Faculty Bibliography

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.

OBJECTIVE: To characterize mortality and morbidity outcomes in patients undergoing surgical Fontan conversion. BACKGROUND: Indications for and anticipated clinical outcomes associated with Fontan conversion are controversial. METHODS: A retrospective single-center cohort study of consecutive patients undergoing Fontan conversion between 1990 and 2006 stratified according to concomitant arrhythmia surgery. RESULTS: Forty patients underwent Fontan conversion at a median age of 19.0 years and were followed for 4.2 years. Six (15%) died, two perioperatively, three early postoperatively, and one following heart transplant. Older age was a univariate risk factor. Major perioperative complications occurred in 9 of 35 (26%) early survivors. Patients with concomitant arrhythmia surgery (N=21) were older at conversion and had longer interoperative intervals. They experienced a reduction in prevalence (95% vs. 28%, P<0.0001) and severity (severity score 7.3 vs. 3.3, P=0.001) of atrial tachyarrhythmias, in contrast to patients without arrhythmia surgery (47% vs. 53%; 3.3 vs. 3.9, P=NS). NYHA functional class improved in both groups. In a subgroup (N=14) with non-urgent late postoperative catheterization, filling pressures were unchanged from preoperative values. CONCLUSIONS: Mortality and morbidity after Fontan conversion are substantial, but survivors experience a subjective improvement in functional status. Concomitant arrhythmia surgery reduces the arrhythmia burden without a detectable increase in complication rates.

BACKGROUND: Atrial pacing is indicated for sinus node dysfunction (SND) after Fontan surgery; preferred lead implantation technique is debated. We compare outcomes of transvenous (TV) and epicardial (Epi) atrial lead implants in this population. METHODS: Retrospective review of Fontan patients undergoing atrial lead implant between 1992 and 2007. Demographics, lead performance data, and outcomes were analyzed. RESULTS: 78 patients had 90 leads implanted: 25 via TV route and 65 via Epi route. Median follow-up was 1.6 years (TV) and 3.6 years (Epi). TV leads were implanted in older patients (23.1 vs 9.3 years, P < 0.001) and at longer intervals after Fontan (15.2 vs 4.9 years, P < 0.001). Pacing indication for most TV leads was SND, while Epi leads were also indicated for atrioventricular block. Acute complication rates were similar (8% TV vs 19% Epi, P = 0.23), but median hospital stay was shorter for TV (2 vs 5 days, P = 0.03). Thrombus was observed in five patients (two in TV; three in Epi), but no thromboembolic events were observed. Mean lead survival was similar (TV 9.9 vs Epi 7.8 years, P = NS). Energy threshold was lower at implant for TV leads (0.9 vs 2.2 microJ, P = 0.049), but similar at follow-up (1.2 vs 2.6 microJ, P = 0.35). Atrial sensing was unchanged over time for TV (2.2 to 2.1 mV, P = NS), but decreased for Epi (3.3 to 2.5 mV, P = 0.02). CONCLUSIONS: Compared to epicardial leads, transvenous atrial pacing leads may be placed in Fontan patients with lower procedural morbidity and equivalent expectation of lead performance and longevity.

BACKGROUND: Pulmonary valve replacement (PVR) in repaired tetralogy of Fallot (TOF) reduces pulmonary regurgitation and decreases right ventricular (RV) dilation, but its long-term impact on ventricular tachycardia (VT) and mortality is unknown. This study aimed to determine the incidence of death and VT in TOF after PVR and to test the hypothesis that PVR leads to improvement in these outcomes. METHODS AND RESULTS: A total of 98 patients with TOF and late PVR for RV dilation were identified. Matched control subjects were identified for 77 of these patients; control subjects had TOF with RV dilation but no PVR. Matching was done by age (+/-2 years) and baseline QRS duration (+/-30 ms). No significant differences were found in age, QRS duration, type or decade of initial repair, age at TOF repair, or presence of pre-PVR VT between the 2 groups; limited echocardiographic and magnetic resonance imaging data showed no difference in left ventricular function but more RV dilation among PVR patients than control subjects. In the PVR group, 13 events occurred over 272 patient-years. No significant change in QRS duration was seen for any group. Overall 5- and 10-year freedom from death, VT, or both was 80% and 41%, respectively. In the matched comparison, no significant differences were seen in VT, death, or combined VT and/or death (P=0.32, P=0.06 [nearly favoring controls], and P=0.21). CONCLUSIONS: This cohort experienced either VT or death every 20 patient-years. In a matched comparison with a similar TOF group, late PVR for symptomatic pulmonary regurgitation/RV dilation did not reduce the incidence of VT or death.

