Baig K, Fields R C, Gaca J, Hanish S, Milton L G, Koch W J, Lawson J H
Department of Surgery, Duke University Medical Center, Durham USA.
J Vasc Access. 2003 Jul-Sep;4(3):111-7.
Vascular access polytetrafluoroethylene (PTFE) graft failure is a major cause of morbidity in the hemodialysis population. The most common cause of graft failure is thrombosis secondary to stenosis at the venous outflow tract. Venous outflow stenosis is characterized by intimal-medial hyperplasia. We have developed a porcine arteriovenous (AV) graft model that may be used to investigate this proliferative response and aid in the development of new therapies to prevent intimal-medial hyperplasia and improve graft patency.
Left carotid to right external jugular vein PTFE (6 mm) grafts were implanted in the necks of swine. Immediately following anatomosis, flow rates were recorded. In one group of animals (n = 4) the venous outflow tract was harvested after 7 days and morphometric analysis of intimal and medial area was performed. In a second group (n = 8) the graft patency was monitored until 28 days.
All porcine PTFE fistula grafts were patent at 7 days and 100% patency was maintained until 14 days. After 28 days, 75% of the grafts failed due to thrombosis. The venous outflow tract developed a significant proliferative response. After 7 days the intimal and medial areas were 469 +/- 9 microm2 and 875 +/- 26 microm2 respectively. At 28 days the intimal and medial areas were 913 +/- 55 microm2 and 1437 +/- 182 microm2 respectively. Luminal flow rate of the venous outflow tract was reduced significantly (344 +/- 11 ml/min at Day 0 to 129 +/- 14 ml/min at Day 7, p < 0.05).
This porcine model rapidly, reliably and robustly reproduces the flow reducing stenosis and intimal-medial hyperplasia at the venous outflow tract of PTFE arteriovenous fistula. It represents a promising tool for investigating the mechanisms of intimal-medial hyperplasia, evaluating therapeutic interventions and new graft materials.
血管通路聚四氟乙烯（PTFE）移植物失功是血液透析人群发病的主要原因。移植物失功最常见的原因是静脉流出道狭窄继发血栓形成。静脉流出道狭窄的特征是内膜-中膜增生。我们建立了一种猪动静脉（AV）移植物模型，可用于研究这种增殖反应，并有助于开发新的治疗方法以预防内膜-中膜增生并提高移植物通畅率。
将左颈动脉至右颈外静脉的PTFE（6mm）移植物植入猪的颈部。吻合后立即记录流速。在一组动物（n = 4）中，7天后采集静脉流出道，并对内膜和中膜面积进行形态计量分析。在第二组（n = 8）中，监测移植物通畅情况直至28天。
所有猪PTFE动静脉内瘘移植物在7天时均通畅，直至14天保持100%通畅。28天后，75%的移植物因血栓形成而失功。静脉流出道出现明显的增殖反应。7天后内膜和中膜面积分别为469±9μm²和875±26μm²。28天时内膜和中膜面积分别为913±55μm²和1437±182μm²。静脉流出道的管腔流速显著降低（第0天为344±11ml/min，第7天为129±14ml/min，p<0.05）。
该猪模型能快速、可靠且有力地再现PTFE动静脉内瘘静脉流出道的血流减少性狭窄和内膜-中膜增生。它是研究内膜-中膜增生机制、评估治疗干预措施和新型移植物材料的有前景的工具。
