The Optimal Timing of Stage 2 Palliation for Hypoplastic Left Heart Syndrome: An Analysis of the Pediatric Heart Network Single Ventricle Reconstruction Trial Public Data Set.

BACKGROUND: In infants requiring 3-stage single-ventricle palliation for hypoplastic left heart syndrome, attrition after the Norwood procedure remains significant. The effect of the timing of stage 2 palliation (S2P), a physician-modifiable factor, on long-term survival is not well understood. We hypothesized that an optimal interval between the Norwood and S2P that both minimizes pre-S2P attrition and maximizes post-S2P survival exists and is associated with individual patient characteristics. METHODS: The National Institutes of Health/National Heart, Lung, and Blood Institute Pediatric Heart Network Single Ventricle Reconstruction Trial public data set was used. Transplant-free survival (TFS) was modeled from (1) Norwood to S2P and (2) S2P to 3 years by using parametric hazard analysis. Factors associated with death or heart transplantation were determined for each interval. To account for staged procedures, risk-adjusted, 3-year, post-Norwood TFS (the probability of TFS at 3 years given survival to S2P) was calculated using parametric conditional survival analysis. TFS from the Norwood to S2P was first predicted. TFS after S2P to 3 years was then predicted and adjusted for attrition before S2P by multiplying by the estimate of TFS to S2P. The optimal timing of S2P was determined by generating nomograms of risk-adjusted, 3-year, post-Norwood, TFS versus the interval from the Norwood to S2P. RESULTS: Of 547 included patients, 399 survived to S2P (73%). Of the survivors to S2P, 349 (87%) survived to 3-year follow-up. The median interval from the Norwood to S2P was 5.1 (interquartile range, 4.1-6.0) months. The risk-adjusted, 3-year, TFS was 68±7%. A Norwood-S2P interval of 3 to 6 months was associated with greatest 3-year TFS overall and in patients with few risk factors. In patients with multiple risk factors, TFS was severely compromised, regardless of the timing of S2P and most severely when S2P was performed early. No difference in the optimal timing of S2P existed when stratified by shunt type. CONCLUSIONS: In infants with few risk factors, progressing to S2P at 3 to 6 months after the Norwood procedure was associated with maximal TFS. Early S2P did not rescue patients with greater risk factor burdens. Instead, referral for heart transplantation may offer their best chance at long-term survival. CLINICAL TRIAL REGISTRATION: URL: https://www.clinicaltrials.gov. Unique identifier: NCT00115934.

Hyperglycaemia is negatively associated with systemic and cerebral oxygen transport in neonates after the Norwood procedure.

OBJECTIVE: Hyperglycaemia has been identified as a risk factor for adverse outcomes in critically ill patients, including those who have undergone cardiopulmonary bypass. Tight glucose control with insulin therapy has been shown to improve outcomes, but is not common practice for children following cardiopulmonary bypass. We examined the relationship between blood glucose level and systemic and cerebral oxygen transport in a uniform group of neonates after the Norwood procedure. METHODS: Systemic oxygen consumption was measured using respiratory mass spectrometry in 17 neonates for 72 hours postoperatively. Cardiac output, systemic and total pulmonary vascular resistances - including the Blalock-Taussig shunt, systemic oxygen delivery and oxygen extraction ratio, as well as arterial lactate and glucose, were measured at 2- to 4-hour intervals. Cerebral oxygen saturation was measured by near-infrared spectroscopy. RESULTS: Blood glucose levels ranged from 2.8 to 24.6 millimoles per litre. Elevated glucose level showed a significant negative correlation with cardiac output (p = 0.02) and cerebral oxygen saturation (p = 0.03), and a positive correlation with oxygen extraction ratio (p = 0.03). It tended to correlate positively with systemic vascular resistance (p = 0.09) and negatively with oxygen delivery (p = 0.09), but did not correlate with oxygen consumption (p = 0.13). CONCLUSIONS: Hyperglycaemia is negatively associated with systemic haemodynamics, oxygen transport, and cerebral oxygenation status in neonates after the Norwood procedure. Further study is warranted to examine tight glucose control with insulin therapy on postoperative systemic and cerebral oxygen transport and functional outcomes in neonates after cardiopulmonary bypass.

Validity of the LaFarge equation for estimation of oxygen consumption in ventilated children with congenital heart disease younger than 3 years--a revisit.

