No abstract

Summary.-Post-mortem studies suggest that liver metastases obtain the majority of their nutrition from the hepatic artery; however, cytotoxic arterial perfusion with or without hepatic-artery ligation has not proved entirely successful as a therapeutic regime.In this study we have measured blood flow into colorectal liver metastases using xenon-133 (133Xe) clearance in patients undergoing surgery for colorectal cancer.Pre-operative measurements after direct parenchymal injection gave a mean flow of 41-5 i 22.5 ml/min/100 g which after hepatic arterial occlusion perfusion, was reduced to a mean of 5o% of the pre-occlusion value.Dynamic blood-flow studies using the gamma camera were performed in the postoperative period by administration of 133Xe into both hepatic arterial and portal venous catheters. The initial distribution images indicated a predominant arterial perfusion to the metastases, but after hepatic-artery ligation, portal-vein perfusion to the metastases was statistically significantly increased.Hence, a compensatory haemodynamic mechanism exists which may account for the poor results of hepatic-artery ligation and perfusion alone.

No abstract

The physical characteristics of the arterial wall exert a major influence over blood flow patterns and the pulse wave velocity is strongly affected by the elasticity of the vessel. We have developed a technique for manufacturing latex tubing which has physical characteristics similar to those of human arteries. Tubes were produced by painting a plastic rod of diameter 7 x 10(-3) m (the internal diameter of the superficial femoral artery) with liquid latex. The number of coats applied controlled the thickness, and hence the elasticity of the resulting tube. Values of compliance and pulse wave velocity were similar to those observed in vivo. The tubing was tested in a model of the femoral arterial circulation and the typical triphasic arterial now was seen. The mean flow in the vessels was also analysed, and found to be higher for the more elastic vessels, supporting existing mathematical theories and qualitative physiological data. These vessels provide a reliable method of producing physiologically accurate test segments for use in a range of arterial flow models.

The aetiology of transient cerebral ischaemia is complex. For these reasons the development of non-invasive techniques that can detect lesions in the vessels supplying the affected cerebral hemisphere has been pursued. These include ophthalmodynamometry (Liversedge and Smith, 1961), thermography (Wood, 1965), carotid phonoangiography (Duncan et al., 1975), ocular plethysmography (Gee et al., 1974), and radioisotope cerebral perfusion (Weissman et al., 1975).