Significant Difference In Patency Rates Research Articles

Long-Term Results of Angioplasty and Stent Placement for Treatment of Central Venous Obstruction in 126 Hemodialysis Patients: A 10-Year Single-Center Experience

The objective of our study was to report and compare long-term results of percutaneous transluminal angioplasty and stenting of central venous obstruction in hemodialysis patients. Hemodialysis patients who underwent successful endovascular treatment of central venous obstruction were retrospectively evaluated. Stenotic lesions greater than 50% or inducing extremity swelling were subject to treatment. The primary treatment was angioplasty, and stent placement was accomplished in angioplasty-resistant obstructions. Angioplasty was the primary treatment of recurrence after stent placement. Additional stenting was reserved for angioplasty-resistant recurrences. One hundred forty-seven veins in 126 patients (63 males, 63 females) between 15 and 82 years old primarily underwent 101 angioplasties and 46 stent placements. The mean follow-up was 22.1 +/- 16.3 (SD) months. The average number of interventions per vein in the stent group (2.7 +/- 2.4 interventions) was significantly higher than that in the angioplasty group (1.5 +/- 1.0 interventions). Primary patency was significantly higher in the angioplasty group (mean, 24.5 +/- 1.7 months) than that in the stent group (mean, 13.4 +/- 2.0 months). Assisted primary patency of the angioplasty group (mean, 31.4 +/- 2.0 months) and that of the stent group (mean, 31.0 +/- 4.7 months) were equivalent. The overall mean primary patency was 21.1 +/- 1.4 months, and the overall mean assisted primary patency was 31.7 +/- 2.5 months. There were no significant differences in patency rates with regard to patient sex, the type of stent used, the vein or veins treated, or the type of lesions. Endovascular treatment of central venous obstruction is a safe and effective procedure in hemodialysis patients. Stenting has a significantly lower primary patency rate than angioplasty but adds to the longevity of vein patency in angioplasty-resistant lesions; therefore, stent placement should be considered in angioplasty-resistant lesions.

Arteriovenous fistula for chronic hemodialysis in pediatric candidates for renal transplantation: Technical details and refinements

AVFs may be considered the best type of venous access for chronic hemodialysis in pediatric patients with more than 20 kg who are not likely to receive a kidney transplant or be transitioned to peritoneal dialysis within one yr. The aim of the study was to report the experience in the creation of AVFs in pediatric candidates for renal transplantation using microsurgical vascular techniques, with emphasis on the details of the surgical technique. Forty children underwent 50 fistula creations - 31 radial-cephalic, 11 brachial-cephalic, five brachial-basilic and three saphenous-femoral. The vein was anastomosed to the artery in an end-to-lateral fashion by using two separate 8/0 prolene running sutures. The overall patency rate was 76.0%:22 (70.9%) of the radial-cephalic fistulas, nine (81.8%) of the brachial-cephalic, five (100.0%) of the brachial-basilic and two (66.6%) of the saphenous-femoral. There was no significant difference in patency rates between the brachial-cephalic, brachial-basilic and radial-cephalic fistulas. The incidences of fistula patency were not different for patients weighing <20 kg compared with patients weighing >20 kg. AVF remains as a satisfactory method for providing hemodialysis in children. The utilization of microsurgical techniques with some technical refinements described herein permits the achievement of high fistula patency rates.

Antithrombotische Therapie beim femoropoplitealen Venenbypass

BACKGROUND: Postoperative oral antithrombotic therapy in patients after femoro-popliteal saphenous vein bypass still remains a matter of debate. Aim of this study was to evaluate bypass patency, morbidity and mortality in patients treated by primary saphenous femoro-popliteal vein bypasses with either postoperative oral antiaggregation or oral anticoagulation. METHODS: Retrospective analysis of prospectively maintained database in a university tertiary care hospital. Patients underwent surgery for peripheral vascular disease. The only procedure investigated was primary reversed femoro-popliteal saphenous vein bypass. RESULTS: Between January 2000 and December 2003 two-hundred-and-thirty-four patients received 243 primary femoro-popliteal saphenous vein bypass procedures. Postoperatively either oral antiaggegants (Aspirin® 100 mg/day) or oral anticoagulants (phenprocoumon or acenocoumarol, INR: 2–4) were prescribed. There was no significant difference in patency rates between the antiaggregation group (AGG) and the oral anticoagulation group (AC) at all time intervals studied. After 1 year, the primary patency rate of femoro-popliteal vein bypasses in the AGG was 90% as compared to 91% in the AC, and after 6 years it was 86 and 91%, respectively (p = 0.26). There were 69 deaths of 195 patients in the AGG and 17 deaths of 39 patients in the AC (risk ratio 80%; confidence interval 0.5–1.2; p > 0.05). Major hemorrhagic events with fatal outcome occurred in 3 patients (all of them in the AGG, p = 0.59). Limb salvage was achieved in 97% in the AGG and in 93% in the AC. CONCLUSIONS: We could not show a significant difference between patients who received postoperative aspirin or oral anticoagulation in terms of bypass graft patency, morbidity and mortality after femoro-popliteal saphenous vein bypass procedures.

