Polyurethane Vascular Access Graft Research Articles

Patency rate of polyurethane vascular access graft (THORATEC<sup>®</sup>) and the factors related to graft survival

Patency rate of polyurethane vascular access graft (THORATEC<sup>®</sup>) and the factors related to graft survival

Hemolytic Anemia with Fragmented Red Blood Cells Following Vascular Access Grafting for Hemodialysis in a Patient with Chronic Kidney Disease

A 57-year-old male who had been treated with hemodialysis due to end-stage chronic kidney disease for 3 years received arterio-venous bypass grafting with a polyurethane vascular access graft in his left upper arm. Two months later, he was diagnosed with hemolytic anemia with fragmented red blood cells (RBC). He had never shown clinical symptoms such as fever or neurological abnormalities characteristic of thrombotic thrombocytopenic purpura (TTP). Moreover, neither thrombocytopenia nor coagulation abnormality was found on routine laboratory examination. He received arterial banding to reduce the blood flow entering the artificial vascular access graft, which led to rapid recovery from hemolytic anemia, without recurrence. This was an extremely rare case of angiopathic hemolytic anemia with fragmented RBC caused by unfavorable bypass grafting, successfully treated with simple reoperation to reduce the blood flow entering the vascular access graft.

Use of a “composite” vascular access graft in a young child on hemodialysis

Although arterio-venous fistulae (AVF) are currently considered to be the first choice of permanent vascular access for hemodialysis, there are some patients who are not candidates for fistulae and synthetic grafts provide other options. The Thoratec (Vectra) polyurethane vascular access graft is a new prosthetic graft that may be cannulated within days of insertion due to "self-sealing" properties. However, a tendency for kinking at the suture site due to the strong elasticity of this graft, leading to undesirable complications such as thrombosis, have been reported. We describe a surgical modification of the anastomosis by interposing a segment of expanded polytetrafluoroethylene graft (ePTFE, Venaflo) between the native vessels and the polyurethane graft sections in a pediatric patient. This modification may overcome the kinking complication associated with use of the polyurethane graft and the resulting thrombosis.

Survival and infection rates of a polyurethane vascular access graft compared to tunnelled dialysis catheters and brachiobasilic arteriovenous fistulas

Survival and infection rates of a polyurethane vascular access graft compared to tunnelled dialysis catheters and brachiobasilic arteriovenous fistulas

Insertion of Short Introducer Sheaths into a Polyurethane Vascular Access Graft for Immediate Hemodialysis Access

While native AV fistulae are considered the 'gold standard' for hemodialysis patients in need of long-term access, synthetic grafts are the best option for patients who are not candidates for an AV fistula. While AV fistulae should be allowed to mature for 3 - 4 months prior to cannulation, PTFE grafts may be cannulated 14 days after placement. Despite the benefit of earlier cannulation in PTFE graft recipients compared to AV fistulae patients, one critical limitation is that immediate post-operative cannulation is not possible. The self-sealing nature of the polyurethane Vectra(R) Graft overcomes the time restriction until first cannulation, allowing much earlier vascular access than conventional PTFE grafts. We describe here a procedure for insertion of 5-French DialEasetrade mark Introducer Sheaths into the Vectra Graft for immediate, post-operative hemodialysis access. This procedure eliminates time restrictions until first cannulation of the Vectra Graft; the sheath's large diameter sideport ensures high flow for efficient hemodialysis. Moreover, insertion of the sheath into a new or existing Vectra Graft provides vascular access for inspection of the graft anastomoses, angiography, angioplasty, venography, and declotting procedures. The post-operative introduction of DialEase Sheaths into a Vectra Graft for immediate hemodialysis was successfully performed in 35 patients. All patients then immediately received high-flow hemodialysis (400 - 500 ml) with venous pressures < 125 mmHg and negative arterial pressure ~100 mmHg. To date, there have been no infections, immediate graft thrombosis or other complications associated with this procedure, and all patients have remained free of anastomotic problems. (The Journal of Vascular Access 2003; 4: 62-7).

