New developments in the treatment of hypoplastic left heart syndrome.

Hypoplastic left heart syndrome (HLHS) was once a uniformly fatal disease, accounting the majority of neonatal deaths due to congenital heart defects. Twenty-five years of advances in the surgical and medical management of this disease have resulted in dramatic improvements in survival for these children. The goal for patients with HLHS should be survival of near 100% with a good quality of life. The advances described in this manuscript detail some of the new techniques used in the surgical and medical management. For infants undergoing staged reconstruction, the Norwood procedure is performed in the newborn period, followed by a hemi-Fontan operation at 6 months of age, and a modified Fontan operation at 1 to 2 years of age. A significant recent modification of the Norwood procedure is the placement of a right ventricle to pulmonary artery (RV-PA) conduit instead of a systemic artery to pulmonary shunt (modified Blalock-Taussig or BT shunt) as the source of pulmonary blood flow. Our recent experience with this modification demonstrated an incremental increase in survival, improved postoperative stability, and decreased inter-stage mortality. At catheterization, significant differences in hemodynamic parameters were present that were consistent with improved coronary blood flow, decreased volume load to the single right ventricle, and improved pulmonary artery growth in those patients with the RV-PA conduit. The 3rd stage in the surgical treatment of HLHS is the modified Fontan operation or cavo-pulmonary anastamosis. A new approach for Fontan completion is the placement of a stent covered with a thin layer of Goretex from the inferior vena cava to the hemi-Fontan baffle. This can be performed in the catheterization laboratory, with a decrease in post-procedure pleural effusions, lower mortality, and a shorter length of stay. The future of treatment for HLHS may eventually involve a single open-heart procedure with initial and final interventions being performed in the catheterization laboratory. Some cardiac centers perform transplantation for management of HLHS. Survival following transplantation has improved as advances in the pre- and post-operative management continue, along with new options for immunosuppression. Treatment for HLHS continues to evolve, as ongoing work has resulted in improved short and long-term survival. The future for children with this disease is encouraging as evidenced by the remarkable achievements made to date and the current worldwide interest and study of HLHS.

Coil occlusion of a femoral arteriovenous fistula.

A femoral arteriovenous fistula was discovered in a 17-mo-old child with congenital heart disease and prior femoral cardiac catheterization. The fistulous connection was clearly visible by angiography with vein compression, and the fistula was closed percutaneously using a Gianturco coil. Cathet. Cardiovasc. Intervent. 51:308-311, 2000.

Characterization of plasmids encoding the adherence factor of enteropathogenic Escherichia coli.

Volunteer studies have shown that a 60-megadalton plasmid is required for full virulence of the human enteropathogenic Escherichia coli (EPEC) strain E2348/69 (O127:H6). The plasmid, designated pMAR2, encodes localized adherence to HEp-2 cells in tissue culture via the adhesin known as the EPEC adherence factor (EAF). Using a DNA probe for the EAF, we have previously shown that these genes are specific for EPEC and are usually encoded on plasmids ranging from 55 to 65 megadaltons. In this study, Southern blot analysis and S1 nuclease homology determination reveal a high degree of sequence conservation among these plasmids, despite some variation in restriction maps. Phenotypic characterization of the prototype EAF plasmid pMAR2 reveals that the plasmid belongs to the group IncFII and is negative for alpha-hemolysin, colicin, and aerobactin synthesis, as well as biochemical markers and antibiotic resistance. Regions encoding adherence to HEp-2 cells were localized by Tn801 insertion mutagenesis. Adherence genes were then cloned as two distinct plasmid regions which confer the adherence phenotype only when complementing each other in trans.

Molecular epidemiology of neonatal meningitis due to Citrobacter diversus: a study of isolates from hospitals in Maryland.

Six cases of neonatal meningitis due to Citrobacter diversus were diagnosed in three Baltimore (Maryland) hospitals between 1983 and 1985. Using plasmid profiles, biotypes, serotypes, and chromosomal restriction endonuclease digests as epidemiological markers, we studied 63 isolates of C. diversus (including four isolates from cerebrospinal fluid) from these and seven other hospitals in Maryland. Within two of the three hospitals with meningitis cases, the same strain of C. diversus was isolated from case infant(s), healthy neonates, and nursery personnel. In all three hospitals, C. diversus strains different from those implicated as a cause of meningitis were also isolated. Other than the meningitis-associated strains, 15 different strains of C. diversus were isolated from infants in the hospitals studied, with several distinct clusters of asymptomatic, colonized infants identified.

Molecular techniques in the study of Salmonella typhi in epidemiologic studies in endemic areas: comparison with Vi phage typing.

We examined 141 Salmonella typhi strains of known phage type isolated during ongoing epidemiologic studies in Santiago, Chile, and Lima, Peru. Plasmids were present in 12 (17%) of 70 S. typhi isolates from Santiago and 5 (7%) of 71 isolates from Lima; these plasmids were not associated with antimicrobial resistance. Identical 21 kilobase (kb) plasmids (as defined by restriction endonuclease digest pattern) were present in 13 of the 17 plasmid-containing isolates. Virtually identical digest patterns were identified when chromosomal DNA of selected strains from Santiago, Lima, and the United States was extracted and then digested with restriction endonucleases. The similarities among plasmids and chromosomal digest patterns emphasize the homogeneity and possible clonal origin of S. typhi isolates; these data also suggest that there is only a limited role for plasmid and chromosomal analysis as a substitute for phage typing in epidemiologic studies.