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ObjectiveTo test the hypothesis that delayed brain development in fetuses with d-transposition of the great arteries or hypoplastic left heart syndrome heightens their postnatal susceptibility to acquired white matter injury.MethodsThis is a cohort study across 3 sites. Subjects underwent fetal (third trimester) and neonatal preoperative magnetic resonance imaging of the brain to measure total brain volume as a measure of brain maturity and the presence of acquired white matter injury after birth. White matter injury was categorized as no-mild or moderate-severe based on validated grading criteria. Comparisons were made between the injury groups.ResultsA total of 63 subjects were enrolled (d-transposition of the great arteries: 37; hypoplastic left heart syndrome: 26). White matter injury was present in 32.4% (n = 12) of d-transposition of the great arteries and 34.6% (n = 8) of those with hypoplastic left heart syndrome. Overall total brain volume (taking into account fetal and neonatal scan) was significantly lower in those with postnatal moderate-severe white matter injury compared with no-mild white matter injury after adjusting for age at scan and site in d-transposition of the great arteries (coefficient: 14.8 mL, 95% confidence interval, -28.8 to -0.73, P = .04). The rate of change in total brain volume from fetal to postnatal life did not differ by injury group. In hypoplastic left heart syndrome, no association was noted between overall total brain volume and change in total brain volume with postnatal white matter injury.ConclusionsLower total brain volume beginning in late gestation is associated with increased risk of postnatal moderate-severe white matter injury in d-transposition of the great arteries but not hypoplastic left heart syndrome. Rate of brain growth was not a risk factor for white matter injury. The underlying fetal and perinatal physiology has different implications for postnatal risk of white matter injury.

Objective: It is recognized that there are numerous anatomic variants that result in hypoplastic left heart physiology. One such variant includes critical aortic stenosis or atresia, a hypoplastic aortic arch, and a reasonably well-developed left ventricle due to the presence of a ventricular septal defect. These patients are candidates for 1 of 3 surgical options: (1) a Norwood procedure followed by a single-ventricle pathway; (2) a Norwood procedure followed by a Rastelli procedure (2-stage Yasui); or (3) a single-stage Yasui procedure. Because 2 of the 3 options include a Norwood procedure as the initial step, the purpose of this study was to evaluate the contemporaneous results of the Yasui and Norwood procedures at a single institution., Methods: This was a retrospective review of patients who underwent a Yasui or Norwood procedure at Lucile Packard Children's Hospital between 2004 and 2013. Eighteen patients underwent a Yasui, of whom 15 had a single-stage procedure and 3 had a 2-stage procedure. During this time frame, 113 patients underwent a Norwood procedure. Kaplan-Meier survival curves and freedom from reoperation were compared for the 2 procedures., Results: The operative mortality (using the Society of Thoracic Surgeons definition) for the single-stage Yasui was 6.7% compared with 16% for the Norwood procedure (P < .05); survival was 85% versus 62% at 1 year, 85% versus 60% at 3 years, and 85% versus 58% at 5 years, respectively (log-rank P = .06). The average interval to first reoperation was 13.5 ± 3 months versus 4.5 ± 1 months for the Yasui and Norwood procedures, respectively (P < .001)., Conclusions: The Yasui procedure had a significantly lower operative mortality compared with the Norwood procedure. Early and midterm survival was also higher in the Yasui group versus the Norwood followed by a single ventricle pathway. These results indicate that the Yasui procedure has significant midterm benefits compared with the Norwood procedure and should be pursued when the anatomy is amenable for this approach., (Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Objectives: To demonstrate the technical feasibility and describe intermediate outcomes for the initial patients undergoing handcrafted, area-preserving, Y-graft modification of the Fontan procedure., Methods: A retrospective review of a pilot study was undertaken to describe preoperative, intraoperative, and postoperative results., Results: Six patients underwent successful procedures and remain alive 3 to 4 years later. The median age at operation was 3.3 years, and median weight was 13.2 kg. Five operations were done without cardiopulmonary bypass and no intraoperative pressure gradients were found. Five patients were extubated by postoperative day 1, Fontan pressures were 12 to 14 mm Hg, transpulmonary gradients were 6 to 8 mm Hg, and no renal or hepatic function abnormalities were found. Length of stay was 10 to 64 days. One patient required venovenous extracorporeal membrane oxygenation for previously undiagnosed plastic bronchitis (64-day stay); another required reoperation for an incidentally diagnosed aortic thrombus (44-day stay). One patient had occlusion of a Y-graft limb noted on magnetic resonance imaging follow-up at 3 months. Catheterization showed excellent hemodynamic parameters and no Fontan obstruction. Occlusion was believed to be due to right-sided pulmonary arteriovenous malformations and widely discrepant flow (80%) to the right lung leading to low flow in the left limb., Conclusions: The area-preserving, bifurcated Y-graft Fontan modification is technically feasible and shows excellent intermediate outcomes. Additional study is required to determine whether the advantages seen in the computational models will be realized in patients over the long-term, and to optimize patient selection for each of the various Fontan options now available., (Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Objectives: In this study, with the use of computational fluid dynamics, we evaluate the postoperative hemodynamic performance of the first cohort of patients undergoing a handcrafted Y-graft Fontan procedure and validate simulation predictions of hepatic blood flow distribution against in vivo clinical data., Methods: An 18-12 × 2-mm handcrafted Y-graft modification of the Fontan procedure was performed in 6 patients. Early (at the time of discharge) and 6-month postoperative 3-dimensional magnetic resonance imaging data were collected. Patient-specific models were constructed for flow simulations., Results: Hepatic blood flow distribution varied among patients. Lung perfusion data (n = 3) showed good agreement with simulations. Postoperative asymmetry in hepatic blood flow distribution was reduced 6 months postoperatively. In 1 patient, low wall shear stress was found in the left limb of the Y-graft, corresponding to the location of subsequent thrombosis in the patient., Conclusions: The credibility and accuracy of simulation-based predictions of postoperative hepatic flow distribution for the Fontan surgery have been validated by in vivo lung perfusion data. The performance of the Y-graft design is highly patient-specific. The anastomosis location is likely the most important factor influencing hepatic blood flow distribution. Although the development of thrombosis is multifactorial, the occurrence in 1 patient suggests that simulations should not solely consider the hepatic blood flow distribution but also aim to avoid low wall shear stress in the limbs., (Copyright © 2015 The American Association for Thoracic Surgery. Published by Elsevier Inc. All rights reserved.)

