Thrombogenicity and related biological properties of heparin bonded collagen coated polyester and human umbilical vein prosthetic vascular grafts

BACKGROUND: Multiple factors contribute to the process of prosthetic graft failure. Some of them are specifically related to the biological behavior of the used materials. To pursue the ideal substitute for the autologous vein graft, many materials have been taken into consideration. Of these, polyester (Dacron) and human umbilical vein (HUV, Dardik) bypass grafts have gained much attention in vascular surgical practice over the years. This study compares the results of both in vivo and in vitro investigations on graft thrombogenicity and neo-intimal formation in collagen-coated heparin bonded Dacron and in HUV bypass grafts. It is an adjunct to our clinical comparison of graft materials in infrainguinal arterial reconstruction. METHODS: In 12 adult Beagle dogs, a patch was sewn onto the abdominal aorta (Dacron, n = 6; HUV, n = 6). At defined interval times, thrombocyte aggregation was measured with nuclear imaging of 99mTechnetium labeled platelets. Post-mortem histological analysis of the interface between the native vessel wall and the patch was performed in all animals. RESULTS: At 4 h (2.67, SD = 0.77) and after 2 weeks (2.21, SD = 0.28) after implantation, significantly higher thrombogenicity was measured in the HUV grafts compared to Dacron grafts (1.98, SD = 0.10 and 1.98, SD = 0.11, P = 0.02 and 0.025, respectively). At 4 weeks, no significant difference could be found (HUV, 2.26; SD = 0.29; Dacron, 2.11; SD = 0.16; P = 0.23). Measurement of 'neo-intimal' thickness after explantation of the patch at 28 days after the initial procedure showed a significant difference: in HUV grafts the mean thickness of the inner lining was 0.76 mm (SD = 0.50), compared to 0.16 mm (SD = 0.10) in the Dacron grafts (P = 0.013). CONCLUSION: HUV grafts showed a higher thrombogenicity at 4 h and 2 weeks after insertion of the graft compared to Dacron grafts. At 4 weeks this difference is not present. After 28 days the inner ('neo-intimal') lining is significantly more pronounced in HUV grafts than in Dacron grafts.     

Operative transluminal laser angioplasty as the sole treatment for late stenoses of femorodistal artery bypass graft: Experimental and clinical studies

To determine the role of Nd:YAG laser thermal angioplasty as the sole treatment for late stenoses of femorodistal artery bypass graft, the lasing effect of a larger size of hot-tip probe (3, 4, and 5 mm) was experimentally studied in vitro. For an adequate lasing effect, 30 watts of laser power output for 3 seconds was needed for the 3 mm probe, 40 watts for the 4 mm probe, and 50 watts for the 5 mm probe, respectively. Based on these results, we used Nd:YAG laser thermal angioplasty alone for 25 grafts, including 16 polytetrafluoroethylene (PTFE) grafts, eight saphenous vein grafts, and one externally supported (EXS) Dacron graft in which the stenotic lesions were detected by deterioration of the Doppler flow waveform pattern or a significant fall in the ankle/brachial pressure index (ABPI). Follow-up was from 3 to 24 months (average of 9 months) for PTFE grafts, from 5 to 21 months (average of 11 months) for saphenous vein grafts, and 13 months for the EXS Dacron graft following femorodistal artery reconstructions. Stenotic lesions were most common in the distal anastomotic sites: 11 PTFE grafts, three saphenous vein grafts, and one EXS Dacron graft. Among these, 13 grafts showed a type II flow waveform pattern at the time of surgery. Clinical success was achieved in 12 of the PTFE grafts (75%), in five of the vein grafts (62.5%), and in the single EXS Dacron graft. Four PTFE and three saphenous vein grafts failed subsequent to repeat intraoperative balloon angioplasty in three and graft extension in three and one graft interposition. Perforation occurred in only one vein graft. Continuing patency has now been maintained for up to 25 months after lasing. Nd:YAG laser thermal angioplasty using a 3 to 5 mm hot-tip probe is effective as the sole procedure for widening a stenotic lesion and improving patency after femorodistal artery reconstruction.     

