Extracardiac valved conduits are routinely employed in the correction of complex congenital heart lesions. Compression of a conduit and/or of the heart may present serious operative and postoperative complications. We believe its occurrence can be minimized and hemodynamic results improved by adhering to simple surgical techniques. It is important to select a conduit which will produce minimal resistance to flow. Partial or subtotal thymectomy may increase the mediastinal space to accommodate the conduit. The conduit should be cut into the appropriate shape and should be placed in such a way that it does not cross the midline. Finally, the posterior pericardium may be opened to allow the heart to move posteriorly and to rotate to the left, thus moving the conduit away from the sternum.

Bioprosthesis↗

PubMedDate not supplied

The U22 host gene (UHG): chromosomal localization of UHG and distribution of U22 small nucleolar RNA.

The U22 host gene (UHG) is very unusual because it encodes a spliced, polyadenylated RNA that has little apparent coding capacity and is rapidly degraded. The stable RNA products from this locus are actually encoded within eight different introns of the UHG pre-RNA. These small nucleolar RNAs (snoRNAs) assemble into ribonucleoproteins, some of which have been shown to function in rRNA processing and modification. In order to more fully characterize the locus, we have mapped UHG to chromosome 11q13 by fluorescence in situ hybridization (FISH). Radiation hybrid mapping placed this sequence-tagged site with very high probability (lod >19) to chromosome 11, approximately 10.1 cR distal to framework marker WI-8652. We also investigated the possibility that the expression of UHG was subject to genomic imprinting. Several laboratories have shown that non-protein-coding mRNAs are frequently associated with imprinted domains in mammalian cells. We used a novel somatic cell hybrid method to assay parent-of-origin effects in the expression of UHG alleles and found that, unlike XIST, IPW, and H19, this RNA is expressed biparentally. Additional FISH experiments using anti-U22 oligonucleotides revealed that, as with U3, this sno-RNA is localized throughout the nucleolus.

Cell Nucleolus↗

PubMedDate not supplied

Endomyocardial biopsy after heart transplantation in children.

Clinical evaluation, physical examination, and noninvasive testing have been suggested as adjuncts to endomyocardial biopsy for diagnosing acute graft rejection in children after heart transplantation. Because the consequences of delayed diagnosis or unnecessary treatment of rejection may be serious in pediatric transplant recipients, we reviewed our experience with repeated endomyocardial biopsy in seven children (aged 6 months to 19 years) and assessed the sensitivity and specificity of clinical and noninvasive data for diagnosing acute rejection. There were no serious complications in 71 biopsy procedures. In no patient did the presence of abnormal clinical findings or noninvasive testing coincide with treatable rejection that was proved on biopsy. However, there were nine episodes of treatable rejection in the absence of abnormal physical findings or noninvasive studies. At this time we consider repeated endomyocardial biopsy to be a feasible and safe procedure in infants and children and do not consider clinical findings and noninvasive testing sufficient to make therapeutic judgments in regard to acute graft rejection.

Adolescent↗

PubMedDate not supplied

Pediatric heart transplantation at St. Christopher's Hospital for Children.

Heart transplantation has become the standard of care for patients with end-stage heart failure. The efficacy and therapeutic advantages of transplantation in the pediatric population have not been fully determined. Between March 1985 and September 1986, nine pediatric heart transplantations were performed; the ages ranged from 39 days to 19 years; weight ranged from 2.3 to 100 kg. The underlying disease was acquired cardiomyopathy (four patients); cardiomyopathy caused by congenital mitral valve disease (two patients); unresectable fibroma of the left ventricle in a newborn (one patient); hypoplastic left heart syndrome (one patient); and hypertrophic obstructive cardiomyopathy (one patient). Initial immunosuppression therapy consisted of cyclosporine, prednisone, and antithymocyte globulin. Recently, newer protocols have evolved through experience. Seven patients survived the perioperative period and had follow-up from 1 to 19 months, for a total of 41 transplant months. Rejection occurred at a rate of 1.4 episodes per month in children compared with 0.8 episodes per month in our adult patients. There was no statistical difference in the number, severity, or timing of rejection episodes in the pediatric versus adult population. Major complications included cyclosporine-induced seizures in two patients, mild hypertension in two, five infectious episodes (three bacterial and two viral), and three late deaths. All children who survived are in New York Heart Association functional class I with no developmental delays. This series is heavily weighted with children (33% less than age 1 year). Early results demonstrate that pediatric and infant heart transplantation is technically practical. Improved results are to be expected with additional experience and further modification of adult protocols to assure patient growth and minimize the high infection rate.

Adolescent↗