Faculty Bibliography

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: 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- 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: 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: As mortality in patients with D-loop transposition of the great arteries (D-TGA) has decreased after the arterial switch operation (ASO), the focus has shifted to higher risk groups and outcomes that impact long-term morbidity and mortality, such as left ventricular (LV) dysfunction. We sought to examine the perioperative factors associated with LV dysfunction in patients with D-TGA and ventricular septal defects (VSD) after ASO. METHODS: A retrospective study was made of all patients with D-TGA/VSD who underwent ASO/VSD closure from 2001 to 2011. Patients with prematurity, L-looped ventricles, and straddling atrioventricular valves were excluded. The primary endpoint was moderate or severe LV dysfunction measured by echocardiogram 2 months or more after surgery. RESULTS: A total of 112 patients underwent ASO/VSD closure at a median age of 5 days. Median time of follow-up was 6.5 months, with no mortality noted. Six patients (8%) were noted to have at least moderate LV dysfunction. Risk factors were heart block requiring pacemaker placement (p < 0.001) and length of intensive care unit admission (p = 0.04). All 6 patients with heart block had an epicardial lead on the right ventricular free wall; 4 had moderate or severe LV dysfunction and underwent upgrade to cardiac resynchronization therapy (CRT); median time from initial pacemaker to CRT was 5 months. With a median follow-up of 5 months after CRT, LV function improved to normal (2 patients) or mild dysfunction (2 patients). CONCLUSIONS: Left ventricular dysfunction after surgical repair for D-TGA/VSD is low, with heart block and pacemaker insertion playing a significant role. The LV function improved after patients were upgraded to a CRT device.