Collagen- versus gelatine-coated Dacron versus stretch PTFE bifurcation grafts for aortoiliac occlusive disease: long-term results of a prospective,randomized multicenter trial

BACKGROUND: In this prospective randomized multicenter trial, knitted gelatine-coated Dacron, knitted collagen-coated Dacron, and stretch polytetrafluoroethylene (PTFE) aortic bifurcation grafts were compared for their long-term results. METHODS: Between 1991 and 1998, 149 patients undergoing elective revascularization for aortoiliac occlusive disease were prospectively randomized at 3 tertiary referral centers of vascular surgery. The patients received either gelatine-coated Dacron (GEL-D) grafts (n = 52), collagen-coated Dacron (COL-D) grafts (n = 49), or stretch PTFE grafts (n = 48). RESULTS: No intraoperative deaths were recorded. The 30-day mortality was 4%. The mean follow-up time was 97 months. Primary patency rates were 77% for GEL-D, 78% for COL-D, and 79% for PTFE at 8 years. The differences were not different (P >.8). Secondary corrected 8-year patency rates were also not significantly different (P >.5): 91% for GEL-D, 96% for COL-Dm and 90% for PTFE. Five Dacron and 1 PTFE grafts were affected by infections. CONCLUSIONS: Bifurcation grafts for revascularization of aortoiliac occlusive disease using these 3 materials were comparable in terms of primary and secondary patency and long-term complication rates.     

Collagen versus gelatin-coated Dacron versus stretch polytetrafluoroethylene in abdominal aortic bifurcation graft surgery: results of a seven-year prospective, randomized multicenter trial

BACKGROUND: A prospective randomized multicenter trial was performed to compare knitted gelatin-coated Dacron bifurcation grafts, knitted collagen-coated Dacron grafts, and stretch polytetrafluoroethylene (PTFE) grafts. METHODS: Between 1991 and 1998, 315 elective patients were randomized by age, gender, diabetes, runoff, indication (aneurysm, aortoiliac occlusive disease), and nicotine consumption at 3 centers of vascular surgery in Austria. The patients received gelatin-coated Dacron (GEL-D) grafts (n = 109), collagen-coated Dacron (COL-D) grafts (n = 100), or stretch PTFE grafts (n = 106). RESULTS: No intraoperative deaths occurred. The 30-day mortality was 3%. No difference was found between the 3 graft materials in long-term patency. The primary 5-year patency rates were 92% for GEL-D, 89% for COL-D, and 91% for stretch PTFE (P =.6001). The secondary 5-year patency rates also differed: 97% for GEL-D, 100% for COL-D, and 97% for stretch PTFE (P =.2062). Early occlusions were observed overall in 3% and late occlusions in 5% of patients. When both Dacron grafts were compared collectively with stretch PTFE, a difference was found in infection rate: Dacron 3% (6/209) versus PTFE 0% (0/106); P <.03. CONCLUSIONS: The bifurcation grafts of all 3 materials were comparable in primary and secondary patency rates, incidence of false aneurysms, and rate of perioperative complications. Graft infections were confined to the 2 Dacron grafts and did not occur in stretch PTFE grafts.     

Reoperation for graft failure of femoropopliteal bypass with externally supported knitted Dacron prosthesis

BACKGROUND: Aggressive reoperation for failing or failed femoropopliteal (FP) bypass has been affirmative despite graft material. There has been no report regarding results of reoperation for FP bypass with externally supported knitted Dacron prosthesis (EXS). The aim of this study is to justify aggressive reoperation of FP bypass with EXS and to examine risk factors affecting the result of reoperation. METHODS: A retrospective review was performed on 204 patients undergoing 212 FP bypasses (with EXS between January 1982 and December 1997 and 34 FP EXSes of 32 patients underwent reoperation for graft failure until March 1998. The cumulative graft patency (GP) and limb salvage (LS) rate after first reoperation for 34 FP bypass EXS were calculated and the importance of each perioperative factor on GP or LS was estimated by uni- and multivariate analysis. RESULTS: Reoperated 34 FP EXSes included 12 failing and 22 failed grafts and 14 limbs with failed grafts underwent reoperation for limb salvage. The GP of 34 grafts and LS of 14 limbs rate were 58 and 67% at 2 years, respectively. Univariate analysis identified graft thrombosis (2 years GP; failing graft: failed graft=78: 48%) and continuance of smoking (2 years LS; smoker: non-smoker=43: 100%) as a significant risk factor of GP and IS, respectively, neither of which was significant by multivariate analysis. CONCLUSIONS: Early diagnosis and treatment, before graft thrombosis, can lead to superior durability of GP and discontinuance of smoking is important for LS.     

