In situ pericardial extracardiac lateral tunnel Fontan operation: fifteen-year experience.

BACKGROUND: The study purpose is to evaluate the long-term outcome of the in situ pericardial extracardiac lateral tunnel Fontan operation. METHODS: From June 1994 to August 2009, 160 patients with single ventricle (boys, n = 96, 60%, median age = 39 months, mean weight 15.5 kg) underwent the pedicled pericardial extracardiac lateral tunnel operation. Patients' charts were reviewed for perioperative and long-term follow-up data, outcome, and mortality. The potential growth of these tunnels was evaluated. RESULTS: The main diagnoses included tricuspid atresia (n = 44, 27%); double-outlet right ventricle (n = 29, 18%), and hypoplastic left heart syndrome (n = 26, 16%). The mean follow-up was 6.5 ± 3.7 years (range: 0.1-15 years). There were 2 (1.3%) operative and 6 (3.7%) late deaths. Actuarial survival at 14 years was 93%. Early complications included prolonged effusions (n = 35, 22%), chylothorax (n = 5, 3.1%), readmissions (n = 35, 22%), cerebrovascular accidents (n = 8, 5%), contralateral phrenic nerve palsy (n = 1, 0.8%), and transient arrhythmias (n = 5, 3.1%). No pacemaker was needed. Late complications included tunnel stenosis (n = 3, 1.8%) managed with balloon dilatation and stenting in 2 patients and surgical revision in 1; tunnel thrombosis (n = 2, 1.2%) causing death in both patients; and protein losing-enteropathy (n = 4, 2.5%). Follow-up echocardiography of 10 patients showed laminar flow, no turbulence/gradient at the inferior vena cava and mid-tunnel levels. The diameter indexed to body surface area showed growth, reduction, or no change depending on flow demands. CONCLUSIONS: The construction of the extracardiac lateral tunnel Fontan conduit using viable pedicled pericardium is a relatively simple, durable, and safe operation. Long-term follow-up confirms low morbidity and mortality. Fenestration is unnecessary in most patients. This viable tunnel adapts to physiologic flow demands.

Decreased exercise performance with age in children with hypoplastic left heart syndrome.

OBJECTIVE: Children born with hypoplastic left heart syndrome (HLHS) may experience cardiac dysfunction after staged surgery or transplantation, which may worsen with age. We examined the hypothesis that exercise testing can address cardiovascular capacity and suggest interventions to improve quality of life. STUDY DESIGN: Children with HLHS > or = 8 years old performed treadmill or bicycle ergometric testing at 4 centers. Results were compared with norms for age and sex. RESULTS: Of the 42 participants, the mean age was 12.9 years (range, 8.5-17.0 years), 64% were boys, 20 had staged surgery, and 34 completed metabolic assessment. The percent of predicted maximal oxygen uptake (mVO2) was higher in younger children. Children aged 8 to 12 years achieved 70% of predicted mVO2; children aged 13 to 17 years achieved 60% of predicted mVO2 (P = .02). The percent of predicted peak heart rate trended higher in younger patients (83% versus 75%, P = .07). Electrocardiographic changes were more common in older children. In treadmill testing, patients who had a transplant had better exercise performance than patients who underwent staged surgery in percent of predicted exercise time (82% versus 54%, P < .0001) and peak rate-pressure product (241 x 10(3) versus 195 x 10(3), P = .02). The percent of predicted mVO2 did not differ between patients who had a transplant (66%) and patients who underwent staged surgery (61%, P = .25). CONCLUSION: Children with HLHS showed considerable age-related decline in exercise performance, regardless of surgical strategy.

Exercise assessment in infants after cardiac transplantation.

