Thomas L'Ecuyer

Role of plasma B-type natriuretic peptide in screening for hemodynamically significant patent ductus arteriosus in preterm neonates.

BACKGROUND:B-type natriuretic peptide (BNP) is a hormone secreted by the ventricles under hemodynamic stress and congestive failure.OBJECTIVE:The objective of the present study was to evaluate whether BNP can be used as a valid screening test for the presence of a hemodynamically significant patent ductus arteriosus (hsPDA) in the preterm neonate.MATERIALS AND METHODS:This was a prospective blinded study involving preterm neonates with birth weights ≤1500 g and gestational age ≤34 weeks. Each enrolled neonate underwent the initial echocardiogram for a clinical suspicion of patent ductus arteriosus (PDA) and BNP assay within 3 hours of each other. Those neonates who did not have a PDA or who were not treated underwent a repeat echo and BNP measurement 48 to 72 hours after the first echo. In patients who received treatment for a PDA, an echo and BNP were repeated 48 to 72 hours after completion of treatment.RESULTS:A total of 29 newborns with a median birth weight of 870 g (560 to 1325 g) and a median gestation of 26 weeks (24 to 31 weeks) were enrolled at a median age of 7 days (2 to 28 days). BNP levels were significantly higher in neonates with hsPDA (n=14) compared to those without (n=15) (508.5±618.2 vs 59.5±69.9 pg/ml, p<0.005). At a cutoff value of 70 pg/ml, BNP had a sensitivity of 92.9%, specificity of 73.3%, positive likelihood ratio of 3.5 and negative likelihood ratio of 0.09 for detection of hsPDA. BNP levels dropped significantly after medical or surgical closure of hsPDA (n=12), (404.9±159.2 to 25.1±4.1 pg/ml, p=0.03).CONCLUSIONS:Elevation of plasma BNP accurately detects the presence of hsPDA in premature infants. Successful closure is reflected by a corresponding decrease in BNP. At a cutoff of 70 pg/ml, BNP is a useful screening tool for diagnosis and for monitoring efficacy of treatment of hsPDA.

B-type natriuretic peptide as a marker for cardiac dysfunction in anthracycline-treated children.

Anthracyclines (AC) are useful antineoplastic agents, whose utility is limited by progressive cardiotoxicity. Our purpose was to evaluate plasma B‐type natriuretic peptide (BNP), as a screening test for detecting late cardiac dysfunction in AC‐treated children and to determine the prevalence of late cardiac dysfunction at low cumulative AC doses.

Outcomes of children with restrictive cardiomyopathy listed for heart transplant: a multi-institutional study.

BACKGROUND Restrictive cardiomyopathy (RCM) in children often has a progressive nature, with a high risk of clinical deterioration and death. Heart transplantation (HTx) is a widely accepted therapy that offers long-term survival, but criteria for and outcomes after listing have not been well defined. METHODS A multi-institutional, prospective, event-driven data registry of 3,147 patients aged < 18 years listed for HTx from January 1993 to December 2006 was used to assess risk factors and survival of 145 listed RCM patients. RESULTS Mean age at listing was 8.1 years, with 44% listed as United Network of Organ Sharing status 1, 33% on inotropic support, 10% on a ventilator, and 5% on mechanical support. At 1 year, 82% of these patients survived to HTx, whereas 9% died waiting. Univariate risk factors for death while waiting included younger age (p < 0.001), ventilator dependence (p < 0.001), status 1 (p < 0.001), and inotrope usage (p < 0.001). Use of multiple support devices at listing (ventilator, extracorporeal membrane oxygenation, ventricular assist device, intraaortic balloon pump) was also an important risk factor for early phase death while waiting (relative risk; 9.01, p < 0.0001). Survival after listing was 63% at 10 years and compared favorably with survival for non-cardiomyopathy patients (p = 0.01). CONCLUSIONS Children with RCM awaiting HTx have a generally low waitlist mortality and reasonable overall survival. Children requiring mechanical support and infants had a significantly higher risk of death while waiting. Further study is warranted to identify factors important in determining the optimal timing of listing in children with RCM before the need for inotropic or mechanical support.