A comparative evaluation of polytetrafluoroethylene, umbilical vein, and saphenous vein bypass grafts for femoral-popliteal above-knee revascularization: a prospective randomized Department of Veterans Affairs cooperative study

PURPOSE: Currently, the choice of a vascular prosthesis for a femoral-popliteal above-knee arterial bypass graft is left to the surgeon's preference, because the available information on comparative evaluations is inconclusive. The Department of Veterans Affairs (VA) Cooperative Study 141 was established to identify whether improved patency exists with different bypass graft materials for patients with femoral-popliteal above-knee bypass grafts. METHODS: Between June 1983 and June 1988, 752 patients at 20 VA medical centers were randomized to receive either an externally supported polytetrafluoroethylene (PTFE; N = 265), human umbilical vein (HUV; N = 261), or saphenous vein (SV; N = 226) for an above-knee femoral-popliteal bypass graft. The indication for the bypass grafting operation was limb salvage in 67.5% of the patients. Patients were observed every 3 months for the first year and every 6 months thereafter. All patients were instructed to take aspirin (650 mg) daily for the duration of the study.Doppler-derived ankle-brachial indices (ABIs) were determined preoperatively and serially postoperatively. A bypass graft was considered to be patent when the Doppler-derived postoperative ABI remained significantly improved (more than 0.15 units higher than their preoperative value) and additional objective information, such as angiograms or operations, did not contradict these observations. Patency failure also included bypass grafts that were removed because of an infection or aneurysmal degeneration. Patency rates were compared by using the Kaplan-Meier life table analysis. RESULTS: The cumulative assisted primary patency rates were statistically similar among the different conduit types at 2 years (SV, 81%; HUV, 70%; PTFE, 69%). After 5 years, above-knee SV bypass grafts had a significantly (P 相似文献   

Human umbilical vein versus heparin-bonded polyester for femoro-popliteal bypass: 5-year results of a prospective randomized multicentre trial.

PURPOSE: To compare long-term patency of Heparin-Bonded Dacron (HBD) and Human Umbilical Vein (HUV) vascular prostheses in above-knee femoro-popliteal bypass surgery. DESIGN: A prospective randomized multi-centre clinical trial. PATIENTS AND METHODS: Femoro-popliteal bypasses were performed in 129 patients between 1996 and 2001. After randomization 70 patients received an HUV and 59 an HBD prosthesis. Patients were followed up every three months during the first postoperative year and yearly thereafter. The median follow-up was 60 months (range 3-96 months). Graft occlusions were detected by duplex scanning, angiography or surgical exploration. RESULTS: The cumulative primary patency rates were 79%, 66% and 58% at 1, 3 and 5 years postoperatively. Primary patency rates for HUV were 74%, 64% and 58% at 1, 3 and 5 years and 84%, 68% and 58% for HBD, respectively (log-rank test, p=0.745). Overall secondary patency rates were 82%, 72% and 61% at 1, 3 and 5 years postoperatively. The overall cumulative limb salvage at 5 years follow-up was 89% (CI 80%-91%) and was not dependent on graft type. Smoking (p=0.019), number of patent crural arteries (p=0.030) and previous cerebro-vascular events (p=0.030) were significant predictors of graft occlusion. CONCLUSION: There was no difference in long-term graft performance between HUV and HBD for above knee infrainguinal bypass.     

Clinical results of femoropopliteal bypass using externally supported (EXS) Dacron grafts: with a comparison of above- and below-knee anastomosis

As of the end of September 1989, 52 EXS Dacron grafts had been implanted for femoropopliteal bypass operations. The distal ends of 27 grafts were anastomosed to above-knee popliteal arteries and those of 25 grafts to below-knee popliteal arteries. The cumulative patency rate of above-knee grafts was 71.3% at 54 months, and that of below-knee grafts was 78.8% at 48 months (n.s.). Kinking and stenosis of the arteriosclerotic proximal and/or mid popliteal artery when the knee was bent were angiographically remarkable. These changes may explain why some femoropopliteal grafts occlude with time and why the late results of above-knee grafts are not much better than those of below-knee grafts.     

