PubMed · 13040071
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S BELLMAN. 1953. Microangiography.. https://pubmed.ncbi.nlm.nih.gov/13040071/
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The general design of catheters is bound by many needs. Angiographic catheters must be rigid enough to be torquable and to maintain lumen structural integrity, but also flexible enough to bend with the curves of a blood vessel. They should cause minimal tissue damage; avoid biocompatibility-related complications, and be reliable over time. This study proposes a new testing approach to clearly identify the flexural rigidity of catheters by using a buckling test to evaluate the peak compressive load. This study also tests several angiographic catheters for axial and torsional rigidity. Seven different catheters used for short-term procedures, with and without reinforcement and of various sizes, were evaluated as a preliminary evaluation of test methods for future in vitro testing of catheters; it was found that the buckling test works very well and provides repeatable results.
PURPOSE: Isolated pelvic perfusion (IPP) therapy exposes target tissues to high doses of anticancer drugs with low systemic concentrations, but the major drawback is drug leakage into the systemic circulation, which often thwarts the increased drug concentration. In this study, the efficacy of altering the in-out flow rate during IPP in order to decrease the leakage was assessed in adult pigs. METHODS: The abdominal aorta and the infrarenal vena cava were occluded with two balloon catheters, blood in the extracorporeal circuit was circulated with twin rotary pumps, and the IPP was performed with platinum. Three sets of in-out flow rates were used, and the degree of drug leakage into the systemic circulation was evaluated. The volume of blood withdrawn was equal to the volume returned (300 ml/min; group A), 5% higher (group B), or 10% higher (group C). The platinum concentrations in the pelvic circulation, systemic circulation, and urine were measured and compared. RESULTS: The average and maximum plasma platinum concentrations in the pelvic circulation did not significantly differ among the three groups. The plasma platinum concentrations in the systemic venous circulation of the three groups significantly (P<0.01) decreased as the volume withdrawn during IPP increased. The percentage of platinum eliminated in the urine during IPP was significantly (P<0.01) lower in group B and C than in group A. CONCLUSIONS: Setting the volume withdrawn higher than the volume returned decreased leakage into the systemic circulation under isolated pelvic perfusion.
The mechanism of the antithrombotic effects of heparin and the synthetic antithrombin agent argatroban was evaluated in a dog model. Thrombus formation following balloon injury was evaluated by angioscopy in the right iliac arteries of 20 dogs to serve as a control. After the evaluation of the growth of thrombus on the control side, heparin (200 U/kg) or argatroban (0.2 mg/kg) was infused intravenously, and the distal site of the contralateral left iliac artery was injured in the same manner. At 30 to 120 min before the final examination, the proximal site of the left iliac artery also was injured. After antithrombotic drug infusion, the percent angioscopic stenosis at the distal site was much lower (P<0.0001) than that of the control site (mean stenosis index: 0.67 in heparin vs. 3.8 in control, and 0.25 in argatroban vs. 4.3 in control); however, thrombus formation was observed at the proximal site. With local delivery of a low dose of either antithrombotic drug (n=10), an antithrombotic effect was maintained until 4 h after the infusion. A very weak fluorescence of FITC-heparin was detected at the injured artery 2 h after infusion. In a shunt experiment involving 5 dogs, carotid arteries were injured and incubated in oxygenated Krebs--Henseleit solution before auto grafting into the femoral artery. At 2 h after the grafting, no thrombus was formed in the grafted vessels incubated for 4 h, but was formed in those incubated for 10 min. These results indicate that the relatively long antithrombotic effect of these drugs may be due to a local drug effect at the injured artery, as well as the recovery of the anti-thrombogenicity of the injured artery.