Hypothermic cardiopulmonary bypass alters oxygen/glucose uptake in the pediatric brain

AbstractObjectives: Neurologic morbidity related to cardiac surgery has been recognized as a major morbidity. A variety of causes related to cardiopulmonary bypass, including microemboli, nonpulsatile flow, hemodilution, and inflammatory mediation, have been proposed. Because oxygen and glucose are the predominant metabolic substrates for the brain, we sought to examine the uptake of these substrates by the pediatric brain during hypothermic cardiopulmonary bypass. Methods: Eleven children (median age 5 months, range 1 day-17 years) undergoing a variety of cardiac surgical procedures with the use of hypothermic cardiopulmonary bypass were studied. Cerebral arteriovenous differences for oxygen, glucose, and lactate were obtained before, during, and after bypass. On the basis of the predictable stoichiometric relationship for the oxidation of glucose, the relationship of substrate uptake was expressed as the oxygen/glucose index. Oxygen/glucose index (%) = (arteriovenous oxygen difference [μmol/mL]/arteriovenous glucose difference [μmol/mL] × 6) × 100 Results: All children survived with no obvious neurologic sequelae. During cooling on cardiopulmonary bypass, the oxygen/glucose indexes fell significantly from prebypass values (53% ± 19% at 28°C and 54% ± 25% at 24°C vs 117% ± 70%; P <.05, analysis of variance). This decline resulted from decreased oxygen uptake with stable glucose uptake (P <.05). Although oxygen and glucose uptake both increased with rewarming, the net effect was only a slight increase in oxygen/glucose index (62% ± 16%). Postbypass oxygen/glucose index exceeded prebypass values (149% ± 83%). Conclusions: Hypothermic cardiopulmonary bypass alters the relationship between oxygen and glucose uptake in the pediatric brain. The relationship of these findings to bypass-related neurologic morbidity remains to be explored. (J Thorac Cardiovasc Surg 2001;121:366-73

Early repair of hemitruncus: Excellent early and late outcomes

ObjectiveAnomalous origin of 1 of the branch pulmonary arteries from the aorta with 2 normal semilunar valves (hemitruncus) is a rare entity. There have been several small case series reported. We report here our single-institution surgical experience with hemitruncus from 1982 to 2006.MethodsA retrospective case review of all cases of conotruncal anomalies at Children’s Hospital Boston revealed 16 patients with hemitruncus. Ten patients had surgery in the neonatal period (<30 days), 4 at 1 to 6 months, 1 at 8 months, and 1 at 2 years. Diagnosis of hemitruncus was the indication for operation in all but 1. Fourteen of the 16 had anomalous right pulmonary artery from aorta, and 2 had left pulmonary artery from aorta. Common associated anomalies included patent foramen ovale in 14, patent ductus arteriosus in 11, and ventricular septal defect in 4. All patients had elevated right ventricular pressures with systemic pressures in 5 and suprasystemic pressures in 9.ResultsThere was 1 operative death in this series in an infant who died from sepsis following ligation of a tracheoesophageal fistula. One patient required reoperation for supravalvar aortic stenosis and right pulmonary artery stenosis 1 year postoperatively. Three patients required 4 catheter-based interventions postoperatively. At 20 years, survival by Kaplan–Meier was 93%; freedom from reoperation, 93%; and freedom from catheter reintervention, 79%.ConclusionsEarly repair of hemitruncus results in excellent hemodynamic and anatomic results. Survival is excellent, with a low incidence of reoperation or reintervention

Mitral valve replacement in infants and children 5 years of age or younger: Evolution in practice and outcome over three decades with a focus on supra-annular prosthesis implantation

ObjectiveSuccessful mitral valve replacement in young children is limited by the lack of small prosthetic valves. Supra-annular prosthesis implantation can facilitate mitral valve replacement with a larger prosthesis in children with a small annulus, but little is known about its effect on the outcomes of mitral valve replacement in young children.MethodsOne hundred eighteen children underwent mitral valve replacement at 5 years of age or younger from 1976–2006. Mitral valve replacement was supra-annular in 37 (32%) patients.ResultsSurvival was 74% ± 4% at 1 year and 56% ± 5% at 10 years but improved over time (10-year survival of 83% ± 7% from 1994–2006). Factors associated with worse survival included earlier mitral valve replacement date, age less than 1 year, complete atrioventricular canal, and additional procedures at mitral valve replacement, but not supra-annular mitral valve replacement. As survival improved during our more recent experience, the risks of supra-annular mitral valve replacement became apparent; survival was worse among patients with a supra-annular prosthesis after 1991. A pacemaker was placed in 18 (15%) patients within 1 month of mitral valve replacement and was less likely in patients who had undergone supra-annular mitral valve replacement. Among early survivors, freedom from redo mitral valve replacement was 72% ± 5% at 5 years and 45% ± 7% at 10 years. Twenty-one patients with a supra-annular prosthesis underwent redo mitral valve replacement. The second prosthesis was annular in 15 of these patients and upsized in all but 1, but 5 required pacemaker placement for heart block.ConclusionsSupra-annular mitral valve replacement was associated with worse survival than annular mitral valve replacement in our recent experience. Patients with supra-annular mitral valve replacement were less likely to have operative complete heart block but remained at risk when the prosthesis was subsequently replaced