Background: From 2002 to 2005, the interstage mortality after a modified Norwood procedure was 7% in our program. An interstage home monitoring program (HMP) was established to identify Norwood procedure patients at increased risk of decompensation and to reduce interstage mortality., Methods: Results of the first 5 years of the Norwood HMP were reviewed retrospectively. Interstage was defined as the time between Norwood hospital discharge and admission for second stage surgical palliation. In the HMP, families documented oxygen saturation, heart rate, weight, and feedings daily. Nurse practitioners called each family at least weekly, and when issues arose, action plans were determined based on symptom severity., Results: Between October 2005 and October 2010 there were 46 Norwood procedure patients who survived to hospital discharge. All were enrolled in the HMP. Forty-five patients had a Norwood procedure with right ventricle to pulmonary artery conduit, and 1 patient had a modified Blalock-Taussig shunt. Interstage survival was 100%. Nineteen patients (41%) were admitted interstage; 5 patients were admitted twice, 1 patient was admitted 4 times. Seventeen patients (37%) required interstage interventions. Eight patients (17%) required major interventions: conduit stenting, aortic arch balloon angioplasty, emergent shunt, or early Glenn surgery. Minor interventions included supplemental oxygen, blood transfusion, intravenous hydration, diuresis, anti-arrhythmic therapy, or feeding adjustments., Conclusions: In the first 5 years of the HMP, all infants discharged after a modified Norwood procedure survived the interstage period. The HMP altered clinical management in 37% of patients. Home monitoring of oxygen saturation, heart rate, weight, and feedings, along with comprehensive care coordination, allowed timely interventions and reduced interstage mortality from 7% to 0%., (Copyright © 2014 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objective: Fetal cardiac surgery is a potential innovative treatment for certain congenital heart defects that have significant mortality and morbidity in utero or after birth, but it has been limited by placental dysfunction after fetal cardiac bypass. We have used the TinyPump device for fetal cardiac bypass in sheep fetuses at 90 to 110 days gestation., Methods: Ten mixed-breed pregnant ewes were used over a period of 6 months, and 10 fetuses were placed on bypass for 30 minutes. Five fetuses with a mean gestational age of 104 ± 4.5 days and mean weight of 1.4 ± 0.4 kg were placed on bypass using the TinyPump device, and 5 fetuses with a mean gestational age of 119 ± 4.5 days and mean weight of 3.4 ± 0.4 kg were placed on bypass using the roller head pump. The fetuses were monitored for up to 3 hours after bypass or until earlier demise., Results: Progressive respiratory and metabolic acidosis developed in all fetuses. The TinyPump group had a lower gestational age and weight compared with the roller head pump group. However, the rate of postbypass deterioration in the TinyPump group, as measured with blood gases, was noted to be significantly slower compared with the roller head pump group., Conclusions: We demonstrate the feasibility of the TinyPump device for fetal cardiac bypass in a fetal sheep model. The TinyPump group showed improved results compared with the roller head group despite more immature fetuses. The TinyPump device seems to be a promising device for future studies of fetal cardiac bypass in immature fetal sheep and in primates., (Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objectives: Peripheral pulmonary artery stenosis is a rare congenital heart defect frequently found in association with Williams and Alagille syndromes. Controversy exists regarding the optimal treatment of peripheral pulmonary artery stenosis, with most centers favoring catheter-based interventions. In contrast, we have preferentially used surgical reconstruction of peripheral pulmonary artery stenosis. The purpose of the present study was to review our experience with surgical reconstruction of peripheral pulmonary artery stenosis., Methods: We performed a retrospective review of patients who underwent surgical reconstruction of peripheral pulmonary artery stenosis. A total of 16 patients were identified: 7 had Williams syndrome, 6 had Alagille syndrome, and 3 had no identifiable syndrome. Detailed pulmonary angiography was performed in all patients to define stenoses at the main, branch, lobar, and segmental arterial levels. The mean preoperative right ventricular/left ventricular pressure ratio was 0.88 ± 0.07. The surgical approach was a median sternotomy with cardiopulmonary bypass. All peripheral stenoses were augmented with pulmonary artery homograft tissue. The median age at surgery was 14 months, and concomitant procedures were performed in 9 of the 16 patients., Results: There was 1 operative mortality (6%). The mean right ventricular/left ventricular pressure ratio decreased to 0.40 ± 0.04 postoperatively (P < .005), representing a 55% reduction compared with the preoperative values. The patients were followed up for a median of 5 years. No late mortality occurred and reoperation was not required., Conclusions: The data have demonstrate that this comprehensive surgical approach to the treatment of peripheral pulmonary artery stenosis was associated with low early and no late mortality. Surgical reconstruction of the peripheral pulmonary artery stenosis resulted in a significant decrease in right ventricular pressure. We hypothesize that this reduction in right ventricular pressures will confer a long-term survival advantage for this cohort of patients., (Copyright © 2013 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objectives: This study investigated the time-dependent remodeling and growth potential of porcine small intestine submucosa as a biomaterial for the reconstruction of pulmonary arteries in a lamb model., Methods: Left pulmonary arteries were partially replaced with small intestine submucosal biomaterial in 6 lambs. Two animals each were humanely killed at 1, 3, and 6 months. Computed tomographic angiography, macroscopic examination of the implanted patch, and microscopic analysis of tissue explants were performed., Results: All animals survived without complications. Patency and arborization of the pulmonary arteries were detected 6 months after implantation. There was no macroscopic narrowing or aneurysm formation in the patch area. The luminal appearance of the patch was similar to the intimal layer of the adjacent native pulmonary artery. Scanning electron microscopy showed that the luminal surface of the patch was covered by confluent cells. Immunohistochemical examination confirmed endothelialization of the luminal side of the patch in all of the explanted patches. The presence of smooth muscle cells in the medial layer was confirmed at all time points; however, expression of elastin, growth of the muscular layer, and complete degradation of patch material were detectable only after 6 months. The presence of c-Kit-positive cells suggests migration of multipotent cells into the patch, which may play a role in remodeling the small intestine submucosal biomaterial., Conclusions: Our data confirmed that remodeling and growth potential of the small intestine submucosal biomaterial are time dependent. Additional experiments are required to investigate the stability of the patch material over a longer period., (Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objective: The objectives of this study were (1) to determine the use of temporary epicardial pacing wires to diagnose and treat early postoperative arrhythmias in pediatric cardiac surgical patients and (2) to determine the predictive factors for the need of pacing wires for diagnostic or therapeutic purposes., Methods: We collected preoperative, intraoperative, and postoperative data in a prospective, observational format from patients undergoing pediatric cardiac surgery between August 2010 and January 2011 at a single academic children's hospital., Results: A total of 157 patients met the inclusion criteria during the study period. Of these 157 patients, pacing wires were placed in 127 (81%). Pacing wires were used in 25 patients (19.6%) for diagnostic purposes, 26 patients (20.4%) for therapeutic purposes, 15 patients (11.8%) for both diagnostic and therapeutic purposes, and 36 patients (28.3%) for diagnostic or therapeutic purposes. Need for cardioversion in the operating room, presence of 2 or more intracardiac catheters, severely reduced ventricular ejection fraction, and elevated serum lactate level at the time of operating room discharge were found to be independent predictors for the use of pacing wires. The only complication noted in the cohort was a skin infection at a pacing wire insertion site in 1 patient. A permanent pacemaker was required in 8 (6.2%) of all patients with temporary pacing wires., Conclusions: Our data support the use of temporary epicardial pacing wires in approximately 30% of children after congenital heart surgery. We found the need for cardioversion in the operating room, presence of 2 or more intracardiac catheters, severely reduced ventricular ejection fraction, and high serum lactate level at the time of discharge from the operating room to be independent predictors of the use of pacing wires in the early postoperative period., (Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objectives: A novel Y-shaped baffle has been proposed for the Fontan operation with promising initial results. However, previous studies have relied either on idealized models or a single patient-specific model. The objective of this study is to comprehensively compare the hemodynamic performance and hepatic blood flow distribution of the Y-graft Fontan baffle with 2 current designs using multiple patient-specific models., Methods: Y-shaped and tube-shaped grafts were virtually implanted into 5 patient-specific Glenn models forming 3 types of Fontan geometries: Y-graft, T-junction, and offset. Unsteady flow simulations were performed at rest and at varying exercise conditions. The hepatic flow distribution between the right and left lungs was carefully quantified using a particle tracking method. Other physiologically relevant parameters such as energy dissipation, superior vena cava pressure, and wall shear stress were evaluated., Results: The Fontan geometry significantly influences the hepatic flow distribution. The Y-graft design improves the hepatic flow distribution effectively in 4 of 5 patients, whereas the T-junction and offset designs may skew as much as 97% of hepatic flow to 1 lung in 2 cases. Sensitivity studies show that changes in pulmonary flow split can affect the hepatic flow distribution dramatically but that some Y-graft and T-junction designs are relatively less sensitive than offset designs. The Y-graft design offers moderate improvements over the traditional designs in power loss and superior vena cava pressure in all patients., Conclusions: The Y-graft Fontan design achieves overall superior hemodynamic performance compared with traditional designs. However, the results emphasize that no one-size-fits-all solution is available that will universally benefit all patients and that designs should be customized for individual patients before clinical application., (Copyright © 2012 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objective: This study was undertaken to assess the risks and benefits of the double-switch operation using a hemi-Mustard atrial switch procedure and the bidirectional Glenn operation for congenitally corrected transposition of the great arteries. To avoid complications associated with the complete Senning and Mustard procedures and to assist right-heart hemodynamics, we favor a modified atrial switch procedure, consisting of a hemi-Mustard procedure to baffle inferior vena caval return to the tricuspid valve in conjunction with a bidirectional Glenn operation., Methods: Between January 1994 and September 2009, anatomic repair was achieved in 48 patients. The Rastelli-atrial switch procedure was performed in 25 patients with pulmonary atresia and the arterial-atrial switch procedure was performed in 23 patients. A hemi-Mustard procedure was the atrial switch procedure for 70% (33/48) of anatomic repairs., Results: There was 1 in-hospital death after anatomic repair. There were no late deaths or transplantation. At a median follow-up of 59.2 months, 43 of 47 survivors are in New York Heart Association class I. Bidirectional Glenn operation complications were uncommon (2/33), limited to the perioperative period, and seen in patients less than 4 months of age. Atrial baffle-related reoperations or sinus node dysfunction have not been observed. Tricuspid regurgitation decreased from a mean grade of 2.3 to 1.2 after repair (P = .00002). Right ventricle-pulmonary artery conduit longevity is significantly improved., Conclusions: We describe a 15-year experience with the double-switch operation using a modified atrial switch procedure with favorable midterm results. The risks of the hemi-mustard and bidirectional Glenn operation are minimal and are limited to a well-defined patient subset. The benefits include prolonged conduit life, reduced baffle- and sinus node-related complications, and technical simplicity., (Copyright © 2011 The American Association for Thoracic Surgery. Published by Mosby, Inc. All rights reserved.)

