Impact of obesity on post-operative arrhythmias after congenital heart surgery in children and young adults.

BACKGROUND: Obesity increases the risk of post-operative arrhythmias in adults undergoing cardiac surgery, but little is known regarding the impact of obesity on post-operative arrhythmias after CHD surgery. METHODS: Patients undergoing CHD surgery from 2007 to 2019 were prospectively enrolled in the parent study. Telemetry was assessed daily, with documentation of all arrhythmias. Patients aged 2-20 years were categorised by body mass index percentile for age and sex (underweight <5, normal 5-85, overweight 85-95, and obese >95). Patients aged >20 years were categorised using absolute body mass index. We investigated the impact of body mass index category on arrhythmias using univariate and multivariate analysis. RESULTS: There were 1250 operative cases: 12% underweight, 65% normal weight, 12% overweight, and 11% obese. Post-operative arrhythmias were observed in 38%. Body mass index was significantly higher in those with arrhythmias (18.8 versus 17.8, p = 0.003). There was a linear relationship between body mass index category and incidence of arrhythmias: underweight 33%, normal 38%, overweight 42%, and obese 45% (p = 0.017 for trend). In multivariate analysis, body mass index category was independently associated with post-operative arrhythmias (p = 0.021), with odds ratio 1.64 in obese patients as compared to normal-weight patients (p = 0.036). In addition, aortic cross-clamp time (OR 1.007, p = 0.002) and maximal vasoactive-inotropic score in the first 48 hours (OR 1.03, p = 0.04) were associated with post-operative arrhythmias. CONCLUSION: Body mass index is independently associated with incidence of post-operative arrhythmias in children after CHD surgery.

Neonatal Aortic Arch Reconstruction With Direct Splanchnic Perfusion Avoids Deep Hypothermia.

BACKGROUND: Neonatal aortic arch reconstruction, typically performed with deep hypothermia and selective cerebral perfusion, leaves splanchnic organ protection dependent on hypothermia alone. A simplified method of direct in-field descending aortic perfusion during neonatal arch reconstruction permits the avoidance of deep hypothermia. We hypothesize that direct splanchnic perfusion at mild hypothermia provides improved or equivalent safety compared with deep hypothermia and may contribute to postoperative extracardiac organ recovery. METHODS: Included were 138 biventricular patients aged younger than 90 days undergoing aortic arch reconstruction with cardiopulmonary bypass. Patients were grouped according to perfusion method A (selective cerebral perfusion with deep hyperthermia at 18° to 20°C) or method B (selective cerebral perfusion and splanchnic perfusion at 30° to 32°C). Patient characteristics and perioperative clinical and serologic data were analyzed. Significance was assigned for p of less than 0.05. RESULTS: Of the 138 survivors, 63 underwent method A and 75 underwent method B. The median age at operation was 8.5 days (range, 6 to 15 days), and median weight was 3.2 kg (range, 2.8 to 3.73 kg), with no significant differences between groups. Cardiopulmonary bypass times were comparable between the two perfusion methods (p = 0.255) as were the ascending aortic cross-clamp times (p = 0.737). The postoperative glomerular filtration rate was significantly different between our groups (p = 0.028 to 0.044), with method B achieving a higher glomerular filtration rate. No significant differences were seen in ventilator time, postoperative length of stay, fractional increase of postoperative serum creatinine over preoperative serum creatinine, and postoperative lactate. CONCLUSIONS: A simplified method of direct splanchnic perfusion during neonatal aortic arch reconstruction avoids the use of deep hypothermia and provides renal protection at least as effective as deep hypothermia.

Acetaminophen attenuates lipid peroxidation in children undergoing cardiopulmonary bypass.

