A case of hypoplastic left heart syndrome and bicuspid aortic valve in monochorionic twins.

The etiology of hypoplastic left heart syndrome (HLHS) remains unclear. Since a genetic cause for HLHS has not been obvious, it is generally considered to be inherited in a multifactorial manner. Studies of twins are valuable in elucidating the genetic contribution to a birth defect such as HLHS. We report a case of monochorionic twins in whom one has HLHS and the other has a bicuspid aortic valve. Predisposing genetic and environmental influences on individuals with identical genotypes, such as twins, may result in discordance of left-sided flow lesions.

Airway growth after pediatric lung transplantation.

BACKGROUND: Lung transplantation (LT) has been successfully offered to pediatric patients. Very little is known about the growth of the transplanted lung, especially in the infant population. Computerized tomography (CT) scanning is a simple method for studying pediatric patients who have undergone LT. We evaluated the use of CT scans to assess airway growth after pediatric LT, compare airway diameter indexed to somatic growth between LT patients and normals, and compare the growth of pre-anastomotic and post-anastomotic airways indexed to somatic growth in pediatric LT patients. METHODS: We reviewed CT scans on all pediatric patients who underwent primary LT before their fifteenth birthday between January 1995 and September 1998. Uniform measurements of diameter were made in pre-anastomotic (trachea, and proximal right and left bronchi) and post-anastomotic (distal right and left bronchi) sites. These measurements were then correlated with height and compared to previously published normal values. RESULTS: Of the 16 patients who underwent LT during the study period, 11 had at least 2 sequential CT scans (LT age 3 months to 14 years, median 2 years). Thirty-one CT scans were reviewed. Inter-observer variability was within 1 standard deviation (2 mm) in 93% of the measurements and inter-observer reliability was 0.91 by analysis of variance. Tracheal transverse diameter plotted against body height (slope 0.0072, correlation coefficient 0.88) was virtually identical to previously published norms. A similar relationship between airway diameter and height was observed in pre-anastomotic and post-anastomotic segments. CONCLUSION: CT scanning is a reliable method for assessing airway growth in pediatric LT recipients. Tracheal growth in pediatric LT recipients is similar to that of normal children. Post-anastomotic large airways grow similarly to native, pre-anastomotic airways.

Permanent epicardial pacing in pediatric patients: seventeen years of experience and 1200 outpatient visits.

BACKGROUND: The purpose of this study was to evaluate the long-term outcome of all pediatric epicardial pacing leads. METHODS AND RESULTS: All epicardial leads and 1239 outpatient visits between January 1, 1983, and June 30, 2000, were retrospectively reviewed. Pacing and sensing thresholds were reviewed at implant, at 1 month, and at subsequent 6-month intervals. Lead failure was defined as the need for replacement or abandonment due to pacing or sensing problems, lead fracture, or phrenic/muscle stimulation. A total of 123 patients underwent 207 epicardial lead (60 atrial/147 ventricular, 40% steroid) implantations (median age at implant was 4.1 years [range 1 day to 21 years]). Congenital heart disease was present in 103 (84%) of the patients. Epicardial leads were followed for 29 months (range 1 to 207 months). The 1-, 2-, and 5-year lead survival was 96%, 90%, and 74%, respectively. Compared with conventional epicardial leads, both atrial and ventricular steroid leads had better stimulation thresholds 1 month after implantation; however, only ventricular steroid leads had improved chronic pacing thresholds (at 2 years: for steroid leads, 1.9 muJ [from 0.26 to 16 mu]; for nonsteroid leads, 4.7 muJ [from 0.6 to 25 muJ]; P<0.01). Ventricular sensing was significantly better in steroid leads 1 month after lead implantation (at 2 years: for steroid leads, 8 mV [from 4 to 31 mV]; for nonsteroid leads, 4 mV [from 0.7 to 10 mV]; P<0.01). Neither congenital heart disease, lead implantation with a concomitant cardiac operation, age or weight at implantation, nor the chamber paced was predictive of lead failure. CONCLUSIONS: Steroid epicardial leads demonstrated relatively stable acute and chronic pacing and sensing thresholds. In this evaluation of >200 epicardial leads, lead survival was good, with steroid-eluting leads demonstrating results similar to those found with historical conventional endocardial leads.