PTFE or HUV for femoro-popliteal bypass: a multi-centre trial

Despite wide clinical experience the choice between human umbilical vein (HUV) or polytetrafluoroethylene (PTFE) when the saphenous vein is inadequate remains unclear. In a multi-centre trial of 801 femoro-popliteal bypasses, autogenous vein could not be used in 252 (31%), of which 191 were randomised to either HUV or PTFE and started on aspirin 300 mg plus dipyridamole 150 mg (ASA + DPM) twice daily. Graft patency measured objectively by independent trial coordinators was expressed on an "intention to treat" basis by life table and analysed statistically by log rank and confidence intervals (95% CI). Overall, 101 grafts failed and cumulative patency was 53% (45-61%) at 3 years compared with 60% (55-65%) in 549 vein grafts. Prosthetic bypass patency above knee was 65% (55-75%); markedly better than 35% (23-47%) below knee (p less than 0.001) and comparable with 62% (55-69%) in 217 above knee saphenous vein grafts. Most failures occurred early at a rate of 52/1000 patient-months in the first 3 months (43/1000 for vein) falling to 21/1000 by 6 to 12 months and around 10/1000 subsequently. Randomisation produced comparable groups of 87 HUV and 104 PTFE grafts. Cumulative primary patency for HUV was 68, 63 and 57% at 1, 2 and 3 years, respectively compared with 61, 56 and 48% for PTFE with wide confidence intervals for the difference at 3 years (-20 to 38%, p = 0.27).(ABSTRACT TRUNCATED AT 250 WORDS)     

Is the Preferential Use of ePTFE Grafts in Femorofemoral Bypass Justified?

The choice of prosthetic graft material for cross-femoral bypass has been evolving in the past two decades. Expanded polytetrafluoroethylene (ePTFE) has become our preferred graft material since 1995. However, few studies have looked into the optimal graft material in this procedure. Justification for the preferential use of ePTFE graft in lower limb revascularization remains unknown. The aim of the present study was to compare the long-term outcomes of Dacron and ePTFE grafts in femorofemoral bypass. The records of 61 consecutive patients who underwent femorofemoral bypass at the University of Hong Kong Medical Center from 1981 to 1998 were retrospectively reviewed. Dacron grafts were used in 27 patients and 34 patients had ePTFE grafts. The demographic features, patency, and limb salvage rates of the two groups of patients were compared. The 3-year primary patency rates of Dacron and ePTFE grafts were 85% (SE = 9.5%) and 66% (SE = 14.5%), respectively. The difference was not statistically significant. The limb salvage rates of Dacron and ePTFE grafts were 91% and 83% at 3 years, respectively (p = 0.27). The long-term outcomes of Dacron and ePTFE grafts in femorofemoral bypass were equivalent. The preferential use of ePTFE graft in femorofemoral bypass is not evidence based. Selection of an appropriate prosthetic graft for femorofemoral bypass should be based on the cost and its handling characteristics.     

Heparin-bonded Dacron or polytetrafluoroethylene for femoropopliteal bypass grafting: a multicenter trial

BACKGROUND: Dacron (polyester fiber) was largely abandoned for femoropopliteal bypass grafts 30 years ago because saphenous vein achieved better patencies. However, in patients taking aspirin, patency in above-knee femoropopliteal bypass grafts has recently been shown to be equivalent to that with saphenous vein. We compared heparin-bonded Dacron (HBD) and polytetrafluoroethylene (PTFE) in a randomized multicenter trial including below-knee popliteal or tibioperoneal trunk bypass graft where the long saphenous vein was absent or inadequate. METHODS: Over 28 months, 209 patients undergoing femoropopliteal bypass grafts (180 above-knee, 29 below-knee) were randomized to HBD (n = 106) or PTFE (n = 103). Each patient was given aspirin (300 mg/d) before surgery, and this continued unless the patient had intolerance to the aspirin. RESULTS: The mean follow-up was 42 months (range, 28-55). Fifteen (7.1%) patients died with patent grafts, and three (1.4%) infected grafts were removed. Patency (measured with Kaplan-Meier survival analysis) at 1, 2, and 3 years for HBD was 70%, 63%, and 55% compared with 56%, 46%, and 42%, respectively, for PTFE (P =.044). A total of 67 secondary interventions were performed on 48 thrombosed grafts; long-term patency was achieved in only three. Risk factors for arterial disease did not significantly influence patency. Amputations have been performed in 23 patients, six after HBD and 17 after PTFE bypass grafts (P =.015). CONCLUSIONS: HBD achieved better patency than PTFE, which carried a high risk of subsequent amputation.     