BACKGROUND: The LaFarge equation is the most commonly used equation to estimate oxygen consumption (Vo(2)) in patients of all ages with congenital heart disease, although it was generated in patients older than 3 years. We sought to determine the validity of the LaFarge equation in estimating Vo(2) in children younger than 3 years undergoing cardiac catheterization with general anesthesia. METHODS: Vo(2) was measured directly using respiratory mass spectrometry in 75 sedated, paralyzed, and mechanically ventilated children in the pediatric cardiac catheterization laboratory. Age ranged from 0.13 to 24 years; 40 children being younger than 3 years. Estimated values for Vo(2) were calculated using the LaFarge equation for all patients. The agreement between measured and estimated Vo(2) was evaluated by the bias and limits of agreement in the 2 age groups. Regression analysis was used to analyze the influence of age on the agreement. RESULTS: A failure of agreement between measured and estimated Vo(2) was noted in both groups of children. As compared to the older group of patients, the agreement was significantly poorer in children younger than 3 years, with a significantly greater overestimation introduced by the LaFarge equation (11% +/- 21% vs 53% +/- 52%, P < .0001). CONCLUSION: The LaFarge equation introduces significant error in the estimation of Vo(2) in ventilated patients with congenital heart disease of all ages, particularly in children younger than 3 years.

Comparison of the profiles of postoperative systemic hemodynamics and oxygen transport in neonates after the hybrid or the Norwood procedure: a pilot study.

BACKGROUND: After the Norwood procedure, early postoperative neonatal physiology is characterized by hemodynamic instability and imbalance of oxygen transport that is commonly attributed to surgical myocardial injury and a systemic inflammatory response to cardiopulmonary bypass (CPB). Because the Hybrid procedure (arterial duct stenting and bilateral pulmonary artery banding) avoids CPB, cardioplegic arrest, and circulatory arrest, we hypothesized that the Hybrid procedure is associated with superior postoperative hemodynamics and oxygen transport. METHODS AND RESULTS: Oxygen consumption (VO2) was continuously measured using respiratory mass spectrometry for 72 hours after Hybrid (n=6) and Norwood (n=13) procedures. Arterial, superior vena cava, and pulmonary venous blood gases and pressures were measured at 2- to 4-hour intervals to calculate systemic and pulmonary blood flows (Qs, Qp), and systemic vascular resistance (SVR), total pulmonary vascular resistance including pulmonary arterial band or B-T shunt (tPVR), cardiac output (CO), oxygen delivery (DO2), and oxygen extraction ratio (ERO2). Rate-pressure product was calculated as heart rate x systolic arterial pressure. When compared with the Norwood procedure, the early postoperative Hybrid patients had lower CO, higher SVR, and higher Qp:Qs ratios. In addition, the DO2 and VO2 were both lower in the Hybrids with higher ERO2 and lactate levels. This early postoperative pattern reversed after 48 hours. CONCLUSIONS: Although Hybrid procedure avoids CPB and cardioplegic arrest, the early hemodynamic profile is not superior to the Norwood in terms of cardiac output and control of pulmonary blood flow. These data strongly suggest that a "hands off" approach to postoperative care in Hybrid patients may not be appropriate in patients with preoperative diminished myocardial function; and in such patients a Norwood-derived management strategy (afterload reduction and inotropic support) should be considered.

Improved results with single-stage total correction of Taussig-Bing anomaly.

OBJECTIVE: The arterial-switch operation (ASO) for management of Taussig-Bing anomaly is associated with important morbidity, mainly related to multiple associated cardiac anomalies. Our surgical management has evolved to suggest a single-stage total repair strategy tailored to address all abnormalities on an individual basis. We examine the efficacy of this treatment approach. METHODS: Thirty-three children, (infants n=29), with Taussig-Bing underwent ASO (1979-2005). In our earlier experience (group 1, n=17), initial palliation was performed as needed, including pulmonary-artery banding (n=9), coarctation repair (n=6), and atrial septostomy (n=3) followed by ASO at a later age. In our later experience (group 2, n=16), single-stage total repair was performed; ASO with ventricular septal defect closure and baffling of left ventricle to neo-aorta performed in neonates with arch obstruction (n=8), or at age 6 weeks in those with no arch obstruction (n=8). Concomitant relief of right-ventricle outflow-tract obstruction (RVOTO) was performed in 14 patients. Demographics and operative variables affecting outcomes were analyzed. RESULTS: Mean age at operation for group 1 and 2 patients was 312+/-477 and 42+/-31 days (p<0.0001). Aortic arch obstruction (52%), sub-aortic RVOTO (61%) and unusual coronary patterns (52%) were similar for both groups. One-year survival for group 1 and 2 patients was 47+/-5% and 100% (p=0.001). Associated anomalies such as great vessels position, arch obstruction, and unusual coronaries were not significant risk factors for mortality on multivariable analysis. Ten-year freedom from RVOT and arch re-operation was 55+/-5% and 96+/-4%. Five-year event-free survival for groups 1 and 2 was 35+/-6% and 87+/-1% (p=0.0016). Significant factors affecting event-free survival were group 1 (HR 108, p=0.0005), and larger weight at surgery (HR 1.3, p=0.02). CONCLUSIONS: The Taussig-Bing anomaly is complex and often associated with other cardiac anomalies (arch obstruction, RVOTO, unusual coronary pattern). Advances in perioperative care have significantly mitigated mortality. In our experience with single-stage total repair, event-free survival, especially freedom from RVOT re-operation, has significantly improved.