Primary left ventricular rehabilitation is effective in maintaining two-ventricle physiology in the borderline left heart

ObjectiveBorderline left heart disease is characterized by left heart obstructive lesions (coarctation, aortic and mitral stenoses, left ventricular hypoplasia) and endocardial fibroelastosis. The multilevel obstruction and impaired left ventricular systolic and diastolic function contribute to failure of biventricular circulation. We studied the effects of left ventricular rehabilitation—endocardial fibroelastosis resection with mitral or aortic valvuloplasty—on left ventricular function and clinical outcomes.MethodsAll patients with borderline left heart structures and endocardial fibroelastosis who underwent a primary left ventricular rehabilitation procedure were retrospectively analyzed to determine operative mortality, reintervention rates, and hemodynamic status. Left heart dimensions and hemodynamics were recorded from preoperative and postoperative echocardiogram and cardiac catheterization. Postoperative left atrial pressure was obtained from the intracardiac line early after left ventricular rehabilitation. Preoperative and postoperative values were compared by paired t test.ResultsBetween 1999 and 2008, 9 patients with endocardial fibroelastosis and borderline left heart disease underwent left ventricular rehabilitation at a median age of 5.6 months (range, 1–38 months). There was no operative mortality, and at a median follow-up of 25 months (6 months to 10 years) there was 1 death from noncardiac causes and 2 patients required reoperations. Significant increases in ejection fraction and left ventricular end-diastolic volume were observed, whereas left atrial pressure and right ventricular/left ventricular pressure ratios decreased postoperatively.ConclusionIn patients with borderline left hearts, primary left ventricular rehabilitation with endocardial fibroelastosis resection and mitral and aortic valvuloplasty results in improved left ventricular systolic and diastolic performance and decreased right ventricular pressures. This approach may provide an alternative to single-ventricle management in this difficult patient group

Staged Left Ventricular Recruitment After Single-Ventricle Palliation in Patients With Borderline Left Heart Hypoplasia

ObjectivesThe goal of this study was to review results of a novel management strategy intended to rehabilitate the left heart (LH) in patients with LH hypoplasia who have undergone single-ventricle palliation (SVP).BackgroundManagement of patients with hypoplastic LH syndrome and borderline left ventricle (LV) involves 2 options: SVP or biventricular repair. We hypothesized that staged LV recruitment and biventricular conversion may be achieved after SVP by using a strategy consisting of relief of inflow and outflow tract obstructions, resection of endocardial fibroelastosis, and promotion of flow through the LV.MethodsPatients with hypoplastic LH and borderline LV who underwent traditional SVP (n = 34) or staged LV recruitment (n = 34) between 1995 and 2010 were retrospectively analyzed and compared with a control SVP group.ResultsMean initial z-scores for LH structures before stage 1 SVP were not significantly different between groups. Mortality occurred in 4 of 34 patients after LV recruitment and in 7 of 34 after traditional SVP. LH dimension z-scores increased significantly over time after LV recruitment, whereas they declined after traditional SVP, with significant interaction between stage of palliation and treatment group. Restriction of the atrial septum (conducted in 19 of 34 patients) was the only predictor of increase in left ventricular end-diastolic volume (p < 0.001). Native biventricular circulation was achieved in 12 patients after staged LV recruitment; all of these patients had restriction at the atrial septum.ConclusionsIn these patients with borderline LH disease who underwent SVP, it is possible to increase LH dimensions by using an LV recruitment strategy. In a subset of patients, this strategy allowed establishment of biventricular circulation