Long-term follow-up of extended aortoplasty for supravalvular aortic stenosis

Extended aortoplasty is an operation that was designed to provide a symmetric reconstruction of the aortic root in patients with supravalvular aortic stenosis. The aim of this report is to provide long-term follow-up of the original cohort of 15 patients who underwent extended aortoplasty between 1975 and 1983. Follow-up was obtained in 14 patients. One patient was lost to follow-up 3 years after operation; he was included in this report. An echocardiogram, chest radiograph, and electrocardiogram were obtained for each surviving patient. The median length of follow-up was 141 months (range 36 to 238). The median preoperative gradient was 90 mm Hg (range 55 to 150). The median immediate postoperative gradient was 20 mm Hg (range 0 to 50, p < 0.05 compared with preoperative gradient) and the median long-term gradient was 32 mm Hg (range 6 to 96, p < 0.05 compared with preoperative gradient; p = not significant compared with immediate postoperative gradient). Two patients died: one of left ventricular failure after a subsequent aortic valve replacement and one of chronic left ventricular failure. The Kaplan-Meier estimate of survival at 218 months for all patients was 77.4% (70% confidence limits 62% to 93%). The estimated freedom from reoperation for all patients was 69% at 218 months (70% confidence limits 56% to 82%). Univariate analysis revealed that the presence of a bicuspid valve is a significant risk factor for reoperation (p = 0.038), but not for death (p = 0.51). The Kaplan-Meier estimate of freedom from reoperation for patients with a bicuspid aortic valve was 42.9% at 141 months (70% confidence limits 21% to 65%). Extended aortoplasty provides effective long-term relief of the pressure gradient across the supravalvular ridge. However, a significant number of patients require subsequent operations, particularly those with a bicuspid aortic valve.

Rejection with hemodynamic compromise in the current era of pediatric heart transplantation: a multi-institutional study.

BACKGROUND Survival after pediatric heart transplant has improved over time, as has the incidence of overall rejection. We studied the effect of era on the occurrence and outcome of rejection with hemodynamic compromise (HC). METHODS Data from 2227 patients who received allografts between 1993 and 2006 at 36 centers in the Pediatric Heart Transplant Study were analyzed to determine incidence, outcome, and risk factors for rejection with HC in early (1993-1999) and recent (2000-2006) eras. Rejection with HC was classified as severe (RSHC) when inotropes were used for circulatory support and mild (RMHC) when inotropes were not used. RESULTS Of 1217 patients with any episode of rejection, 541 had rejection with HC. Freedom from RMHC improved at 1 year (81% vs 90%, p < 0.001) and at 5 years (74% vs 85%, p < 0.001) in the early vs recent eras, but freedom from RSHC was similar between eras (93% vs 95% at 1 year and 85% vs 87% at 5 years, p = 0.24). Survival after RSHC (63% at 1 year and 49% at 5 years) was worse than after RMHC (87% at 1 year and 72% at 5 years, p < 0.001) and did not change over time. Risk factors for RSHC were non-white race (hazard ratio [HR], 1.73; 95% confidence interval [CI], 1.29-2.32, p < 0.01), older age (HR, 2.85; 95% CI, 1.24-6.53; p = 0.01), and non-A blood type (HR, 1.51;, 95% CI, 1.11-2.04,; p = 0.01), but the only risk factor for RMHC was earlier era of transplant (HR, 1.94; 95% CI, 1.56-2.41; p < 0.001). CONCLUSIONS The incidence of RMHC has declined over time but the same era effect has not occurred with RSHC. Close follow-up after RSHC is crucial because mortality is so high.