Objectives: The objective of this work is to evaluate the hemodynamic performance of a new Y-graft modification of the extracardiac conduit Fontan operation. The performance of the Y-graft design is compared to two designs used in current practice: a t-junction connection of the venae cavae and an offset between the inferior and superior venae cavae., Methods: The proposed design replaces the current tube grafts used to connect the inferior vena cava to the pulmonary arteries with a Y-shaped graft. Y-graft hemodynamics were evaluated at rest and during exercise with a patient-specific model from magnetic resonance imaging data together with computational fluid dynamics. Four clinically motivated performance measures were examined: Fontan pressures, energy efficiency, inferior vena cava flow distribution, and wall shear stress. Two variants of the Y-graft were evaluated: an "off-the-shelf" graft with 9-mm branches and an "area-preserving" graft with 12-mm branches., Results: Energy efficiency of the 12-mm Y-graft was higher than all other models at rest and during exercise, and the reduction in efficiency from rest to exercise was improved by 38%. Both Y-graft designs reduced superior vena cava pressures during exercise by as much as 5 mm Hg. The Y-graft more equally distributed the inferior vena cava flow to both lungs, whereas the offset design skewed 70% of the flow to the left lung. The 12-mm graft resulted in slightly larger regions of low wall shear stress than other models; however, minimum shear stress values were similar., Conclusions: The area-preserving 12-mm Y-graft is a promising modification of the Fontan procedure that should be clinically evaluated. Further work is needed to correlate our performance metrics with clinical outcomes, including exercise intolerance, incidence of protein-losing enteropathy, and thrombus formation.

