Heat-denatured albumin-coated Dacron vascular grafts: physical characteristics and in vivo performance

Dacron fabrics with a wide range of porosities were autoclaved for 3 minutes after being soaked in serum, 5% albumin, or 25% albumin. Porosity of compound Dacron grafts made with 25% albumin was less than 1 ml/min/cm2 regardless of the fabric base, whereas porosity of grafts made with serum or 5% albumin was proportional to the porosity of the base fabric. Porosity of the compound grafts remained stable for more than 48 hours and to pressure greater than 450 mm Hg, if the grafts were kept moist. Tubes of Marlex mesh coated with heat-denatured albumin, implanted as infrarenal aortic replacements in dogs, showed complete albumin absorption by 3 weeks. However, perigraft tissue reaction and graft incorporation were minimal and extensive false aneurysm formation resulted. Knitted filamentous Dacron 6 mm tubes coated with heat-denatured albumin were implanted as iliofemoral bypass grafts in 12 dogs, with blood-preclotted knitted filamentous Dacron grafts implanted as contralateral control grafts. Comparison of the albumin-coated grafts with the blood-preclotted control grafts showed no differences in healing or patency at 4 to 6 months. Heat-denatured 25% albumin forms a strong and hemostatic coating regardless of fabric base. Albumin-Dacron compound grafts are easily and rapidly made in the operating room, handle well, and are suitable for large and medium-sized arterial replacements without changes in healing or patency. Because of slow tissue incorporation, however, albumin-coated knitted Dacron grafts should be avoided in patients who require long-term anticoagulation therapy.     

Regeneration of endothelium in knitted and velour dacron vascular grafts in dogs

Velour Dacron vascular grafts have been developed for clinical use because previous investigations of conventional fabric grafts in animals suggested that fibroblastic ingrowth contributed directly to neoendothelialization. In order to determine whether fibroblastic ingrowth was casually related to regeneration of endothelium in velour grafts, composite grafts of knitted and velour Dacron were used to replace either the carotid arteries or the abdominal aorta in 12 adult dogs and were studied by scanning electron microscopy and light microscopy. Partial or complete endothelialization occurred in all aortic grafts. Regeneration of endothelium was identified in three of six carotid velour grafts but was not observed in carotid knitted grafts. although velour grafts stimulated more aggressive perigraft fibrosis in both carotid and aortic replacement than did knitted grafts, transmural migration of fibroblasts from perigraft tissues was not observed in any specimen. The results of this study do not support a causal relationship between fibroblastic ingrowth and regeneration of endothelium in dogs.     

Seeding arterial prostheses with vascular endothelium. The nature of the lining.

Arterial prostheses seeded with autogenous vascular endothelium demonstrate a well-organized, cellular, inner lining. To determine the nature of the lining cells, six animals underwent replacement of the infrarenal aorta with Dacron prostheses. During the preparation of three such grafts, endothelium was scraped from the saphenous vein with a steel wool pledget, suspended in chilled Sack's solution, and mixed with blood used to preclot the graft. This suspension was omitted from the three control grafts. After six weeks, the grafts were removed, rinsed and examined. Fluorescent Factor VIII related antigen (F VIII-RA) strongly stained the lining cells. Silver nitrate Haütchen and electron microscopy preparations revealed a lining pattern characteristic of vascular endothelium. Endothelial cell-specific Weibel-Palade bodies were identified in the lining cell cytoplasm. Masson's trichrome staining revealed a relatively collagen-poor connective tissue within the seeded fabric. Transmission electron microscopy disclosed vascular smooth muscle cells between the seeded graft fabric and the lining cells. Vasa vasorum, arising from the outer capsule, penetrated the fabric to supply the inner capsules of the seeded grafts. It is concluded that the cells lining seeded canine arterial prostheses are true vascular endothelium supported by vascular smooth muscle cells, that the lining contains minimal connective tissue, and that vasa vasorum develop. Unseeded control grafts lacked these features.     

