Combined effects of nitric oxide and oxygen during acute pulmonary vasodilator testing.

OBJECTIVES: We compared the ability of inhaled nitric oxide (NO), oxygen (O2) and nitric oxide in oxygen (NO+O2) to identify reactive pulmonary vasculature in pulmonary hypertensive patients during acute vasodilator testing at cardiac catheterization. BACKGROUND: In patients with pulmonary hypertension, decisions regarding suitability for corrective surgery, transplantation and assessment of long-term prognosis are based on results obtained during acute pulmonary vasodilator testing. METHODS: In group 1, 46 patients had hemodynamic measurements in room air (RA), 100% O2, return to RA and NO (80 parts per million [ppm] in RA). In group 2, 25 additional patients were studied in RA, 100% O2 and 80 ppm NO in oxygen (NO+O2). RESULTS: In group 1, O2 decreased pulmonary vascular resistance (PVR) (mean+/-SEM) from 17.2+/-2.1 U.m2 to 11.1+/-1.5 U.m2 (p < 0.05). Nitric oxide caused a comparable decrease from 17.8+/-2.2 U.m2 to 11.7+/-1.7 U.m2 (p < 0.05). In group 2, PVR decreased from 20.1+/-2.6 U.m2 to 14.3+/-1.9 U.m2 in O2 (p < 0.05) and further to 10.5+/-1.7 U.m2 in NO+O2 (p < 0.05). A response of 20% or more reduction in PVR was seen in 22/25 patients with NO+O2 compared with 16/25 in O2 alone (p = 0.01). CONCLUSIONS: Inhaled NO and O2 produced a similar degree of selective pulmonary vasodilation. Our data suggest that combination testing with NO + O2 provides additional pulmonary vasodilation in patients with a reactive pulmonary vascular bed in a selective, safe and expeditious fashion during cardiac catheterization. The combination of NO+O2 identifies patients with significant pulmonary vasoreactivity who might not be recognized if O2 or NO were used separately.

Inhaled nitric oxide and hemodynamic evaluation of patients with pulmonary hypertension before transplantation.

OBJECTIVES: We investigated the effect of inhaled nitric oxide and infused acetylcholine in patients with pulmonary hypertension undergoing cardiac catheterization before cardiopulmonary transplantation. BACKGROUND: The fate of patients under consideration for transplantation of the heart or lungs, or both, is influenced by the evaluation of their pulmonary vascular reactivity. METHODS: We evaluated 11 patients who were classified into two groups on the basis of mean left atrial pressure > 15 mm Hg (group I, n = 6) or < or = 15 mm Hg (group II, n = 5). All patients inhaled nitric oxide at 80 ppm. This was preceded by an infusion of 10(-6) mol/liter of acetylcholine in seven consecutive patients (n = 3 in group I, n = 4 in group II). RESULTS: In group I, inhaled nitric oxide decreased pulmonary artery pressure from (mean +/- SE) 71 +/- 13 to 59 +/- 10 mm Hg (p < 0.05), pulmonary vascular resistance from 14.9 +/- 3.8 to 7.6 +/- 1.7 Um2 (p < 0.05) and intrapulmonary shunt fraction from 17.8 +/- 3.6% to 12.7 +/- 2.1% (p < 0.05). Left atrial pressure tended to increase from 27 +/- 4 to 32 +/- 5 mm Hg (p = 0.07). In group II pulmonary vascular resistance decreased in response to nitric oxide from 36.4 +/- 9.0 to 31.1 +/- 7.9 Um2 (p < 0.05). Cardiac index, systemic pressure and resistance did not change in either group. Seven patients who received acetylcholine had no significant alteration in pulmonary hemodynamic variables. CONCLUSIONS: These preliminary observations suggest that nitric oxide is a potent pulmonary vasodilator with minimal systemic effects. It may be useful in discriminating patients needing combined heart and lung transplantation from those requiring exchange of the heart alone.

Evaluation of a staged treatment protocol for rapid automatic junctional tachycardia after operation for congenital heart disease.