OBJECTIVE: Hemolysis, occurring during cardiopulmonary bypass, is associated with lipid peroxidation and postoperative acute kidney injury. Acetaminophen inhibits lipid peroxidation catalyzed by hemeproteins and in an animal model attenuated rhabdomyolysis-induced acute kidney injury. This pilot study tests the hypothesis that acetaminophen attenuates lipid peroxidation in children undergoing cardiopulmonary bypass. DESIGN: Single-center prospective randomized double-blinded study. SETTING: University-affiliated pediatric hospital. PATIENTS: Thirty children undergoing elective surgical correction of a congenital heart defect. INTERVENTIONS: Patients were randomized to acetaminophen (OFIRMEV [acetaminophen] injection; Cadence Pharmaceuticals, San Diego, CA) or placebo every 6 hours for four doses starting before the onset of cardiopulmonary bypass. MEASUREMENT AND MAIN RESULTS: Markers of hemolysis, lipid peroxidation (isofurans and F2-isoprostanes), and acute kidney injury were measured throughout the perioperative period. Cardiopulmonary bypass was associated with a significant increase in free hemoglobin (from a prebypass level of 9.8 ± 6.2 mg/dL to a peak of 201.5 ± 42.6 mg/dL postbypass). Plasma and urine isofuran and F2-isoprostane concentrations increased significantly during surgery. The magnitude of increase in plasma isofurans was greater than the magnitude in increase in plasma F2-isoprostanes. Acetaminophen attenuated the increase in plasma isofurans compared with placebo (p = 0.02 for effect of study drug). There was no significant effect of acetaminophen on plasma F2-isoprostanes or urinary makers of lipid peroxidation. Acetaminophen did not affect postoperative creatinine, urinary neutrophil gelatinase-associated lipocalin, or prevalence of acute kidney injury. CONCLUSION: Cardiopulmonary bypass in children is associated with hemolysis and lipid peroxidation. Acetaminophen attenuated the increase in plasma isofuran concentrations. Future studies are needed to establish whether other therapies that attenuate or prevent the effects of free hemoglobin result in more effective inhibition of lipid peroxidation in patients undergoing cardiopulmonary bypass.

Standardized postoperative handover process improves outcomes in the intensive care unit: a model for operational sustainability and improved team performance*.

OBJECTIVE: To determine whether structured handover tool from operating room to pediatric cardiac intensive care unit following cardiac surgery is associated with a reduction in the loss of information transfer and an improvement in the quality of communication exchange. In addition, whether this tool is associated with a decrease in postoperative complications and an improvement in patient outcomes in the first 24 hrs of pediatric cardiac intensive care unit stay. DESIGN: Prospective observational clinical study. SETTING: Pediatric cardiac intensive care unit of an academic medical center. PATIENTS: Pediatric cardiac surgery patients over a 3-yr period. Evaluation of communication and patients studied for two time periods: verbal handover (July 2007-June 2009) and structured handover (July 2009-June 2010). INTERVENTIONS: None. MEASUREMENTS AND MAIN RESULTS: Two anonymous surveys administered to the entire clinical team of the pediatric cardiac intensive care unit evaluated loss of information transfer for each of the two handover processes. Quality of structured handover tool was evaluated by Likert scale responses in the second survey. Patient complications including cardiopulmonary resuscitation, mediastinal reexploration, placement on extracorporeal membrane oxygenation, development of severe metabolic acidosis, and number of early extubations in the first 24-hr pediatric cardiac intensive care unit stay were compared for the two time periods. Survey results showed the general opinion that the structured handover tool was of excellent quality to enhance communication (Likert scale: 4.4 ± 0.7). In addition, the tool was associated with a significant reduction (p < .001) in loss of information for every category of patient clinical care including patient, preoperative, anesthesia, operative, and postoperative details and laboratory values. Patient data revealed significant decrease (p < .05) for three of the four major complications studied and a significant increase (p < .04) in the number of early extubations following introduction of our standardized handover tool. CONCLUSIONS: In this setting, a standardized handover tool is associated with a decrease in the loss of patient information, an improvement in the quality of communication during postoperative transfer, a decrease in postoperative complications, and an improvement in 24-hr patient outcomes.

Angiotensin-converting enzyme inhibition alters the inflammatory and fibrinolytic response to cardiopulmonary bypass in children.