Posterior-Wall-First Continuous Suturing Combined with Conventional Interrupted Suturing for Microvascular Anastomosis

Vascular anastomosis with conventional interrupted suturing is often difficult to perform when the vascular clamp is not reversed, because of a narrow operative field or a short vascular pedicle. A posterior-wall-first continuous suture technique combined with the standard interrupted suture technique is one method of solving this problem. The authors conducted a comparative study of posterior-wall-first continuous suturing combined with standard interrupted suturing and conventional interrupted suturing in rat vessels. There was no statistically significant difference in patency rates or suturing times. Electron microscopy demonstrated no significant difference in recoverability of the intima. The posterior-wall-first continuous suture technique combined with the standard interrupted suture technique is a useful alternative to the conventional interrupted suture technique.

Posterior-Wall-First Continuous Suture Combined with a Standard Interrupted Suture in Microvascular Anastomosis in Rats

Vascular anastomosis with conventional interrupted suture technique is often difficult to perform when the vascular clamp is not reversed because of a narrow operative field or a short vascular pedicle. A posterior–wall–first continuous suture, combined with the standard interrupted suture suturing method, is one of the means to solve this problem, but this method is not reliable. These authors did a comparative study in rats of the posterior–wall–first continuous suture combined with the standard interrupted suture and the conventional interrupted suture technique. The results showed no significant difference in patency rates or suturing times. There was also no significant difference in the recoverability process of the intima revealed from electron microscopic images. The posterior–wall–first continuous suture combined with standard interrupted suture is a useful alternative to the conventional interrupted suture technique.

In vitro and in vivo hemocompatibility evaluation of graphite coated polyester vascular grafts.

Attempts have been made in this study to prepare a homogeneous and stable coating of graphite on polyester vascular grafts (GPVG) using an electrophoresis method to evaluate thromboresistant and blood compatibility of GPVG in comparison to non-coated PVG and InterGard (collagen sealed PVG) as control. Lactate dehydrogenase (LDH) activity measurement was carried out on all PVG types to evaluate platelet adhesion. To examine tissue reaction GPVG and non-coated sheets of knitted polyester fabric were implanted simultaneously in the dorsal flank of rats subcutaneously. The GPVG, non-coated and control were implanted in descending aorta as end-to-end or end-to-side implantation substitution in 25 sheep for 4-60 weeks. Results showed that the graphite coating on polyester vascular grafts reduced the number of adherent platelets and prevent platelet activation and spreading on the surface in comparison with non-coated and control. Pathological investigation showed inflammatory reactions were totally resolved after 12 weeks and there was no difference in the tissue reaction between graphite coated, non-coated and control patches. All grafts remained patent and there was no significant difference in patency rate between these three types of PVG. We found that GPVG has no need for pre-clotting and it showed lower platelet aggregation, thinner capsule formation and lower calcification after 15 months. However, suturing of GPVG was more difficult in comparison with the other types.

In vitro and in vivo hemocompatibility evaluation of graphite coated polyester vascular grafts

Attempts have been made in this study to prepare a homogeneous and stable coating of graphite on polyester vascular grafts (GPVG) using an electrophoresis method to evaluate thromboresistant and blood compatibility of GPVG in comparison to non-coated PVG and InterGard (collagen sealed PVG) as control. Lactate dehydrogenase (LDH) activity measurement was carried out on all PVG types to evaluate platelet adhesion. To examine tissue reaction GPVG and non-coated sheets of knitted polyester fabric were implanted simultaneously in the dorsal flank of rats subcutaneously. The GPVG, non-coated and control were implanted in descending aorta as end-to-end or end-to-side implantation substitution in 25 sheep for 4–60 weeks. Results showed that the graphite coating on polyester vascular grafts reduced the number of adherent platelets and prevent platelet activation and spreading on the surface in comparison with non-coated and control. Pathological investigation showed inflammatory reactions were totally resolved after 12 weeks and there was no difference in the tissue reaction between graphite coated, non-coated and control patches. All grafts remained patent and there was no significant difference in patency rate between these three types of PVG. We found that GPVG has no need for pre-clotting and it showed lower platelet aggregation, thinner capsule formation and lower calcification after 15 months. However, suturing of GPVG was more difficult in comparison with the other types.