OBJECTIVES: This study sought to 1) develop an efficient treatment protocol for postoperative automatic junctional tachycardia (JT) using conventional drugs and techniques, and 2) identify clinical features associated with this disorder by analyzing a large study group. BACKGROUND: Postoperative JT is a transient arrhythmia that may be fatal after operation for congenital cardiac defects. Its precise cause is unknown. A variety of palliative treatments have evolved, but because of a low incidence of JT, large studies of the most efficient therapeutic sequence are lacking. METHODS: A protocol for rapid JT (>170 beats/min) was adopted in 1986, and was tested in 71 children between 1986 and 1994. Staged therapy involved 1) a reduction of catecholamines; 2) correction of fever; 3) atrial pacing to restore synchrony; 4) digoxin; 5) phenytoin or propranolol or verapamil; 6) procainamide or hypothermia; and 7) combined procainamide and hypothermia. Effective therapy was defined as a sustained reduction of JT rate <170 beats/min within 2 h. Clinical profiles of the study group were contrasted with all patients without JT from this same era to identify features associated with JT. RESULTS: Of the multiple treatment stages, only correction of fever and combined procainamide and hypothermia appeared to be efficacious. By refining the protocol to eliminate nonproductive stages, the time to JT control was significantly shortened for the last 30 patients. Treatment was ultimately successful in 70 of 71 children. Postoperative JT was strongly associated with young age, transient atrioventricular block and operations involving ventricular septal defect closure. CONCLUSIONS: A staged approach to therapy, with emphasis on combined hypothermia and procainamide in difficult cases, appears to be an effective management strategy for postoperative JT. These results may also serve as comparison data for evaluation of newer and promising JT options, such as intravenous amiodarone. Trauma to conduction tissue may play a central role in the etiology of this disorder.

Results of the arterial switch operation in patients with transposition of the great arteries and abnormalities of the mitral valve or left ventricular outflow tract.

Between January 1983 and October 1989, 290 patients underwent an arterial switch operation for transposition of the great arteries; 30 (10.3%) of the patients had abnormalities of the left ventricular outflow tract or mitral valve, or both. These abnormalities included isolated pulmonary valve stenosis (n = 9), septal (dynamic) subpulmonary stenosis (n = 5), anatomic (fixed) subpulmonary stenosis (n = 7), abnormal mitral chordae attachments (n = 2) or a combination of abnormalities (n = 7). There were two early deaths, one of which was due to previously unrecognized mitral stenosis and a subpulmonary (neo-aortic) membrane and one late death due to presumed coronary obstruction. Of the nine patients with pulmonary valve abnormalities due to either a bicommissural (n = 5) or a thickened tricommissural (n = 4) valve, only one underwent valvotomy. Peak systolic ejection gradients in these nine patients measured preoperatively ranged from 0 to 50 mm Hg. At follow-up study 5 to 30 months postoperatively, the neo-aortic valve gradient was less than or equal to 15 mm Hg in all patients; three patients had mild neo-aortic regurgitation. Preoperative gradients may overestimate the degree of obstruction because of the increased pulmonary blood flow present in transposition. No patient with "dynamic" subpulmonary obstruction before the arterial switch operation had a surgical procedure performed on the left ventricular outflow tract; none had evidence of subaortic obstruction after the arterial switch.(ABSTRACT TRUNCATED AT 250 WORDS)

Cognitive development of children following early repair of transposition of the great arteries using deep hypothermic circulatory arrest.

Twenty-eight children who underwent corrective cardiac surgery in early infancy had developmental evaluations to explore whether cardiopulmonary bypass perfusion variables are associated with later cognitive function. All had transposition of the great arteries repaired by the arterial switch operation using deep hypothermic circulatory arrest. The mean duration of deep hypothermic circulatory arrest was 64 +/- 10 minutes (mean +/- SD). Median age at repair was 4 days (range 1 to 125 days). Tests of development were administered at age 7 to 53 months: Bayley Scales for children younger than 30 months of age (n = 18) and McCarthy Scales for older children (n = 10). Overall cognitive development score was 101.2 +/- 11.1. Duration of deep hypothermic circulatory arrest was not associated with performance. However, for core cooling periods of less than 20 minutes' duration, shorter cooling periods were associated with lower scores (r = .85, n = 11, P less than .001). These data suggest that patients undergoing relatively long periods of deep hypothermic circulatory arrest may require some minimum time of cardiopulmonary bypass cooling to avoid central nervous system injury.

Inhaled nitric oxide in children with pulmonary hypertension and congenital mitral stenosis.

We demonstrated selective pulmonary vasodilation in patients with congenital mitral stenosis with inhaled NO, and used NO as prolonged therapy to stabilize the postintervention course of these children. The pulmonary vasoreactivity was greater than that previously reported in adults and may be due to particular sensitivity of pulmonary veins to inhaled NO when pulmonary venous hypertension has been present since birth.