Fluoropolymer-coated dacron versus PTFE grafts for femorofemoral crossover bypass: randomised trial.

OBJECTIVES: To investigate whether patency of a thin walled 8 mm fluoropassivated Dacron graft was similar to that of a standard 8mm PTFE graft for femorofemoral crossover bypass surgery. DESIGN: A randomised multicentre clinical trial comparing two vascular grafts with participation of 10 departments of vascular surgery in Denmark, Sweden and Norway. PATIENTS AND METHODS: 198 patients were randomised to PTFE (n=107) or fluoropolymer-coated Dacron grafts (n=91), 63% underwent surgery for claudication, 27% for ischaemic rest pain and 10% for tissue loss. The median follow-up time was 24 months (IQR 19-26 months). RESULTS: The primary patency rate of the two grafts was similar (log rank test: p=0.35). The primary patency rates (95% CI) for coated Dacron and PTFE grafts were 92% (86-98) and 94% (89-99) at 12 months and 87% (74-95) and 93% (87-99) at 24 months, respectively. CONCLUSION: In patients with unilateral iliac artery disease not amenable to angioplasty, the femoral-femoral bypass is durable and effective. No difference in patency was found between the two graft materials (fluoropolymer coated Dacron and PTFE).     

A clinical survey of aortobifemoral bypass using two inherently different graft types.

The performance of knitted Dacron and polytetrafluoroethylene (PTFE) bifurcated grafts are compared in this study of 312 patients at a single institution. Patients of the two graft groups were statistically well-matched in risk factors and degree of distal obstructive disease. Operating time needed to implant either graft was approximately equal. For patients with abdominal aortic aneurysms, mean volume of blood transfused was 2.2 units for Dacron grafts and 0.2 units for PTFE grafts; for patients with aortoiliac occlusive disease, the comparable figures were 1.1 units and 0.1 units, respectively. Four-year cumulative patency for Dacron (90%) and PTFE (97%) grafts were not significantly different (p greater than 0.01). Complications affected 13% of the patients of the Dacron group and 4% of the PTFE group. All six graft infections and all seven graft double-limb thromboses occurred in Dacron grafts. Anastomotic aneurysms, amputations, and late graft revisions occurred with greater frequency in patients with Dacron grafts.     

Limitations of human umbilical vein grafts

Sixty modified human umbilical vein (HUV) grafts were used for arterial reconstruction in 48 patients between December 1979 and December 1981. Forty-four patients had limb-threatening ischemia (rest pain or tissue loss) and four had disabling claudication. Thirty-four patients had HUV grafting after a primary arterial reconstruction had failed. Fourteen had HUV used for their initial arterial bypass. The distal anastomosis was to the popliteal artery in 27 grafts (5 above and 22 below the knee) and the distal calf arteries in 33 (anterior tibial 10, posterior tibial 9, peroneal 14). The cumulative patency rate, calculated by the modified life-table method, was 34% at 1 year and 18% at 2 years. Fifteen patients required major amputation after graft failure; 13 of these healed below the knee. Preoperative and postoperative ankle/brachial systolic pressure indices and intraoperative blood flow did not correlate with graft failure. These results reflect the limitations of HUV as a graft material in patients with severe ischemia of the lower extremities. The prognostic factors that determined the outcome of arterial reconstruction with HUV in these patients remain to be defined.     

Dacron versus polytetrafluoroethylene for Y-aortic bifurcation grafts: a six-year prospective, randomized trial.