OBJECTIVE: Many children with a congenital heart defect undergo surgical correction requiring cardiopulmonary bypass. One-sixth of these patients take an angiotensin-converting enzyme inhibitor for heart failure treatment. The effect of angiotensin-converting enzyme inhibition on the fibrinolytic and inflammatory response in children undergoing cardiopulmonary bypass is unknown. In adults, angiotensin-converting enzyme inhibition attenuates the increase in plasminogen activator inhibitor-1 after cardiopulmonary bypass, whereas the effect on the interleukin-6 response is uncertain. This study tests the hypothesis that preoperative angiotensin-converting enzyme inhibition attenuates postoperative plasminogen activator inhibitor-1 and interleukin-6 expression after cardiopulmonary bypass in children. DESIGN: Single-center prospective, randomized, nonblinded study. SETTING: University-affiliated pediatric hospital. PATIENTS: Children undergoing elective surgical correction of a congenital heart defect requiring cardiopulmonary bypass and taking an angiotensin-converting enzyme inhibitor. INTERVENTIONS: Children were randomized to continue angiotensin-converting enzyme inhibitor until the morning of surgery (angiotensin-converting enzyme inhibitor group, n = 11) or to discontinue therapy 72 hrs before surgery (no angiotensin-converting enzyme inhibitor group, n = 9). MEASUREMENT AND MAIN RESULTS: Blood samples were collected at baseline before cardiopulmonary bypass, at 30 mins of cardiopulmonary bypass, on arrival to the intensive care unit, and on postoperative day 1. Baseline bradykinin concentrations were significantly higher and angiotensin-converting enzyme activity significantly lower in the angiotensin-converting enzyme inhibitor group compared with the no angiotensin-converting enzyme inhibitor group (p = .04 and .001, respectively). Plasminogen activator inhibitor-1 antigen increased 15-fold after cardiopulmonary bypass and peaked on postoperative day 1 (from 4.6 ± 1.2 to 67.7 ± 9.5 ng/mL; p < .001). Postoperative day 1 plasminogen activator inhibitor-1 antigen correlated significantly with cardiopulmonary bypass time (r2 = 0.40, p = .03) and was significantly lower in the angiotensin-converting enzyme inhibitor group compared with the no angiotensin-converting enzyme inhibitor group (p = .03). The proinflammatory markers interleukin-6 and interleukin-8 as well as the anti-inflammatory marker interleukin-10 increased significantly after cardiopulmonary bypass (all p < .001). Interleukin-6 concentrations were significantly higher in the angiotensin-converting enzyme inhibitor group after cardiopulmonary bypass (p = .02) even after controlling for potential confounding factors such as age, cardiopulmonary bypass time, and transfusion volume. CONCLUSION: Angiotensin-converting enzyme inhibition attenuates the increase in postoperative plasminogen activator inhibitor-1 but enhances the interleukin-6 response in children undergoing cardiopulmonary bypass.

Congenitally corrected transposition of the great arteries: a unique case from Iraq.

A severely cyanotic 27-month-old Iraqi child was transferred to the United States for surgical treatment of suspected tetralogy of Fallot. Her diagnostic studies showed dextrocardia, congenitally corrected transposition of the great arteries, hypoplastic left-sided ventricle, interrupted inferior vena cava, and severe pulmonic stenosis. Given the anatomic constraints as well as the absence of long-term medical care, the decision was made to pursue single-ventricle palliation. The patient recovered from a superior cavopulmonary anastomosis without event and has since returned to her native Iraq.

Right-sided pulmonary venous obstruction between a right aortic arch and an amplatzer septal occlusion device following closure of a secundum atrial septal defect.

Right-sided pulmonary venous obstruction between a right aortic arch and an Amplatzer Septal Occluder device developed following closure of a large secundum atrial septal defect. The obstruction was not apparent on postprocedure transesophageal echocardiogram but developed over time. The patient recovered completely following surgical removal of the device.

Pharmacokinetics and safety of intravenously administered citrulline in children undergoing congenital heart surgery: potential therapy for postoperative pulmonary hypertension.