Fibrinolytic therapy for femoral arterial thrombosis after cardiac catheterization in infants and children.

The charts of 79 patients who required femoral arterial (FA) thrombectomy after cardiac catheterization were reviewed. Fifteen patients (19%) had poor pulses after thrombectomy and 2 had an extremity amputated. One thousand consecutive patients undergoing cardiac catheterization were also studied to prospectively determine the safety and efficacy of systemic fibrinolytic therapy for treatment of FA thrombosis. Among these, 771 patients underwent retrograde arterial catheterization, including 31 patients with left-sided obstructive lesions who had undergone transarterial balloon dilation procedures with large catheters. All patients were given heparin at the time of arterial cannulation. Patients who had a pulseless extremity 4 hours after catheterization continued to receive heparin therapy for 24 to 48 hours. If the extremity continued to have no palpable pulse and the systolic blood pressure was less than 50% of that in the contralateral leg, intravenous streptokinase infusion was begun. The overall incidence of FA thrombosis was 3.6% (28 of 771), including 39% (12 of 31) of all patients undergoing transarterial balloon dilation procedures; 97% (27 of 28) of patients weighed less than 14 kg and the majority weighed less than 10 kg. After an average treatment period of 33 hours, 16 patients continued to have a pulseless extremity and were treated with streptokinase for an average duration of 13 hours. Normal pulses and systolic blood pressure returned in 14 (88%) and were nearly normal in 1 other patient (6%). The incidence of bleeding at the arterial puncture site was 25% and was highest in the patients who had a transarterial balloon dilation procedure. No serious complications occurred.

Postoperative ectopic atrial tachycardia in children with congenital heart disease.

The causes and significance of postoperative ectopic atrial tachycardia (EAT) remain unknown. To identify factors associated with postoperative EAT in children after cardiac surgery, we retrospectively studied pre-, intra-, and postoperative variables. The median age for postoperative EAT cases was younger than the general population admitted for cardiac surgical procedures (6 vs 17 months old, p = 0.09). Trends for EAT cases included lower preoperative oxygen saturation (84% vs 99%, p = 0.001), more pre- and postoperative inotropic support, and atrial septostomy (24% vs 6%, p = 0.08). EAT cases had longer cardiopulmonary bypass times and clamp times (115 vs 88 minutes, p = 0.08; 63 vs 46 minutes, p = 0.03, respectively) and had a prolonged intensive care unit stay (10 vs 3 days, p <0.001). Deaths were recorded in 2 of 17 EAT cases versus 0 of 36 randomly selected controls (p = 0.10). EAT resolved before discharge in 10 of 16 surviving patients. The etiology of EAT appears to be multifactorial, and may include disruption of atrial septum, longer pump times, need for inotropic support, and potassium depletion. Thus, young, ill, cyanotic patients were most at risk for postoperative EAT. Although EAT was associated with prolonged intensive care, it resolved in most cases over time.

Preoperative management of pulmonary venous hypertension in hypoplastic left heart syndrome with restrictive atrial septal defect.

A severely restrictive atrial septal defect (ASD) in neonates with hypoplastic left heart syndrome (HLHS) results in pulmonary venous hypertension, pulmonary edema, and intractable hypoxia. Between January 1983 and June 1998, 21 of 355 neonates presenting with HLHS (5.9%) underwent cardiac catheterization at median age 1 day (range 0 to 25), for creation or enlargement of a restrictive or absent interatrial communication. One patient died during preliminary angiography. Three underwent blade septostomy with 2 procedure-related deaths, and 1 had balloon atrial septostomy (BAS); all 4 died before surgical intervention. Fifteen underwent Brockenbrough atrial septoplasty with transatrial needle puncture and serial balloon dilations of the new ASD, 5 after unsuccessful BAS. The most recent patient had a stent placed across the atrial septum after transatrial needle puncture. In the 16 patients treated with septoplasty or stent, oxygen saturation increased from 50 +/- 4% to 83 +/- 2% (p <0.0001) and transatrial pressure gradient decreased from 16 +/- 1 to 6 +/- 1 mm Hg (p <0.0001). One patient died awaiting transplantation, supportive care only was requested in 1, and 14 underwent stage 1 palliation. Eight of 14 (57%) survived to hospital discharge. Six of 7 (86%) survived bidirectional Glenn and the 3 who have undergone fenestrated Fontan are alive. In neonates with HLHS, a restrictive ASD resulting in profound cyanosis demands urgent intervention. BAS is frequently unsuccessful and blade septostomy has high mortality. Pulmonary venous hypertension can be adequately relieved by Brockenbrough atrial septoplasty or stenting, allowing stabilization before reconstructive surgery or while awaiting transplant.