Benefits, morbidity, and mortality associated with long-term administration of oral anticoagulant therapy to patients with peripheral arterial bypass procedures: A prospective randomized study

The benefits of the long-term administration of oral anticoagulant therapy remain unclear in patients with lower extremity arterial bypass surgery. We studied the effect of warfarin plus aspirin therapy (WASA) versus aspirin therapy alone (ASA) on patient mortality, morbidity and bypass patency rates in a randomized clinical trial. In a multicenter, prospective, nonmasked clinical trial, 831 patients who underwent peripheral arterial bypass surgery were compared in a long-term treatment program of WASA (target international normalized ratio of 1.4 to 2.8; 325 mg/day) with ASA (325 mg/day). The primary end point was bypass patency, and mortality and morbidity were the secondary endpoints. There were 133 deaths in the WASA group (31.8%) and 95 deaths in the ASA group (23.0%; risk ratio, 1.41; 95% confidence interval, 1.09 to 1.84; P =.0001). Major hemorrhagic events occurred more frequently in the WASA group (WASA, n = 35; ASA, n = 15; P =.02). In the prosthetic bypass group, there was no significant difference in patency rate in the 8-mm bypass subgroup, but there was a significant difference in patency rate in the 6-mm bypass subgroup (femoral-popliteal; 71.4% in the WASA group versus 57.9% in the ASA group; P =.02). In the vein bypass group, patency rate was unaffected (75.3% in the WASA group versus 74.9% in the ASA group). The long-term administration of warfarin therapy when combined with aspirin therapy has only a few selected indications for improvement of bypass patency and is associated with an increased risk of morbidity and mortality.

Features of malignant biliary obstruction affecting the patency of metallic stents: A multicenter study

Background: Although placement of a metallic stent is an established therapeutic option for the palliation of patients with malignant biliary obstruction, it remains unclear which stricture-related or stent-related factors influence stent patency. Methods: Metallic stents were inserted endoscopically in 68 patients (38 men, 30 women; mean age 70.2 ± 8.5 years) with malignant biliary obstruction. Patency rates were prospectively analyzed according to malignant stricture characteristics, including length, morphologic type, and degree of narrowing. Furthermore, patient age, initial serum bilirubin level, length of stent, time to adequate expansion, and the location of the distal end of the stent were evaluated as possible factors affecting the stent patency. Stent patency was assessed by using the survival analysis of the Kaplan-Meier estimation and Cox regression analysis. Results: Median overall stent patency was 231 days (range 27-379 days) and the overall rate of stent occlusion 41.2% (28/68). The causes of occlusion were tumor ingrowth in 23 patients (33.8%), distal overgrowth in 3 (4.4%), proximal overgrowth in 1 (1.5%), and encrustation with sludge in 1 patient (1.5%). No significant differences in patency rates according to patient age, initial serum bilirubin level, primary tumor type, length and morphologic type of stricture, and length and location of the distal end of the stent were found. Cox regression analysis demonstrated that the degree of narrowing assessed by cannula or guidewire passage and the time to adequate expansion of the stent were independent factors associated with stent patency. Conclusion: Early expansion of the stent and easy passage of larger-caliber instruments through the stricture were favorable factors for long-term patency of the Wallstent. (Gastrointest Endosc 2002;55:359-65.)