OBJECTIVE: Pulmonary hypertension may complicate surgical correction of congenital heart defects, resulting in increased morbidity and mortality. We have previously shown that plasma levels of the nitric oxide precursors citrulline and arginine drop precipitously after congenital cardiac surgery and that oral citrulline supplementation may be protective against the development of pulmonary hypertension. In this study, we assessed the safety and pharmacokinetic profile of intravenous citrulline as a potential therapy for postoperative pulmonary hypertension. METHODS: The initial phase of this investigation was a dose-escalation study of intravenously administered citrulline in infants and children undergoing one of five congenital cardiac surgical procedures (phase 1). The primary safety outcome was a 20% drop in mean arterial blood pressure from the baseline pressure recorded after admission to the intensive care unit. Based on our previous work, the target circulating plasma citrulline trough was 80 to 100 micromol/L. Each patient was given two separate doses of citrulline: the first in the operating room immediately after initiation of cardiopulmonary bypass and the second 4 hours later in the pediatric intensive care unit. Stepwise dose escalations included 50 mg/kg, 100 mg/kg, and 150 mg/kg. After model-dependent pharmacokinetic analysis, we enrolled an additional 9 patients (phase 2) in an optimized dosing protocol that replaced the postoperative dose with a continuous infusion of citrulline at 9 mg/(kg.h) for 48 hours postoperatively. RESULTS: The initial stepwise escalation protocol (phase 1) revealed that an intravenous citrulline dose of 150 mg/kg given after initiation of cardiopulmonary bypass yielded a trough level of in the target range of approximately 80 to 100 micromol/L 4 hours later. The postoperative dose revealed that the clearance of intravenously administered citrulline was 0.6 L/(h.kg), with a volume of distribution of 0.9 L/kg and estimated half-life of 60 minutes. Because of the short half-life, we altered the protocol to replace the postoperative dose with a continuous infusion of 9 mg/(kg.h). An additional 9 patients were studied with this continuous infusion protocol (phase 2). Mean plasma citrulline levels were maintained at approximately 125 mumol/L, with a calculated clearance of 0.52 L/(h.kg). None of the 17 patients studied had a 20% drop in mean arterial blood pressure from baseline. CONCLUSIONS: In this first report of the use of intravenous citrulline in humans, we found citrulline to be both safe and well tolerated in infants and young children undergoing congenital cardiac surgery. Because of the rapid clearance, the optimal dosing regimen was identified as an initial bolus of 150 mg/kg given at the initiation of cardiopulmonary bypass, followed 4 hours later by a postoperative infusion of 9 mg/(kg.h) continued up to 48 hours. Using this regimen, plasma arginine, citrulline, and nitric oxide metabolite levels were well maintained. Intravenous citrulline needs to be studied further as a potential therapy for postoperative pulmonary hypertension.

Recombinant factor seven therapy for postoperative bleeding in neonatal and pediatric cardiac surgery.

BACKGROUND: Severe bleeding is a major complication in the postoperative pediatric cardiac surgery patients. We evaluated the efficacy and safety of recombinant factor seven (rFVIIa) therapy in this patient population. METHODS: A retrospective unmatched case-control study for the previous five years in a single institution was undertaken. Patients with severe bleeding treated with rFVIIa therapy (study group) were compared with patients treated with blood products only (control group) using analysis of variance. Mediastinal bleeding, blood products transfusion, and coagulation studies before and six hours after the first dose of rFVIIa therapy were analyzed using the Student paired t test. The dose, frequency, and side-effects of rFVIIa therapy were studied. RESULTS: Forty-six patients with severe bleeding were studied. Twenty-three of 24 patients in the study group, including 12 patients placed on extracorporeal membrane oxygenation (ECMO), responded to rFVIIa therapy (mean dose 43 +/- 22.9 microg/kg/dose). There was significant reduction in chest tube drainage (from 52.3 +/- 36.1 mL/kg/hour to 18.8 +/- 20.9 mL/kg/hour, p = 0.0003) along with significant reduction of blood products transfusion (p < 0.001) in the study group patients as compared with control group patients. One patient who failed to respond had surgical bleeding. Two patients developed major thrombotic complications that included clots in the ECMO circuit and thrombosis at bleeding arterial line site resulting in limb ischemia. Four additional patients in the study group developed mediastinal clots. Overall, 25% of patients developed thrombosis after rFVIIa therapy. CONCLUSIONS: The rFVIIa therapy seems to be an effective treatment for severe bleeding in postoperative pediatric cardiac surgery patients in the absence of surgical bleeding. It must be judiciously used in patients bleeding from multiple sites or having preexistent clots in the ECMO circuit to prevent major thrombotic complications.

Genetic variation in the mitochondrial enzyme carbamyl-phosphate synthetase I predisposes children to increased pulmonary artery pressure following surgical repair of congenital heart defects: a validated genetic association study.