Delayed sternal closure after cardiac operations in a pediatric population.

OBJECTIVE: The purpose of this study was to assess morbidity and mortality associated with delayed sternal closure after pediatric cardiac operations. METHODS: Hospital records were reviewed of all patients with an open sternum after a cardiac operation at Children's Hospital, Boston, from January 1992 to December 1995. RESULTS: A total of 178 patients had delayed sternal closure with an overall mortality rate of 19%. The most common diagnosis of patients with delayed sternal closure was hypoplastic left heart syndrome (29%). Although myocardial distention or chest wall edema (n = 47) was a common indication to delay sternal closure, in many patients (n = 47) the sternum was left open electively to avoid postoperative cardiac or respiratory compromise. Successful sternal closure was achieved in 158 patients (89%) at a mean of 3.4 +/- 1.8 days after opening. There were significant increases in left atrial pressure (7.7 +/- 3.4 to 9.8 +/- 4.1 mm Hg, p = 0.00001) and right atrial pressure (8 +/- 3.2 to 10.1 +/- 3.3 mm Hg, p = 0.00001) with sternal closure. There was a small but statistically significant drop in pH (7.44 +/- 0.05 to 7.41 +/- 0.08, p < 0.0001) during sternal closure. The peak inspiratory pressure, delivered breaths per minute, and fraction of inspired oxygen all significantly increased during sternal closure. Clinical evidence of surgical site infection occurred in 12 (6.7%) of the patients with delayed sternal closure; mediastinitis developed in 7 (3.9%) patients. CONCLUSIONS: Although delayed sternal closure after complex operations for congenital heart disease is often necessary in the operating room because of edema, unstable hemodynamic conditions, or bleeding, it can also be used electively to aid in hemodynamic and respiratory stability in the initial postoperative period. Our review supports a low morbidity associated with delayed sternal closure in a pediatric population.

Whole blood ionized magnesium: age-related differences in normal values and clinical implications of ionized hypomagnesemia in patients undergoing surgery for congenital cardiac disease.

OBJECTIVES: We sought to (1) determine reference values for whole blood ionized magnesium concentrations in newborns, children, and young adults and (2) evaluate the frequency and clinical implications of ionized hypomagnesemia in patients undergoing surgery for congenital heart disease. METHOD: We prospectively measured ionized magnesium concentrations in 299 subjects (113 control subjects and 186 patients undergoing surgery for congenital heart disease). Subjects were categorized by age. In the surgical group blood samples were obtained before bypass, during bypass (cooling and rewarming), after bypass, and during admission to the intensive care unit. Ionized hypomagnesemia was defined as ionized magnesium level 2 standard deviations below the mean of control subjects in the same age group. Patients were analyzed, controlling for cardiopulmonary bypass time. RESULTS: In the control group ionized magnesium concentrations differed by age. Neonates and adults showed lower ionized magnesium concentrations compared with those of other age groups. Infants exhibited the highest ionized magnesium concentration. In the surgical group patients older than 1 month showed a higher proportion of ionized hypomagnesemia compared with that found in neonates at baseline (P <.001), after bypass (P =. 03), and at admission to the intensive care unit (P =.02). Controlling for cardiopulmonary bypass time, patients older than 1 month who were hypomagnesemic during bypass showed longer intubation time (P =.001) and longer intensive care stay (P =.01) and tended to have a higher pediatric severity of illness score on intensive care admission (P =.14) compared with patients without ionized hypomagnesemia. CONCLUSIONS: There are age-related differences in normal ionized magnesium concentrations. Ionized hypomagnesemia is a common and clinically relevant occurrence among patients older than 1 month of age undergoing surgery for congenital heart disease.

Changes in whole blood lactate levels during cardiopulmonary bypass for surgery for congenital cardiac disease: an early indicator of morbidity and mortality.