INTRODUCTION: Clinical evidence supports the use of cardiac resynchronization therapy (CRT) in adults with heart failure, but experience in pediatrics and congenital heart disease (CHD) is limited in terms of patient numbers and follow-up. We sought to determine the functional assessment and clinical outcomes in pediatric and CHD CRT patients followed uniformly at one institution. METHODS: Retrospective review of 60 consecutive patients who underwent CRT between 2002 and 2007. RESULTS: At implantation, median age was 15.0 years (5 months to 47 years). Overall, 46 patients had CHD (77%) and 14 had dilated cardiomyopathy. Prior to CRT, 92% were on heart failure treatment drugs and 55% had pacemakers. Median follow-up time was 0.7 years (1 day-5.3 years). Median QRS width decreased from 149 to 120 ms (P < 0.001). Median ejection fraction (EF) increased from 36% to 42% (P < 0.001) and improvement was particularly evident in the group with CHD. Of note, 8 of 13 patients with single ventricle morphology had a "strong CRT response," defined as either an improvement of 2-3 ordinal points in NYHA classification and/or increased ventricular function by >or= 10 EF units. Overall, an improvement in functional status was observed in 39 of 45 patients (87%) with sufficient follow-up data. CONCLUSIONS: Children and CHD patients treated with CRT have acute improvement in ventricular function, but implantation may require individualized planning and unconventional approaches. Future important goals include preimplant determination of CRT responders in pediatric and CHD patients, optimizing lead placement and programing, as well as long-term CRT device management issues.

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.

INTRODUCTION: Recalls of implantable cardioverter defibrillator (ICD) generators have affected many patients. No information is available regarding the impact specifically on pediatric and congenital heart disease (CHD) patients. This study was undertaken to determine implications of ICD manufacturers' advisories and recalls on children and CHD patients. METHODS: The first part of this study involved single-center review of patients who underwent ICD placement between 2000 and 2005. Patients with ICDs affected by the 2005 advisories/recalls were reviewed for incidence of explantation, malfunction and complications. Secondly, members of the Pediatric and Congenital Electrophysiology Society (PACES) were queried for patients with affected devices, incidences of explantation, malfunction, and explant-related complications. Data were pooled for aggregate summary. RESULTS: Among 233 patients who underwent ICD implantation at our institution during the study period, 58 (25%) patients had advisory/recalled devices and 13 of 58 (22%) underwent explantation following 3.1 +/- 1.3 years implant duration. No defects were identified by the manufacturer. No patients experienced complications requiring reintervention or rehospitalization. Questionnaire responses were received from 22 PACES institutions, included 177 patients with affected devices, of which 76 (43%) were removed. One patient died from complications following revision, and 1 patient had complications requiring reoperation. Two explanted devices had loose headers; no other defects were discovered. Taken together, 2 of 89 explanted devices were defective, and 2 complications occurred from explantation. CONCLUSIONS: Advisories and recalls affect substantial numbers of pediatric and CHD patients. A significant proportion underwent explantation. Although complications are infrequent, there are important medical, psychosocial, and financial impacts associated with ICD replacement.

BACKGROUND: Left cardiac sympathetic denervation is one of the therapeutic modalities used in the management of patients with medically refractory long QT syndrome. Traditionally, a thoracotomy or cervical incision has been used as the standard surgical approach for performing left cardiac sympathetic denervation. Video-assisted thoracoscopic surgery allows a minimally invasive technique. There is only one published series on the use of video-assisted thoracoscopic surgery for left cardiac sympathetic denervation in patients with long QT syndrome. METHODS: We performed a retrospective clinical review of pertinent medical records and report a series including 9 pediatric patients (4 long QT syndrome, 4 catecholaminergic polymorphic ventricular tachycardia, and 1 idiopathic ventricular tachycardia) who underwent a left cardiac sympathetic denervation by means of video-assisted thoracoscopic surgery. RESULTS: There were no severe complications, and 6 of 7 symptomatic patients with available follow-up experienced marked improvement in the first month after sympathectomy. CONCLUSIONS: This minimally invasive procedure provides a safe novel therapeutic option for children with drug-refractory catecholaminergic polymorphic ventricular tachycardia and other catecholamine-triggered arrhythmias.