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To determine the role of the vasoconstrictor peptide endothelin-1 in cardiopulmonary bypass in neonates, we measured plasma endothelin-1 concentrations in infants before and after cardiopulmonary bypass for arterial switch procedures and studied the effects of endothelin-1 on coronary tone and contractility in normal and reperfused neonatal pig hearts. Endothelin-1 blood concentrations (picograms per milliliter, mean +/- standard error) were significantly higher in neonates with arterial transposition and in umbilical venous blood (22.9 +/- 2.3 and 19.2 +/- 2.9, respectively) than in older children with atrial septal defects (13.2 +/- 1.6) or in healthy adults (10.7 +/- 2.5). After cardiopulmonary bypass, endothelin-1 concentrations increased 29% in neonates undergoing arterial switch procedure and 28% in children undergoing atrial septal defect repair (p < 0.05 versus before bypass). In isolated, blood-perfused neonatal pig hearts, endothelin-1 had dose-related coronary constrictor and inotropic effects between 25 and 100 pmol. Endothelin-1 concentrations that did not increase coronary perfusion pressure (5 to 10 pmol) caused significant coronary constriction in the presence of norepinephrine (10 nmol/L). During reperfusion after 30 minutes of global normothermic ischemia, the coronary vasoconstrictor effects of both endothelin-1 alone and endothelin-1 plus norepinephrine were significantly enhanced. Nitroglycerin reversed vasoconstriction produced by endothelin-1 and endothelin-1 plus norepinephrine both before and after ischemia-reperfusion. We conclude that endothelin-1 concentrations are significantly elevated in neonates and are further increased after cardiopulmonary bypass. Coronary vasoconstriction caused by endothelin-1 is enhanced by ischemia-reperfusion and by norepinephrine present in concentrations typically observed after neonatal cardiopulmonary bypass. Nitroglycerin reverses coronary vasoconstriction induced by endothelin-1 and may therefore be beneficial in the postoperative management of neonates after cardiac operations.

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BACKGROUND: Mechanical circulatory support for intractable heart failure as a bridge to transplantation has been used infrequently in children. The lack of clinically available ventricular assist devices has resulted in the use of conventional extracorporeal circuits with oxygenator as the main modality for circulatory support. In this study we reviewed our experience with extracorporeal membrane oxygenation (ECMO) support in children with irreversible heart failure who were awaiting heart transplantation. METHODS AND RESULTS: Since 1985, 14 children were placed on ECMO support for circulatory failure and were considered candidates for heart transplantation: 8 children had postcardiotomy contractile failure, 3 had dilated cardiomyopathy, and 3 had viral myocarditis. Five of these children had cardiac arrest and were placed on support during cardiopulmonary resuscitation. Mean duration of ECMO support was 109 +/- 20 hours. Eight patients developed pulmonary edema requiring decompression of the left ventricle, 3 by blade atrial septostomy and 5 by left atrial vent cannula. Nine of 14 received a heart transplant, 1 child recovered spontaneously (myocarditis), and 4 died of sepsis on ECMO. Of the children who received transplants, 6 were early survivors with 1 late death (lymphoproliferative disease), for a total of 7 of 14 (50%) early and 6 of 14 (43%) late survivors. CONCLUSIONS: Our experience suggests that ECMO is an effective means of circulatory support as a bridge to transplantation in children. Decompression of the left ventricle is often required to prevent pulmonary edema. Sepsis and bleeding remain a limitation to prolonged mechanical support with ECMO in children.

