women) were enrolled. The complexity of CHD was classified as mild in 32 (18%), moderate in 93 (52%), and severe in 54 (30%) subjects. In ICD recipients, a high level of shock-related anxiety was identified (Florida Shock Anxiety Scale score 16; interquartile range 12-23.5), which was slightly higher than the median score for ICD recipients in the general population (P = .057). A higher level of shock-related anxiety was associated with poorer sexual function scores in both men (Spearman's rho =-.480; P<.001) and women (Spearman's rho =-.512; P<.01). It was also associated with self-reported depressive symptomatology (Spearman's rho = .536; P< .001). CONCLUSIONS: Adults with CHD and ICDs demonstrate a high level of shock-related anxiety, which is associated with lower sexual functioning scores in men and women. These results underscore the need for increased clinical attention related to ICD-related shock anxiety and impaired sexual function in this population.

BACKGROUND: Patients with congenital heart disease carry a high burden of arrhythmias and may pose special challenges when these arrhythmias are addressed invasively. We sought to describe our early experience with radiofrequency (RF) needle transseptal perforation to facilitate ablation procedures in this population. METHODS: Retrospective chart review to identify all cases of attempted transseptal access with a commercial RF needle at Children's Hospital Boston between February 2007 and January 2010. RESULTS: A total of 10 patients had attempted RF transseptal perforation. Median age was 27 years. Five patients had undergone atrial switch procedures (Mustard/Senning), four had undergone Fontan operations, and one had atrial septal defect repair. The indication for left atrial access was mapping/ablation of atrial flutter in nine cases, and left-sided accessory pathway in one case. The RF needle was chosen primarily in eight of 10 cases, whereas in the remaining two cases RF was used only after failed attempts with a conventional Brockenbrough needle. Septal material was atrial muscle in five cases, pericardium in three, and synthetic fabric in two. In nine of 10 patients, RF transseptal perforation was successful, including both patients in whom a conventional needle had failed. There were no clinically significant complications. CONCLUSIONS: RF transseptal perforation can be an effective method of obtaining left atrial access for electrophysiologic procedures in patients with complex congenital heart disease, including cases where a conventional Brockenbrough needle has failed.

BACKGROUND: Ebstein anomaly is a rare and heterogeneous congenital heart defect affecting the tricuspid valve and right ventricular (RV) myocardium. Few studies have analysed the electrocardiographic features of Ebstein anomaly and none has addressed correlations with disease severity. METHODS: Patients with Ebstein anomaly who had undergone electrocardiography and cardiac magnetic resonance (CMR) within 6 weeks between 2001 and 2009 were included. Exclusion criteria were: associated congenital cardiac defect, previous RV myoplasty and/or reduction surgery, class I anti-arrhythmic drug therapy, and paced/pre-excited QRS. Standard electrocardiogram (ECG) findings were correlated with CMR-based RV measures and clinical profile. RESULTS: The mean age of the 63 study patients was 22 +/- 13 years. An RV conduction delay (rsR' pattern in right precordial leads) was present in 45 patients (71%). The QRS duration correlated with anatomic RV diastolic volume (r = +0.56, P < 0.0001) and inversely with RV ejection fraction (EF; r = -0.62, P < 0.0001). The presence of QRS fractionation predicted greater atrialized RV volume (80 +/- 31 vs. 45 +/- 37 mL/m(2), P < 0.001). Normal QRS duration was associated with smaller anatomic RV diastolic volume (150 +/- 57 vs. 256 +/- 100 mL/m(2); P < 0.0001), higher RV EF (48 +/- 6 vs. 34 +/- 14%; P < 0.0001), higher oxygen consumption (VO(2)) at cardiopulmonary exercise (25.8 vs. 21.8 mL/kg/min, P = 0.05) and lower incidence of oxygen desaturation with exercise (25 vs. 65%, P = 0.02). CONCLUSION: Delayed and prolonged depolarization of the RV is common in patients with Ebstein anomaly. The QRS duration is a marker of RV enlargement and dysfunction. QRS fractionation is associated with a greater atrialized RV volume. A preserved surface ECG identifies a subset of patients with Ebstein anomaly with mild morphological and functional abnormalities and better clinical profile.

OBJECTIVE: Although many Fontan patients undergo pacemaker placement, there are few studies characterizing this population. Our purpose was to compare clinical characteristics, functional status and measures of ventricular performance in Fontan patients with and without a pacemaker. PATIENTS AND DESIGN: The National Heart, Lung, and Blood Institute funded Pediatric Heart Network Fontan Cross-Sectional Study characterized 546 Fontan survivors. Clinical characteristics, medical history and study outcomes (Child Health Questionnaire [CHQ]), echocardiographic evaluation of ventricular function, and exercise testing) were compared between subjects with and without pacemakers. RESULTS: Of 71 subjects with pacemakers (13%), 43/71 (61%) were in a paced rhythm at the time of study enrollment (age 11.9 +/- 3.4 years). Pacemaker subjects were older at study enrollment, more likely to have single left ventricles, and taking more medications. There were no differences in age at Fontan or Fontan type between the pacemaker and no pacemaker groups. There were no differences in exercise performance between groups. CHQ physical summary scores were lower in the pacemaker subjects (39.7 +/- 14.3 vs. 46.1 +/- 11.2, P =.001). Ventricular ejection fraction z-score was also lower (-1.4 +/- 1.9 vs. -0.8 +/- 2.0, P =.05) in pacemaker subjects. CONCLUSIONS: In our cohort of Fontan survivors, those with a pacemaker have poorer functional status and evidence of decreased ventricular systolic function compared to Fontan survivors without a pacemaker.

BACKGROUND: The presence of multiple accessory pathways (MultAP) is described in structural heart disease (SHD) such as Ebstein's anomaly and cardiomyopathies. Structural defects can impact the tolerability of tachyarrhythmia and can complicate both medical management and ablation. In a large cohort of pediatric patients with and without SHD undergoing invasive electrophysiology study, we examined the prevalence of MultAP and the effect of both MultAP and SHD on ablation outcomes. METHODS: Accessory pathway number and location, presence of SHD, ablation success, and recurrence were analyzed in consecutive patients from our center over a 16-year period. RESULTS: In 1088 patients, 1228 pathways (36% retrograde only) were mapped to the right side (TV) in 18%, septum (S) in 39%, and left side (MV) in 43%. MultAP were present in 111 pts (10%), involving 250 distinct pathways. SHD tripled the risk of MultAP (26% SHD vs 8% no SHD, P < .001). Multivariable adjusted risk factors for MultAP included Ebstein's (OR 8.7[4.4-17.5], P < .001) and cardiomyopathy (OR 13.3[5.1-34.5], P < .001). Of 1306 ablation attempts, 94% were acutely successful with an 8% recurrence rate. Ablation success was affected by SHD (85% vs 95% for no SHD, P < .01) but not by MultAP (91% vs 94% for single, P = .24). Recurrence rate was higher for SHD (17% SHD vs 8% no SHD, P < .05) and MultAP (19% MultAP vs 8% single, P < .001). CONCLUSIONS: MultAP are found in 10% of pediatric patients, and are more common in SHD compared to those with normal hearts. Both the presence of MultAP and SHD negatively influence ablation outcomes.

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