Epicardial pacemaker implantation and follow-up in patients with a single ventricle after the Fontan operation.

OBJECTIVES: There is an increasing incidence of sinus node dysfunction after the Fontan procedure. Inability to maintain atrioventricular synchrony after the Fontan operation has been associated with an adverse late outcome. Although pacing may be helpful as a primary or adjunct modality after the Fontan procedure, the effects of performing a late thoracotomy or sternotomy for epicardial pacemaker implantation are unknown. In addition, little is known about the long-term effectiveness of epicardial leads in patients with single ventricles. The purpose of this study was to compare the hospital course and follow-up of epicardial pacing lead implantation in patients with Fontan physiology and patients with 2-ventricle physiology. METHODS: We retrospectively reviewed all isolated epicardial pacemaker implantations and outpatient evaluations performed between January 1983 and June 2000. RESULTS: There was no difference in the perioperative course for the 31 Fontan patients (27 atrial and 41 ventricular leads [68 total]) compared with the 56 non-Fontan subjects (9 atrial and 61 ventricular leads [70 total]). The median length of stay in Fontan and non-Fontan patients was 3 and 4 days, respectively. There was no early mortality in either group. Pleural drainage for 5 days or longer was reported in 4% of the Fontan cohort and 3% of the non-Fontan group. Late pleural effusions were identified in only 2 patients in the Fontan group and 2 patients in the non-Fontan group. There was no significant difference in epicardial lead survival between the Fontan group and the non-Fontan group (1 year, 96%; 2 years, 90%; 5 years, 70%). The overall incidence of lead failure was 17% (24/138). CONCLUSIONS: Epicardial leads can be safely placed in Fontan patients at no additional risk compared to patients with biventricular physiology. Sensing and pacing qualities were relatively constant in both the Fontan and non-Fontan groups over the first 2 years after implantation.

Frequency of restenosis after balloon pulmonary arterioplasty and its causes.

Restenosis has been described after balloon pulmonary arterioplasty (BPA), but litte is known about its frequency, settings, and time course. We undertook this study to (1) determine the incidence of restenosis after BPA, and (2) identify its potential determinants. We reviewed clinical data and measured pulmonary artery diameters from angiograms of 134 dilations on 75 patients (median 2.1 years, range 0.3 to 32) who had BPA from January 1990 to June 1998. Successful BPA was defined as a > or = 50% increase in predilation diameter, whereas restenosis was said to occur if there was a > or = 50% loss in initial diameter gain. The success rate after BPA by angiographic criteria was 64% (95% confidence interval 56% to 73%). Seventy-four percent of BPAs were successful by published standard criteria (angiographic criteria or > or = 20% change in right ventricular/aortic pressure). Baseline demographic variables and predilation parameters were not predictive of initial dilation success. Restenosis occurred in 35% (95% confidence interval 22% to 49%) of successfully dilated vessels. Only weight at follow-up (p = 0.02) was associated with an increased likelihood of restenosis. Predilation parameters, technical aspects of dilation, or immediate results of BPA were not predictive of restenosis. We therefore conclude that restenosis is unpredictable and more common after BPA than previously recognized.

Necrotizing enterocolitis in neonates with congenital heart disease: risk factors and outcomes.