Effect of inhaled hydrogen sulfide on metabolic responses in anesthetized, paralyzed, and mechanically ventilated piglets.

OBJECTIVE: Induced hypometabolism may improve the balance between oxygen delivery and consumption and may help sustain tissue viability in critically ill patients with low cardiac output state. Inhaled hydrogen sulfide (H2S) has been shown to induce a suspended animation-like state in mice with a 90% decrease in oxygen consumption. We conducted a preclinical study to explore the potential effect of H2S on metabolic rate in large mammals. DESIGN: Prospective study. SETTING: Animal laboratory in a university hospital. SUBJECTS: Eleven anesthetized, paralyzed, and mechanical ventilated piglets (5.8 +/- 0.7 kg). INTERVENTIONS: The right carotid artery and superior vena cava were cannulated for arterial pressure monitoring and blood gas sampling. Seven piglets were sequentially exposed to 20, 40, 60, and 80 ppm of H2S over a period of 6 hrs (each level for 1.5 hrs) (H2S group), and additionally four piglets were exposed to air over the same period (control group). MEASUREMENTS AND MAIN RESULTS: Ambient temperature was fixed at 22 degrees C throughout. Central body temperature, arterial pressure, and heart rate were continuously monitored. Oxygen consumption and carbon dioxide production were continuously measured using respiratory mass spectrometry. Cardiac output was calculated using the Fick principle. Central temperature and oxygen consumption significantly and linearly decreased over the H2S exposures (p < .0001 for both), the rates of which were significantly less compared with those in the control group (p < .01 for both). Mean arterial pressure increased significantly (p = .007), whereas heart rate (p = .14), cardiac output (p = .89), and lactate (p = .67) did not change significantly during H2S exposures in H2S group; all the variables decreased significantly in the control group (p < .01 for all), and p < .01 by comparison with H2S group except for lactate (p = .05). CONCLUSIONS: H2S does not appear to have hypometabolic effects in ambiently cooled large mammals and conversely appears to act as a hemodynamic and metabolic stimulant.

Surgical outcomes in the treatment of patients with tetralogy of Fallot and absent pulmonary valve.

OBJECTIVE: Tetralogy of Fallot and absent pulmonary valve (TOF/APV) is associated with significant pulmonary artery dilatation and airway compression. Treatment of infants presenting with respiratory symptoms early in life is associated with high mortality (20-60%). We aim to report our results and identify factors associated with survival and prolonged ventilation. METHODS: We performed a retrospective review of 62 consecutive patients following repair of TOF/APV (1982-2006). Median age at repair was 1.4 years (1 day-35 years). Twenty patients required preoperative intubation. RESULTS: Sixty-one patients underwent complete repair. Thirty-three patients underwent pulmonary artery plication (n=15) or reduction (n=18). The right ventricular outflow tract (RVOT) was reconstructed with valved conduit (n=31), bioprosthetic valve (n=18), monocusp (n=8), or transannular patch (n=4). There were three perioperative and five late deaths. All perioperative deaths were in neonates and before 1995. Five- and ten-year survival was 93+/-4% and 87+/-5%. Mean ventilatory requirements for neonates, infants, and children > or =1 year were 36+/-35, 8+/-8, and 2.6+/-2.4 days (p<0.0001). On multivariable analysis, significant factors associated with prolonged ventilation were neonates (p<0.0001) and preoperative mechanical ventilation (p=0.088). Eight airway reinterventions were needed in seven infants with persistent postoperative airway compromise, pulmonary artery suspension (n=4), innominate artery suspension (n=2), and lobectomy (n=2). Freedom from RVOT reoperation was 89+/-5% and 59+/-9% at 5 and 10 years. There were no significant risk factors for time-related survival or RVOT reoperation on multivariable analysis. CONCLUSIONS: In contrast to children and adults with TOF/APV, neonates and small infants presenting with respiratory symptoms require prolonged ventilation and additional reinterventions for airway compression. Our current surgical approach which includes reduction and suspension of pulmonary arteries, reconstruction of a competent RVOT, and aggressive postoperative ventilatory management to relieve airway obstruction offers satisfactory outcomes.