Multicenter evaluation of a polyurethaneurea vascular access graft as compared with the expanded polytetrafluoroethylene vascular access graft in hemodialysis applications

Objectives: The purpose of this study was to compare in a randomized, prospective, and controlled study, the performance of a multilayered, self-sealing polyurethane vascular access graft (PVAG) and expanded polytetrafluoroethylene (ePTFE) vascular access grafts in hemodialysis applications. Performance measures included graft survival, complications, time to early cannulation, and hemostasis times after cannulation. Study Design: A total of 142 patients were randomized equally to receive one of the two grafts after meeting all eligibility requirements. All patients were followed up prospectively to 12 months or to the end of secondary patency. Specifically, this study documented the performance of the PVAG and ePTFE grafts by determining the patencies and complications for both grafts. Results: Patient characteristics between the two groups were similar with respect to risk factors and demographic characteristics (P >.05). Life-table patencies from the date of first dialysis were primary patency: PVAG 55% versus ePTFE 47% (6 months) and PVAG 44% versus ePTFE 36% (12 months) and secondary patency: PVAG 87% versus ePTFE 90% (6 months) and PVAG 78% versus ePTFE 80% (12 months). None of these differences were significant (P >.05). Both primary and secondary patencies were also not significantly different when the date of implantation was the starting point. Adverse events and complications were similar for the two groups, except the PVAG group had a higher incidence of technical complications manifested by graft kinking when compared with the control cohort (P <.05). Additionally, there was no significant difference in complication rates between these two groups with regard to infection and bleeding. When the time to hemostasis after cannulation was compared at 5 minutes or less, there were more PVAG cannulation sites that achieved hemostasis compared with ePTFE sites, and this difference was significant (P <.0001). When time to first dialysis access was compared between the two grafts, 53.9% of all PVAG grafts were cannulated before 9 days versus none with the ePTFE grafts (P <.001). However, long-term graft survival was not significantly different when PVAG patients were stratified into early (< 9 days) and the late access (9 ≥ days) groups (P =.29). Conclusions: The PVAG graft allows for early access without compromising long-term performance. Both PVAG and standard ePTFE grafts have similar long-term outcomes, despite early access with the PVAG vascular access grafts. (J Vasc Surg 2001;34:465-73.)

USEFULLNESS OF A NEW POLYURETHANE VASCULAR ACCESS GRAFT AS AN ARTERIOVENOUS FISTULA FOR HEMODIALYSIS

We evaluated a new polyurethane vascular access graft (Thoratec Vascular Access Graft, TVAG) as a vascular access for hemodialysis. Subjects were 16 patients with chronic renal failure and TVAG was implanted as arteriovenous fistula in them. These were one case of loop in the fore arm, one case of a loop in the upper arm, eight cases of straight in the upper arm and six cases of loop configuration in the thigh. TVAG is characterized by its elasticity and self-sealing property that require careful subcutaneous positioning of TVAG and deliberate sutures during anastomosis, but it resulted in no postoperative limb edema and easy hemostasis after needle removal in our subjects. These findings indicate that TVAG can be used for hemodialysis in early postoperative days. In our cases, hemodialysis was able to start with in 4 days after implantation of TVAG, with an average of 2.4 days. Shorter hospital stay is consequently expected. Early occulusion of fistula due to thrombosis occurred in two cases. Thrombectomy was easily performed in both cases using Fogarty balloon catheters and they could be used for hemodialysis again. It is concluded that TVAG is useful as a vascular access for hemodialysis. Further assessment of its long-term patency and possible complications are necessary.

Australian multicentre evaluation of a new polyurethane vascular access graft.

A new three-layered cast polyurethane vascular access graft (Thoratec VAG) is the most recent addition to the list of materials used in the search for the perfect prosthetic graft material for haemodialysis vascular access. Despite its use in 23 countries, a clinical assessment has not been published. An independent retrospective evaluation by questionnaire was obtained for 145 implantation procedures performed by 30 surgeons. Ninety-two per cent of procedures were performed for an acute need for vascular access and 73% had prior failed vascular access surgery. Patients were hospitalized for a median of 4 days and the graft was initially used at a median of 3 days. Median follow-up was 306 days. Thoratec VAG had a problem-free (primary) patency of 44.9% and a functional (secondary) patency 64.5% at 1 year. Major causes of graft loss were thrombosis (17%) and infection (11%). Intra-operative thrombosis was the only significant risk factor for subsequent thrombosis (P = 0.013). Infection was less in patients with antibiotic prophylaxis that included vancomycin (P = 0.02). The ability to use the graft soon after surgery is a major advance for patients who urgently need reliable medium to long-term haemodialysis access.