OBJECTIVE: Our objective was to evaluate the change in lactate level during cardiopulmonary bypass and the possible predictive value in identifying patients at high risk of morbidity and mortality after surgery for congenital cardiac disease. METHODS: We prospectively studied lactate levels in 174 nonconsecutive patients undergoing cardiopulmonary bypass during operations for congenital cardiac disease. Arterial blood samples were taken before cardiopulmonary bypass, during cardiopulmonary bypass (cooling and rewarming), after cardiopulmonary bypass, and during admission to the cardiac intensive care unit. Complicated outcomes were defined as open sternum as a response to cardiopulmonary instability, renal failure, cardiac arrest and resuscitation, extracorporeal membrane oxygenation, and death. RESULTS: The largest increment in lactate level occurred during cardiopulmonary bypass. Lactate levels decreased between the postbypass period and on admission to the intensive care unit. Patients who had circulatory arrest exhibited higher lactate levels at all time points. Nonsurvivors had higher lactate levels at all time points. A change in lactate level of more than 3 mmol/L during cardiopulmonary bypass had the optimal sensitivity (82%) and specificity (80%) for mortality, although the positive predictive value was low. CONCLUSIONS: Hyperlactatemia occurs during cardiopulmonary bypass in patients undergoing operations for congenital cardiac disease and may be an early indicator for postoperative morbidity and mortality.

The neonate with critical congenital heart disease: repair--a surgical challenge.

Primary neonatal repair of congenital heart defects offers a number of potential advantages over a two-stage approach, but the application of this principle has been limited by the perceived increased risk of neonatal repair. However, the patient with palliative CHD continues to suffer from secondary effects on the central nervous system, the pulmonary arteries, the airways, and the heart itself. Because these consequences have been increasingly recognized, we have undertaken primary repair of a variety of defects within the first months of life. From January 1983 through August 1988, 304 neonates with a critical congenital heart defect underwent primary repair with deep hypothermic circulatory arrest or low flow perfusion techniques. The total mortality rate was 11.8%. The largest number of patients had transposition of the great arteries--167 neonates--with a total hospital mortality of 8.9%. Aspects of preoperative evaluation and management, intraoperative care, including anesthesia and cardiopulmonary bypass, and deep hypothermia (with or without circulatory arrests), as well as postoperative management, are discussed. These data suggest that many forms of complex congenital heart defects may be successfully repaired during the neonatal period. Improved methods of preoperative resuscitation and postoperative care have contributed to these results. Follow-up hemodynamic and electrophysiologic studies have confirmed the advantages of early repair. Elective repair of the neonate with a complex congenital heart defect looms as a goal in the not-too-distant future.

Regional cerebral perfusion abnormalities after cardiac operations. Single photon emission computed tomography (SPECT) findings in children with postoperative movement disorders.

Despite the clinical and pathologic indicators implicating injury to the basal ganglia in children with hyperkinetic movement disorders, we were previously unable to identify lesions in these structures by means of cranial computed tomography or magnetic resonance imaging. We evaluated regional cerebral perfusion measured by single photon emission computed tomography (SPECT) with technetium 99m hexamethyl propylene amine oxime as a technique to localize functional cerebral abnormalities in eleven children who had a movement disorder after hypothermic cardiac surgery. Perfusion defects of the deep gray matter were noted in six of these eleven patients and cortical perfusion defects in nine. For both cortical and subcortical defects a strong right-sided predilection was present. Our findings suggest functional brain injury not detectable by conventional cranial computed tomography and magnetic resonance imaging in these patients. We speculate that these perfusion defects might relate to the behavioral and developmental sequelae in survivors of this syndrome. SPECT may identify subclinical injury in patients at risk for future neurodevelopmental problems and contribute to our understanding of the mechanisms of cerebral injury in the patient operated on for cardiac disease.

Repair of truncus arteriosus in the neonate.

From September 1986 through December 1991, 63 patients with truncus arteriosus underwent surgical repair. The management approach evolved over the period of the study from elective primary repair at 3 months of age to elective primary repair in the early neonatal period. Thirty variables were examined as potential risk factors for the outcome events of death, reoperation, and presence of pulmonary vascular morbidity. According to both univariate and multivariate techniques, severe truncal valve regurgitation, interrupted aortic arch, coronary artery anomalies, and age at repair greater than 100 days were important risk factors for perioperative death. In the 33 patients without these risk factors, early survival was 100%. In the 30 patients with one or more of these risk factors, survival was 63%. Pulmonary hypertensive episodes were fewer, and duration of ventilator dependence and pulmonary artery pressure were significantly less in patients undergoing the operation before 30 days of age. Seven patients required reoperation for right ventricular outflow tract obstruction at a mean follow-up time of 23.4 months, with no deaths. In conclusion, interrupted aortic arch, severe truncal valve insufficiency, coronary anomalies, and repair later than 100 days of age were risk factors for death after repair of truncus arteriosus. In the absence of these associations, truncus arteriosus can be repaired with excellent surgical outcome in the neonatal and early infancy period. Repair in the early neonatal period reduces the prevalence of postoperative pulmonary vascular morbidity.