Clinical Hemodynamic Parameters Do Not Accurately Reflect Systemic Oxygen Transport in Neonates after the Norwood Procedure.

OBJECTIVES: Clinical hemodynamic parameters (heart rate, systolic arterial pressure [SAP], and arterial and venous oxygen saturation saturations [SaO2 and SvO2 ]) are commonly used to guide management to optimize oxygen transport after the Norwood procedure. The adequacy of this practice has not been demonstrated. We examined the correlations between these clinical parameters and direct measurements of oxygen transport in these patients. METHODS: Oxygen consumption (VO2 ) was measured using respiratory mass spectrometry for 72 hours in 17 neonates after the Norwood procedure. Arterial, superior vena caval, and pulmonary venous blood gases and pressures were measured at intervals of 2-4 hours to calculate cardiac output (CO), systemic and pulmonary blood flows (Qs , Qp), systemic vascular resistance (SVR), total pulmonary vascular resistance including the Blalock-Taussig shunt (tPVR), oxygen delivery (DO2), and extraction ratio (ERO2 ). Heart rate and SAP were also recorded. RESULTS: Heart rate was positively correlated with VO2 (P = .004) and ERO2 (P = .005). SAP was positively correlated with CO (P = .006), VO2 (P = .02), ERO2 (P = .01), and SVR (P = .08). SaO2 was negatively correlated with tPVR, Qs, and DO2 but positively with Qp and SVR (P < .05 for all). SvO2 was positively correlated with CO, Qs , and DO2 (P < .0001 for all) and negatively correlated with SVR, VO2, and ERO2 (P < .05 for all). CONCLUSIONS: Routine clinical hemodynamic parameters do not accurately reflect oxygen transport after the Norwood procedure, except for SvO2, which does not differentiate between VO2 and DO2. Higher heart rate and SAP are correlated with a worse balance of oxygen transport. The results of clinical hemodynamic monitoring should be interpreted with caution. Direct measurements of oxygen transport parameters are important in the care of neonates after the Norwood procedure.

The relationship between plasma concentrations of ionized calcium and magnesium with cardiac energetics and systemic oxygen transport in neonates after the Norwood procedure.

OBJECTIVE: We sought to determine the relationship between plasma calcium and magnesium concentrations with postoperative systemic hemodynamics and oxygen transport in neonates after the Norwood procedure. METHODS: Postoperative systemic oxygen consumption was continuously measured using respiratory mass spectrometry for 72 hours in 17 neonates. Arterial, superior vena caval and pulmonary venous blood gases and pressures, plasma calcium, and lactate levels were measured at 2- to 4-hour intervals to calculate cardiac output, rate pressure product, cardiac power output, systemic oxygen delivery, and oxygen extraction ratio. Plasma magnesium levels were measured at 2- to 8-hour intervals. RESULTS: Plasma calcium levels decreased in the first 8 hours from 1.08±0.13 mmol/L to 0.98±0.08 mmol/L, followed by an increase to 1.10±0.26 mmol/L at 72 hours (P<.0001). Mg2þ change was significantly related to time after logarithmic transformation, rapidly decreasing from 1.62±0.25 mg/L to 0.90±0.15 mg/L in the first 40 hours and further decreasing slowly thereafter to 0.64±0.13 mg/L at 72 hours (P<.0001). Plasma magnesium levels had a significant positive correlation with cardiac output (P=.008) and cardiac power output (P=.01), and a negative correlation with heart rate (P=.05). Plasma magnesium levels correlated positively with systemic oxygen delivery and negatively with systemic oxygen consumption (P=.08 for both), resulting in significant negative correlations with oxygen extraction ratio (P=.04) and lactate levels (P=.05). For a given cardiac power output, plasma magnesium showed a significantly negative correlation with rate pressure product (P=.01). Plasma calcium levels showed the opposite trend, which was statistically insignificant except for lactate (P=.007). CONCLUSIONS: Plasma magnesium may exert favorable effects on myocardial energetics and systemic oxygen transport in neonates after the Norwood procedure, whereas plasma calcium may be harmful. Maintaining a relatively high level of plasma magnesium and a low level of plasma calcium may improve myocardial work efficiency and the balance of systemic and myocardial oxygen transport.

Aortic atresia is associated with an inferior systemic, cerebral, and splanchnic oxygen-transport status in neonates after the Norwood procedure.

