Background: Many factors affect outcomes after congenital cardiac surgery. Objectives: The RLS (Residual Lesion Score) study explored the impact of severity of residual lesions on post-operative outcomes across operations of varying complexity. Methods: In a prospective, multicenter, observational study, 17 sites enrolled 1,149 infants undergoing 5 common operations: tetralogy of Fallot repair (n = 250), complete atrioventricular septal defect repair (n = 249), arterial switch operation (n = 251), coarctation or interrupted arch with ventricular septal defect (VSD) repair (n = 150), and Norwood operation (n = 249). The RLS was assigned based on post-operative echocardiography and clinical events: RLS 1 (trivial or no residual lesions), RLS 2 (minor residual lesions), or RLS 3 (reintervention for or major residual lesions before discharge). The primary outcome was days alive and out of hospital within 30 post-operative days (60 for Norwood). Secondary outcomes assessed post-operative course, including major medical events and days in hospital. Results: RLS 3 (vs. RLS 1) was an independent risk factor for fewer days alive and out of hospital (p ≤ 0.008) and longer post-operative hospital stay (p ≤ 0.02) for all 5 operations, and for all secondary outcomes after coarctation or interrupted arch with VSD repair and Norwood (p ≤ 0.03). Outcomes for RLS 1 versus 2 did not differ consistently. RLS alone explained 5% (tetralogy of Fallot repair) to 20% (Norwood) of variation in the primary outcome. Conclusions: Adjusting for pre-operative factors, residual lesions after congenital cardiac surgery impacted in-hospital outcomes across operative complexity with greatest impact following complex operations. Minor residual lesions had minimal impact. These findings may provide guidance for surgeons when considering short-term risks and benefits of returning to bypass to repair residual lesions.

Objective: Surgery for heart defects in children with trisomy 13 or 18 is controversial. We analyzed our 20-year experience. Methods: Since 2002, we performed 21 operations in 19 children with trisomy 13 (n = 8) or trisomy 18 (n = 11). Age at operation was 4 days to 12 years (median, 154 days). Principal diagnosis was ventricular septal defect in 10 patients, tetralogy of Fallot in 7 patients, arch hypoplasia in 1 patient, and patent ductus arteriosus in 1 patient. Results: The initial operation was ventricular septal defect closure in 9 patients, tetralogy of Fallot repair in 7 patients, pulmonary artery banding in 1 patient, patent ductus arteriosus ligation in 1 patient, and aortic arch/coarctation repair in 1 patient. There were no operative or hospital deaths. Median postoperative intensive care and hospital stays were 189 hours (interquartile range, 70-548) and 14 days (interquartile range, 8.0-37.0), respectively, compared with median hospital stays in our center for ventricular septal defect repair of 4.0 days and tetralogy of Fallot repair of 5.0 days. On median follow-up of 17.4 months (interquartile range, 6.0-68), 1 patient was lost to follow-up after 5 months. Two patients had reoperation without mortality. There have been 5 late deaths (4 with trisomy 18, 1 with trisomy 13) predominately due to respiratory failure from 4 months to 9.4 years postoperatively. Five-year survival was 66.6% compared with 24% in a group of unoperated patients with trisomy 13 or 18. Conclusions: Cardiac operation with an emphasis on complete repair can be performed safely in carefully selected children with trisomy 13 or trisomy 18. Hospital resource use measured by postoperative intensive care and hospital stays is considerably greater compared with nontrisomy 13 and 18.

Children with congenital heart diseases have increased morbidity and mortality, despite various surgical treatments, therefore warranting better treatment strategies. Here we investigate the role of age of human pediatric cardiac progenitor cells (hCPCs) on ventricular remodeling in a model of juvenile heart failure. hCPCs isolated from children undergoing reconstructive surgeries were divided into 3 groups based on age: neonate (1 day to 1month), infant (1month to 1 year), and child (1 to 5 years). Adolescent athymic rats were subjected to sham or pulmonary artery banding surgery to generate a model of right ventricular (RV) heart failure. Two weeks after surgery, hCPCs were injected in RV musculature noninvasively. Analysis of cardiac function4weekspost-transplantationdemonstratedsignificantly increased tricuspid annular plane systolic excursion and RV ejection fraction and significantly decreased wall thickness and fibrosis in rats transplanted with neonatal hCPCs compared with saline-injected rats. Computational modeling and systems biology analysis were performed on arrays and gave insights into potential mechanisms at the microRNA and gene level. Mechanisms including migration and proliferation assays, as suggested by computational modeling, showed improved chemotactic and proliferative capacity of neonatal hCPCs compared with infant/child hCPCs. In vivo immune staining further suggested increased recruitment of stem cell antigen 1-positive cells in the right ventricle. This is the first study to assess the role of hCPC age in juvenile RV heart failure. Interestingly, the reparative potential of hCPCs is age-dependent, with neonatal hCPCs exerting the maximum beneficial effect compared with infant and child hCPCs.

