Measurement of left ventricular ejection fraction in pediatric patients using the nuclear stethoscope

Left ventricular (LV) ejection fraction (EF) was measured in 25 patients, aged 2 weeks to 20 years (mean 8.6 years), using a portable nonimaging scintillation stethoscope. Technically satisfactory studies were obtained in 23 patients. LVEF was validated by cineangiography in 19 patients and by standard gated blood pool scintigraphy in 4. EF measured by the nuclear stethoscope correlated well with values obtained by cineangiography or scintigraphy (r = 0.869, p less than 0.001) over a wide range of EF values (18 to 79%). In children younger than 5 years (n = 11), the correlation (r = 0.728, p less than 0.02) was less satisfactory than in those older than 5 years (r = 0.926; p less than 0.001). Although modifications in the instrument and further clinical trials with the stethoscope are needed before the device becomes clinically useful to pediatric cardiologists, our data indicate that the nuclear stethoscope can provide reliable assessment of LVEF in pediatric patients.     

omega-123I-hexadecanoic acid metabolic probe of cardiomyopathy

The utility of omega-123I-hexadecanoic acid myocardial scintigraphy as a metabolic probe of cardiomyopathies was investigated. Sixteen patients with a variety of cardiomyopathies and myopathies that involve cardiac muscle and ten volunteers were imaged in the postabsorptive state in a 40 degrees LAO projection after a standard dose of omega-123I-hexadecanoic acid. An elimination T1/2 was calculated from the left ventricular myocardial time-activity curve. An uptake index, corrected for chest wall attenuation, was also computed in 7 of 10 volunteers and 8 of 16 patients. Of the 16 patients, only 2 had distinctly abnormal omega-123I-hexadecanoic acid myocardial tracer kinetics. The first patient had a metabolic disorder of which carnitine deficiency was one component. The second patient had endocardial fibroelastosis, a process which has been linked to disorders which deprive the myocardium of oxygen and energy. Therefore, the cardiomyopathy may have been caused by some abnormality of cardiac metabolism other than carnitine deficiency. Although of limited utility in the overall cardiomyopathic population, omega-123I-hexadecanoic acid myocardial scintigraphy should be further investigated as a screening test for carnitine deficiency and related metabolic abnormalities in patients at risk.     

Massive infantile nephroblastomatosis: a clinical, radiological, and pathological analysis of four cases.

Four cases of massive infantile nephroblastomatosis with up to three and one-half years follow-up are described. Great similarity was found clinically, radiologically and pathologically, which distinguishes this entity from true Wilms' tumor. The course of the renal lesion following treatment was monitored by sequential radiological and biopsy studies. The pathogenesis, natural history, and management are discussed.     

Fetal pulmonary artery diameters and their association with lung hypoplasia and postnatal outcome in congenital diaphragmatic hernia

OBJECTIVE: We hypothesized that fetal branch pulmonary artery (PA) diameters indirectly reflect lung mass and are associated with postnatal outcome in cases of isolated congenital diaphragmatic hernia (CDH). STUDY DESIGN: We retrospectively reviewed echocardiograms of fetuses with CDH, measuring branch PA diameters and other echocardiographic parameters. Antenatal parameters were correlated with postmortem lung weights in 5 fetuses after pregnancy termination. Fetal echocardiographic measures were correlated with outcome variables in 29 live-born infants with CDH to identify antenatal indices associated with postnatal death and respiratory morbidity. RESULTS: Antenatal branch PA size correlated with postmortem lung weights from 5 terminated fetuses (r = 0.87). In 26 cases of left CDH in which the fetus continued to term, the ipsilateral branch PA diameter was significantly smaller than the contralateral branch PA diameter at presentation (P <.001). In these fetuses, a larger contralateral PA diameter was associated with worse postnatal survival (P =.049). Among survivors with left CDH, the main PA z score and the discrepancy between right and left PA diameters correlated positively with duration of supplemental oxygen requirement (P =.019 and P =.022, respectively) and ventilation (P =.036 and P =.012, respectively). Serial antenatal studies in 8 of 10 cases revealed progressive ipsilateral PA hypoplasia. CONCLUSION: Antenatal branch PA size correlates with postmortem lung weight. A larger contralateral PA, and significant branch PA discrepancy and larger main PA diameter, best correlate with postnatal death and respiratory morbidity, respectively. Progressive ipsilateral PA hypoplasia suggests progressive in utero lung hypoplasia in cases of CDH.     

An outbreak of food poisoning in a military establishment

Background: An outbreak of food poisoning in a military establishment mess was investigated and remedial measures suggested.     

Regression calibration for models with two predictor variables measured with error and their interaction,using instrumental variables and longitudinal data

Regression calibration provides a way to obtain unbiased estimators of fixed effects in regression models when one or more predictors are measured with error. Recent development of measurement error methods has focused on models that include interaction terms between measured‐with‐error predictors, and separately, methods for estimation in models that account for correlated data. In this work, we derive explicit and novel forms of regression calibration estimators and associated asymptotic variances for longitudinal models that include interaction terms, when data from instrumental and unbiased surrogate variables are available but not the actual predictors of interest. The longitudinal data are fit using linear mixed models that contain random intercepts and account for serial correlation and unequally spaced observations. The motivating application involves a longitudinal study of exposure to two pollutants (predictors) – outdoor fine particulate matter and cigarette smoke – and their association in interactive form with levels of a biomarker of inflammation, leukotriene E4 (LTE ₄, outcome) in asthmatic children. Because the exposure concentrations could not be directly observed, we used measurements from a fixed outdoor monitor and urinary cotinine concentrations as instrumental variables, and we used concentrations of fine ambient particulate matter and cigarette smoke measured with error by personal monitors as unbiased surrogate variables. We applied the derived regression calibration methods to estimate coefficients of the unobserved predictors and their interaction, allowing for direct comparison of toxicity of the different pollutants. We used simulations to verify accuracy of inferential methods based on asymptotic theory. Copyright © 2013 John Wiley & Sons, Ltd.