Objective: Our approach to the extracardiac conduit Fontan operation has evolved over time from full-pump, to partial-pump, to completely off-pump. This study is designed to report our overall experience with the extracardiac conduit Fontan operation and to evaluate the evolution in bypass technique on postoperative outcomes., Methods: From September 1992 to April 2005, 285 patients, median age 4.5 years (1.4-44 years), median weight 16 kg (9.4-94 kg), underwent a primary extracardiac conduit Fontan procedure. Early and late outcomes were analyzed for the entire cohort and for 2 patient groups depending on whether an oxygenator was used in the bypass circuit (166 patients; 58%) or not (119 patients; 42%)., Results: Early failure (including death and takedown) occurred in 7 patients (2.5%). Prevalence of new early postoperative sinus node dysfunction necessitating a permanent pacemaker was 0.4%, and that of new tachyarrhythmias necessitating discharge home on a regimen of antiarrhythmia medications was 2.5%. Ten-year actuarial freedom from Fontan failure, new sinus node dysfunction necessitating a permanent pacemaker, and reoperation for conduit thrombosis or stenosis was 90%, 96%, and 98%, respectively. Fenestration rate was lower (P = .001) in the no-oxygenator group (8%) than in the oxygenator group (25%). Patients in the no-oxygenator group had lower intraoperative Fontan pressure (12.0 +/- 2.3 vs 13.5 +/- 2.4 mm Hg, P < .001), common atrial pressure (4.6 +/- 1.8 vs 5.3 +/- 1.8 mm Hg, P = .003), and transpulmonary gradient (7.5 +/- 2.1 vs 8.3 +/- 2.2 mm Hg, P = .013) than did the oxygenator group., Conclusions: The extracardiac conduit Fontan operation coupled with minimal use of extracorporeal circulation is associated with favorable intraoperative hemodynamics, low fenestration rate, minimal risk of thrombosis or stenosis, and minimal early and late rhythm disturbance.