Background: Using a bifurcated Y-graft as the Fontan baffle is hypothesized to streamline and improve flow dynamics through the total cavopulmonary connection (TCPC). This study conducted numerical simulations to evaluate this hypothesis using postoperative data from 5 patients. Methods: Patients were imaged with cardiac magnetic resonance or computed tomography after receiving a bifurcated aorto-iliac Y-graft as their Fontan conduit. Numerical simulations were performed using in vivo flow rates, as well as 2 levels of simulated exercise. Two TCPC models were virtually created for each patient to serve as the basis for hemodynamic comparison. Comparative metrics included connection flow resistance and inferior vena caval flow distribution. Results: Results demonstrate good hemodynamic outcomes for the Y-graft options. The consistency of inferior vena caval flow distribution was improved over TCPC controls, whereas the connection resistances were generally no different from the TCPC values, except for 1 case in which there was a marked improvement under both resting and exercise conditions. Examination of the connection hemodynamics as they relate to surgical Y-graft implementation identified critical strategies and modifications that are needed to potentially realize the theoretical efficiency of such bifurcated connection designs. Conclusions: Five consecutive patients received a Y-graft connection to complete their Fontan procedure with positive hemodynamic results. Refining the surgical technique for implementation should result in further energetic improvements that may help improve long-term outcomes.

Background: Aortic arch reconstruction in neonates is commonly performed using deep hypothermic circulatory arrest. However, concerns have arisen regarding potential adverse neurologic outcomes from this complex procedure, raising questions about the best arterial cannulation approach for cerebral perfusion and effective systemic hypothermia. In this study, we use computational fluid dynamics to investigate the effect of different cannulation strategies in neonates. Methods: We used a realistic template of a hypoplastic neonatal aorta as the base geometry to investigate four cannulation options: (1) right innominate artery, (2) innominate root, (3) patent ductus arteriosus (PDA), or (4) innominate root and PDA. Performance was evaluated according to the numerically predicted cerebral and systemic flow distributions compared with physiologic perfusion under neonatal conditions. Results: The four cannulation strategies were associated with different local hemodynamics; however, this did not translate into any significant effect on the measured flow distributions. The largest difference only represented 0.8% of the cardiac output and was measured in the innominate artery, which received 23.2% of the cardiac output in option 3 vs 24% in option 4. Pulmonary artery snaring benefited all systemic vessels uniformly. Conclusions: Because of the very high vascular resistances in neonates, downstream vascular resistances dictated flow distribution to the different vascular beds rather than the cannulation strategy, allowing the surgical team to choose their method of preference. However, patients with aortic coarctation warrant further investigation and will most likely benefit from a 2-cannulae approach (option 4).

Virtual modeling of cardiothoracic surgery is a new paradigm that allows for systematic exploration of various operative strategies and uses engineering principles to predict the optimal patient-specific plan. This study investigates the predictive accuracy of such methods for the surgical palliation of single ventricle heart defects. Computational fluid dynamics (CFD)-based surgical planning was used to model the Fontan procedure for four patients prior to surgery. The objective for each was to identify the operative strategy that best distributed hepatic blood flow to the pulmonary arteries. Post-operative magnetic resonance data were acquired to compare (via CFD) the post-operative hemodynamics with predictions. Despite variations in physiologic boundary conditions (e.g., cardiac output, venous flows) and the exact geometry of the surgical baffle, sufficient agreement was observed with respect to hepatic flow distribution (90% confidence interval-14 ± 4.3% difference). There was also good agreement of flow-normalized energetic efficiency predictions (19 ± 4.8% error). The hemodynamic outcomes of prospective patient-specific surgical planning of the Fontan procedure are described for the first time with good quantitative comparisons between preoperatively predicted and postoperative simulations. These results demonstrate that surgical planning can be a useful tool for single ventricle cardiothoracic surgery with the ability to deliver significant clinical impact.

OBJECTIVE Optimizing flow and diminishing power loss in the Fontan circuit can improve hemodynamic efficiency potentially improving long-term outcomes. Computerized modeling has predicted improved energetics with a Y-graft Fontan. METHODS From August to December, 2010, six consecutive children had a completion Fontan (n=3) or a Fontan revision (n=3) using a bifurcated polytetrafluoroethylene Y-graft (18×9×9 mm in 2, 20×10×10 mm in 4) connecting the inferior vena cava (IVC) to the right and left pulmonary arteries (PAs) with separate graft limbs. Patents were imaged by magnetic resonance imaging (MRI; n-5) or computerized tomography (n=1). Computational fluid dynamics (CFD) assessed Fontan hemodynamics, power loss, and IVC flow splits to the branch PAs. Clinical parameters were compared with 12 patients immediately preceding this series who had a lateral Fontan procedure. RESULTS Despite longer crossclamp and bypass times (not statistically significant), the Y-graft Fontan patients had postoperative courses similar to the conventional Fontan patients. Other than two early readmissions for pleural effusions managed with diuretics, on 6–12 months follow-up (mean 8 months), all six patients have done well. Postoperative flow modeling demonstrated balanced distribution of IVC flow to both PAs with minimal flow disturbance. Improvements in hemodynamics and efficiency were noted when the Y-graft branches were anastomosed distally and aligned tangentially with the branch PAs. CONCLUSIONS This preliminary surgical experience demonstrates clinical feasibility of the bifurcated Y-graft Fontan. CFD shows acceptable hemodynamics with low calculated power losses and balanced distribution of IVC flow to the PAs as long as the branch grafts are anastomosed distally.

