Faculty Bibliography

OBJECTIVE: To determine the incidence of vasodilatory shock (VDS) in children after cardiopulmonary bypass (CPB), and to describe this syndrome of post-CPB VDS in children. DESIGN: Prospective, observational. SETTING: Pediatric and neonatal intensive care units in a tertiary care, children's hospital. PATIENTS: Three hundred children undergoing CPB. INTERVENTION: None. MEASUREMENTS AND MAIN RESULTS: Three hundred subjects undergoing CPB were evaluated for clinical evidence of VDS following CPB. The incidence of post-CPB VDS was 3%. Characteristics of children who developed VDS: higher peak lactate (6.2 +/- 2.6 vs. 3.0 +/- 2.1 mmol/L; p = 0.0002), higher peak serum blood urea nitrogen (18.5 +/- 4.6 vs. 15.6 +/- 7.2 mg/dL; p = 0.04), lower urine output (1.7 +/- 0.8 vs. 2.6 +/- 0.2 mL/kg/hr; p = 0.04), and fewer intensive care unit free days (14.9 +/- 9.0 vs. 21.1 +/- 7.2 days; p = 0.01). Univariate predictors for the development of post-CPB VDS included children who had heart transplantation (HT) (relative risk [RR], 9.8; 95% confidence interval [CI], 2.7-35.2) or ventricular assist device (VAD) placed (RR, 17.9; 95% CI, 3.8-84.1), a cardiomyopathy diagnosis (RR, 8.5; 95% CI, 2.3-31), age >12 years (RR, 4.5; 95% CI, 1.2-17.0), CPB time >180 minutes (RR, 7.1; 95% CI, 1.9-26.2), and preoperative ventricular dysfunction (RR, 3.7; 95% CI, 1.0-13.4). By stratified analysis, the only independent predictor for the development of VDS was undergoing HT/VAD. CONCLUSIONS: Post-CPB VDS is uncommon in children. However, children who undergo HT or VAD placement are at high risk for developing post-CPB VDS. Recognition that the overall incidence of post-CPB is low-except in the HT/VAD population-may help guide therapy in the pediatric post-CPB patient

OBJECTIVE: Substantial controversy persists regarding the need and efficacy of a routine myectomy in the treatment of discrete subaortic stenosis. Although some believe myectomy more effectively relieves subaortic narrowing, this is uncertain, and complications, including heart block and aortic valve injury, are concerns. The aims of the study were as follows: (1) to analyze the role of enucleation for relief of subaortic stenosis and the risk factors associated with recurrence and reoperation and (2) to delineate the characteristics of the patients who might benefit from enucleation alone. METHODS: From January 1990 through May 2007, 221 patients with subaortic stenosis underwent biventricular repair. Of those, 106 patients had discrete subaortic stenosis. The preoperative peak left ventricular outflow tract gradient, as determined by means of transthoracic echocardiographic analysis, was 67.3 +/- 29 mm Hg. Forty patients had previous operations for other intracardiac anomalies. Mean age at repair was 7 years. Sixty-one patients underwent isolated enucleation, and 45 patients underwent concomitant myectomy. Patients with recurrent subaortic stenosis whose first operation was performed elsewhere were excluded from analysis. RESULTS: There was 1 early death and 1 late death. The postoperative peak left ventricular outflow gradient decreased to 12.5 +/- 12.9 mm Hg (P < .001). No patient had development of heart block or required a pacemaker. A recurrent gradient of greater than 30 mm Hg was found in 26 (27%) patients, and 8 (7.5%) patients had reoperations. Actuarial freedom from reoperation rates at 5, 10, and 15 years were 94.7% +/- 1.8%, 89.6% +/- 3.5%, and 84.8% +/- 4.9%, respectively.Of those patients who had not undergone a previous cardiac operation, there were no significant differences in the rates of recurrence (28% vs 27%) or reoperation (4.7% vs 4.4%) between the enucleation group and the concomitant myectomy group. For the patients who had a previous cardiac operation, the concomitant myectomy group had a significantly lower rate of recurrence (44% for enucleation vs 13% for enucleation plus myectomy, P = .031). CONCLUSIONS: For those patients undergoing primary operations for discrete subaortic stenosis, routine myectomy does not offer superior relief of left ventricular outflow tract obstruction; enucleation alone provides good results in this selected population. However, in those patients with associated cardiac anomalies, concomitant additional myectomy is recommended

BACKGROUND: Tetralogy of Fallot (TOF) typically results in clinical cyanosis or volume overload of the left ventricle (LV), depending on the direction and magnitude of shunting across the ventricular septal defect (VSD). The present study examines the effects of surgical TOF repair on LV mechanics and compares these changes between patients with VSD shunts that are predominantly right-to-left (R-L; 'blue TOF') and those with VSD shunts that are predominantly left-to-right (L-R; 'pink TOF'). METHODS AND RESULTS: Eleven patients (6 R-L and 5 L-R) 4.3 to 18.4 months old (median 7.1 months old) were studied. LV end-diastolic area (EDA) was calculated from transesophageal echocardiograms obtained during initiation and weaning of cardiopulmonary bypass. LV end-diastolic pressure was measured by micromanometer. Compliance was assessed by end-diastolic pressure-area curves. Contractility was assessed from preload recruitable stroke work by the stroke work-versus-LV EDA relation. VSD shunt direction was determined by preoperative Doppler echocardiography. Changes in LV function at the conclusion of cardiopulmonary bypass included decreased stroke area (from 6.6 +/- 0.9 to 4.1 +/- 0.4 cm(2)/m(2), P=0.012) and ejection fraction (from 55 +/- 2% to 41 +/- 3%, P<0.001). LV EDA at a common pressure in 8 patients decreased (from 10.4 +/- 1.4 to 7.6 +/- 1.2 cm(2)/m(2), P=0.003), which suggests a decrease in ventricular compliance. Additionally, the end-diastolic pressure-area curves shifted to the left in all patients. Preload recruitable stroke work decreased (from 34.8 +/- 2.4 to 21.8 +/- 2.6 mm Hg, P=0.007), which demonstrates a decrease in ventricular contractility. When separated by preoperative shunt direction, LV EDA increased in R-L patients by 0.9+/-0.5 cm(2)/m(2) postoperatively but decreased in L-R patients by 4.3 +/- 0.8 cm(2)/m(2) (P<0.001). Area ejection fraction decreased in all patients independent of shunting or change in LV EDA. CONCLUSIONS: LV diastolic and systolic function are depressed after TOF repair. Mechanical effects of the VSD patch and myocardial depressant effects of ischemia and reperfusion during surgery probably contribute to the observed changes in LV mechanics. Different effects of surgical repair on LV preload in pink and blue TOF also contribute to the spectrum of clinical results observed after surgery