Predictors of cardiac allograft vasculopathy in pediatric heart transplant recipients

CAV remains a leading cause of late graft loss and mortality among survivors of pediatric heart transplantation. We sought to define the incidence of CAV and identify its predictors in pediatric heart transplant recipients. The OPTN/UNOS database was analyzed for pediatric recipients who underwent heart transplant between 1987 and 2011. The primary end‐point is time from heart transplantation to development of CAV (CAV‐free survival). To identify predictors of CAV‐free survival, demographic and transplant data were analyzed by the Kaplan–Meier survival method and Cox proportional hazards regression. Of 5211 pediatric heart transplant recipients with at least one‐yr follow‐up, the incidence of CAV at five, 10, and 15 yr was 13%, 25%, and 54%, respectively. Multivariate analysis found that risk of CAV was associated with the following variables: Recipient age 1–4 yr (HR 1.25), 5–9 yr (1.45), 10–18 yr (1.83), donor age >18 yr (1.34), re‐transplantation (2.14), recipient black race (1.55), and donor cigarette use (1.54). Older recipient and donor age, recipient black race, donor cigarette use, and re‐transplantation were highly associated with shorter CAV‐free survival.

Perioperative renal failure in pediatric heart transplant recipients: Outcome and risk factors

Tang L, Du W, L’Ecuyer TJ. Perioperative renal failure in pediatric heart transplant recipients: Outcome and risk factors.
Pediatr Transplantation 2011: 15: 430–436.

Low donor-to-recipient weight ratio does not negatively impact survival of pediatric heart transplant patients.

Tang L, Du W, Delius RE, L’Ecuyer TJ, Zilberman MV. Low donor‐to‐recipient weight ratio does not negatively impact survival of pediatric heart transplant patients.
Pediatr Transplantation 2010: 14:741–745.

Myocardial Infarction Due to Coronary Abnormalities in Pulmonary Atresia with Intact Ventricular Septum

Abstract. We describe the clinical course, angiography, and histopathology of a newborn male with pulmonary atresia and intact ventricular septum who succumbed to a myocardial infarction. Angiography demonstrated right ventricular-dependent coronary circulation and focal areas of coronary narrowing. His clinical course was characterized by attacks of sudden irritability, consistent with ischemia. Histology demonstrated significant coronary artery narrowing secondary to fibromuscular dysplasia as well as evidence of new and old infarction. This case illustrates the severity of coronary lesions in pulmonary atresia and the potential for progression of coronary obstruction and insufficiency, and it provides correlation between angiography, ischemic symptoms, and pathology.

Assembly of tropomyosin isoforms into the cytoskeleton of avian muscle cells.

Tropomyosin (TM) is a component of microfilaments of most eukaryotic cells. In striated muscle, TM helps confer calcium sensitivity to the actin-myosin interaction. TM is a fibrillar, self-associating protein that binds to the extended actin filament system. We hypothesized that these structural features would permit TM to undergo assembly into the cytoskeleton during translation, or cotranslational assembly. Pulse-chase experiments with[35S]methionine and pulse experiments with [3H]puromycin followed by extraction and immunoprecipitation of TM were performed to examine the mechanism of assembly of TM into the cytoskeleton in cultured avian muscle cells. Pulse-chase experiments provide kinetic evidence for cotranslational assembly of TM in skeletal and cardiac muscle. Demonstration of a large majority of completed TM on purified skeletal muscle microfilaments after a short labeling period confirms that these kinetic data are not related to trapping of TM within the actin network of the cytoskeleton. Nascent TM peptides are demonstrated on the cytoskeleton of muscle cells after a short metabolic pulse followed by puromycin treatment to release nascent peptides from ribosomes or after labeling with [3H]puromycin. Nascent chain localization to the cytoskeleton independent of ribosomal attachment further confirms the high degree of cotranslational assembly of this protein. The extent of cotranslational assembly is similar before and after the formation of significant myofibril in myotubes, suggesting that cotranslational assembly of TM is active during contractile apparatus assembly in muscle differentiation. This is the first report where assembly mechanism has been predicted to be cotranslational based upon structural features of a cytoskeletal protein.