Aortoduodenal fistula arising from the dilatation of a knitted dacron graft: Report of a case

A fatal aortoduodenal fistula occurred in a 72-year-old man who underwent a repair of an abdominal aortic aneurysm 16 years previously with a 20×10 mm bifurcated knitted Dacron graft. The aortic part of his bifurcated graft had dilated to 40 mm in diameter, with a discrepancy of 20 mm in the diameter between the graft and infrarenal aorta. The fourth portion of the duodenum adhered to the left side of the anastomosis, where the aortoenteric fistula had occurred. We believe that the graft dilatation was the cause of the anastomotic failure, although other factors such as atherosclerotic degeneration of the host aorta should also be considered. Knitted Dacron grafts that have been implanted for more than 10 years should therefore be monitored carefully because they have an inherent tendency to dilate, especially those manufactured before 1981.     

Primary anastomotic bonding in polytetrafluoroethylene grafts?

Previous studies have demonstrated that standard knitted and woven fabric grafts are forever dependent on the suture material for anastomotic tensile strength. Clinical experience with polytetrafluoroethylene (PTFE) and double velour knitted grafts have shown that there is extensive fibrous capsular bonding between the graft and the surrounding tissues. This would lead to increased anastomotic tensile strength. To test this theory, 34 mongrel dogs underwent replacement of their infrarenal aortas with grafts made of PTFE (10 dogs), of double velour knitted Dacron (DVD, 11 dogs), of single velour knitted Dacron (SVD, 5 dogs), and of woven Dacron (WD, 8 dogs). One anastomosis was constructed with 5-0 Prolene and the opposite anastomosis was constructed with 5-0 Dexon (average absorption time, 21 days). In five grafts each of PTFE and DVD, as well as in all eight WD grafts, the midgraft was divided and resutured with 5-0 Dexon. All grafts were harvested together with adjacent proximal and distal aorta between 3 and 10 months from the time of implantation. The tensile strength of each anastomosis was measured with a tensiometer. The mean graft-to-artery (absorbable suture) anastomotic tensile strength, in pounds, for PTFE (14.3) and DVD (12.6) was significantly higher than that for SVD (6.9) or WD (7.2) (p less than 0.003). Graft-to-graft anastomotic tensile strength for PTFE (mean 17.3) was significantly better than that for DVD (mean 9.0; p less than 0.03) or WD (mean 7.9; p less than 0.001). Analysis of anastomotic tensile strength as a function of time revealed continued increase in PTFE in contrast to a slow decline with time in DVD.(ABSTRACT TRUNCATED AT 250 WORDS)     

Experimental infection of dacron and bovine grafts.

This study compared the susceptibility of Dacron and ficin treated bovine grafts, implanted in dogs, to infection induced by a staphylococcal bacteremia. Forty mongrel dogs had a 2-cm segment of the infrarenal aorta replaced with either a 6-mm diameter Dacron or bovine graft. The dogs were divided into four groups: Control Groups I and II consisted of 5 dogs with Dacron grafts and 5 dogs with bovine grafts, respectively. In Group III, 16 dogs had Dacron grafts implanted and were given a S. aureus bacteremia. Group IV consisted of 15 dogs with bovine grafts subjected to S. aureus bacteremia. All dogs were sacrificed at 6 wk postoperatively, unless death occurred earlier. The grafts were cultured in beefbrain broth, plated, and bacterial growth identified by phage typing. Control Groups I and II showed no growth on cultures of the grafts. In Group III (Dacron grafts) 5 dogs died between the seventh and ninth postoperative days due to disruption of the infected anastomoses. Fifteen of the 16 Dacron grafts yielded growth of S. aureus phage type 29/52/81 on culture. All 15 bovine grafts in Group IV were infected with S. aureus and there were 14 deaths between days 5 and 8 due to hemorrhage from the disrupted grafts. It is concluded that Dacron and bovine grafts are equally susceptible to bacteremic infection, but disruption occurs more frequently and earlier in the infected bovine graft.     