OBJECTIVE: Aortic atresia (AA) is a risk factor for mortality after the Norwood procedure. The mechanisms remain unknown. We compared the profiles of systemic, cerebral, and splanchnic oxygen transport in neonates with hypoplastic left-heart syndrome with AA or aortic stenosis (AS) after the Norwood procedure. METHODS: Systemic oxygen consumption (VO(2)) was measured using respiratory mass spectrometry for 72 h in 17 neonates (nine in the AA group, eight in the AS group). Cardiac output (CO), systemic vascular resistance (SVR), oxygen delivery (DO(2)), and oxygen extraction ratio (ERO(2)) were calculated combining with blood gases and pressures at 2-4-h intervals. Cerebral (ScO(2)) and splanchnic (SsO(2)) oxygen saturations were measured by near-infrared spectroscopy. The doses of dopamine, milrinone, phenoxybenzamine, and vasopressin were recorded. Preoperative echocardiographic left-ventricular morphology and ejection fraction ratio were measured. RESULTS: Compared with the AS group, the AA group had lower CO (p = 0.03), higher SVR (p = 0.002), lower DO(2) (p = 0.07), VO(2) (p = 0.003), and ScO(2) (p = 0.07) during the first 40 h. SsO(2) was insignificantly lower. Despite a similar ERO(2), the AA group had higher lactate (p = 0.01). The AA group received higher doses of milrinone (p < 0.0001), vasopressin (p = 0.005), and phenoxybenzamine (p = 0.02), and lower higher doses of dopamine (p = 0.07). Vasopressin adversely correlated with systemic oxygen-transport variables and SsO(2) (p < 0.05). The AA group had thicker left-ventricular posterior wall (p = 0.05) that was negatively correlated with CO (p = 0.02). CONCLUSIONS: AA is associated with an inferior status of systemic, cerebral, and splanchnic oxygen transport after the Norwood procedure. Aggressive use of vasopressin may worsen systemic oxygen transport and decrease splanchnic perfusion.

Lesion-specific outcomes in neonates undergoing congenital heart surgery are related predominantly to patient and management factors rather than institution or surgeon experience: A Congenital Heart Surgeons Society Study.

OBJECTIVE: To identify the role of institution and surgeon factors, including case volume and experience, on survival of neonates with complex congenital heart disease. METHODS: A total of 2421 neonates from 4 groups-transposition of the great arteries (n = 829), pulmonary atresia with intact ventricular septum (n = 408), Norwood (n = 710), and interrupted aortic arch (n = 474)-were prospectively enrolled from Congenital Heart Surgeons Society institutions. Multivariable analysis of risk-adjusted survival was performed for each group, entering each institution or surgeon into the multivariable analysis separately. Institutional performance was defined as [predicted survival - actual survival]. Neutralization of risk factors within each institution was evaluated using complex interaction terms. Institution and surgeon experience, defined by 5 domains (total case volume, total time each operation was performed, cases per year, rank-order of cases, case velocity), were also investigated. RESULTS: Institutional performance varied among all groups. Improved outcomes in Norwood and pulmonary atresia with intact ventricular septum were unrelated to any "experience" domains, whereas improved outcomes in transposition of the great arteries were significantly related to increased experience in most domains. No institution enrolling in all 4 studies ranked number 1 in performance for all groups. Neutralization of low birth weight as a risk factor contributed to decreased mortality after Norwood in one institution. CONCLUSION: Survival of neonates with complex congenital heart disease is influenced more by patient and management factors than by institution or surgeon experience. Institutional excellence in managing some diagnostic groups does not indicate similar performance for all diagnostic groups. Weighted risk-adjusted comparisons could provide a mechanism to improve results in institutions with less than optimal outcomes.

Persistent risk of subsequent procedures and mortality in patients after interrupted aortic arch repair: a Congenital Heart Surgeons' Society study.

OBJECTIVE: Multiple subsequent procedures directed at the arch and/or the left ventricular outflow tract are frequently required after interrupted aortic arch repair. We the investigated patterns and factors associated with these subsequent procedures and mortality. METHODS: We reviewed the data from 447 patients with interrupted aortic arch at 33 institutions enrolled from 1987 to 1997. We classified the subsequent procedures by type (catheter-based or surgical) and focus (arch, left ventricular outflow tract, and "other" cardiovascular lesions). We used competing risks and modulated renewal analysis to explore subsequent procedures. RESULTS: There were 158 subsequent arch and 100 left ventricular outflow tract procedures. Freedom from death at 21 years was 60% overall. The risk of additional subsequent arch procedures decreased after the first subsequent arch procedure in the acute phase, but did not significantly change in the chronic phase. The risk of additional subsequent left ventricular outflow tract procedures increased after the first subsequent left ventricular outflow tract procedure in the chronic phase. The risk factors for subsequent arch procedures and mortality, but not for subsequent outflow track procedures, were related in a complex way to previous procedures and their timing. CONCLUSIONS: Interrupted aortic arch is a chronic disease in which patients often undergo multiple subsequent procedures with persistent risk for additional intervention and mortality. The risk factors are related to the nature and timing of previous procedures and to the morphology and details of the index procedure. Interrupted aortic arch should be considered a chronic disorder.