Increased pulmonary artery pressure (PAP) can complicate the postoperative care of children undergoing surgical repair of congenital heart defects. Endogenous NO regulates PAP and is derived from arginine supplied by the urea cycle. The rate-limiting step in the urea cycle is catalyzed by a mitochondrial enzyme, carbamoyl-phosphate synthetase I (CPSI). A well-characterized polymorphism in the gene encoding CPSI (T1405N) has previously been implicated in neonatal pulmonary hypertension. A consecutive modeling cohort of children (N=131) with congenital heart defects requiring surgery was prospectively evaluated to determine key factors associated with increased postoperative PAP, defined as a mean PAP>20 mmHg for at least 1h during the 48h following surgery measured by an indwelling pulmonary artery catheter. Multiple dimensionality reduction (MDR) was used to both internally validate observations and develop optimal two-variable through five-variable models that were tested prospectively in a validation cohort (N=41). Unconditional logistic regression analysis of the modeling cohort revealed that age (OR=0.92, p=0.01), CPSI T1405N genotype (AC vs. AA: OR=4.08, p=0.04, CC vs. AA: OR=5.96, p=0.01), and Down syndrome (OR=5.25, p=0.04) were independent predictors of this complex phenotype. MDR predicted that the best two-variable model consisted of age and CPSI T1405N genotype (p<0.001). This two-variable model correctly predicted 73% of the outcomes from the validation cohort. A five-variable model that added race, gender and Down's syndrome was not significantly better than the two-variable model. In conclusion, the CPSI T1405N genotype appears to be an important new factor in predicting susceptibility to increased PAP following surgical repair of congenital cardiac defects in children.

Rapid diagnosis of cannula migration by cerebral oximetry in neonatal arch repair.

Although it has gained much interest in other surgical specialties, the application of near-infrared spectroscopy to assess cerebral perfusion during cardiac surgery is relatively new. Regional cerebral oxygen saturation (rSO2) is a function of cerebral oxygen supply and demand. Continuous monitoring of the rSO2 permits early detection of cerebral ischemia allowing for prompt intervention. The following is a description of a repair of truncus arteriosus with type A interrupted aortic arch during which continuous cerebral oximetry assisted with the positioning of the arterial cannula avoiding a prolonged episode of cerebral ischemia.

Nitric oxide precursors and congenital heart surgery: a randomized controlled trial of oral citrulline.

OBJECTIVE: The study sought to determine whether citrulline supplementation, a precursor to nitric oxide synthesis, is safe and efficacious in increasing plasma citrulline concentrations and decreasing the risk of postoperative pulmonary hypertension. STUDY DESIGN: Forty children, undergoing cardiopulmonary bypass and at risk for pulmonary hypertension, were randomized to receive 5 perioperative doses (1.9 g/m2 per dose) of either oral citrulline or placebo. Plasma citrulline and arginine concentrations were measured at 5 time points. Measurements of systemic blood pressure and presence of pulmonary hypertension were collected. RESULTS: Median citrulline concentrations were significantly higher in the citrulline group versus the placebo group immediately postoperatively (36 micromol/L vs 26 micromol/L, P = .012) and at 12 hours postoperatively (37 micromol/L vs 20 micromol/L, P = .015). Mean plasma arginine concentrations were significantly higher in the citrulline group versus the placebo group by 12 hours postoperatively (36 micromol/L vs 23 micromol/L, P = .037). Mean systemic blood pressure did not differ between groups (P = .53). Postoperative pulmonary hypertension developed in 9 patients, 6 of 20 (30%) in the placebo group and 3 of 20 (15%) in the citrulline group (P = .451), all of whom had plasma citrulline concentrations less than age-specific norms. Postoperative pulmonary hypertension did not develop in patients who demonstrated plasma citrulline concentrations in excess of 37 mumol/L (P = .036). CONCLUSIONS: Oral citrulline supplementation safely increased plasma citrulline and arginine concentrations compared with placebo after cardiopulmonary bypass. Postoperative pulmonary hypertension did not occur in children with naturally elevated citrulline levels or elevations through supplementation. Oral citrulline supplementation may be effective in reducing postoperative pulmonary hypertension.

Plastic bronchitis: is thoracic duct ligation a real surgical option?

Plastic bronchitis is an unusual clinical scenario of unknown cause and occurs in multiple clinical settings. The disease is characterized by the development of arborizing, thick, tenacious casts of the tracheobronchial tree that results in airway obstruction. Patients with congenital heart disease who have undergone a Fontan operation are at high risk for having this problem develop. Management of this distressing situation is difficult with only palliative options being available, such as repeated bronchoscopies, inhaled heparin, tissue plasminogen activator, inhaled bronchodilators, or azithromycin. The patients with Fontan circuits have a myriad of unique complications develop, such as atrial arrhythmias, recurrent pleural effusions, chylothoraces, protein-losing enteropathy, and plastic bronchitis. High intrathoracic lymphatic pressures with nondemonstrable lympho-bronchial fistulas were believed to be the cause for the development of these recurrent bronchial casts in plastic bronchitis. Faced with recurrent plastic bronchitis resistant to medical management in 2 Fontan patients with normal Fontan pressures on cardiac catheterization, we decided to explore a surgical solution by performing a thoracic duct ligation. This resulted in complete resolution of the formation of casts in both patients, who were discharged home and remain asymptomatic on continued follow-up. Thoracic duct ligation provides a surgical cure for plastic bronchitis by decreasing intrathoracic lymphatic pressure and flow.