BACKGROUND. A prospective, randomized trial was conducted to compare Dacron with expanded polytetrafluoroethylene (ePTFE) in reconstructive aortoiliac surgery. No comparable trial with a prospective, randomized design with a comparable number of patients or an equal long-term follow-up period can be found in the literature. METHODS. Between 1984 and 1989, 165 patients were randomized for either Dacron or ePTFE on the basis of age, sex, indication for surgery, diabetes, nicotine consumption, runoff, and operative approach. The two groups were well matched for randomization criteria, as well as the incidence of aneurysms. RESULTS. No statistically significant difference was found between the two graft materials in terms of patency rates (corrected 3-year patency rates: Dacron = 95% vs ePTFE = 95%; Breslow, p = 0.83; Mantel-Cox, p = 0.74). Subgroup analysis comparing long-term patency rates of the two graft materials and relating them to poor runoff, good runoff, aneurysms, and arterial occlusive disease also failed to show any significant differences between ePTFE and Dacron. Early graft failure (n = 6; 3.6% of the patient population; p = 0.045) and severe abdominal graft infection (n = 3; 1.8% of the total population) were seen only in ePTFE grafts. However, these did not affect the corrected long-term patency rate of ePTFE grafts. There were five late graft failures with PTFE (3.0%) and four with Dacron (2.4%). CONCLUSIONS. Graft materials currently available for aortoiliac repair were comparable in terms of corrected long-term patency rates. The alleged advantages of PTFE were not confirmed by our data. PTFE grafts were associated with a higher rate of complications, and more redo operations were required to duplicate the results obtained with Dacron.     

Enhanced endothelialization of Dacron grafts by external vein wrapping

The efficacy of external vein wrapping of vascular grafts in promoting the development of a luminal endothelial surface was assessed in 12 dogs who underwent thoracoabdominal bypasses with 26-29 cm X 6-mm i.d. double-velour knitted Dacron grafts. In group I (n = 6) 6-cm segments of the grafts were wrapped with autologous jugular vein with its endothelial surface applied against the outside of the graft. In group II (n = 6) the wrap procedure was performed using abdominal wall fascia. The degree and character of graft incorporation was quantitated in all prostheses at 28 days postimplantation. Group I vein wrap prostheses demonstrated uniform endothelial surface coverage in the vein wrap area (means = 88%) that was significantly greater (P less than 0.04) than coverage in adjacent unwrapped segments (means = 48%). Group II fascial wrap grafts demonstrated variable endothelial coverage in the wrapped area (means = 48%) that was consistently less than in adjacent unwrapped portions (means = 62%), and significantly less than vein wrap sections of group I animals (P less than 0.04). No significant differences existed in endothelial coverage of unwrapped regions of group I and II grafts. This investigation documented that wrapping knitted Dacron grafts with vein enhanced endothelialization of their luminal surface.     

The effects of aspirin, dipyridamole and warfarin in femorodistal reconstruction: long-term results

This study was done to evaluate the effect of aspirin (ASA), dipyridamole (DIP), and warfarin on 406 patients who had femoropopliteal-tibial operations with saphenous vein (SV), umbilical vein (UV), polytetrafluoroethylene (PTFE) and Dacron (DuPont, Wilmington, DE). Above-knee bypasses were performed in 181 patients: 77 were taking ASA and DIP at the time of operation, 41 were placed on postoperative "low-dose" warfarin, whereas 63 did not receive adjunctive medications. Late patency demonstrated no significant difference among the groups based on graft material used (SV 71%, UV 68%, PTFE 66%, and Dacron 65%) (P less than .25). Below-knee femoro-popliteal bypasses were performed in 183 patients: 82 were taking ASA and DIP at the time of operation, 40 were placed on warfarin postoperatively and no medications were given to 41 patients. Late patency rates (39 months) demonstrated that SV (62%) was superior to UV (51%), PTFE (30%), and Dacron (18%) (P less than .01). Femorotibial-peroneal bypasses were done in 42 patients: 13 patients were taking ASA and DIP at operation, 21 were placed on warfarin postoperatively and 8 received no medication. SV late patency (33 months) was again superior (43%) to UV (31%); no PTFE or Dacron grafts functioned after 24 months. Patients who took warfarin and ASA had the best early (16 months) patency results. Above-knee prosthetic grafts achieved late patency rates similar to SV while reducing operative time, shortening recuperation, and sparing the saphenous vein for use in the coronary or infrapopliteal vessels. In below-knee bypasses SV was superior to prosthetic grafts, with or without the use of ASA and DIP or warfarin.(ABSTRACT TRUNCATED AT 250 WORDS)     

Evaluation of arterial prostheses in a baboon ex vivo shunt: the effect of graft material and flow on platelet deposition