BACKGROUND: The right ventricle (RV) has a lower ability than the left ventricle (LV) to adapt to systemic load. The molecular basis of these differences is not known. We compared hypertrophy-signaling pathways between the RV and the LV in patients with congenital heart disease (CHD). METHODS: Gene expression was measured using DNA microarrays in myocardium from children with CHD with LV or RV obstructive lesions undergoing surgery. The expression of 175 hypertrophy-signaling genes was compared between the LV (n=7) and the RV (n=11). Hierarchic clustering was performed. RESULTS: Seventeen genes (10%) were differentially expressed between the LV and the RV. Expression of genes for angiotensin, adrenergic, G-proteins, cytoskeletal, and contractile components was lower (P < .05) and expression of maladaptive factors (fibroblast growth factors, transforming growth factor-beta, caspases, ubiquitin) was higher in the RV compared with the LV (P < .05). Five of 7 LV samples clustered together. Only 4 of 11 RV samples clustered with the LV. Genes critical to adaptive remodeling correlated with the degree of LV hypertrophy but not RV hypertrophy. CONCLUSION: The transcription of pathways of adaptive remodeling was lower in the RV compared with the LV. This may explain the lower ability of the RV to adapt to hemodynamic load in CHD

BACKGROUND: The combination of transposition of the great arteries and coarctation of the aorta (TGA/CoA) presents a surgical challenge. We have adopted a concurrent aortic arch repair and arterial switch operation with excellent results. These patients tend to have a small aortic (ie, neopulmonary) annulus. This study evaluates the significance of right-sided obstruction after single-stage repair of TGA/CoA. METHODS: Between May 1991 and May 2006, 53 patients with TGA/CoA or Taussig-Bing/CoA (n = 20; 38%) underwent a complete single-stage repair. Surgical technique involved the arterial switch operation and ventricular septal defect closure when present in 51 patients (96%). The aortic arch was enlarged in 36 patients (75%) with patch augmentation. Two patients (4%) underwent the augmentation of the right ventricular outflow tract (RVOT) at the first operation. RESULTS: There was one hospital death (operative mortality, 1.9%) and one late death. The difference between the preoperative aortic and pulmonary annulus was significant (6.7 vs 10.4 mm, p < 0.001). The peak pressure gradient across the proximal RVOT at discharge was 16 +/- 16 mm Hg (range, 0 to 62 mm Hg). There have been six reoperations (11%) and four catheter interventions (7.5%) for right-sided obstruction. Freedom from reintervention/reoperation for right-sided obstruction at 1, 5, and 10 years is 95%, 87%, and 80%, respectively. CONCLUSIONS: Neonatal single-stage repair for TGA/CoA achieves excellent survival without transannular patch repair at the first operation. Although some of the patients have pressure gradient across the RVOT, these lesions were amenable to reintervention with minimal morbidity

OBJECTIVES: The use of mechanical circulatory support to bridge pediatric patients to cardiac transplantation presents unique challenges because of the difficult anatomy and physiology in these patients. METHODS: The United Network for Organ Sharing provided deidentifed patient-level data. The study population included 2532 transplantations performed on patients less than 19 years old in status 1/1A/1B between 1995 and 2005. Mechanical circulatory support was used in 431 patients: 241 (9.5%) received ventricular assist devices, 171 (6.8%) underwent extracorporeal membrane oxygenation, and 19 (0.8%) received intra-aortic balloon pumps. RESULTS: Patients supported on ventricular assist devices had similar levels of hospitalization and intensive care use and less need for inotropic support (P < .0002) than had those not needing support. Five- and 10-year posttransplantation survival was better in patients receiving ventricular assist devices and patients not receiving mechanical circulatory support than in patients receiving extracorporeal membrane oxygenation or intra-aortic balloon pumping (P < .0001). Among mechanically supported patients, patients with a body surface area of less than 0.30 (odds ratio, 1.70; 95% confidence interval, 1.18-2.43) and those requiring extracorporeal membrane oxygenation (odds ratio, 1.65; 95% confidence interval, 1.15-2.35) or intra-aortic balloon pumping (odds ratio, 1.91; 95% confidence interval, 1.02-3.56) had higher long-term mortality. The use of a ventricular assist device at transplantation did not predict higher long-term, posttransplantation mortality. CONCLUSIONS: Pediatric patients requiring a pretransplantation ventricular assist device have long-term survival similar to that of patients not receiving mechanical circulatory support. Early survival among patients undergoing extracorporeal membrane oxygenation and infants is poor, reinforcing the need for improvements in device design and physiologic management of infants and neonates