Inhaled nitric oxide use in bidirectional Glenn anastomosis for elevated Glenn pressures.

BACKGROUND: Children frequently undergo bidirectional Glenn anastomosis in the staged surgical management of single ventricle physiology. The purpose of our study was to investigate the role of inhaled nitric oxide therapy in children with marked elevations in Glenn pressures after this surgery. METHODS: A retrospective study over a 30-month period was performed. The effect of inhaled nitric oxide therapy was analyzed in children with marked elevations of Glenn pressures resulting in decreased systemic perfusion. Effects on Glenn pressures, respiratory indices, and systemic perfusion were evaluated after initiation of nitric oxide therapy and compared with baseline parameters. RESULTS: Sixteen patients were placed on nitric oxide therapy for marked elevations of Glenn pressures (22.4 +/- 3.9 mm Hg). In the 11 responsive patients, there were significant reductions in Glenn pressures (from 22.4 mm Hg to 17.1 mm Hg, p < 0.001) and significant improvement in partial pressure of oxygen to fraction of inspired oxygen ratio (from 49 to 74.3, p = 0.001) and oxygenation index (from 17 to 12, p = 0.005). There was simultaneous significant reduction in inotrope score (from 14.9 to 11.4, p < 0.001) and fluid volume support (from 11.4 mL/kg to 2.3 mL/kg, p < 0.001) in the responsive patients. Five patients that failed to show any response were found, subsequently, to have an anatomic lesion. CONCLUSIONS: Inhaled nitric oxide produces significant reduction in Glenn pressures and improvement in systemic perfusion and pulmonary gas exchange in patients with marked elevations of Glenn pressures after bidirectional Glenn anastomosis. Patients who fail to respond should be investigated for an anatomic lesion.

Clinical outcomes of 84 children with congenital heart disease managed with extracorporeal membrane oxygenation after cardiac surgery.

The purpose of our research was to study the clinical outcomes of children with congenital heart disease (CHD) requiring extracorporeal membrane oxygenation (ECMO) support after cardiac surgery at a tertiary care children's hospital. Retrospective review of all patients with CHD who required postcardiotomy ECMO between January 2001 and September 2004 (45 months) was undertaken. Various outcome predictors were tested for any association with survival to hospital discharge using univariate analysis. A total of 84 children were placed on ECMO after CHD surgery; 39 (46.4%) were placed on ECMO in the operating room. Median age of the patients was 128 days (1 day to 5 years) and median weight was 4.53 kg (2-18 kg). Active cardiopulmonary resuscitation was ongoing at the time of cannulation in 27 children (32%). Fifty-two children (61.9) survived > 24 hours after decannulation and 31 (36.9%) survived to discharge. High arterial serum lactate levels at the time of ECMO initiation were strongly correlated with nonsurvival (p = 0.004). Nonsurvivors had longer duration on ECMO than survivors (p = 0.003). The odds of survival dropped significantly after 144 hours (day 6) of ECMO. ECMO support results in improved outcomes in patients who suffered hemodynamic collapse post cardiac surgery. Underlying cardiac lesion, age, weight, gender, initial arterial pH, location of ECMO initiation, need for hemofiltration and placement of ECMO after active ongoing cardiopulmonary resuscitation did not increase the mortality risk. Initial arterial serum lactate level and inability to wean off by 6 days were strongly correlated with nonsurvival.

Specificity and sensitivity of automated external defibrillator rhythm analysis in infants and children.

