Obstruction of the reconstructed aortic arch, or the neoaortic arch, is now known to be an important factor increasing mortality after the Norwood operation for hypoplastic left heart syndrome. Transcatheter balloon angioplasty has been shown to provide effective relief of both native aortic coarctation and obstructions of the aortic arch occurring subsequent to therapeutic intervention. We sought to determine the outcomes of balloon angioplasty used as an initial treatment for obstruction of the neoaortic arch occurring after the Norwood operation. We gathered the characteristics of 58 patients with such obstruction from 8 institutions, noting procedural factors and outcomes of initial balloon dilation. Obstruction occurred at a median interval of 4 months, with a range from 1.5 months to 6.3 years, after a Norwood operation. Ventricular dysfunction was present before dilation in 13 patients. Mean peak to peak systolic pressure gradients were acutely reduced from 31±20 mm Hg to 6±9 mmHg (p<0.001), with outcome subjectively judged to be successful in 89%- Three patients with pre-existing ventricular dysfunction died within 48 hours of dilation. There were 10 additional deaths during the period of followup, with Kaplan Meier estimates of survival after intervention of 87% at 1 month, 77% at 12 months, and 72% after 15 months. In addition, 9 patients required re-intervention during the period of follow-up, with Kaplan Meier estimates of freedom from re-intervention after dilation of 87% at 6 months, 78% at 12 months and 74% after 18 months. Although transcatheter dilation of neoaortic arch obstructions after Norwood operation is successful, there is a high risk of re-intervention and ongoing mortality in this subgroup of patients. Close follow-up is recommended.

Protein-permeable dense (non-porous) urethane membranes have been evaluated for in vitro cell culture, and in vivo cell encapsulation. Polyurethane membranes were designed to exhibit permeability to proteins, gases, and nutrients without the existence of pores. The membranes are non-cytotoxic, angiogenic, and permeable to gases, nutrients, secretagogues and cell products via purely concentration-driven transport. Non-anchorage and anchorage dependent cells were grown encapsulated within the membrane and with the membrane as a growth substrate. Several non-anchorage dependent cell types proliferated within the membrane both in-vitro and in-vivo. Anchorage-dependent cells were grown on the membranes as a substrate. Encapsulated cells have been maintained in culture for up to six months with nutrients supplied only by the external media. Immuno-isolation has been demonstrated with cells implanted into murine hosts. Explants of membrane encapsulated cells exhibited a high degree of vascularization, with little or no fibrous tissue. The ability to support cell growth and function, and the ability to protect xenogenic cells from immunologic rejection suggest that the membranes would be useful in the construction of hybrid artificial organs, devices for cell transplantation, and substrates for cell and tissue culture.