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Lung injury remains an important problem after cardiopulmonary bypass. The contribution of altered surfactant concentration or activity to pulmonary dysfunction after cardiopulmonary bypass is unclear. Recent evidence indicates that alveolar surfactant exists in specific aggregate forms that differ with respect to density, phospholipid composition, and function. A transition from surface active, higher density, large aggregates of surfactant to lower density, small aggregates that possess reduced surface activity has been demonstrated after experimental lung injury. The purpose of the present study was to examine surfactant aggregate fractions before and after bypass in children. Twelve acyanotic patients, aged 2 to 12 years, underwent intraoperative pulmonary function testing followed by bronchoalveolar lavage before incision and approximately 1 hour after termination of cardiopulmonary bypass. Saturated phosphatidylcholine pool sizes and total protein content of the small- and large-aggregate fractions of bronchoalveolar lavage fluid were determined. One hour after termination of cardiopulmonary bypass, the ratio of saturated phosphatidylcholine in small-aggregate as compared with that in large-aggregate fractions increased (mean +/- standard error) from 0.19 +/- 0.03 to 0.37 +/- 0.07 (p < 0.02), as did the ratio of saturated phosphatidylcholine to protein in the small-aggregate fraction (from 0.04 +/- 0.01 to 0.08 +/- 0.02, p < 0.05). Reductions in forced vital capacity (-19% +/- 5%), inspiratory capacity (-15% +/- 3%), and small airway flow rates (-32% +/- 6%) were also observed after bypass. These changes were accompanied by a fivefold increase in alveolar polymorphonuclear leukocyte content. The present study suggests that cardiopulmonary bypass of moderate duration in relatively healthy children is associated with surfactant changes that are similar in type and magnitude to those observed in experimental lung injury.

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OBJECTIVE: To assess the experience and efficacy of extracorporeal membrane oxygenation (ECMO) for cardiac rescue in patients with presumptively lethal cardiac dysfunction at the Children's Hospital of Pittsburgh. DESIGN: Retrospective analysis of patient records from a 9-yr period. SETTING: A 22-bed tertiary care pediatric intensive care unit (ICU) with an average of 1,400 admissions per year. An average of 150 open cardiotomy surgeries are performed per year, and all postoperative and severely ill cardiac patients are cared for in the ICU. PATIENTS: A total of 29 pediatric ICU patients with myocardial failure received ECMO throughout the 9-yr study period. INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Demographic information, underlying cardiac defect, intraoperative and postoperative data, postoperative course, details of ECMO treatment, and outcome were collected. Comparison of survivors with nonsurvivors was performed using the Mann-Whitney U test for continuous variables. Twenty-three (79%) of 29 patients recovered myocardial function while undergoing ECMO, 18 (62%) of 29 patients were successfully decannulated, and 13 (45%) of 29 patients survived to hospital discharge. Long-term survival rate was 11 (38%) of 29 patients. Three (60%) of five bridge-to-heart transplant patients survived. Eleven (65%) of 17 patients who suffered cardiac arrest before ECMO, survived to discharge and nine (53%) of these 17 patients remain long-term survivors. Survival rate in patients who required cardiac massage for > 15 mins before cannulation was six (55%) of 11 patients. CONCLUSIONS: Patients with severe myocardial dysfunction who fail conventional therapy can be successfully supported with ECMO during the period of myocardial recovery. ECMO can also provide a viable circulatory support system in patients with prolonged cardiac arrest who fail conventional resuscitation techniques. ECMO is also an effective means of support as a mechanical bridge to heart transplantation.

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Long-term morbidity and mortality were evaluated in the 21 survivors of a cohort of 51 consecutive infants with severe aortic valve stenosis who underwent surgical treatment in the first 3 months of life during the period from 1958 to 1988. The 21 early survivors have been followed up from 3 to 27 years (median 7.5 years). There have been two late deaths: one at age 13 year from bacterial endocarditis and the other at age 14 years after dislodgment of a prosthetic valve. The calculated 10-year actuarial survival for this group is 100%, with a 15-year actuarial survival of 75% (standard error 15%). Seven repeat operations have been performed in six patients: Three had persistent stenosis and a repeat valvotomy was performed in two of them, aged 2 years and 15 years. The other underwent placement of a conduit from the left ventricle to the descending aorta at 2 years of age. Replacement of the aortic valve has been performed in four patients because of severe valvular insufficiency 13 to 27 years after the initial operation. One of these had required a repeat valvotomy at the age of 15 years. The calculated actuarial freedom from reoperation at 10 years is 90% (standard error 6%) and at 15 years, 67% (standard error 15%). Aortic insufficiency was progressive throughout the period of follow-up. No patient had more than moderate aortic insufficiency 3 to 5 years after the initial valvotomy, whereas aortic insufficiency was severe in five of the eight patients followed up for 11 or more years. Progression of aortic insufficiency and the need for reoperation were not related to the age at initial valvotomy. Survivors of surgical aortic valvotomy in early infancy have a relatively good long-term prognosis and a high freedom from reoperation in the period leading to adolescence. Aortic insufficiency in these patients is progressive, and valve replacement eventually may be required.