Distal Percutaneous Transluminal Angioplasty Through Infrainguinal Bypass Grafts

Aim: to evaluate the results of transluminal angioplasty (PTA) performed through infrainguinal bypass grafts for stenotic or occlusive lesions at the distal anastomosis and/or in the runoff arteries. Design: retrospective clinical study. Material and methods: forty-one patients underwent 57 procedures at the distal anastomosis (n=13), in the runoff arteries (n=32) or at both locations (n=12) at a median of 9.6 months (range, 2–76 months) after infrainguinal bypass grafting. Nineteen procedures were on the popliteal artery, the rest on the crural arteries. Eleven procedures related to occlusions less than 5 cm in length. Results: technical success was achieved in 91%. Primary and primary assisted graft patency rates at 3 years were 32% and 53%, respectively. There were no significant differences in patency rates with regard to the graft material, the type of lesion, the level of PTA, the status of runoff and the use of thrombolysis before PTA. No patients underwent amputation as a direct consequence of failed PTA or graft occlusion. One patient underwent acute surgical intervention due to graft occlusion at the time of attempted PTA. Conclusion: the results of PTA at the distal anastomosis and/or in the runoff arteries in limbs with infrainguinal bypass seemed to be inferior to the results of surgical revisions reported in literature. However, as failed PTA did not jeopardise vein-patch angioplasty or jump grafting, it is a reasonable alternative to surgical intervention in selected cases.

Central Venous Obstruction in Hemodialysis Patients: The Usefulness of Percutaneous Treatment

Purpose: To analyse the effectiveness of percutaneous treatment of central venous obstruction in patients undergoing hemodialysis. Materials and Methods: In 100 patients, 107 central venous strictures [56 subclavian (occlusion:21, stenosis:35) and 51 innominate (occlusion:23, stenosis:28)] were assessed, and 170 percutaneous angioplasty procedures were performed. Balloon dilation of the venous lumen was the preferred mode, but if dilation was incomplete we inserted a stent at the site of the stricture. Technical success, procedural complications and the long-term patency rate were evaluated, and the patency difference according to location and degree of stricture, the existence of DM, and any history of central catheter insertion were also determined. Results: We inserted 52 stents in 170 procedures, in 157 (92.4%) of which initial technical success was achieved. Stent migration occurred in two cases and balloon rupture in three. The 6- and 12-month primary patency rates were 46.2% and 24.1%, respectively, and the mean patency rate was 8.5 months. The 1-, 2- and 3-year accumulative patency rates were 59.8%, 47.5% and 35.7%, respectively, and the mean patency rate was 23.5 months. Other than in the history of central catheter insertion, there were no statistically significant differences in patency rates (p=0.0128). Conclusion: In hemodialysis patients with a central venous stricture, percutaneous angioplasty is a safe and useful procedure, but to maintain long-term central venous patency, repeated interventions are required.

Vascular Access for Dialysis in the Elderly

Aims: The aim of this study was to analyze early and late outcome of the first vascular accesses performed in the HGUGM of Madrid between 1992 and 1997, comparing the results in patients older and younger than 65 years. Methods: Retrospective study. All the vascular accesses performed in patients without previous permanent angioaccess between January 1992 and March 1997 were studied. Early failure, complication rate (patient-year of follow-up), and cumulative patency rates were analyzed. Results: The difference between grafts required in young (25%) and old patients (34%) was significant (p < 0.01). Complication rate in autologous fistulas was 0.07 per patient-year in the younger group and 0.12 per patient-year in the older (p < 0.01). Complication rate in grafts was 0.5 per patient-year in the younger group and 0.8 per patient-year in the older group (p < 0.05). There were no significant differences in patency rates for both autologous and graft accesses between patients younger or older than 65 years. Better primary patency (log-rank comparison between curves, p < 0.001), and lower complication rates (0.09 patient-year for autologous and 0.58 for grafts, p < 0.001), were observed in autologous fistulas in both groups. Conclusions: Autologous access is the best angioaccess for dialysis also in older patients and can be performed in most patients without a previous permanent access. Yet, we observed in our experience that more grafts were needed in patients older than 65 years.

Does oral anticoagulation improve femoropedal graft patency in diabetic patients? Lessons from the Dutch BOA Study

Graft patency rates after arterial reconstruction benefit from aspirin treatment. The Dutch Bypass Oral anticoagulant or Aspirin (BOA) Study, a randomized controlled trial, compared the use of oral anticoagulants (e.g. phenprocoumon) versus aspirin in a large sample of patients after infrainguinal arterial bypass surgery. Graft occlusion was the primary endpoint. A total of 2650 bypasses were performed, 531 of which were femorocrural or femoropedal grafts. Of the latter, 194 (37%) were carried out in the subgroup of 700 diabetic patients (i.e. 26% of the total study population). There was no significant difference in patency rates of these particular grafts with either drug. Hence, aspirin 100 mg/day is as effective as oral anticoagulation to benefit patency rates in femorocrural and femoropedal bypass grafts, irrespective of the diabetic status of the patients. Aspirin is sufficient, and oral anticoagulation is not required for this particular type of reconstruction.