Objectives: The Single Ventricle Reconstruction trial randomized 555 subjects with a single right ventricle undergoing the Norwood procedure at 15 North American centers to receive either a modified Blalock-Taussig shunt or right ventricle-to-pulmonary artery shunt. Results demonstrated a rate of death or cardiac transplantation by 12 months postrandomization of 36% for the modified Blalock-Taussig shunt and 26% for the right ventricle-to-pulmonary artery shunt, consistent with other publications. Despite this high mortality rate, little is known about the circumstances surrounding these deaths. Methods: There were 164 deaths within 12 months postrandomization. A committee adjudicated all deaths for cause and recorded the timing, location, and other factors for each event. Results: The most common cause of death was cardiovascular (42%), followed by unknown cause (24%) and multisystem organ failure (7%). The median age at death for subjects dying during the 12 months was 1.6 months (interquartile range, 0.6 to 3.7 months), with the highest number of deaths occurring during hospitalization related to the Norwood procedure. The most common location of death was at a Single Ventricle Reconstruction trial hospital (74%), followed by home (13%). There were 29 sudden, unexpected deaths (18%), although in retrospect, 12 were preceded by a prodrome. Conclusions: In infants with a single right ventricle undergoing staged repair, the majority of deaths within 12 months of the procedure are due to cardiovascular causes, occur in a hospital, and within the first few months of life. Increased understanding of the circumstances surrounding the deaths of these single ventricle patients may reduce the high mortality rate.

Flow structures, hemodynamics and the hydrodynamic surgical pathway resistances of the final stage functional single ventricle reconstruction, namely the total cavopulmonary connection (TCPC) anatomy, have been investigated extensively. However, the second stage surgical anatomy (i.e., bi-directional Glenn or hemi-Fontan template) has received little attention. We thus initiated a multi-faceted study, involving magnetic resonance imaging (MRI), phase contrast MRI, computational and experimental fluid dynamics methodologies, focused on the second stage of the procedure. Twenty three-dimensional computer and rapid prototype models of 2nd stage TCPC anatomies were created, including idealized parametric geometries (n = 6), patient-specific anatomies (n = 7), and their virtual surgery variant (n = 7). Results in patient-specific and idealized models showed that the Glenn connection template is hemodynamically more efficient with (83% p = 0.08 in patient-specific models and 66% in idealized models) lower power losses compared to hemi-Fontan template, respectively, due to its direct end-to-side anastomosis. Among the several secondary surgical geometrical features, stenosis at the SVC anastomosis or in pulmonary branches was found to be the most critical parameter in increasing the power loss. The pouch size and flare shape were found to be less significant. Compared to the third stage surgery the hydrodynamic resistance of the 2nd stage is considerably lower (both in idealized models and in anatomical models at MRI resting conditions) for both hemi- and Glenn templates. These results can impact the surgical design and planning of the staged TCPC reconstruction.

Objective: We quantify the geometric and hemodynamic characteristics of extracardiac and lateral tunnel Fontan surgical options and correlate certain anatomic characteristics with their hemodynamic efficiency and patient cardiac index. Methods and Results: The study was conducted retrospectively on 22 patients undergoing Fontan operations (11 extracardiac and 11 lateral tunnel operations). Total cavopulmonary connection geometric parameters such as vessel areas, curvature, and offsets were quantified using a skeletonization method. Energy loss at the total cavopulmonary connection junction was available from previous in vitro experiments and computational fluid dynamic simulations for 5 and 9 patients, respectively. Cardiac index data were available for all patients. There was no significant difference in the mean and minimum cross-sectional vessel areas of the pulmonary artery between the extracardiac and lateral tunnel groups. The indexed energy dissipation within the total cavopulmonary connection was strongly correlated to minimum cross-sectional area of the pulmonary arteries (R2 value of 0.90 and P < .0002), whereas all other geometric features, including shape characteristics, had no significant correlation. Finally, cardiac index significantly correlated with the minimum pulmonary artery area (P = .006), suggesting that total cavopulmonary connection energy losses significantly affect resting cardiac output. Conclusions: The minimum outlet size of the total cavopulmonary connection (ie, minimum cross section of pulmonary artery) governs the energy loss characteristics of the total cavopulmonary connection more strongly than variations in the shapes corresponding to extracardiac and lateral tunnel configurations. Differences in pulmonary artery sizes must be accounted for when comparing energy losses between extracardiac and lateral tunnel geometries.