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BACKGROUND: Conventional cardiopulmonary resuscitation (CPR) for cardiac arrest after open-heart surgery in children is often unsuccessful despite the ability to perform open-chest massage. The purpose of this study was to review our results with mechanical support as rescue therapy in children with sudden circulatory arrest after cardiac surgery. METHODS AND RESULTS: From 1981 through 1991, we have used mechanical support with an extracorporeal membrane oxygenator (ECMO) circuit for cardiac support in 33 children. Eleven of the 33 patients (age, 15 +/- 7 months) suffered cardiac arrest intractable to conventional open-chest massage 39 +/- 15 hours after an open-heart procedure. The mean duration of CPR was 65 +/- 9 minutes until ECMO flow was started. ECMO support was continued for 112 +/- 8 hours. One patient had ECMO discontinued due to bleeding (survived); three were discontinued from ECMO and died from neurological complications; and one died of cardiac dysfunction. Sepsis on ECMO was seen in one patient (survived). Overall early survival was seven of 11 (64%) with one patient requiring heart transplantation due to irreversible cardiac dysfunction. One child died late (1 month) after ECMO support. There were no long-term sequelae in the survivors. CONCLUSIONS: We conclude that ECMO rescue in children with postcardiotomy cardiac arrest is a feasible option in selected patients even after prolonged CPR (as long as 60 minutes).

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At the Children's Hospital of Pittsburgh the extracorporeal membrane oxygenation program was started in 1980. The results of our experience from 1980 to 1985 were previously reported. In the past 2 years 39 additional newborn infants have been treated with this modality, with an overall survival rate of 79% (31/39). This survival rate is much better than that obtained in 33 neonates who had been treated in the previous 5 years (54%; p less than 0.05). A new aspect of our extracorporeal membrane oxygenation program is the use of total apneic lung rest for persisting pulmonary interstitial emphysema during support with the oxygenator. Six neonates were treated with this technique because of worsening pulmonary interstitial emphysema during extracorporeal circulation. Five of them survived. Another indication for extracorporeal membrane oxygenation in our pediatric population has been left ventricular or biventricular failure after cardiopulmonary bypass. Four of our seven patients treated for this indication are long-term survivors. At present, because of the impossibility of using other forms of left ventricular assist devices in the pediatric population, it seems that extracorporeal membrane oxygenation is the most effective treatment for left ventricular failure after cardiopulmonary bypass. From our experience, even in the absence of long-term follow-up of patients supported with extracorporeal membrane oxygenation, it appears that the benefits of this therapeutic modality far exceed the risks in the high-risk population for which it is being used.

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Division of the morphologically left atrium (cor triatriatum) is a recognized clinical and surgical entity. Division of the right atrium (prominence of the eustachian and thebesian valves) is recognized pathologically, but is rare. It is unusual for this entity to be diagnosed during life. Stimulated by our experience with two patients seen at operation, one with an obstructive spinnaker-like formation and the other with a partitioned right atrium in the setting of pulmonary atresia, we reviewed the specimens in the heart museum of Children's Hospital of Pittsburgh that had prominence of the eustachian and thebesian valves. We identified 14 such hearts, which could be divided into two groups. In the first group, comprising six hearts, the valves were prominent in the form of Chiari networks and were of no functional significance. The valves were more extensive in the other eight hearts and partitioned the right atrium. In two of these, the valves themselves were the impediment to flow through the right side of the heart. In the other six, there was either atresia or severe stenosis along the right-sided pathways so that, after birth, the prominent valves retained their role during fetal life; namely, to deflect inferior caval venous return across the atrial septum to the left atrium. The partitions in these latter hearts would be of functional significance only if it were necessary to perform a Fontan procedure, when they might obstruct flow through an atriopulmonary (or atrioventricular) anastomosis.

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When tetralogy of Fallot with absent pulmonary valve syndrome leads to respiratory failure in early infancy, total repair has been advocated. Respiratory insufficiency may persist despite a surgically adequate repair. An infant with this syndrome underwent total surgical correction. Extracorporeal membrane oxygenation was employed in the early postoperative period for intractable pulmonary insufficiency and myocardial dysfunction.

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