Technical aspects and outcome of in situ right internal thoracic artery grafting to the major branches of the circumflex artery via the transverse sinus

Background. Little is known about the anatomic limitations of in situ right internal thoracic artery (RITA) grafting to the circumflex artery.Methods. To evaluate the technical aspects and outcome of revascularization of the proximal and distal major branches of the circumflex artery (obtuse marginal [OM] branch and posterolateral [PL] branch), a total of 145 patients who possessed a graftable branch of the circumflex artery were enrolled into the prospective project. There were 73 patients who had the PL branch as a primary target and 72 patients with OM branches, which were allocated by a blinded observer who reviewed the preoperative angiography.Results. Changes of primary target vessels were required in 9 patients (6.2%), yielding an overall success rate of RITA grafting of 93.8%. The success rates of RITA grafting to the OM branch and the PL branch were 95.8% (69/72; CI 88.3% to 99.1%) and 91.7% (67/73; CI 83.0% to 96.9%), respectively. The univariate analysis identified grafting under hypothermic ventricular fibrillation as predictors of inability to use in situ RITA grafting for revascularization of the circumflex artery. RITA grafting to the PL branch is not identified as a predictor. Postoperative angiography in 136 patients revealed only one occlusion (0.75%) of the RITA graft anastomosed to the marginal artery. There were no significant differences in patency rates between left and right ITA grafts.Conclusions. This prospective study showed that in situ RITA was, in most cases, able to reach most branches of the major circumflex artery and demonstrated an excellent patency rate.

Improved adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in a canine model

Purpose: A significant limitation to using genetically modified endothelial cells (ECs) to seed prosthetic grafts before implantation has been poor cell adherence to the graft lumen. Methodologic changes to improve cell adherence were evaluated in a canine carotid interposition graft model using 4 mm interior diameter expanded polytetrafluoroethylene. Methods: ECs harvested from external jugular veins were grown in culture, with 80% of the cells from each culture transduced by incubation with an LXSN-type retroviral vector carrying a gene for human prourokinase and a neomycin resistance gene for selection in antibiotic G418. Control grafts had passive luminal coating with fibronectin and were seeded with transduced ECs immediately after G418 selection; these grafts were incubated for 2 days before implantation. Experimental grafts had fibronectin forcefully squeezed through the interstices and were seeded with ECs that had recovered in culture for 5 days after G418 selection; these grafts were incubated for 4 days before implantation. For each control (n = 9) and experimental (n = 12) graft, a graft prepared in the same fashion but seeded with the remaining autologous nontransduced cells was placed in the contralateral carotid artery. Grafts were explanted after 30 days and were evaluated for patency, thrombus-free surface area, and cell-free surface area. Results: No significant differences in patency rates were seen between any groups. The thrombus-free surface area was improved for experimental grafts (90%) compared with control grafts (76%), but this improvement did not achieve statistical significance. The cell-free surface area for transduced cells on experimental grafts was 65% compared with 96% for control grafts ( p = 0.021) and was comparable with that for nontransduced cells on both control grafts (62%) and experimental grafts (51%; p = 0.201). Conclusions: Adherence of genetically modified endothelial cells to small-diameter expanded polytetrafluoroethylene grafts in an in vivo physiologic flow model is significantly improved when cells have a more prolonged recovery from G418 selection, when the graft lumen is more uniformly coated with fibronectin before EC seeding, and when seeded grafts are left longer in culture before implantation to develop cell lining stability. The short-term patency rate of these seeded grafts is not affected by increased cell retention; long-term graft patency data and luminal healing require further evaluation. (J Vasc Surg 1998;27:902-9.)

Preliminary clinical experience with polyurethane vascular prostheses in femoro-popliteal reconstruction

Following promising results in animals, implantation of polyurethane vascular prostheses for femoral reconstruction was performed in 15 patients over a 10-month period. This prospective study was carried out to evaluate the patency, limb salvage and complications associated with this type of small diameter conduit for arterial occlusive diseases. The indications for surgery included acute and chronic ischaemia, non-healing ulceration or gangrene. There were five early occlusions, which resulted in a 1-month primary patency rate of 66% and a secondary patency rate of 80%. The mean limb salvage rate at 1 month was 80% and is 66% at the present time. Infection occurred in one patient following multiple attempts at graft thrombectomy. There were no statistically significant differences in patency rates between proximal and distal popliteal graft anastomoses. Two critical phases of healing were identified where the graft was prone to flow deterioration; at 4-6 weeks and at 4-6 months. It is concluded that although this type of graft has many interesting features, e.g. the presence of endothelial cells under poor haemodynamic conditions, excellent graft-host healing and good resistance at the suture site, further investigations on protein absorption and complement activation as well as intensive structural testing are required before further recommendations can be made.