BACKGROUND: Few data describe exercise performance after cardiac transplantation during infancy. The aim of this study was to compare the cardiorespiratory response to exercise in healthy subjects with that of subjects who had undergone heart transplantation during infancy to treat hypoplastic left heart syndrome. METHODS: Subjects (24 heart transplant recipients and 25 healthy controls) exercised on a treadmill using pediatric ramp protocols. We measured heart rate (HR), blood pressure, and metabolic data. Median age at transplantation was 20 days (range, 4 to 97 days). Age of recipients at exercise testing was 9.7 +/- 2.3 years and in healthy subjects was 10.5 +/- 1.4 years (p=not significant [NS]). RESULTS: Exercise duration was similar in both groups (10.3 +/- 2.0 minutes in recipients vs 11.1 +/- 1.5 minutes in healthy subjects, (p=NS). Heart rate at rest was greater in recipients (94 +/- 15 beats per minute [bpm] vs 85 +/- 11 bpm, p=0.02). Peak HR also was less in the recipient group (158 +/- 15 bpm vs 189 +/- 12 bpm, p <0.001). Peak oxygen consumption was 14% less in the recipients (32.3 +/- 5.6 ml/kg/min vs 36.8 +/- 5.5 ml/kg/min, p <0.01). Ventilatory anaerobic threshold was decreased in recipients, 27.6 +/- 9.6 vs 32.8 +/- 6.0, p <0.05. Respiratory exchange ratio at peak exercise was equal in both groups (1.06 +/- 0.06 vs 1.06 +/- 0.08). Oxygen pulse index did not differ significantly, 5.5 +/- 1.1 ml/beat/m2 in recipients and 6.1 +/- 1.7 ml/beat/m2 in healthy subjects (p=NS). CONCLUSIONS: Overall, children who undergo cardiac transplantation in infancy have exercise capacities within the normal range. These recipients have a decreased heart rate reserve that may account for the differences in peak oxygen consumption when compared with healthy subjects.

Inhaled nebulized nitrite is a hypoxia-sensitive NO-dependent selective pulmonary vasodilator.

The blood anion nitrite contributes to hypoxic vasodilation through a heme-based, nitric oxide (NO)-generating reaction with deoxyhemoglobin and potentially other heme proteins. We hypothesized that this biochemical reaction could be harnessed for the treatment of neonatal pulmonary hypertension, an NO-deficient state characterized by pulmonary vasoconstriction, right-to-left shunt pathophysiology and systemic hypoxemia. To test this, we delivered inhaled sodium nitrite by aerosol to newborn lambs with hypoxic and normoxic pulmonary hypertension. Inhaled nitrite elicited a rapid and sustained reduction ( approximately 65%) in hypoxia-induced pulmonary hypertension, with a magnitude approaching that of the effects of 20 p.p.m. NO gas inhalation. This reduction was associated with the immediate appearance of NO in expiratory gas. Pulmonary vasodilation elicited by aerosolized nitrite was deoxyhemoglobin- and pH-dependent and was associated with increased blood levels of iron-nitrosyl-hemoglobin. Notably, from a therapeutic standpoint, short-term delivery of nitrite dissolved in saline through nebulization produced selective, sustained pulmonary vasodilation with no clinically significant increase in blood methemoglobin levels. These data support the concept that nitrite is a vasodilator acting through conversion to NO, a process coupled to hemoglobin deoxygenation and protonation, and evince a new, simple and inexpensive potential therapy for neonatal pulmonary hypertension.

Outcome of aortic valve repair in children with congenital aortic valve insufficiency.

OBJECTIVE: Surgical aortic valvotomy has a long history of providing excellent palliation for aortic stenosis in infancy and childhood. The fate of aortic valve repairs for dominant aortic regurgitation in this same age group is considerably less clear. METHODS: From 1990 to 2000, a total of 21 patients underwent aortic valve repair for aortic regurgitation at our institution. Seventeen patients were younger than 17 years at the time of repair (3-17 years, mean 8.1 +/- 3.7 years). Of these 17 children, 6 (35%) had bicuspid valves and 11 (65%) had tricuspid valves. Type of repair varied with valve type, but repair generally consisted of commissure resuspension, partial commissure closure, triangular resection of redundant leaflets, or some combination. RESULTS: There were no deaths. Follow-up ranged from 1 to 11 years (mean 5.3 +/- 2.4 years). At present 3 of 17 (17.6%) have mild aortic regurgitation according to echocardiography and 6 (35.2%) have moderate aortic regurgitation. In 8 of 17 cases (47.1%) the repair clearly failed, requiring reoperation from 0.5 to 73 months after the original operation (mean 18.9 months). Reoperation consisted of 6 Ross procedures and 2 mechanical aortic valve replacements. There were no deaths at the secondary operation. CONCLUSION: Aortic valve repair in children with a dominant feature of aortic insufficiency tended to fail progressively and at a high rate. Leaflet thickening was associated with higher risk of repair failure in this series. The threshold for aortic valve replacement should remain low.