Objective: Neonates with congenital heart disease might require surgical repair with deep hypothermic circulatory arrest, a technique associated with adverse neurodevelopmental outcomes. Antegrade cerebral perfusion is thought to minimize ischemic brain injury, although there are no supporting experimental data. We sought to evaluate and compare the extent of neurologic injury in a neonatal piglet model of deep hypothermic circulatory arrest and antegrade cerebral perfusion., Methods: Neonatal piglets undergoing cardiopulmonary bypass were randomized to deep hypothermic circulatory arrest or antegrade cerebral perfusion for 45 minutes. Animals were killed after 6 hours of recovery, and brain tissue was stained for evidence of cellular injury and for the apoptotic markers activated caspase 3 and cytochrome c translocation from mitochondria to cytosol., Results: Piglets from the antegrade cerebral perfusion group exhibited less apoptotic or necrotic injury (4 +/- 3 vs 29 +/- 12 cells per field, P = .03). The piglets undergoing antegrade cerebral perfusion also had less evidence of apoptosis, with fewer cells staining for activated caspase 3 (57 +/- 8 vs 93 +/- 9 cells per field, P = .001) or showing cytochrome c translocation (6 +/- 2 vs 15 +/- 4 cells per field, P = .02)., Conclusions: The use of antegrade cerebral perfusion in place of deep hypothermic circulatory arrest reduces evidence of apoptosis and histologic injury in neonatal piglets. Neonates with congenital heart disease might benefit from antegrade cerebral perfusion during complex cardiac surgery to improve their overall neurologic outcome.

Objective: Fetal cardiac surgery has potential benefits for treatment of some congenital heart defects. However, placental dysfunction as a result of fetal bypass, fetal stress, and fetal exposure to external milieu needs to be overcome to optimize the outcomes of fetal cardiac bypass. In this study we evaluated the technical feasibility of cardiac bypass in the nonhuman primate fetus and the efficacy of different anesthetic approaches., Methods: Twelve baboon fetuses, average gestation 146 +/- 8 days and weight 696 +/- 184 g, were used. Three fetuses were excluded from the study because of nuchal cord presentations. The animals were separated into two anesthesia groups: isoflurane (n = 6) and fentanyl and midazolam (n = 3). A miniature roller pump circuit without oxygenator was used for fetal bypass for 30 minutes. No blood transfusion was performed. Fetal blood gas samples were collected before bypass, during bypass, and at 15 and 60 minutes after bypass., Results: All fetuses in the isoflurane group were successfully placed on the cardiac bypass circuit. However, 2 animals in the fentanyl and midazolam group were not placed on the bypass circuit because of sustained elevation in maternal uterine tone. All maternal baboons survived. Of the 6 fetuses in the isoflurane group, 5 survived for 60 minutes; however, placental function continued to deteriorate after bypass (Pa o 2 33 +/- 3 mm Hg before bypass, 23 +/- 6 mm Hg 15 minutes after, and 18 +/- 9 mm Hg 60 minutes after)., Conclusion: The technical feasibility of cardiac bypass in nonhuman primate fetuses weighing less than 1000 g was confirmed. Isoflurane anesthesia appears to be superior to fentanyl and midazolam anesthesia for fetal cardiac surgery because of adequate uterine relaxation.

Objective: Pulmonary arteriovenous malformations occur in up to 60% of patients after cavopulmonary anastomosis. We compared the effects of cavopulmonary anastomosis and pulmonary artery banding on lung gene expression in an ovine model to study the abnormal pulmonary vascular remodeling after the exclusion of inferior vena caval blood independent of reduced pulmonary blood flow. We previously demonstrated by contrast echocardiography that pulmonary arteriovenous malformations develop by 8 weeks after cavopulmonary anastomosis but not after pulmonary artery banding. Hepatocyte growth factor, a pleiotropic factor with morphogenic, mitogenic, and angiogenic activities, signals via its specific receptor c-Met to induce the antiapoptotic factor Bcl-2. In this study, we examined pulmonary artery expression of these factors and their potential role in pulmonary artery remodeling after cavopulmonary anastomosis and pulmonary artery banding., Methods: Eighteen lambs aged 35 to 45 days were placed into 3 groups: cavopulmonary anastomosis, pulmonary artery banding, and control (n = 6/group). In the cavopulmonary anastomosis group, the superior vena cava was anastomosed to the right pulmonary artery in an end-to-end fashion. In the pulmonary artery banding group, the left pulmonary artery was banded to reduce blood flow to 20% of control. The control group had a simple right pulmonary artery clamp for 30 minutes. Lung was harvested for Western blot, reverse transcriptase-polymerase chain reaction, and immunostaining at 2 weeks (n = 3/group) and 5 weeks (n = 3/group) after surgery., Results: The expression of c-Met mRNA after cavopulmonary anastomosis was increased by twofold compared with the control or pulmonary artery banding group. The total lung expression of c-Met by Western blot was also up regulated at 2 weeks (P <.05). However, total lung expression of hepatocyte growth factor and Bcl-2 by Western and reverse transcriptase-polymerase chain reaction was not different from the control and pulmonary artery banding groups at both 2 and 5 weeks after surgery. Immunohistochemical analysis revealed that c-Met expression was localized to the intimal layer of the pulmonary artery in the cavopulmonary anastomosis, while its expression in the control and pulmonary artery banding lungs was localized to the medial layer. Localization of Bcl-2 on the intimal layer in lambs with cavopulmonary anastomosis followed the same pattern as c-Met., Conclusions: After cavopulmonary anastomosis, pulmonary artery expression of the hepatocyte growth factor receptor c-Met and one of its downstream effectors, Bcl-2, had increased in the intimal layer and decreased in the medial layer. Because the hepatocyte growth factor signaling promotes increased endothelial cell survival, it may have a role in pulmonary artery remodeling following cavopulmonary anastomosis. In addition, the change of c-Met expression in the medial layer after cavopulmonary anastomosis suggests a possible mechanism for the smooth muscle cell alteration related to abnormal angiogenesis.