Results of high dose intravenous urokinase for acute myocardial infarction

To determine the outcome of patients after treatment with high-dose intravenous urokinase (3 million U) 102 patients were prospectively evaluated in the setting of acute myocardial infarction. The first 61 patients received intravenous urokinase as a continuous infusion and the last 41 patients were treated with an initial 1.5 million U intravenous bolus. Sixty-two percent of all patients had patent infarct-related arteries by the time of immediate angiography (median time 2.2 hours), which was performed in all patients. There was no significant difference in patency rates between patients treated with or without an initial intravenous bolus. Twenty-eight (28%) patients developed clinical evidence of recurrent ischemia (death, reocclusion, emergency angioplasty, urgent bypass surgery) during hospitalization, whereas only 7 (7%) developed angiographically documented reocclusion. Of 28 patients who failed to achieve successful reperfusion at the time of immediate catheterization, rescue angioplasty was technically successful in establishing reperfusion in all but 1 patient. No significant improvement in median global left ventricular function was seen between immediate (48%) and follow-up catheterization (48%). Significant bleednig complications were unusual except in 1 patient who experienced an intracranial hemorrhage. Eight (8%) patients died during hospitalization. Therefore, the use of high-dose intravenous urokinase in patients with acute myocardial infarction is associated with a 62% patency rate, a low incidence of reocclusion and bleeding complications and a high technical success rate with rescue angioplasty at the time of immediate catheterization. This study supports the need for further randomized controlled trials comparing intravenous urokinase directly with other thrombolytic regimens.

Effect of heparinized irrigating solutions on patency of experimental microvascular anastomoses

The effect of five different irrigating solutions on patency of four different types of microvascular anastomoses was studied. The solutions used were lactated Ringer's without heparin and four lactated Ringer's solutions with varying concentrations of heparin ranging from 10,000 units/liter to 100,000 units/liter. These were tested on four different anastomotic models in the rat: 1) end-to-end femoral arterial anastomosis; 2) end-to-side arterial bypass graft; 3) end-to-end venous anastomosis; and 4) end-to-side venous bypass graft. There were statistically significant differences in patency rates among the solutions only in the end-to-end venous anastomosis group. In these, significantly higher patency was achieved with heparinized lactated Ringer's solution at 20,000 units/liter. The use of higher concentrations of heparin in these solutions resulted in decreasing patency rates and appears to be contraindicated.

Patency Rate of Small Caliber Fibrous Polyurethane Vascular Prostheses Implanted in the Dog Carotid and Femoral Artery Improved by Use of Acetylsalicylic Acid and Dipyridamol

Segments of 3 mm diameter fibrous polyurethane vascular prosthesis of length 3-4 cm were prepared. They were bilaterally implanted in the carotid and femoral arteries of male and female beagles. Four groups consisting of animals receiving either no medication or thrombocyte aggregation drugs were studied: Group A (8 dogs), no medication: group B (19 dogs), 500 mg acetylsalicylic acid (ASA) once daily and 25 mg dipyridamol (DIP) three times daily orally for 6 weeks after the implantation operation; group C (14 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 6 weeks after the implantation operation; group D (12 dogs), 250 mg ASA and 25 mg DIP three times daily orally for 25 weeks after the implantation operation. Medication was started one week prior to the implantation operation. In group A, all prostheses were occluded at week 6. There was a significant difference in patency rates between groups B-D and C-D. No significant differences in patency rates could be found between groups B and C. The best patency rates were obtained 25 weeks after implantation in group D for both the right and left carotid and right and left femoral implantation sites. Highest patency rates were observed when ASA and DIP were given for 25 weeks.

Three years experience with denaturated venous homografts as an arterial substitute: A clinical, pathological and immunological study

Over a three-year-period 105 peripheral arterial reconstructions were performed using a denaturated venous homograft in a group of patients with no suitable autologous vein. A retrospective analysis has been carried out to investigate the patency rate of this graft. After three years 64% of all grafts are functioning well (according to the Life Table Method, Kaplan & Meyer). No significant differences in patency rates were found between reversed autologous veins and the material tested in this study but analysis of grafts removed after failure showed obstruction due to thrombosis or aneurysmal dilatation. No evidence of an immune response to the grafts was seen.