OBJECTIVE: Necrotizing enterocolitis (NEC) is primarily a disease of the premature infant. Among children born at term, however, congenital heart disease may be an important predisposing factor for this condition. To determine risk factors for NEC in patients with congenital heart disease, we conducted a case-control study of neonates with cardiac disease admitted to the cardiac intensive care unit at our center during the 4-year period from January 1995 to December 1998. METHODS: Cardiac diagnosis and age at admission were analyzed for association with NEC among the 643-patient inception cohort. Demographic, preoperative, and operative variables were recorded retrospectively in 21 neonates with congenital heart disease who developed NEC and 70 control neonates matched by diagnosis and age at admission. Using parametric and nonparametric analysis, cases and controls were compared with respect to previously identified risk factors for NEC. RESULTS: Among the entire cohort of 643 neonates with heart disease admitted to the cardiac intensive care unit, diagnoses of hypoplastic left heart syndrome (odds ratio [OR] = 3.8 [1.6-9.1]) and truncus arteriosus or aortopulmonary window (OR = 6.3 [1.7-23.6]) were independently associated with development of NEC by multivariable analysis. In the case-control analysis, earlier gestational age at birth (36.7 +/- 2. 7 weeks vs 38.1 +/- 2.3 weeks), prematurity (OR = 3.9 [1.2-12.5]), highest dose of prostaglandin >0.05 microg/kg/minute (OR = 3.9 [1. 2-12.5]), and episodes of low cardiac output (meeting specific laboratory criteria) or clinical shock (OR = 6.5 [1.8-23.5]) correlated with the development of NEC. Earlier gestational age and episodes of low output were the only factors that remained significantly associated with NEC by multivariable analysis. Although there was no difference in hospital mortality between patients with and without NEC, mean hospital stay was significantly longer in those who developed NEC (36 +/- 22 days vs 19 +/- 14 days). CONCLUSIONS: The risk of NEC in neonates with congenital heart disease is substantial. Factors associated with an elevated risk of NEC in infants with heart disease include premature birth, hypoplastic left heart syndrome, truncus arteriosus, and episodes of poor systemic perfusion or shock. Heightened suspicion is warranted in newborns with these risk factors.

Somatic growth failure after the Fontan operation.

Our study was designed to characterize the patterns of growth, in the medium term, of children with functionally univentricular hearts managed with a hemi-Fontan procedure in infancy, followed by a modified Fontan operation in early childhood. Failure of growth is common in patients with congenital cardiac malformations, and may be related to congestive heart failure and hypoxia. Repair of simple lesions appears to reverse the retardation in growth. Palliation of the functionally single ventricular physiology with a staged Fontan operation reduces the adverse effects of hypoxemia and prolonged ventricular volume overload. The impact of this approach on somatic growth is unknown. Retrospectively, we reviewed the parameters of growth of all children with functionally univentricular hearts followed primarily at our institution who had completed a staged construction of the Fontan circulation between January 1990 and December 1995. Measurements were available on all children prior to surgery, and annually for three years following the Fontan operation. Data was obtained on siblings and parents for comparative purposes. The criterions of eligibility for inclusion were satisfied by 65 patients. The mean Z score for weight was -1.5 +/- 1.2 at the time of the hemi-Fontan operation. Weight improved by the time of completion of the Fontan circulation (-0.91 +/- 0.99), and for the first two years following the Fontan operation, but never normalized. The mean Z scores for height at the hemi-Fontan and Fontan operations were -0.67 +/- 1.1 and -0.89 +/- 1.2 respectively. At most recent follow-up, with a mean age of 6.1 +/- 1.3 years, and a mean time from the Fontan operation of 4.4 +/- 1.4 years, the mean Z score for height was -1.15 +/- 1.2, and was significantly less than comparable Z scores for parents and siblings. In our experience, children with functionally univentricular hearts who have been palliated with a Fontan operation are significantly underweight and shorter than the general population and their siblings.

The characterization of human urine for specimen validity determination in workplace drug testing: a review.

One challenge facing the laboratory forensic toxicologist today is verifying the validity of the random urine specimen submitted for workplace drugs of abuse analysis. Determining whether urine substitution has occurred is best accomplished through the inspection of the specimen's appearance and the performance of specific laboratory tests, such as determining the concentration of biochemical metabolic waste products and measuring indices of urine concentration. Criteria for classifying submitted urine as substituted are postulated after an extensive review of the published scientific literature. Relevant studies that were evaluated include normal random urine reference interval studies, clinical studies involving the analysis of random urine specimens, theoretical dilutional limits, medical conditions resulting in overhydration, and water-loading studies. After compilation of the study data, derived substituted criteria of urinary creatinine < or = 5.0 mg/dL and urinary specific gravity < or = 1.001 are suggested. A urine specimen meeting these criteria may be considered substituted because it is not consistent with the clinical characteristics associated with normal human urine.