Background: Fetal cardiac intervention represents a potential advance in the treatment of congenital cardiac lesions that increase in complexity during development. Prenatal repair of a primary defect might prevent pathologic blood-flow patterns that can result in hypoplasia of a cardiac chamber or great vessel. However, strategies to optimize fetal myocardial protection have not been studied. A biventricular working fetal heart preparation was used to evaluate the cardioprotective properties of induced fibrillation and crystalloid cardioplegia., Methods: Hearts from 16 fetal lambs at 115 to 125 days' gestation were harvested and perfused with Krebs-Henseleit solution. The descending aorta was ligated distal to the ductal insertion and the branch pulmonary arteries were ligated to simulate the parallel circulation of the fetus. Hearts were arrested with normothermic fibrillation (n = 8) or hypothermic crystalloid cardioplegia (n = 8) before reperfusion with Krebs-Henseleit solution. Baseline and postarrest myocardial function measurements were obtained from analysis of pressure-dimension relationships., Results: Fibrillatory and cardioplegic arrest were equally effective at preserving postarrest systolic function (left ventricle, 70% +/- 5% vs 68% +/- 15%, P =.52; right ventricle, 68% +/- 4.5% vs 65% +/- 4.5%, P =.26) and preventing increased diastolic stiffness (left ventricle, 32% +/- 5.3% vs 38% +/- 11%, P =.24; right ventricle, 25% +/- 3.3% vs 27% +/- 2.1%, P =.46). Myocardial water content was unchanged in hearts arrested with fibrillation and cardioplegia (84% +/- 1.5% vs 83.7% +/- 0.9%, P =.71)., Conclusions: Normothermic fibrillation and hypothermic crystalloid cardioplegia provide equal protection of the fetal myocardium. In the setting of diminished fetal myocardial reserve and because of the limited ability to manipulate the surrounding temperature in the fetus, normothermic fibrillation may be preferable for in utero repairs of selected congenital heart defects.

Background: Cavopulmonary anastomosis is used for palliation of cyanotic heart disease. Clinically significant pulmonary arteriovenous malformations occur in up to 25% of patients after surgical intervention. Cavopulmonary anastomosis creates several modifications to pulmonary physiology that may contribute to the development of pulmonary arteriovenous malformations, including reduced pulmonary blood flow and the exclusion of inferior vena caval effluent., Objective: By comparing the expression of angiogenic and stress-related proteins after cavopulmonary anastomosis and pulmonary artery banding, we sought to determine which genes were upregulated independent of reduced pulmonary blood flow., Methods: Lambs aged 35 to 45 days were placed into 1 of 3 groups: cavopulmonary anastomosis (n = 6), pulmonary artery banding (n = 6), and sham control (n = 6) animals. In our model pulmonary arteriovenous malformations are detectable by means of bubble-contrast echocardiography 8 weeks after cavopulmonary anastomosis. Lung tissue was harvested for Western blotting at 2 and 5 weeks after surgery., Results: Cavopulmonary anastomosis and pulmonary artery banding both increased angiogenic gene expression, but only cavopulmonary anastomosis induced the expression of endothelial stress-related genes. Vascular endothelial growth factor was upregulated 2.5-fold after both cavopulmonary anastomosis (P =.002) and pulmonary artery banding (P =.007). Only cavopulmonary anastomosis upregulated 2 stress-related genes, HO1 and GLUT1, 2.7-fold (P =.002) and 3.8-fold (P =.03), respectively. Hypoxia-inducible factor was upregulated 4-fold (P =.003) after cavopulmonary anastomosis. Pulmonary artery banding failed to induce the increased expression of any of these proteins., Conclusions: Reduced pulmonary blood flow induces a pulmonary angiogenic response but not an endothelial stress response. These results suggest that oxidative stress is more relevant to the formation of pulmonary arteriovenous malformations than angiogenic signaling alone because pulmonary artery banding does not result in pulmonary arteriovenous malformations. Oxidative stress of the pulmonary endothelium resulting from cavopulmonary anastomosis may predispose the affected vasculature to arteriovenous shunting.