Significant correlation of comprehensive Aristotle score with total cardiac output during the early postoperative period after the Norwood procedure.

BACKGROUND: The comprehensive Aristotle score has been proposed as an individualized measure of the complexity of a given surgical procedure and has been reported to significantly correlate with postoperative morbidity and mortality after the Norwood procedure. An important factor leading to postoperative morbidity and mortality is low cardiac output. We studied the correlation between the comprehensive Aristotle score and cardiac output (CO) in infants after the Norwood procedure. METHODS AND RESULTS: Respiratory mass spectrometry was used to continuously measure systemic oxygen consumption (VO(2)) in 22 infants for 72 hours postoperatively. Arterial, superior vena caval and pulmonary venous blood gases were measured at 2 to 4 hour intervals to calculate CO. The comprehensive Aristotle score was collected. Hospital mortality was 4.5%. The comprehensive Aristotle score ranged from 14.5 to 23.5 and negatively correlated with CO (P = 0.027). Among the patient-adjusted factors, myocardial dysfunction (n = 10), mechanical ventilation to treat cardiorespiratory failure (n = 9) and atrioventricular valve regurgitation (n = 4) (P = 0.01) negatively correlated with CO (P = 0.06 to 0.07). Aortic atresia (n = 9) was associated with a lower CO (P = 0.01) for the first 24 hours which linearly increased overtime (P = 0.0001). No correlation was found between CO and other factors (P > 0.3 for all). CONCLUSIONS: Comprehensive Aristotle score significantly negatively correlates with CO after the Norwood procedure. A preoperative estimation of the comprehensive Aristotle score, particularly in association with myocardial dysfunction, mechanical ventilation to treat cardiorespiratory failure, atrioventricular valve regurgitation and aortic atresia may help to anticipate a high postoperative morbidity with low cardiac output syndrome.

The influence of systemic hemodynamics and oxygen transport on cerebral oxygen saturation in neonates after the Norwood procedure.

OBJECTIVES: Ischemic brain injury is an important morbidity in neonates after the Norwood procedure. Its relationship to systemic hemodynamic oxygen transport is poorly understood. METHODS: Sixteen neonates undergoing the Norwood procedure were studied. Continuous cerebral oxygen saturation was measured by near-infrared spectroscopy. Continuous oxygen consumption was measured by respiratory mass spectrometry. Pulmonary and systemic blood flow, systemic vascular resistance, oxygen delivery, and oxygen extraction ratio were derived with measurements of arterial, and superior vena cava and pulmonary venous gases and pressures at 2- to 4-hour intervals during the first 72 hours in the intensive care unit. RESULTS: Mean cerebral oxygen saturation was 66% +/- 12% before the operation, reduced to 51% +/- 13% on arrival in the intensive care unit, and remained low during the first 8 hours; it increased to 56% +/- 9% at 72 hours, still significantly lower than the preoperative level (P < .05). Postoperatively, cerebral oxygen saturation was closely and positively correlated with systemic arterial pressure, arterial oxygen saturation, and arterial oxygen tension and negatively with oxygen extraction ratio (P < .0001 for all). Cerebral oxygen saturation was moderately and positively correlated with systemic blood flow and oxygen delivery (P < .0001 for both). It was weakly and positively correlated with pulmonary blood flow (P = .001) and hemoglobin (P = .02) and negatively correlated with systemic vascular resistance (P = .003). It was not correlated with oxygen consumption (P > .05). CONCLUSIONS: Cerebral oxygen saturation decreased significantly in neonates during the early postoperative period after the Norwood procedure and was significantly influenced by systemic hemodynamic and metabolic events. As such, hemodynamic interventions to modify systemic oxygen transport may provide further opportunities to reduce the risk of cerebral ischemia and improve neurodevelopmental outcomes.

Outcomes after surgical treatment of children with partial anomalous pulmonary venous connection.