Mechanical circulatory support for the treatment of children with acute fulminant myocarditis.

BACKGROUND: Viral myocarditis may follow a rapidly progressive and fatal course in children. Mechanical circulatory support may be a life-saving measure by allowing an interval for return of native ventricular function in the majority of these patients or by providing a bridge to transplantation in the remainder. METHODS: A retrospective chart review of 15 children with viral myocarditis supported with extracorporeal membrane oxygenation (12 patients) or ventricular assist devices (3 patients) was performed. RESULTS: All patients had histories and clinical findings consistent with acute myocarditis. The median age was 4.6 years (range 1 day-13.6 years) with a median duration of mechanical circulatory support of 140 hours (range 48-400 hours). Myocardial biopsy tissue demonstrated inflammatory infiltrates or necrosis, or both, in 8 (67%) of the 12 patients who had biopsies. Overall survival was 12 (80%) of 15 patients, with 10 (83%) survivors of extracorporeal membrane oxygenation and 2 (67%) survivors of ventricular assist device support. Nine (60%) of the 15 patients were weaned from support, with 7 (78%) survivors; the remaining 6 patients were successfully bridged to transplantation, with 5 (83%) survivors. All survivors not undergoing transplantation are currently alive with normal ventricular function after a median follow-up of 1.1 years (range 0.9-5.3 years). CONCLUSION: Eighty-percent of the children who required mechanical circulatory support for acute myocarditis survived in this series. Recovery of native ventricular function to allow weaning from support can be anticipated in many of these patients with excellent prospects for eventual recovery of full myocardial function.

Use of rapid-deployment extracorporeal membrane oxygenation for the resuscitation of pediatric patients with heart disease after cardiac arrest.

INTRODUCTION: We have recently used extracorporeal membrane oxygenation as a means of rapidly resuscitating pediatric patients with heart disease after cardiopulmonary arrest, in whom conventional resuscitation measures have failed. METHODS: We developed a fully portable extracorporeal membrane oxygenation circuit that is maintained vacuum and carbon dioxide-primed at all times. When needed, the circuit is crystalloid-primed and can be ready for use within 15 minutes. Since February 1996, we have used this rapid-deployment circuit to resuscitate 11 pediatric patients in full cardiopulmonary arrest. RESULTS: The median age of the 11 patients was 120 days (2 days to 4.6 years). Nine patients had a cardiac arrest after cardiac surgery. One patient had a cardiac arrest during cardiac catheterization and one patient had a cardiac arrest before cardiac surgery. Median duration of cardiopulmonary resuscitation was 55 minutes (range 20 to 103 minutes), with no difference in the duration of cardiopulmonary resuscitation between survivors and nonsurvivors. Ten of 11 patients (91%) were weaned from extracorporeal membrane oxygenation and seven (64%) survived to hospital discharge. Six patients are long-term survivors, five of whom are in New York Heart Association class I; one survivor is in class II. Seven patients resuscitated with extracorporeal membrane oxygenation before the use of this rapid-deployment circuit had a median duration of cardiopulmonary resuscitation of 90 minutes, with two (28.6%) survivors. CONCLUSIONS: The use of rapid-deployment extracorporeal membrane oxygenation results in shorter resuscitation times and improved survival in pediatric patients with heart disease after cardiopulmonary arrest.

Mechanical circulatory support in children with cardiac disease.

