Outcomes of stent implantation for obstruction of intracardiac lateral tunnel Fontan pathways.

BACKGROUND: Factors associated with obstruction of the cavopulmonary pathway in patients with a lateral tunnel (LT) intracardiac Fontan connection and outcomes of percutaneous stent implantation for this complication have not been characterized. METHODS AND RESULTS: Between 1999 and 2011, 51 patients underwent stent implantation for LT pathway stenosis at a median age of 10.2 years and a median of 6.9 years after Fontan completion. Compared with control patients undergoing catheterization for other indications, patients had significantly higher inferior vena cava pressures (15.6 versus 13.7 mm Hg; P=0.007), but only 18 (35%) had a measurable pressure gradient in the catheterization laboratory. The morphology of the obstructions varied considerably and was not amenable to straightforward classification. Stenting increased mean diameter of the LT stenosis from 8.5 to 14.2 mm (P<0.001) and eliminated the pressure gradient when present. After stenting, 1 patient developed a significant new baffle leak that was treated with surgical Fontan revision 1.2 months later. A trivial baffle leak was observed in 1 other patient after stenting but required no treatment. Eight patients (16%) underwent successful redilation of the LT stent because of patient growth, symptomatic presentation, or during catheterization for other indications, but 1 developed a new baffle leak during redilation. CONCLUSIONS: It was possible to enlarge the narrowed LT baffle substantially in patients with a variety of forms of obstruction, with few adverse events. The physiological implications of LT narrowing and target size for stenting deserve further investigation.

An automated process for layer-by-layer assembly of polyelectrolyte multilayer thin films on viable cell aggregates.

An automated process for modifying the surface of pancreatic islets grows uniform polyelectrolyte multilayer thin films, eliminating user variability associated with previous manual methods. Machine vision feedback allows for tight control of small fluid volumes, maintaining an islet microenvironment. This process is adaptable to other fragile micrometer-scale particle systems.

Cell surface engineering with polyelectrolyte multilayer thin films.

Layer-by-layer assembly of polyelectrolyte multilayer (PEM) films represents a bottom-up approach for re-engineering the molecular landscape of cell surfaces with spatially continuous and molecularly uniform ultrathin films. However, fabricating PEMs on viable cells has proven challenging owing to the high cytotoxicity of polycations. Here, we report the rational engineering of a new class of PEMs with modular biological functionality and tunable physicochemical properties which have been engineered to abrogate cytotoxicity. Specifically, we have discovered a subset of cationic copolymers that undergoes a conformational change, which mitigates membrane disruption and facilitates the deposition of PEMs on cell surfaces that are tailorable in composition, reactivity, thickness, and mechanical properties. Furthermore, we demonstrate the first successful in vivo application of PEM-engineered cells, which maintained viability and function upon transplantation and were used as carriers for in vivo delivery of PEMs containing biomolecular payloads. This new class of polymeric film and the design strategies developed herein establish an enabling technology for cell transplantation and other therapies based on engineered cells.