A new device for slow progressive narrowing of vessels

Abstract

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.

Response of the right ventricle to progressive pressure loading in pigs

“…In all experiments an increase of CI was only observed during the phase of actual pressure loading and was most pronounced during slow progressive pressure loading ( fig. 3) achieved with a new device (17). A markedly increased muscle mass of RV was observed in all pigs (table 1), however, no correlation was found between muscle mass and rate of pressure increase or muscle mass and absolute increase of pressure in the right ventricle.…”

“…Median sternotomy and insertion of catheters into femoral or jugular veins (modified Seldinger technique) were performed under sterile conditions. Constrictors with ameroid cylinders of different sizes (17) were placed close to the bifurcation of the pulmonary artery to prevent impairment of pulmonary valve function. To facilitate easy subsequent restudies a sheath with obturator was kept in the vein.…”

“…Rapid excessive increase of pressure loading leads to degenerative alterations of the myocardium (11). A newly developed device (17), which produces a slow progressive stenosis of the pulmonary artery was used to raise RV pressure to systemic levels in young pigs within 4 to 5 weeks. The aim was to determine speed and duration of pressure development which achieves adequate RV hypertrophy without impairment of myocardial function.…”

Effect of Petrolatum Coating on the Rate of Occlusion of Ameroid Constrictors in the Peritoneal Cavity

“…23 Others have commented that the AC currently used in treatment of PSS do not reach complete luminal closure. 11 However, to our knowledge, the current study was the first to specifically measure the rate of luminal closure of AC in the peritoneal cavity.…”

“…It has been reported that AC undergo an initial 14 day period of rapid expansion, followed by 2 months of more gradual expansion. 23 Vascular occlusion is thought to occur by a combination of extraluminal compression and perivascular inflammation and fibrosis. 11 Research of original literature regarding the use of AC revealed that early investigators had coated the rings in petrolatum, thereby delaying water absorption and expansion of the casein ring.…”