Fate of polytetrafluoroethylene monocusp pulmonary valves in an animal model.

Creation of a competent pulmonary monocusp valve facilitates transition from pressure to volume overload following right ventricular outflow tract reconstruction. To determine intermediate-term results and performance of the different types of polytetrafluoroethylene membrane used to construct monocusp valves and transannular patches, 12 infant lambs underwent excision of the native pulmonary valve and insertion of a monocusp valve and transannular patch made from one of 4 types of membrane. Echocardiography was performed after 3, 6, 9, and 12 months, and cardiac catheterization was carried out prior to animal sacrifice at 6 (n = 4) or 12 (n = 8) months. There was no postoperative morbidity or mortality. On echocardiography, 6 valves were mobile (50%), 4 had diminished mobility (33%), and 2 were fixed (17%) prior to sacrifice. At catheterization, mild, moderate, and severe pulmonary regurgitation was observed in 4 valves each (33%), with no stenosis. Right ventricular outflow tract reconstruction with polytetrafluoroethylene monocusp valves can be safely accomplished with good early competence, variable degrees of late insufficiency, and no stenosis. Compared to an open microstructure, the closed polytetrafluoroethylene microstructure showed a milder fibroinflammatory reaction and fewer foci of microcalcification, with sparing of the free edge of the monocusp; this correlated with better intermediate-term hemodynamic performance.

Late rejection episodes more than 1 year after pediatric heart transplantation: risk factors and outcomes.

BACKGROUND: Little is known about late rejection episodes after pediatric heart transplantation. We determined the frequency of late rejection episodes (>1 year) after pediatric heart transplantation, defined risk factors for its occurrence, and evaluated outcome after late rejection. METHODS: We analyzed data from 685 pediatric recipients (<18 years at transplantation) who underwent transplantation between January 1, 1993, and December 31, 1997, at 18 centers in the Pediatric Heart Transplant Study (PHTS). Probability of freedom from late rejection was determined and risk factors for late rejection and for death after late rejection were sought using univariate and multivariate analyses. RESULTS: We followed 431 patients for >1 year (median follow-up, 32.9 months) of whom 106 (24.6%) experienced 1 or more late rejection episodes (total of 178 episodes, 27 with severe hemodynamic compromise). Probability of freedom from first late rejection was 73% at 3 years and 66% at 4 years after transplantation. Risk factors (multivariate analysis) for first late rejection were >1 episode of rejection in the first year (p = 0.009), recipient black race (p = 0.0002), and older age at transplantation (p = 0.0003). Only 4 of 325 (1.2%) children who survived beyond 1 year without late rejection died compared with 26 of 106 (24.6%) with late rejection (p < 0.0001). Nine of these 26 died within 1 month of the first late rejection episode, and 17 died subsequently: 5 of acute rejection, 3 of sudden unexplained deaths, 3 of documented coronary artery disease, and 6 of other causes. Severe hemodynamic compromise with late rejection was identified as a risk factor for death among children with 1 or more episodes of late rejection. CONCLUSIONS: Approximately 25% of pediatric recipients in the PHTS who survived beyond 1 year experienced late rejection episodes. Late rejection is associated with poor survival, especially when associated with hemodynamic compromise. Absence of late rejection episodes is associated with very low risk of death during medium-term follow-up after pediatric heart transplantation. Determining the risk factors for late rejection will help to identify a cohort of patients who may benefit from enhanced rejection surveillance and treatment.

Scoring system to determine need for balloon atrial septostomy for restrictive interatrial communication in infants with hypoplastic left heart syndrome.