Assessment of pulmonary/systemic blood flow ratio after first-stage palliation for hypoplastic left heart syndrome: development of a new index with the use of doppler echocardiography.

OBJECTIVE: Circulatory maldistribution is believed to be a major cause of early death after first-stage palliation for hypoplastic left heart syndrome. Flow reversal in the reconstructed aorta may reflect the pulmonary/systemic blood flow ratio. The purpose of our study was to investigate the utility of arterial PO (2), arterial oxygen saturation, and a newly developed Doppler-derived flow index in predicting the pulmonary/systemic flow ratio after first-stage palliation for hypoplastic left heart syndrome. METHODS: Twenty-four infants who underwent first-stage palliation for hypoplastic left heart syndrome or a variant were studied. Superior vena cava blood samples were drawn to estimate the mixed venous saturation and permit calculation of the pulmonary/systemic blood flow ratio. Fifty-four samples were evaluated within the first 24 hours after surgery. Simultaneous blood draw and Doppler echocardiography were performed with interrogation in the distal aspect of the arch reconstruction. The ratio of the Doppler velocity-time integral of retrograde flow to the velocity-time integral of forward flow was calculated and compared with the pulmonary/systemic blood flow ratio RESULTS: The median mixed venous saturation for the 54 samples was low (38.5%; range, 18%-64%). The median calculated pulmonary/systemic blood flow ratio was 1.4:1 (range, 0.3:1 to 4. 2:1). Pulse pressure, mixed venous saturation, and arterial PO (2) were not statistically significant predictors of the measured pulmonary/systemic blood flow ratio. Although both aortic oxygen saturation (R (2) = 0.84, P <.01) and Doppler flow reversal ratio (R (2) = 0.94, P <.001) were significantly associated with the measured pulmonary/systemic blood flow ratio, the model coefficient of determination was greatest for Doppler flow reversal ratio. CONCLUSION: Measures of arterial oxygen saturation and arterial PO (2) may be misleading in assessing the circulatory status of infants after first-stage palliation for hypoplastic left heart syndrome. Doppler echocardiography, through use of the Doppler flow reversal ratio, provides a more useful measure of pulmonary/systemic blood flow ratio. Low mixed venous saturation after surgery may be due to factors other than pulmonary overcirculation, such as ventricular dysfunction and low cardiac output.

Plasminogen activator inhibitor (PAI)-1 overexpression in retinal microvessels of PAI-1 transgenic mice.

PURPOSE: Previous studies have suggested that disturbances in plasminogen activator inhibitor (PAI)-1 may be relevant to the development of diabetic microvascular complications. To determine whether overexpression of PAI-1 in cells of retinal microvasculature would result in a disease similar to that observed in diabetes, ocular tissue from transgenic mice that overexpress human PAI-1 were examined. METHODS: Transgenic mice were administered ZnSO4 (25 mM) in their water for up to 49 weeks to activate the metallothionein promoter and stimulate human PAI-1. Colloidal gold immunocytochemistry was used to quantify the human PAI-1 antigen at 7, 20, 34, and 49 weeks of ZnSO4 administration. Cross sections of retinal microvessels were examined by electron microscopy for changes in basement membrane (BM) thickness. Retinal digest preparations were examined by light microscopy for possible microangiopathy, including changes in endothelial cell-to-pericyte ratios. RESULTS: Human PAI-1 immunoreactivity was detected throughout the retinal capillaries of transgenic mice receiving zinc and increased significantly (P < 0.001) after 20 to 49 weeks of ZnSO4 administration compared with age-matched transgenic control mice. At 20 and 49 weeks, retinal capillaries of transgenic mice that received zinc showed significantly thickened BMs compared with control animals (P < 0.001). Moreover, wholemounts of the retinal vasculature from PAI-1 transgenic mice demonstrated an increased endothelial cell-to-pericyte ratio. CONCLUSIONS: PAI-1 overexpression in retinal microvasculature leads to retinal disease similar to that observed in diabetic retinopathy.