OBJECTIVE: To review the experience from a single center that uses both extracorporeal membrane oxygenation and ventricular assist devices for children with cardiac disease requiring mechanical circulatory support. METHODS: A retrospective chart review was performed for all pediatric patients with cardiac disease who required support with extracorporeal membrane oxygenation or ventricular assist devices. Statistical analysis of the impact of multiple clinical parameters on survival was performed. RESULTS: From 1987 through 1996 we provided mechanical circulatory support for children with a primary cardiac diagnosis using extracorporeal membrane oxygenation (67 patients) and ventricular assist devices (29 patients). Twenty-seven of 67 (40.3%) patients supported with extracorporeal membrane oxygenation and 12 of 29 (41.4%) patients supported with ventricular assist devices survived to hospital discharge. Failure of return of ventricular function within 72 hours of the institution of support was an ominous sign in patients supported with either modality. Univariate analysis revealed the serum pH at 24 hours of support, the serum bicarbonate at 24 hours of support, the urine output over the first 24 hours of support, and the development of renal failure to have a statistically significant association with survival in children supported with extracorporeal membrane oxygenation. None of the clinical parameters evaluated by univariate analysis were significantly associated with survival in the patients supported with ventricular assist devices. CONCLUSIONS: Extracorporeal membrane oxygenation and ventricular assist devices represent complementary modalities of mechanical circulatory support that can both be used effectively in children with cardiac disease.

Perioperative effects of alpha-stat versus pH-stat strategies for deep hypothermic cardiopulmonary bypass in infants.

OBJECTIVES: In a randomized, single-center trial, we compared perioperative outcomes in infants undergoing cardiac operations after use of the alpha-stat versus pH-stat strategy during deep hypothermic cardiopulmonary bypass. METHODS: Admission criteria included reparative cardiac surgery, age less than 9 months, birth weight 2.25 kg or more, and absence of associated congenital or acquired extracardiac disorders. RESULTS: Among the 182 infants in the study, diagnoses included D-transposition of the great arteries (n = 92), tetralogy of Fallot (n = 50), tetralogy of Fallot with pulmonary atresia (n = 6), ventricular septal defect (n = 20), truncus arteriosus (n = 8), complete atrioventricular canal (n = 4), and total anomalous pulmonary venous return (n = 2). Ninety patients were assigned to alpha-stat and 92 to pH-stat strategy. Early death occurred in four infants (2%), all in the alpha-stat group (p = 0.058). Postoperative electroencephalographic seizures occurred in five of 57 patients (9%) assigned to alpha-stat and one of 59 patients (2%) assigned to pH-stat strategy (p = 0.11). Clinical seizures occurred in four infants in the alpha-stat group (4%) and two infants in the pH-stat group (2%) (p = 0.44). First electroencephalographic activity returned sooner among infants randomized to pH-stat strategy (p = 0.03). Within the homogeneous D-transposition subgroup, those assigned to pH-stat tended to have a higher cardiac index despite a lower requirement for inotropic agents; less frequent postoperative acidosis (p = 0.02) and hypotension (p = 0.05); and shorter duration of mechanical ventilation (p = 0.01) and intensive care unit stay (p = 0.01). CONCLUSIONS: Use of the pH-stat strategy in infants undergoing deep hypothermic cardiopulmonary bypass was associated with lower postoperative morbidity, shorter recovery time to first electroencephalographic activity, and, in patients with D-transposition, shorter duration of intubation and intensive care unit stay. These data challenge the notion that alpha-stat management is a superior strategy for organ protection during reparative operations in infants using deep hypothermic cardiopulmonary bypass.

Rebound pulmonary hypertension after inhalation of nitric oxide.

BACKGROUND: We describe the hemodynamic response to initiation and withdrawal of inhaled nitric oxide (NO) in infants with pulmonary hypertension after surgical repair of total anomalous pulmonary venous connection. METHODS: Between January 1, 1992, and January 1, 1995, 20 patients underwent repair of total anomalous pulmonary venous connection. Nine patients had postoperative pulmonary hypertension and received a 15-minute trial of inhaled NO at 80 parts per million. Five of these patients received prolonged treatment with NO at 20 parts per million or less. RESULTS: Mean pulmonary artery pressure decreased from 35.6 +/- 2.4 to 23.7 +/- 2.0 mm Hg (mean +/- standard error of the mean) (p = 0.008), and pulmonary vascular resistance decreased from 11.5 +/- 2.0 to 6.4 +/- 1.0 U.m2 (p = 0.03). After prolonged treatment with NO, pulmonary artery pressure increased transiently in all patients when NO was discontinued. CONCLUSIONS: After operative repair of total anomalous pulmonary venous connection, inhaled NO selectively vasodilated all patients with pulmonary hypertension. Withdrawal of NO after prolonged inhalation was associated with transient rebound pulmonary hypertension that dissipated within 60 minutes. Appreciation of rebound pulmonary hypertension may have important implications for patients with pulmonary hypertensive disorders when interruption of NO inhalation is necessary or when withdrawal of NO is planned.