LeSar C J, Merrick H W, Smith M R
Department of Surgery, Medical College of Ohio, Toledo 43614-2598, USA.
J Am Coll Surg. 1999 Jul;189(1):73-9; discussion 79-81. doi: 10.1016/s1072-7515(99)00086-1.
Vascular access-related complications are an important cause of morbidity, and they account for 14% to 17% of dialysis patients' hospitalizations with an annual cost in the United States of approximately $1 billion. Previous studies have related the major predisposing factor of thrombotic complications to stenosis of the graft anastomosis. Several recent reports suggest that antiphospholipid antibodies may cause frequent thrombotic complications. The broad spectrum of diseases that cause hypercoagulable states has not been correlated with frequent PTFE graft thrombosis.
A retrospective case series study was performed to determine the frequency of hypercoagulable states in dialysis patients who had repeated thrombotic complications of their PTFE grafts. Between May 1996 and June 1998, 91 operations were performed on 34 patients with end-stage renal disease. All arteriovenous fistulas were created with PTFE grafts and placed by a single surgeon. All patients were evaluated at operation for anastomotic stenosis, and the majority of patients were studied for hypercoagulable states. Patients with a documented hypercoagulable state were considered for warfarin therapy.
Twenty-two individuals (64.7%) developed 67 thrombotic complications. Twelve of the 14 patients tested (85.7%) were shown to have hypercoagulable states of various causes and degrees. Thirteen patients developed multiple thrombotic complications, 11 (81.8%) were tested and proved to be hypercoagulable. Thirty-eight of the thrombotic complications had nonanatomic causes and 28 (41.8%) had hypercoagulability as the only determinable cause. Ten of the 12 hypercoagulable patients (83.3%) were relegated to intermediate to high-intensity warfarin therapy to reduce the incidence of thrombotic events. Hypercoagulable patients not receiving warfarin had a thrombosis rate of 4.0 events per year; patients on warfarin had a rate of 1.2 events per year. Twenty-three thrombotic events occurred in the anticoagulated group all with an International Normalized Ratio (INR) less than 2.7. This incidence of vascular access thrombosis may be prevented when patients are maintained at an optimal INR of 2.7-3.0.
Hypercoagulability has been a major etiologic factor in PTFE graft thrombosis. Hypercoagulable states are often found in patients with multiple graft thromboses and in patients with nonanatomic causes for thrombosis. Antiphospholipid antibodies are prevalent in the patients with PTFE graft thrombosis, as well as abnormalities in the Protein-C, Protein-S, and Antithrombin III systems. PTFE graft thrombosis has been a frequent cause of morbidity in patients on hemodialysis, and diagnostic evaluation should include a hypercoagulability profile. Based on our data, warfarin therapy should be instituted when hypercoagulable states are found, unless otherwise contraindicated, and INR maintained at 2.7-3.0 to decrease morbidity and frequency of graft thrombosis.
血管通路相关并发症是发病的重要原因，在美国占透析患者住院率的14%至17%，每年花费约10亿美元。既往研究将血栓形成并发症的主要诱发因素与移植血管吻合口狭窄相关联。最近的几份报告表明，抗磷脂抗体可能导致频繁的血栓形成并发症。导致高凝状态的多种疾病与聚四氟乙烯（PTFE）移植血管频繁血栓形成并无关联。
进行了一项回顾性病例系列研究，以确定发生PTFE移植血管反复血栓形成并发症的透析患者中高凝状态的发生率。1996年5月至1998年6月期间，对34例终末期肾病患者进行了91次手术。所有动静脉内瘘均采用PTFE移植血管创建，且由同一位外科医生操作。所有患者在手术时均评估吻合口狭窄情况，大多数患者研究高凝状态。记录有高凝状态的患者考虑接受华法林治疗。
22例患者（64.7%）发生67次血栓形成并发症。14例接受检测的患者中有12例（85.7%）显示存在各种原因和程度的高凝状态。13例患者发生多次血栓形成并发症，其中11例（81.8%）接受检测并证实为高凝状态。38次血栓形成并发症有非解剖学原因，28次（41.8%）以高凝状态为唯一可确定原因。12例高凝患者中有10例（83.3%）接受中至高强度华法林治疗以降低血栓形成事件的发生率。未接受华法林治疗的高凝患者血栓形成率为每年4.0次事件；接受华法林治疗的患者为每年1.2次事件。抗凝组发生23次血栓形成事件，国际标准化比值（INR）均小于2.7。当患者INR维持在2.7 - 3.0的最佳水平时，可预防这种血管通路血栓形成的发生率。
高凝状态是PTFE移植血管血栓形成的主要病因。高凝状态常见于多次移植血管血栓形成的患者以及血栓形成有非解剖学原因的患者。抗磷脂抗体在PTFE移植血管血栓形成患者中普遍存在，同时蛋白C、蛋白S和抗凝血酶III系统也存在异常。PTFE移植血管血栓形成一直是血液透析患者发病的常见原因，诊断评估应包括高凝状态检查。根据我们的数据，发现高凝状态时应开始华法林治疗，除非有其他禁忌证，并将INR维持在2.7 - 3.0以降低发病率和移植血管血栓形成的频率。