BACKGROUND: We explore early results and time-related morbidity after surgical repair of partial anomalous pulmonary venous connection (PAPVC) at our institution. METHODS: Between 1982 and 2006, 306 consecutive patients underwent surgery for PAPVC; of these, 236 (77%) were children with a median age of 5.3 years (range, 0.47 to 18 years). Clinical and echocardiographic follow-up was obtained. RESULTS: PAPVC was right-sided in 214 patients (90%), left-sided in 17 (7%), and bilateral in 5 (2%). Anomalous veins were partial in 186 patients (79%) and involved the entire lung in 50 (21%). The most common type was right PAPVC into the superior vena cava in 175 (74%), with 87% associated with sinus-venosus atrial septal defect; followed by right PAPVC into the right atrium in 29 (12%), left PAPVC into the innominate vein in 22 (9%), and scimitar syndrome in 15 (6%). Repair strategy included intracardiac baffle in 203, pulmonary vein implantation in 22, and SVC division with reimplantation on the right atrial appendage in 14. There was no early or late mortality. Freedom from reoperation, vena cava obstruction, pulmonary vein obstruction, and pacemaker implantation at 15 years was 97%, 97.8%, 86%, and 99.1%, respectively. Pulmonary vein obstruction was significantly more common in patients with scimitar compared with others (22.4% versus 98.3%, p < 0.0001). Postoperative quantitative lung perfusion scans in 13 of 15 scimitar patients showed decreased right lung perfusion (mean, 22.5%). CONCLUSIONS: Surgical treatment of PAPVC is associated with excellent outcomes and low time-related morbidity. However, management of children with scimitar syndrome is complicated by an exceptionally high incidence of postoperative pulmonary venous obstruction and abnormally diminished perfusion of the right lung.

Outcomes of different surgical strategies in the treatment of neonates with aortic coarctation and associated ventricular septal defects.

BACKGROUND: We reviewed surgical results after treatment of aortic coarctation (CoA) associated with ventricular septal defect (VSD) in neonates. We examined morbidity associated with the two different therapeutic strategies of combined repair versus initial coarctation repair alone and attempted to identify preoperative predictors to guide optimal surgical management. METHODS: Between 1990 and 2006, 141 neonates with CoA and VSDs underwent operation using two management strategies. In group A (n = 89), initial simple CoA repair was done through posterolateral thoracotomy, plus concomitant pulmonary artery banding (n = 54), followed by VSD closure. In group B (n = 52), both defects were repaired simultaneously through a sternotomy. RESULTS: Overall 10-year survival was 90.8%, with no difference between groups. The 5-year freedom from arch reoperation was 93.5%, with no difference between groups. The 10-year freedom from reoperation for subaortic obstruction was 95% for group A and 75% for group B (p = 0.016). In group A, 41 patients required secondary VSD closure at a median interval of 48 days after CoA repair. Freedom from reoperation at 1 month and 5 years was 78.5% and 45.8% in group A versus 97.8% for both in group B. Preoperative predictors for requirement for later VSD closure in group A were VSD type other than muscular (p = 0.0009) and larger VSD identified by higher VSD diameter/aortic valve annulus ratio (p < 0.0001). CONCLUSIONS: Results of both treatment strategies are good. Neonates with larger VSDs, especially outlet, malalignment, and perimembranous types, are likely to require VSD closure. Although midline sternotomy and combined treatment strategy may be necessary in neonates with proximal arch hypoplasia, initial coarctation repair alone is valid option at the possible expense of additional operation.

Profiles of hemodynamics and oxygen transport derived by using continuous measured oxygen consumption after the Norwood procedure.

OBJECTIVES: The lack of accurate measurement of hemodynamics and oxygen transport has limited our understanding of Norwood physiology and postoperative management. We used measured oxygen consumption to characterize hemodynamics and oxygen transport after the classic Norwood procedure. METHODS: Fourteen neonates had continuous respiratory mass spectrometry to measure oxygen consumption (VO2). Arterial, superior vena caval, and pulmonary venous saturations were measured at 2- to 4-hour intervals for 72 hours postoperatively. Systemic (Qs) and pulmonary (Qp) blood flows, systemic vascular resistance (SVR) and pulmonary vascular resistance inclusive of the Blalock-Taussig shunt (BT-PVR), systemic oxygen delivery (DO2), and the oxygen extraction ratio (ERO2) were calculated. RESULTS: Qs and DO2 were low during the first 12 hours (1.8 +/- 0.6 L x min(-1) x m(-2) and 281 +/- 86 mL x min(-1) x m(-2) at the 12th hour, respectively) and increased over the study period (P < .05 for both). VO2 decreased markedly during the first 24 hours (101 +/- 26 to 86 +/- 16 mL x min(-1) x m(-2), P < .0001). Consequently, ERO2 decreased significantly over the study, most rapidly during the first 24 hours (0.44 +/- 0.11 to 0.28 +/- 0.09, P < .0001). There was a close correlation of DO2 to SVR and to Qs (P < .0001 for both). There was no correlation of DO2 to BT-PVR (P = .14) or to Qp (P = .67). DO2 was closely correlated with hemoglobin value (P < .0001), weakly correlated with PaO2 (P = .0002), and not correlated with arterial oxygen saturation (P = .32). CONCLUSIONS: There is wide variability of hemodynamics and oxygen transport after the Norwood procedure. The decrease in VO2 during the first 24 hours is the main contributor to improving the balance of oxygen transport. DO2 is most closely correlated to SVR and hemoglobin and weakly correlated to PaO2. It is not correlated to Qp. Postoperative management strategies to decrease VO2 and maintain a high hemoglobin level and a low SVR appear to be rational.