Objective: The morphologic characteristics of the pulmonary circulation vary widely in patients with pulmonary atresia, ventricular septal defect, and major aortopulmonary collaterals. Although we favor single-stage unifocalization and complete repair as the procedure of choice, a subgroup of patients who meet specific criteria have been treated with initial surgical creation of an aortopulmonary window., Methods: Eighteen patients who were considered unsuitable candidates for single-stage repair underwent surgical creation of an aortopulmonary window. Selection criteria included the following: (1) presence of centrally confluent true pulmonary arteries 1.0 to 2.5 mm in diameter, with a well-developed peripheral arborization pattern; (2) multiple small aortopulmonary collateral vessels, most of which communicated with the true pulmonary arterial system; and (3) the presence of marked cyanosis., Results: There were no early deaths, and the 2 late deaths were both unrelated to the procedure. Follow-up angiography (n = 17) demonstrated good growth of true pulmonary arteries in 15 of 17 cases (88%). Mean pulmonary artery diameter increased from 1.76 mm to 3.45 mm. Subsequent operations have been performed in 15 of 18 cases (83%). Intracardiac repair with or without additional unifocalization was achieved in 8 of these 15 (53%). Seven patients (47%) have undergone staged unifocalization as the next procedure; of these, 3 were able to have intracardiac repair. Thus 11 of the 15 patients who have undergone second operations (73%) have had complete intracardiac repair., Conclusions: The initial surgical creation of an aortopulmonary window in carefully selected patients can increase the size of the true pulmonary arteries, making these patients better candidates for eventual intracardiac repair. The procedure should be avoided in patients with pulmonary overcirculation, a predominance of isolated supply collaterals, or true pulmonary arteries larger than 2.5 mm in diameter, and it is not applicable without a true pulmonary artery central confluence.

Background: Cavopulmonary anastomosis is used for palliation of cyanotic cardiac lesions. Postoperative development of pulmonary arteriovenous malformations can be significant in 10% to 25% of patients. To study the basis for formation of arteriovenous malformations, we developed an ovine model that reliably induces their development 8 weeks after cavopulmonary anastomosis. Previously, we found that cavopulmonary anastomosis inhibits the expression of pulmonary angiotensin-converting enzyme and suppresses angiotensin II production., Objective: This study examines the role of the angiotensin II receptors, type 1 and type 2, in this setting of pulmonary vascular remodeling., Methods: Lambs, aged 40 to 50 days, underwent cavopulmonary anastomosis. In age-matched control animals, a sham operation was performed. Messenger RNA and protein expression in lung specimens was measured at successive time points after cavopulmonary anastomosis or sham operations (n = 3 at each time point)., Results: Angiotensin type 1 mRNA was maximally upregulated 2-fold at 5 weeks after cavopulmonary anastomosis (P =.006). Expression of angiotensin type 1 protein was increased at least 2-fold at 2, 5, and 15 weeks after cavopulmonary anastomosis (P =.005). Cavopulmonary anastomosis also increased angiotensin type 2 mRNA and protein expression at least 2-fold at 2 and 5 weeks (P =.02) after surgical intervention. At 15 weeks, expression of angiotensin type 2 mRNA and protein was unchanged from that seen in control animals. Immunolocalization in pulmonary tissue sections 2 weeks after cavopulmonary anastomosis revealed markedly enhanced staining of angiotensin II receptor type 1 in vascular smooth muscle and angiotensin II receptor type 2 in the endothelium of pulmonary arteries., Conclusions: Rapid elevation in the expression of the type 1 and 2 angiotensin II receptors in the affected pulmonary vasculature after cavopulmonary anastomosis suggests their involvement in the pathologic vascular remodeling that occurs after cavopulmonary anastomosis.

Objectives: After a Fontan procedure, forward pulmonary blood flow is augmented during inspiration because of negative intrathoracic pressure. Total pulmonary blood flow is higher during inspiration. With hemidiaphragmatic paralysis, inspiratory augmentation of pulmonary flow is lost or diminished. The objective of this study was to compare early postoperative morbidity after the modified Fontan operation in patients with and without hemidiaphragmatic paralysis., Methods: A case-control analysis was performed comparing 10 patients with documented hemidiaphragmatic paralysis against 30 patients without paralysis who were matched for diagnosis, fenestration, and age. The following early postoperative outcomes were assessed: duration of ventilator support, duration of hospital stay, incidence of ascites, prolonged effusions, and readmission., Results: Preoperatively, there were no significant differences between the 2 groups. However, among the postoperative outcomes, the duration of hospital stay (25.4 +/- 16.6 days vs 10.8 +/- 6.3 days; P =.03), incidence of ascites (70% vs 3%; P <.001), prolonged pleural effusions (60% vs 13%; P =.007), and readmission (50% vs 7%; P =.007) were significantly greater in patients with hemidiaphragmatic paralysis than in those without hemidiaphragmatic paralysis., Conclusions: Hemidiaphragmatic paralysis after the modified Fontan operation is associated with an increase in early morbidity. Care should be taken to avoid injury to the phrenic nerve. Patients with prolonged effusions should be evaluated for hemidiaphragmatic paralysis.