The Safety and Efficacy of Antifibrinolytic Therapy in Neonatal Cardiac Surgery

Background: Neonates undergoing open-heart surgery are particularly at risk of postoperative bleeding requiring blood transfusion. Aprotinin has attained high efficacy in reducing the requirement for a blood transfusion following a cardiopulmonary bypass, but is seldom studied in the neonatal age group. The aim of this study was to compare the efficacy and adverse effects of aprotinin and tranexamic acid in neonates undergoing open-heart surgery at a single centre. Methods: Between October 2003 and March 2008, perioperative data of 552 consecutive neonatal patients undergoing open-heart surgery in Children’s Hospital Boston were reviewed. Among them, 177 did not receive antifibrinolytic therapy (Group A); 100 were treated with tranexamic acid only (Group B); and 275 patients received aprotinin with or without tranexamic acid (Group C). Except for antifibrinolytic therapy, the anaesthesiological and surgical protocols remained identical. Postoperative complications and in-hospital mortality were the primary study endpoints. Results: Body weight and Risk Adjustment for Congenital Heart Surgery (RACHS-1) scores were statistically comparable among the three groups. No statistically significant differences were observed between the duration of hospitalization, chest tube drainage, reexploration for bleeding, and kidney function impairment. In Group C, less blood was transfused within 24 hours than in GroupB. Operative mortality was similar among the three groups. Conclusion: No further risk and kidney injury were observed in the use of aprotinin in neonatal cardiac surgery, aprotinin demonstrated a reduced requirement for blood transfusion compared with tranexamic acid. Our data provide reasonable evidence that aprotinin and tranexamic acid are safe and efficacious as antifibrinolytic modalities in neonatal patients undergoing cardiac surgery

Survival and Clinical Course at Fontan After Stage One Palliation With Either a Modified Blalock-Taussig Shunt or a Right Ventricle to Pulmonary Artery Conduit

ObjectivesWe sought to determine whether the type of shunt used at stage one palliation (S1P) affected the survival and the perioperative course through Fontan completion.BackgroundAlthough improved surgical and interstage survival have been demonstrated with the use of the right ventricle to pulmonary artery (RV-PA) conduit compared with a modified Blalock-Taussig shunt (BTS) at S1P, it is unknown whether this effect will be observed in long-term follow-up.MethodsAll patients who underwent a S1P during 2002 and 2003 (n = 80) at our institution were included for analysis. Patients were followed until death or June 1, 2007. Perioperative variables at Fontan completion were recorded.ResultsFor the entire cohort, cumulative survival for those who underwent a RV-PA conduit (n = 34) was 79.4% at 3 years compared with 65.8% in the modified BTS group (n = 46) (log-rank = 0.31). At Fontan (n = 44), when compared with those who had received a modified BTS, those who had a RV-PA conduit placed at S1P had no difference in the median duration of ventilation (21 h [range 10 to 96 h] vs. 26.5 h [range 7 to 204 h], p = 0.09) or hospital stay (9 days [range 5 to 29 days] vs. 10 days [range 6 to 48 days], p = 0.89), although length of stay in the intensive care unit was shorter (2 days [range 0 to 6 days] vs. 4 days [range 1 to 25 days], p = 0.01). Sixty-seven percent of the RV-PA conduit group had at least one PA intervention 3 years after S1P compared with 42.8% in the modified BTS group (log-rank = 0.11).ConclusionsNonstatistically significant trends toward improved cumulative survival and increased PA interventions were demonstrated in patients who had a RV-PA conduit placed at S1P. Longitudinal follow-up of larger groups of randomized patients is required to determine the influence of the RV-PA conduit on long-term outcomes

Design and Rationale of Safe Pediatric Euglycemia After Cardiac Surgery (SPECS): A Randomized Controlled Trial of Tight Glycemic Control After Pediatric Cardiac Surgery

Objectives: To describe the design of a clinical trial testing the hypothesis that children randomized to tight glycemic control with intensive insulin therapy after cardiac surgery will have improved clinical outcomes compared to children randomized to conventional blood glucose management. Design: Two-center, randomized controlled trial. Setting: Cardiac ICUs at two large academic pediatric centers. Patients: Children from birth to those aged 36 months recovering in the cardiac ICU after surgery with cardiopulmonary bypass. Interventions: Subjects in the tight glycemic control (intervention) group receive an intravenous insulin infusion titrated to achieve normoglycemia (target blood glucose range of 80–110 mg/dL; 4.4–6.1 mmol/L). The intervention begins at admission to the cardiac ICU from the operating room and terminates when the patient is ready for discharge from the ICU. Continuous glucose monitoring is performed during insulin infusion to minimize the risks of hypoglycemia. The standard care group has no target blood glucose range. Measurements and Main Results: The primary outcome is the development of any nosocomial infection (bloodstream, urinary tract, and surgical site infection or nosocomial pneumonia). Secondary outcomes include mortality, measures of cardiorespiratory function and recovery, laboratory indices of nutritional balance, immunologic, endocrinologic, and neurologic function, cardiac ICU and hospital length of stay, and neurodevelopmental outcome at 1 and 3 yrs of age. A total of 980 subjects will be enrolled (490 in each treatment arm) for sufficient power to show a 50% reduction in the prevalence of the primary outcome. Conclusions: Pediatric cardiac surgery patients may recognize great benefit from tight glycemic control in the postoperative period, particularly with regard to reduction of nosocomial infections. The Safe Pediatric Euglycemia after Cardiac Surgery trial is designed to provide an unbiased answer to the question of whether this therapy is indeed beneficial and to define the associated risks of therapy