Surface thrombogenicity is recognized as an important factor in the failure of small caliber vascular prostheses. The baboon ex vivo shunt was developed to study small caliber grafts under controlled conditions at different flow rates. The shunt was created by percutaneous insertion of catheters into the baboon femoral artery and vein. Platelet-graft interactions were studied using autogenous indium 111 labeled platelets. Two graft materials were placed in series and exposed to blood flow for 2 1/2 hours at flow rates of 25 and 200 ml/min. At the end of this period, the grafts were removed for morphologic examination. Platelet adhesion to the grafts, especially with the less thrombogenic materials (PTFE and HUV), was found to be independent of flow rate. PTFE was found to be the least platelet-reactive material, HUV was intermediate, and knitted Dacron was the most thrombogenic surface. Platelet deposition on the flow surface was confirmed by light microscopy and scanning electron microscopy.     

Heparin-bonded Dacron or polytetrafluorethylene for femoropopliteal bypass: five-year results of a prospective randomized multicenter clinical trial

OBJECTIVE: Dacron was largely abandoned for femoropopliteal bypass 30 years ago, because better patency rates were achieved with saphenous vein. Despite the range of potential prosthetics, polytetrafluoroethylne (PTFE) clearly predominates in current femoropopliteal practice. We compared heparin-bonded Dacron (HBD) with PTFE in a randomized multicenter clinical trial. METHOD: Over 28 months, 209 patients (179 above-knee disease, 30 below-knee disease) were randomized to receive HBD (n = 106) or PTFE (n = 103) grafts. Aspirin, 300 mg/d, was started before surgery, and was continued if tolerated. RESULTS: At follow-up for a minimum of 5 years (mean, 76 months; range, 60-89 months), 37 patients (17.7%) had died with patent grafts and 121 (58%) grafts were occluded. Primary patency rate, measured with Kaplan-Meier survival analysis, was 46% (95% confidence interval [CI], 35%-57%) at year 5 for HBD, compared with 35% for PTFE (CI, 25%-45%; P < .055). Long-term patency was achieved in only 4 of 78 interventions performed in 55 thrombosed grafts. Secondary patency rate for HBD was 47% (CI, 36%-58%), and for PTFE was 36% (CI, 26%-46%). Risk factors for arterial disease did not significantly influence prosthetic patency. Major limb amputation was necessary in 9 patients with HBD grafts and 20 patients with PTFE grafts (P < .025). Two amputations in the HBD group and 8 amputations in the PTFE group were in patients undergoing bypass surgery to treat claudication only. Limb salvage rate was 86% (CI, 77%-95%) and 74% (CI, 64%-84%), respectively. CONCLUSIONS: Significantly better patency rates were achieved with HBD than with PTFE at 3 years (P < .044), but the difference was no longer statistically significant at 5 years (P < .055). The incidence of major limb amputation, however, was significantly greater (P < .025) in the PTFE group compared with the HBD group at both 3 and 5 years of follow-up.     

A five-to seven-year experience with externally-supported Dacron prostheses in axillofemoral and femoropopliteal bypass

We have examined the clinical results of 56 externally-supported (EXS) Dacron grafts in the axillofemoral position and 117 in the femoropopliteal position. Results have been analyzed from two perspectives: primary patency concerns only those grafts that had never occluded; extended patency refers to all open grafts including those whose continued patency is the result of thrombectomy. The 5-to 7-year life-table patency rates are: axillofemoral 8 mm and 6 mm bypass: primary 75% and extended 97%; above-knee femoropopliteal 6 mm bypass: primary 78% and extended 93%; below-knee 6 mm femoropopliteal bypass: primary 41% and extended 91%. In contrast, the results for the 5 mm grafts used for femoropopliteal bypass were inferior to the 6 mm grafts: femoropopliteal 5 mm bypasses had an above-knee primary patency rate of 44% and an extended rate of 55%, with a below-knee primary patency rate of 15% and an extended rate of 32%. Rendering the noncrimped porous Dacron prosthesis kink and compression resistant by an external support coil appears to increase its potential for successful use, especially in 8 mm axillofemoral and 6 mm femoropopliteal bypasses. Presented to the Western Vascular Society, January 1986, Laguna Niguel, California.