Extracorporeal life support after staged palliation of a functional single ventricle: subsequent morbidity and survival.

OBJECTIVE: We sought to review the outcome of infants with a functional single ventricle receiving postoperative extracorporeal life support. METHODS: We reviewed all patients with a functional single ventricle receiving postoperative extracorporeal life support between January 1997 and May 2003. RESULTS: We supported 25 infants (age range, 2-139 days; median age, 15 days; weight range, 1.9-5.9 kg; median weight, 3.4 kg) with extracorporeal life support. Operative procedures were Norwood stage 1 procedure in 18 patients, modified Blalock-Taussig shunt in 4 patients, bidirectional superior cavopulmonary shunt in 2 patients, and pulmonary vein repair in 1 patient. Indications for extracorporeal life support included cardiac arrest (14/25) and low cardiac output state (11/25). Extracorporeal membrane oxygenation was initiated in 19 patients, with conversion to a ventricular assist device in 7 patients. Ventricular assist device alone was initiated in 6 patients. Survival to decannulation was 76%, with 5 late deaths from multiorgan failure and 56% intensive care unit survival. Survival to hospital discharge was 44%. On univariate analysis, the presence of arrhythmia before extracorporeal life support (P = .005), renal failure (P = .0007), Candida species-induced sepsis (P = .026), and multiorgan failure (P = .0009) were significant risk factors in the nonsurvivors. Median hospital stay was 43.5 days (range, 6-181 days) for the whole group and 93 days (range, 36-181 days) for survivors. Eight patients completed next stage palliation. CONCLUSIONS: Twenty percent of patients were supported with a ventricular assist device alone, with 50% conversion to a ventricular assist device from extracorporeal membrane oxygenation. Survival to decannulation was encouraging. Multiorgan failure and risk of invasive infection in the post-extracorporeal membrane oxygenation period mitigate against survival to hospital discharge. Use of extracorporeal life support before cardiac arrest might reduce attrition between decannulation and hospital discharge.

Inclusion of oxygen consumption improves the accuracy of arterial and venous oxygen saturation interpretation after the Norwood procedure.

OBJECTIVE: Management strategy for the postoperative Norwood neonate has been formulated from models that have estimated oxygen consumption (VO2). Superior vena caval oxygen saturation (SVO2), systemic arterial and superior vena caval oxygen saturation difference (Sa-VO2), and oxygen excess factor (Omega = arterial oxygen saturation/Sa-VO2) have been used as indirect indicators to estimate systemic blood flow (Qs) and oxygen delivery (DO2). We sought to examine the correlation of the indirect indicators to VO2-derived measures of oxygen transport. METHODS: Respiratory mass spectrometry was used to continuously measure VO2 after the Norwood procedure (n = 13). Measured saturations and the direct Fick equation were used to obtain pulmonary blood flow, Qs, DO2, and oxygen extraction ratio (ERO2) values. Correlations to SVO2, Sa-VO2, and Omega were sought. RESULTS: There was a close correlation of SVO2, Sa-VO2, and Omega to ERO2 (r = 0.92, 0.96, and 0.97, respectively; P < .0001). Correlation to Qs and DO2 was variable (r = 0.39 to 0.78, respectively; P < .0001). Correlation to VO2 was poor but significant (r = 0.24 to 0.40, P < .0001). Inclusion of VO2 improved the correlation to Qs and DO2 (r = 0.66 to 0.97, P < .0001). CONCLUSIONS: The close correlation of SVO2, Sa-VO2, and Omega to ERO2 indicates that each is a measure of the balance of DO2 and extraction. The significant but less reliable correlation to DO2 and VO2 indicates the values for SVO2, Sa-VO2, and Omega do not discriminate between the contribution of DO2 and VO2. Measured VO2 and hemodynamics may improve the optimization of postoperative management strategy in the individual neonate.