SCRAM: A scoring and ranking system for persistent, bioaccumulative, and toxic substances for the North American Great Lakes. Part IV: Results from representative chemicals, sensitivity analysis, and discriminatory power.

The Chemical Scoring and Ranking Assessment Model (SCRAM) has been described in Parts I-III of this series (Snyder et al.: , 1999a; 1999b; 1999c). SCRAM is a chemical scoring and ranking (CSR) system that scores chemicals on the basis of bioaccumulation potential, environmental persistence, and toxicity. Part IV describes various tests and descriptions of the performance of this system. A group of 21 representative chemicals was chosen and scored to test the system. For those chemicals, the percentages of the scores associated with fate-related properties and associated with data uncertainty were determined. The scoring of four of these chemicals is described in greater detail, and the suitability of the scores is discussed. An analysis of the sensitivity of the system to incomplete data sets is presented. And finally, the discriminatory power of the system is described.

SCRAM: A scoring and ranking system for persistent, bioaccumulative, and toxic substances for the North American Great Lakes. Part II: Bioaccumulation potential and persistence.

Part I (Snyder et al.: , 1999a) of this series introduced SCRAM, a chemical scoring and ranking system for contaminants of the North American Great Lakes. Here, in Part II, scoring of the bioaccumulation potential and persistence of chemicals is discussed, including acceptable types of data, specific scoring instructions, and the basis for criteria and scores for these categories of the system. Difficulties encountered during the process of determining which types of data adequately represent the properties of interest are discussed. Also, justification is given for an emphasis on scoring on the basis of persistence.

SCRAM: A scoring and ranking system for persistent, bioaccumulative, and toxic substances for the North American Great Lakes. Part III: Acute and subchronic or chronic toxicity.

In Part I of this series (Snyder: et al., 1999a), the Chemical Scoring and Ranking Assessment Model (SCRAM) was introduced. This system produces scores for chemicals based on their bioaccumulation potential, environmental persistence, and toxicity. In Part II, scoring of the potential for a chemical to persist in the environment and bioaccumulate was described (Snyder et al., 1999b). In Part III, scoring of chemical toxicity is discussed, including definitions and descriptions of effects that are scored, specific scoring instructions, the basis for the criteria and scores, and specific conditions or concerns regarding the types of data used for scoring. A score for each chemical screened is determined from available test data from acute or subchronic and chronic toxicity tests conducted on aquatic and terrestrial organisms. Subchronic and chronic human health effects, including carcinogenicity, are also considered. Part IV includes an evaluation of the performance of the scoring and ranking system (Snyder: et al., 1999c).

SCRAM: A scoring and ranking system for persistent, bioaccumulative, and toxic substances for the North American Great Lakes. Part I: Structure of the scoring and ranking system.

Hundreds of chemical contaminants have been identified in the Great Lakes System of North America. Depending on the agency or organization, various subset lists of these contaminants have been identified as chemicals of potential concern. However, there is no agreement on the method that should be used to make management decisions. Except for consensus on approximately 40 chemicals that most North American agencies agree can cause deleterious effects if released into the environment, no agreement has been reached regarding the priority that contaminants should receive for further action. That leaves hundreds of chemicals that have been, are being, or potentially could be released into the environment that have not been evaluated yet. A profile for potential chemicals of concern is generally thought to include persistence in the environment, potential to bioaccumulate, and ability to cause toxic effects at environmentally relevant concentrations. Except for the International Joint Commission's definition of persistence (> 8 weeks residence time in air, water, soil or sediment), there is little concurrence about what defines these characteristics. For instance, the State of Michigan currently has no established definitions or profiles of persistent, bioaccumulative, toxic substances. Furthermore, there is no standard process to rank chemicals relative to these characteristics. The Chemical Scoring and Ranking Assessment Model (SCRAM) has been developed to provide a process to rank-order chemicals based on these characteristics. The SCRAM system was developed primarily for use in the Great Lakes region of North America and particularly in Michigan, but it is not site-specific. Use of this system may assist in pollution prevention activities and other future chemical control efforts, allowing attention to be focused first on those chemicals likely to present the greatest hazard.

