A new device for slow progressive narrowing of vessels.

The purpose of this work was to develop a device which allows slow progressive banding of a great artery in infants within 4 to 5 weeks. Employed was the hygroscopic casein ameroid. When brought in contact with fluids, an ameroid cylinder expands characteristically. An early phase of fast expansion proceeds gradually to a phase of slow growth. Size, shape, and encasement of ameroid as well as temperature and type of surrounding fluid modify but do not alter the typical pattern of expansion. The developed constrictor (weight: 5.8 kg, length: 18 mm, diameter: 12 mm) includes a stainless steel socket containing an ameroid cylinder (length: 8.5 mm, diameter: 8 mm). The expanding ameroid pushes a piston with a concave extension (makrolon) a maximum of 2 mm against the artery, which is fixed to the metal housing by a teflon band (width: 4 mm, thickness: 0.5 mm). The band runs in 2 fitting grooves on the metal housing to which it is fixed by a metal ring with a precisely manufactured internal thread allowing exact tightening and loosening of the band around the artery. Utilization of inert materials like teflon, makrolon, and stainless steel warrants experimental and possibly clinical application of the developed small constrictor.