BACKGROUND: Restrictive interatrial communication (IAC) causes morbidity and mortality in infants with hypoplastic left heart syndrome awaiting cardiac transplantation. We sought to create a scoring system, based on echocardiographic and clinical findings, to serve as a guide for determining the need for balloon atrial septostomy (BAS). METHODS: We retrospectively reviewed echocardiograms of 44 infants with hypoplastic left heart syndrome. Infants were studied from the time of admission to the final end-point of transplantation, Norwood procedure, or death. Seventeen infants underwent BAS for clinical indications of oxygen saturation <80% in room air. Data collected included age at BAS, maximum velocity (V(max)), and IAC diameter throughout the clinical course. We assigned higher IAC scores to smaller IAC diameter, greater V(max) through the IAC, and lower oxygen saturation value. The minimum score was 3, and the maximum score was 9. RESULTS: Only 10% of infants with a score <6 at presentation required BAS, whereas 67% of those with scores > or =6 required BAS. Higher IAC scores at presentation were associated with earlier need for BAS (p = 0.04). CONCLUSIONS: The IAC scoring system can serve as a reliable clinical guide for identifying infants with hypoplastic left heart syndrome who are likely to require BAS for relief of critically restrictive IAC while awaiting cardiac transplantation.

Moderate acute rejection detected during annual catheterization in pediatric heart transplant recipients.

BACKGROUND: Acute rejection commonly occurs within the first year after heart transplantation, and then decreases in frequency with time. Recently, the long-term utility of endomyocardial biopsy during routine annual catheterization has been questioned. The purpose of this study was to retrospectively review the prevalence of biopsy-proven rejection during routine annual catheterization in our patient population, determine whether biopsies late after transplant are useful, and identify factors that correlate with late unsuspected rejection. METHODS: Biopsy results from the annual catheterization were evaluated from 1986 to August 2000. The prevalence of moderate rejection was evaluated and compared with the patient's immunosuppressive regimen; the prevalence of late rejection; and how late rejection correlated with recipient age, number of first-year rejections and presence of sub-therapeutic cyclosporine. RESULTS: A total of 1108 biopsies were performed in 269 children with a mean follow-up of 5 +/- 3 years (median 5 years, range 1 to 11 years). Three-drug immunosuppressive therapy, including steroids, was used in 93 patients. There was a persistent 8% to 10% prevalence of moderate rejection at up to 10 years post-transplantation. Moderate rejection was more likely in patients: (1). on 3-drug immunosuppressive therapy; (2). with a recipient age >1 year; and (3). with a relatively lower cyclosporine level. CONCLUSIONS: These data suggest that continued surveillance of pediatric transplant patients for acute rejection is indicated for long-term follow-up.

Usefulness of cardiac transplantation in children with visceral heterotaxy (asplenic and polysplenic syndromes and single right-sided spleen with levocardia) and comparison of results with cardiac transplantation in children with dilated cardiomyopathy.

Surgical mortality is high in children with visceral heterotaxy (VH), particularly if atrioventricular valve insufficiency, ventricular dysfunction, or aortic atresia is present. This study reviews the outcome of cardiac transplantation (CT) in infants and children with VH and congenital heart disease who are at high risk for standard palliative or corrective surgery. We reviewed CT outcomes in 29 children with VH, congenital heart disease, atrioventricular valve insufficiency, ventricular dysfunction, and/or aortic atresia. Median age at CT was 3.1 years. Cardiac surgery had been performed in 20 patients (69%) before CT. Follow-up since CT has been 8.5 +/- 2.2 years. Outcomes were compared with 45 children who underwent transplantation for dilated cardiomyopathy. Actuarial graft survival in the VH group at 30 days and 1, 5, and 10 years was 100%, 86%, 68%, and 50%, respectively, compared with 100%, 96%, 83%, and 68% in children who underwent transplantation for dilated cardiomyopathy (p = 0.12). Splenic status, cardiac position, age at CT, number of prior cardiac surgeries, or systemic venous anomalies were not predictors of mortality after CT. Cardiopulmonary bypass and graft ischemic times were longer in the VH group; time on the ventilator after CT, length of hospitalization, and rejection, infection, post-transplant lymphoproliferative disease, and transplant coronary artery disease rates were equal. Thus, CT is a viable alternative therapy for high-risk patients with VH, possibly offering improved survival over standard surgical management.