Expression of IGF-1, IGF-1 receptor and TGF-beta following balloon angioplasty in atherosclerotic and normal rabbit iliac arteries: an immunocytochemical study.

Growth factors have been implicated in the pathogenesis of restenosis (myointimal hyperplasia after coronary interventions). In this study, we examined the expression of insulin-like growth factor-I (IGF-1), IGF-1 receptor, and transforming growth factor-beta (TGF-beta) in atherosclerotic and normal rabbit iliac arteries following overstretch balloon angioplasty of the iliac arteries to create a vascular lesion. Animals were sacrificed at 0, 3, 7, 15 and 42 days post angioplasty. The iliac arteries were processed for immunocytochemical localization of IGF-1, IGF-1 receptor and TGF-beta using colloidal gold and the data were quantitatively analyzed. IGF-1, IGF-1 receptor and TGF-beta immunoreactivity were all significantly increased in atherosclerotic arteries compared to control at all of the time points examined. Following balloon angioplasty, the levels of IGF-1 and IGF-1 receptor increased significantly in both control and even further in hypercholesterolemic vessels. In control vessels, the IGF-1 levels returned to preintervention levels, while in atherosclerotic vessels, the levels of IGF-1 and IGF-1 receptor remained elevated. In addition, TGF-beta levels in control vessels showed an initial rise in the first week following injury but then returned to baseline levels. In contrast, atherosclerotic vessels demonstrated a sustained expression of TGF-beta. Thus, IGF-1 and TGF-beta expression is different in normal vs. atherosclerotic vessels following vascular injury. The intensity of expression of IGF-1 and its receptor, which is not reduced at 42 days compared to 15 days following injury, support a role for IGF-1 in smooth muscle cell proliferation and migration. The sustained increase in TGF-beta could facilitate extracellular matrix (ECM) accumulation. Local vascular therapy that is directed towards modulating the effects of IGF-1 and TGF-beta could reduce restenosis.

Fibronectin fragments modulate human retinal capillary cell proliferation and migration.

Capillary morphogenesis involves cell-cell and cell-matrix interactions. Proteases elaborated by capillary cells modify the extracellular matrix (ECM) to facilitate capillary tube formation. Previously, we detected the presence of fibronectin fragments (Fn-f) associated with the proform of matrix metalloprotease-2 (MMP-2) in conditioned medium of human retinal endothelial cells (HRECs). Association of this fragment to latent MMP-2 prevented autocatalytic activation of MMP-2, suggesting a modulatory role of Fn-f in MMP-2 activation. In this report, we examined the potential role of Fn-f on two processes involved in angiogenesis, proliferation and migration of vascular cells. The effects of Fn-f on proliferation were determined by DNA synthesis and cell counts. Their effects on migration were assessed using modified Boyden chambers. Seven Fn-f were tested on vascular cell migration and/or proliferation. Three Fn-f induced migration. Fn-f of 30-kDa and 120-kDa size positively affected proliferation of microvascular cells but not macrovascular cells. A 45-kDa gelatin binding fragment of Fn inhibited HREC proliferation but stimulated pericyte and smooth muscle cell proliferation. The potency of these fragments exceeded that of the known angiogenic growth factor, basic fibroblast growth factor (bFGF), on HREC migration. ECM components such as fibronectin may influence capillary morphogenesis by the generation of fragments that can modulate proliferation, migration, and protease activation. In the setting of diabetes, excess Fn is generated and is available for degradation. Thus, the production of Fn-f may be specifically relevant to the angiogenesis observed in proliferative diabetic retinopathy.