STUDY OBJECTIVES: The rhythm detection algorithms of automated external defibrillators have been derived from adult rhythms, and their ability to discriminate between shockable and nonshockable rhythms in children is largely unknown. This study evaluates the performance of 1 automated external defibrillator algorithm in infants and children and evaluates algorithm performance with anterior-posterior versus sternal-apex lead placement. METHODS: We enrolled pediatric patients in a critical care unit, an electrophysiology laboratory, and a cardiac operating room. A monitor-defibrillator recorded ECGs by means of standard defibrillation-monitor pads. Selected 15-second rhythm samples were played into a LIFEPAK 500 automated external defibrillator, and the automated external defibrillator "shock/no shock" decision was documented. To determine sensitivity and specificity, the automated external defibrillator decision was compared with the "shockable" versus "nonshockable" rhythm classification provided by 3 expert clinicians who were blinded to the automated external defibrillator decision. RESULTS: We recorded 1,561 rhythm samples from 203 pediatric patients (median age 11 months; range, day of birth to 7 years). The automated external defibrillator recommended a shock for 72 of 73 rhythm samples classified as coarse ventricular fibrillation by expert review (sensitivity 99%; 95% confidence interval [CI] 93% to 100%); and correctly reached a "no shock advised" decision for 1,465 of 1,472 rhythm samples classified as nonshockable by experts (specificity 99.5%). Specificity was 99.1% (95% CI 97.8% to 99.8%) with the sternal-apex lead and 99.4% (95% CI 98.1% to 99.9%) with the anterior-posterior lead. CONCLUSION: This automated external defibrillator algorithm has high specificity and sensitivity when used in infants and children with either sternal-apex or anterior-posterior lead placement.

A modified bronchial anastomosis technique for lung transplantation.

BACKGROUND: Low rates of major complications have been reported for the intussuscepting bronchial anastomotic technique but stenosis, malacia, and granulation tissue at the anastomosis may cause clinically important morbidity. We hypothesized that a modification of the telescoping technique that improves bronchial wall apposition might be associated with improved bronchial healing and clinical outcomes. METHODS: The telescoping horizontal mattress "U-stitch" suture technique was modified to incorporate figure-of-eight sutures placed in the cartilaginous wall between each of three intussuscepting U stitches. Serial videotape records of 152 individual anastomoses (99 modified, 53 telescoped) in 118 consecutive operative survivors were retrospectively reviewed by examiners blinded with respect to technique used. Stenosis, airway instability, mucosa quality, and devascularized luminal tissue were graded at 4 to 14 days (initial), 4 to 12 weeks (early), and 6 to 12 months (late) after transplantation. RESULTS: The incidence of anastomotic stenosis was significantly lower using the modified technique at the initial (p = 0.025) and late (p = 0.015) observations. In the initial phase airway instability (p = 0.015) and devascularization grades (p = 0.001) were also significant lower in the modified group. There were no significant differences in mucosal condition between techniques. The modified telescoping technique was associated with significant survival advantage (mean 17.7%; p = 0.029) by multivariate analysis. The incidence of major airway complications (dehiscences and stenoses required stents) tended to be lower (3% versus 6%) in the modified group. CONCLUSIONS: The modified telescoping bronchial anastomosis technique is associated with improved early and late bronchial healing and higher 5-year survival without increased major airway complications.

Effect of cardiopulmonary bypass on urea cycle intermediates and nitric oxide levels after congenital heart surgery.

OBJECTIVE: To test the hypothesis that cardiopulmonary bypass used for repair of ventricular septal defects and atrioventricular septal defects would decrease availability of urea cycle intermediates including arginine and subsequent nitric oxide availability. STUDY DESIGN: Consecutive infants (n = 26) undergoing cardiopulmonary bypass for repair of an unrestrictive ventricular septal defect or atrioventricular septal defect were studied. Blood samples were collected immediately before surgery, immediately after surgery, and 12 hours, 24 hours, and 48 hours after surgery. Urea cycle intermediates, including citrulline, arginine, and ornithine, were measured by amino acid analysis. Nitric oxide metabolites were measured by means of the modified Griess reaction. RESULTS: Cardiopulmonary bypass caused a significant decrease in the urea cycle intermediates arginine, citrulline, and ornithine at all postoperative time points compared with preoperative levels. The ratio of ornithine to citrulline, a marker of urea cycle function, was elevated at all postoperative time points compared with preoperative values, indicating decreased urea cycle function. Nitric oxide metabolites were significantly decreased at all postoperative time points except for 48 hours, compared with preoperative levels. CONCLUSIONS: Cardiopulmonary bypass significantly decreases availability of arginine, citrulline, and nitric oxide metabolites in the postoperative period. Decreased availability of nitric oxide precursors may contribute to the increased risk of postoperative pulmonary hypertension.