Prolonged QT interval and cardiac arrhythmias in two neonates: sudden infant death syndrome in one case

Two neonates with arrhythmias and the long QT syndrome are described. The arrhythmias were detected in utero and both infants were apparently well after birth. The first infant, although well, had a bradycardia for the first 9 days of life. A normal heart rate was documented at 10 days but a prolonged QT interval was not appreciated on the ECG. He was discharged from hospital but died suddenly and unexpectedly 3 days later. A post-mortem examination failed to find a cause for his death which therefore fell into the category of the sudden infant death syndrome (SIDS). A retrospective analysis of the perinatal electrocardiogram showed a probable junctional rhythm with 2:1 conduction to the ventricle; the QT interval was prolonged at 0.52 seconds (QTC = 0.63). The second infant had a QT interval of 0.52 seconds (QTC = 0.54) and frequent ventricular premature beats on a 24-hour electrocardiogram. She was treated with propranolol and remains well 2 years later. Sudden infant death has often been described in the siblings of children with the long QT syndrome and one other report described a case of SIDS which was said to have had a prolonged QT interval on the perinatal ECG. This report, however, provides unquestionable evidence, in one case, of an association between the long QT syndrome and SIDS.     

Excretory urography with iohexol: evaluation in children

A multicenter clinical study was conducted using iohexol, a second-generation nonionic contrast medium, for excretory urography performed in 130 children. Doses of iohexol (300 mg iodine/ml) ranged between 150 and 660 mgI/kg (0.5 and 2.2 ml/kg). Iohexol was tolerated well, and no significant adverse reactions occurred. Sixty-five iohexol urograms were evaluated to determine the minimum dose for adequate visualization of the kidneys and collecting systems. A dose greater than 300 mgI/kg (1.0 ml/kg) always resulted in a urogram of diagnostic quality, while visualization was insufficient for diagnosis in 10% of studies done with doses of 150-300 mgI/kg (0.5-1.0 ml/kg). Another 65 iohexol urograms were compared in a blinded manner with a similar number of studies performed using iothalamate meglumine at comparable iodine concentration and dose. Visualization of calyces and pelvoinfundibular structures achieved with iohexol was rated better with statistical significance, but there was no difference in visualization of the renal parenchyma or ureters. Use of iohexol in excretory urography may be advantageous in children who are at greatest risk for an adverse reaction to contrast media or in those most likely to benefit from use of a low osmolality contrast agent.     

Volumetric rendering techniques: applications for three-dimensional imaging of the hip

Volumetric rendering is a new approach to three-dimensional (3D) imaging that overcomes many of the drawbacks of currently available surface-rendering systems. Its application on the Pixar Imaging System in two cases of acetabular fracture was assessed to illustrate the features of the technique. The fast-computing architecture and large memory of this system allow rapid generation of a series of high-quality 3D images in each plane of rotation (x or spinal axis, z or somersaulting axis) that can be viewed as independent static images or as an animated real-time video loop. Editing to remove the normal contralateral hemipelvis enhances appreciation of acetabular abnormalities. Every pixel of computed tomographic data is preserved, allowing representation of both soft tissue and bone as translucent overlap. The presentation of data also allows detection of subtle abnormalities and features and minimizes the artifact generation common in surface-rendered images.     

Myocardial tagging in polar coordinates with use of striped tags

Regional deformation abnormalities in the heart wall provide a good indicator of ischemia. Myocardial tagging with magnetic resonance imaging is a new method of assessing heart wall motion during contraction. Current methods of myocardial tagging either do not provide two-dimensional information or lack a coordinate system well adapted to the morphology of the heart. In this article, the authors describe a new tagging method that provides a true polar coordinate system, with both radial and angular dimensions. This is accomplished with use of a section-selective version of spatially modulated magnetization resulting in striped tags (STAGs). These STAG planes are placed in the myocardium in a star pattern so that they intersect on the long axis of the heart and stripes appear through the width of the heart wall. In the short-axis view during contraction, rotation around the long axis yields angular information such as shear and twist, while separation of the stripes within the myocardium permits measurement of radial thickening. Therefore, this method provides a coordinate system for calculating two-dimensional strain that is adapted to the morphology of the left ventricle.     