Background: Superior cavopulmonary anastomosis is widely used for palliation of various forms of univentricular heart defects. However, clinically significant pulmonary arteriovenous malformations develop in 15% to 25% of patients after surgery., Objective: To assess altered regulation of pulmonary vascular tone caused by superior cavopulmonary anastomosis in an ovine model., Methods: Lambs, aged 35 to 45 days, underwent an end-to-end anastomosis of the superior vena cava to the right pulmonary artery. In age-matched controls, a sham operation was performed. Arteriovenous malformations were detectable by contrast echocardiography by 8 weeks after surgery. Animals (n = 24) were studied at various time points after the operations. Expression of angiotensin-converting enzyme messenger RNA, protein levels, and enzyme activity were measured in lung homogenates. Levels of angiotensin II were measured by enzyme-linked immunosorbent assay., Results: Expression of angiotensin-converting enzyme messenger RNA and protein was significantly reduced at 1 to 5 weeks after superior cavopulmonary anastomosis. Angiotensin-converting enzyme activity in the right lung of animals subjected to superior cavopulmonary anastomosis was reduced 86% +/- 1% (standard deviation) compared with control values at 1 week (P =.003) and 77% +/- 8.5% at 2 weeks (P <.001) after surgery. This correlated with a 59% +/- 3.5% (P =.007) reduction in angiotensin II levels up to 5 weeks after cavopulmonary anastomosis. By 15 weeks after the operations, angiotensin II levels were equivalent to control levels (P =.19)., Conclusions: Superior cavopulmonary anastomosis causes an early reversible reduction in activity and expression of angiotensin-converting enzyme, resulting in decreased circulating levels of the vasoconstrictor angiotensin II. These results suggest that the ability of the pulmonary endothelium to regulate vascular tone is inhibited after superior cavopulmonary anastomosis. Dilation of the affected vasculature induced by cavopulmonary anastomosis may contribute to the disordered vascular remodeling observed in this setting.

Background: Modified ultrafiltration has been touted as superior to conventional ultrafiltration for attenuating the consequences of hemodilution after cardiac surgery with cardiopulmonary bypass in children. We conducted a prospective randomized study to test the hypothesis that modified and conventional ultrafiltration have similar clinical effects when a standardized volume of fluid is removed., Methods: From October 1998 to September 1999, 110 children weighing 15 kg or less (median weight 6.1 kg, median age 6.3 months) undergoing surgery with cardiopulmonary bypass for functionally biventricular congenital heart disease were randomized to conventional (n = 67) or arteriovenous modified ultrafiltration (n = 43) for hemoconcentration. The volume of fluid removed with both methods was standardized as a percentage of effective fluid balance (the sum of prime volume and volume added during cardiopulmonary bypass minus urine output): in patients weighing less than 10 kg, 50% of effective fluid balance was removed, whereas 60% was removed in patients weighing 10 to 15 kg. Hematocrit, hemodynamics, ventricular function, transfusion of blood products, and postoperative resource use were compared between groups., Results: There were no significant differences between groups in age, weight, or duration of cardiopulmonary bypass. The total volume of fluid added in the prime and during bypass was greater in patients undergoing conventional ultrafiltration than in those receiving modified ultrafiltration (205 +/- 123 vs 162 +/- 74 mL/kg; P =.05), although the difference was due primarily to a greater indexed priming volume in patients having conventional ultrafiltration. There was no difference in the percentage of effective fluid balance that was removed in the 2 groups. Accordingly, the volume of ultrafiltrate was greater in patients receiving conventional than modified ultrafiltration (95 +/- 63 vs 68 +/- 28 mL/kg; P =.01). Preoperative and postoperative hematocrit levels were 35.6% +/- 6.6% and 36.3% +/- 5.6% in patients having conventional ultrafiltration and 34.4% +/- 6.7% and 38.7% +/- 7.5% in those having modified ultrafiltration. By repeated-measures analysis of variance, patients receiving modified and conventional ultrafiltration did not differ with respect to hematocrit value (P =.87), mean arterial pressure (P =.85), heart rate (P =.43), or left ventricular shortening fraction (P =.21) from baseline to the postbypass measurements. There were no differences between groups in duration of mechanical ventilation, stay in the intensive care unit, or hospitalization., Conclusions: When a standardized volume of fluid is removed, hematocrit, hemodynamics, ventricular function, requirement for blood products, and postoperative resource use do not differ between pediatric patients receiving conventional and modified ultrafiltration for hemoconcentration after cardiac surgery.

Background: Disease of the aortic valve in children and young adults is a complex entity whose management is the subject of controversy. The Ross and the Ross-Konno procedures have become the primary choices for aortic valve replacement in children because of growth potential, optimal hemodynamic performance, and lack of the need for anticoagulation. However, concern persists regarding the longevity of the pulmonary autograft, especially in patients with aortic insufficiency., Methods: Between June 1993 and February 2000, 72 Ross and Ross-Konno procedures were performed at our institution: 81% of the patients were less than 15 years old. Preoperative, postoperative, and follow-up clinical, echocardiographic, and hemodynamic data were reviewed. Statistical analysis was performed to identify the risk factors for deteriorating autograft function., Results: Aortic insufficiency was an indication for the Ross procedure in 17 patients and mixed lesions with predominant aortic insufficiency in 10. Of the 45 other patients, 32 had aortic stenosis and 13 had mixed lesions with predominant aortic stenosis. There were no deaths during a follow-up of 5 to 80 months. Autograft reoperation was necessary in the follow-up period in 7 patients for severe aortic insufficiency. Moderate insufficiency was identified in 5 additional patients. Aortic insufficiency or predominant aortic insufficiency, as a preoperative hemodynamic indication for the Ross procedure, reached statistical significance (P =.031) as a risk factor for autograft failure., Conclusion: The Ross and the Ross-Konno procedures have changed the prognosis of children and young adults with complex aortic valve disease. However, the Ross procedure should be performed with caution in older children in whom aortic insufficiency is a preoperative hemodynamic indication. Further follow-up to delineate the risk factors for autograft dysfunction in children and young adults is necessary to better define the indications for the Ross procedure.