Faculty Bibliography

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

OBJECTIVE: Studies of high-risk pediatric cardiac transplant recipients are lacking. The purpose of this study is to evaluate early posttransplant survival in high-risk pediatric patients. METHODS: The United Network for Organ Sharing (UNOS) provided de-identified patient-level data. The study population included 3502 recipients aged less than 21 years who underwent transplantation from January 1, 1995, through December 31, 2005. Recipients were stratified on the basis of the presence or absence of high-risk criteria: pulmonary vascular resistance index greater than 6 Wood units/m2 (n = 285, 8.1%), creatinine clearance less than 40 mL/min (308, 8.8%), hepatitis C positivity (33, 0.9%), donor/recipient weight ratio less than 0.7 (80, 2.3%), panel reactive antibody greater than 40% (235, 6.7%), retransplantation (235, 6.7%), and age less than 1 year old (840, 24.0%). RESULTS: Overall, 1575 (45.0%) patients met at least one high-risk criterion. Higher numbers of high-risk criteria in a patient were correlated with increased 30-day mortality (0 high-risk criteria: 5.2%; 1 criterion: 7.9%; 2 criteria: 12.9%; and 3 or more criteria: 25.0%; P < .0001) and poor long-term survival (P < .0001). Among patients with high-risk criteria, a simplified scoring scale accurately predicts both 30-day and contingent 1-year mortality (P < .0001). CONCLUSIONS: Individually, the effect of high-risk criteria on posttransplant survival varied; however, increasing numbers of criteria in a patient resulted in a cumulative increase in mortality. A scoring scale allows for the prediction of approximate mortality rates after transplantation. These findings suggest that recipient criteria for transplantation should focus on the number of high-risk criteria as well as clinical status, rather than the presence or absence of a single risk factor

Idiopathic restrictive cardiomyopathy (RCM) is a rare cardiomyopathy in children notable for severe diastolic dysfunction and progressive elevation of pulmonary vascular resistance (PVR). Traditionally, those with pulmonary vascular resistance indices (PVRI) >6 W.U. x m(2) have been precluded from heart transplantation (HTX). The clinical course of all patients transplanted for RCM between 1986 and 2006 were reviewed. Preoperative, intraoperative and postoperative variables were evaluated. A total of 23 patients underwent HTX for RCM, with a mean age of 8.8 +/- 5.6 years and a mean time from listing to HTX of 43 +/- 60 days. Preoperative and postoperative (114 +/- 40 days) PVRI were 5.9 +/- 4.4 and 2.9 +/- 1.5 W.U. x m(2), respectively. At time of most recent follow-up (mean = 5.7 +/- 4.6 years), the mean PVRI was 2.0 +/- 1.0 W.U. x m(2). Increasing preoperative mean pulmonary artery pressure (PA) pressure (p = 0.04) and PVRI > 6 W.U. x m(2) (chi(2)= 7.4, p < 0.01) were associated with the requirement of ECMO postoperatively. Neither PVRI nor mean PA pressure was associated with posttransplant mortality; 30-day and 1-year actuarial survivals were 96% and 86%, respectively. Five of the seven patients with preoperative PVRI > 6 W.U. x m(2) survived the first postoperative year. We report excellent survival for patients undergoing HTX for RCM despite the high proportion of high-risk patients

OBJECTIVE: To determine the efficacy of decreasing cardiopulmonary bypass (CPB) prime volume for neonates and small infants by using low prime oxygenators, small diameter polyvinyl chloride (PVC) tubing and removing the arterial line filter (ALF) in an effort to reduce intraoperative exposure to multiple units of packed red blood cells (PRBC). METHODS: Two retrospective database studies comparing neonatal CPB prime volume were undertaken: Study 1--A CPB circuit consisting of a 1/8 inch arterial line, a 3/16 inch venous line and a low prime oxygenator with 172 ml total circuit prime (n=74) was compared to a circuit with a 3/16 inch arterial line, a 1/4 inch venous line and a higher prime oxygenator with a 350 ml total circuit prime (n=74). Study 2--The 172 ml circuit (n=389) was compared to a circuit that included an ALF and had a total circuit prime volume of 218 ml (n=389). RESULTS: Study 1--of the 74 neonates and small infants whose CPB prime volume was 350 ml, 19 were exposed to two or more intraoperative exogenous PRBC units while only 3 neonates and small infants in the 172 ml prime group (n=74) received two or more units (p = 0.0002). Study 2--of the 389 neonates and small infants where an ALF was used (prime volume 218 ml), 54 were exposed to two or more exogenous PRBC units while only 36 of the 389 patients where an ALF was not used (prime volume 172 ml) received two or more units of intraoperative PRBCs (p = 0.0436). CONCLUSION: Decreasing the neonatal and small infant extracorporeal circuit prime volume by as little as 46 ml resulted in significantly fewer multiple exposures to exogenous PRBC units

BACKGROUND: The bidirectional Glenn cavopulmonary anastomosis (BDG) represents the standard interim procedure in treatment of patients with single-ventricle physiology. Anterograde pulmonary blood flow (APBF) maintained after BDG has been shown both to improve and to complicate postoperative clinical course. We studied its effects on outcome after BDG and eventual Fontan completion. METHODS: From November 1995 to November 2005, 60 patients underwent BDG and Fontan. All patients had APBF from the ventricle to the pulmonary artery at time of BDG. In group 1 (n = 39) APBF was maintained after BDG, whereas APBF was interrupted at BDG in group 2 (n = 21). Cardiac catheterization data, interstage morbidity, and postoperative outcome variables were recorded. RESULTS: Pre-BDG hemodynamics differed only in that the mean pulmonary artery pressure was higher in group 2 (17.0 +/- 4.4 mm Hg) than in group 1 (13.8 +/- 4.5 mm Hg; p = 0.03). There were no differences between groups 1 and 2 in BDG outcome variables. At pre-Fontan catheterization, group 1 had higher mean pulmonary artery pressure (13.3 versus 10.9 mm Hg, p = 0.01), arterial oxygen saturation (85.8 versus 80.9%, p = 0.0001), and fewer collateral vessels were coil embolized than in group 2 (0.9 versus 1.6, p = 0.02). Mean ventricular end-diastolic pressure was similar between groups. The Nakata index in group 1 remained stable from pre-BDG to pre-Fontan (348 versus 391, p = 0.24), but it decreased in group 2 (375 versus 227, p = 0.046). CONCLUSIONS: Patients with anterograde pulmonary blood flow after BDG had a modest increase in pulmonary artery growth and arterial oxygen saturations, and decreased collateral vessel formation. This did not, however, confer additional benefit on outcome after BDG or on eventual Fontan completion