The sensitivity and specificity of the immediate-spin crossmatch

The immediate-spin (IS) crossmatch is used to detect ABO incompatibility between donor red cells (RBCs) and the serum of the intended recipient. However, this test may be positive in the absence of ABO incompatibility (false positive) or it may be negative when ABO incompatibility exists (false negative). During a 25-month study, the rates of both false-positive and false-negative IS crossmatch results were evaluated, and the sensitivity and specificity of the IS crossmatch were determined. During the study period, 53,656 IS crossmatches were performed for patients without significant RBC antibodies. Fifty-five patients had positive IS crossmatches, and no false-negative reactions were found. In tests of 55 patients with positive IS crossmatches, 77 false-positive and 5 true-positive reactions were noted. The causes of the false-positive reactions were rouleaux (36 patients), cold-reactive antibodies (8 patients), a combination of rouleaux and cold-reactive antibodies (2 patients), fibrin clot (1 patient), and undetermined (3 patients). The sensitivity and specificity of the IS crossmatch were 100 and 99.86 percent, respectively. Laboratory personnel should be aware that the IS crossmatch may have false-positive or false-negative results, and they should develop written protocols to distinguish quickly between true-positive and false-positive reactions.     

Kell blood group activity of gram-negative bacteria

To understand better the relationships between blood-group antigens and bacterial constituents, examples of 23 gram-negative bacteria (representing the 10 genera Citrobacter, Edwardsiella, Enterobacter, Escherichia, Klebsiella, Proteus, Pseudomonas, Salmonella, Serratia, and Shigella) were tested for the presence of Kl-like antigens by hemagglutination-inhibition (HAI) assays against both IgG and IgM anti-Kl. Saline-suspended whole organisms, cell-free culture media, and disrupted organisms were used to test for such antigens in, on, and secreted by the microorganisms examined. Disrupted organisms of an isolate of Shigella sonnei nonspecifically inhibited IgG anti-Kl as well as IgG antibodies of the specificities Kpb, Fya, S, and c. However, only Escherichia coli 0125:B15, subtype 12808, had specific K1-like activity (no activity with other IgG [(k, Kpb, Jka, Fya, S, c] and IgM [A, B, M, P1] antibodies). Disrupted organisms inhibited IgM but not IgG anti-K1 in the HAI assay. A second subtype, E. coli 0125:B15, subtype 12809, exhibited no K1-like activity. These findings support the report of K1 activity in cell-free broth cultures of E. coli 0125:B15 (subtype unspecified). Thus, although not all E. coli 0125:B15 possesses K1-like activity, the finding of such activity in at least one E. coli subtype confirms the idea that bacterial components may play a role in the production of naturally occurring antibodies directed against non-ABO red cell antigens.     

Survey on pretransfusion testing

BACKGROUND: Hospitals and blood centers throughout the United States use a variety of reagents and methods to perform pretransfusion testing. A survey was developed to determine the reagents and methods in use and their relative prevalence in different work settings. STUDY DESIGN AND METHODS: A national survey on pretransfusion testing was conducted. Surveys were distributed to state and regional blood bank associations, which then distributed them to hospitals and blood centers within their region. In most instances, the blood centers distributed the survey to the local hospitals. Completed surveys were returned to the authors for review, and all information was entered into a database for analysis. RESULTS: Analysis of the data shows that the majority of blood banks use monoclonal reagents for ABO testing and monoclonal-polyclonal blended reagents for Rh testing. The data show that anti-IgG and polyclonal antihuman globulin reagents are used almost equally for antibody screening (detection) tests and that most blood banks use a three-cell antibody-screening test. Slightly more than 50 percent of hospitals use an immediate-spin crossmatch in the absence of unexpected antibodies. CONCLUSION: A number of approved reagents and methods are used by blood bank laboratories for pretransfusion testing. Facility size (number of beds) and type tend to influence the choice of methods and reagents employed. This survey provides an opportunity for blood bank laboratories to compare their current practices with those of their peers.     

Detection of Hepatitis B Virus DNA Sequences in Liver in HBsAg Seronegative Patients with Liver Disease with and without Anti-HBc Antibodies

Excluding studies from Brechot and co-workers, little supporthas been found for a role of the hepatitis B virus in the pathogenesisof HBsAg seronegative patients with predominantly chronic liverdiseases, including primary liver cancer. In this study liverDNA from 59 predominantly British patients (four cases withpaired biopsies, 6–12 months apart) with different, mostlychronic, liver diseases was analysed by molecular hybridization.All were seronegative for HBsAg and serum hepatitis B virusDNA (dot blot hybridization) and their liver diseases were believedto be unrelated to hepatitis B virus infection. Hepatitis Bvirus DNA was detected in liver of 11 (18.6 per cent) patients;nine had episomal(3.2 Kb) DNA and eight had higher molecularweight bands suggesting integrated forms. Six patients werealso seronegative for anti-HBc. Patients of UK and non-UK originwere equally represented. Hepatitis B virus DNA was detectedin serum of six of nine patients tested using the polymerasechain reaction. The detection of hepatitis B virus DNA in liverand in serum by this assay in a significant proportion of patientswith chronic liver disease, hitherto unsuspected of being hepatitisB virus-related, suggests a possible role for this virus inlow- as well as high-prevalence countries.