PubMed · 6101814
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J E Ballard. 1980-02-16. Which vascular prosthesis?. https://doi.org/10.1016/s0140-6736(80)90909-5
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Defining the most appropriate conditions for strengthening the retention of endothelial cells (ECs) by small-diameter prosthetic endothelialized grafts is indispensable to their clinical application. The incubation time after seeding is one of the most important factors in EC retention. The effects of different postincubation times (0, 2, 4, 8, 16, 24, and 36 hr) on EC monolayers on two different types of graft, fibronectin-coated expanded polytetrafluoroethylene (ePTFE) and collagen-coated knitted Dacron grafts (4 mm x 5 cm) were examined. In situ counting of ECs on the grafts was performed by light microscopy. The percentage cell retention was calculated by dividing the cell counts for grafts exposed to pulsatile flow for 90 min by those for control grafts. To characterize the EC coverage of the grafts, scanning electron microscopy was also performed. The average cell density of control grafts ranged from 5.59 +/- 1.1 to 6.69 +/- 1.5 x 10(4) cells/cm2 and did not differ according to the kind of graft or incubation time. The knitted Dacron grafts showed the maximal cell retention (88 +/- 5%) after incubation for 8 hr, whereas ePTFE grafts did so after 24 hr (83 +/- 6%). Scanning electron microscopic examination after incubation for 8 hr revealed that the density of human ECs on the surfaces of ePTFE and Dacron grafts differed, although there was no morphological difference between the ECs on the two types of graft. Knitted Dacron grafts achieved a high percentage retention in a shorter time than ePTFE grafts.
This study was conducted to assess the mechanical characteristics of dilated polytetraflouroethylene (PTFE) for use in transluminally placed endovascular grafts (TPEGs). Ten-centimeter lengths of 3- and 4-mm thinwalled PTFE were dilated to 8, 10, 12, and 15 mm diameters (3 mm) and 10-, 14-, 16-, and 20-mm diameters (4 mm), respectively (n = 6 for each size). The dilated PTFE segments were evaluated for leakage, further dilation, structural changes (with electron microscopy), and changes in wall thickness occurring after 24 hours of perfusion at pressures of 300-350 mmHg. Both 3- and 4-mm thinwalled PTFE could be dilated to five times their initial diameter before rupture occurred. Three-millimeter grafts dilated to 12- and 4-mm grafts dilated to 14 mm remained resistant to leakage at perfusion pressures up to 350 mmHg. When 3-mm grafts were dilated to 15 mm, the PTFE leaked saline at a rate of 20.3 +/- 9.3 cc per hour at 300 mmHg. pressure. Four-millimeter grafts dilated to 16- and 20-mm diameters leaked saline at 8.4 +/- 7.8 and 52.8 +/- 22 cc per minute, respectively, at the same pressure. No grafts were found to increase in diameter after 24 hours of pressure perfusion. Electron microscopy revealed that PTFE node size was significantly smaller in dilated grafts than in undilated grafts, but there was no significant change in internodal distance. This data suggests that thinwalled PTFE can be dilated to large diameters and retain sufficient strength to resist supraphysiologic pressures. Long-term studies are needed to determine the late structural integrity of dilated PTFE.
Prolonged cardiopulmonary bypass requiring femoral arterial cannulation may lead to ipsilateral leg ischemia. A technique described of femoral cannulation via an end-to-side femoral artery graft allows distal femoral perfusion and eliminates the complication of leg ischemia.