The effect of pancreatopeptidase E (elastase) on anastomotic intimal thickness in two types of vascular prosthesis

To determine the effects of pancreatopeptidase E (elastase) on anastomotic intimal thickness in vascular prostheses, expanded polytetrafluoroethylene (ePTFE) and Dacron grafts were implanted in the infrarenal aortas of 28 adult mongrel dogs, divided into four groups of seven dogs each according to the type of graft used and whether or not elastase was given. Thus, group E received ePTFE grafts without elastase; group D received Dacron grafts without elastase; group E + Ela received ePTFE grafts with concomitant oral elastase, 8 mg/kg per day; and group D + Ela received Dacron grafts with elastase given at the same dosage as in group E + Ela. Each graft was harvested 4 months following surgery for histologic examination. It was clearly observed that elastase suppressed intimal growth at the proximal and distal anastomoses in the ePTFE grafts (P<0.05), but not in the Dacron grafts. Furthermore, when we measured the smooth muscle cell percent extinction (%E) on microspectrophotometry in the intima within 2 mm of the proximal and distal anastomoses, it was found that elastase reduced intimal smooth muscle proliferation at the anastomosis of the ePTFE grafts, but not the Dacron grafts (P<0.05). These data suggest that elastase suppresses intimal growth by inhibiting smooth muscle cell migration and proliferation in the vascular prostheses of low but not of high porosity.     

The effect of anti-thrombotic drugs on prosthetic grafts in the canine inferios vena cava.

The effect of phenylbutazone, an anti-thrombotic agent, on the occlusion rate of knitted Dacron grafts placed in the infrarenal inferior vena cava of dogs was studied. Grafts places in dogs treated with phenylbutazone remained patent significantly longer than those in untreated animals. All the grafts in the untreated group occluded, but 2 remained patent in the treated animals.     

Use of an antibiotic-bonded graft for in situ reconstruction after prosthetic graft infections.

We have developed an infection resistant vascular prosthesis by bonding rifampin to Dacron grafts with the use of a collagen matrix release system. The purpose of this study was to determine the efficacy of this antibiotic-bonded graft in resisting infection after an in situ reconstruction of a previously infected prosthetic bypass. Eighty-three adult mongrel dogs underwent implantation of a 3 cm untreated Dacron graft into the infrarenal aorta. This initial graft was deliberately infected, at the time of operation, with 10(2) organisms of Staphylococcus aureus by direct inoculation. One week later, the dogs were reexplored, the retroperitoneum debrided, and the animals randomized to undergo an end-to-end in situ graft replacement with either one of two types of prosthetic grafts: group I (collagen, n = 36) received control collagen-impregnated knitted Dacron grafts; group II (rifampin, n = 47) received experimental collagen-rifampin-bonded Dacron grafts. Each group of animals was then subdivided to receive one of four treatment protocols: (a) no antibiotic therapy, (b) cephalosporin peritoneal irrigation solution (cefazolin 500 mg/1000 ml) during operation and two doses of cephalosporin (cefazolin, 500 mg intramuscularly) postoperatively, (c) treatment as in protocol group b plus 1 week of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily), and (d) treatment as in protocol group b plus 2 weeks of cephalosporin (cefazolin, 500 mg intramuscularly, twice daily). All grafts were sterilely removed between 3 and 4 weeks after implantation. There were no anastomotic disruptions and all grafts were patent at the time of removal.(ABSTRACT TRUNCATED AT 250 WORDS)     

Comparison of polytetrafluoroethylene (PTFE) and dacron as long, small-diameter arterial grafts in dogs

A canine model in which joined carotid arteries were anastomosed to 6-mm grafts (average length, 45 cm) of polytetrafluoroethylene (PTFE) or Dacron double velour and the grafts were anastomosed to the ligated distal abdominal aorta was used to study long-term graft patency. The 16 dogs with PTFE grafts and the 15 dogs with Dacron grafts were sacrificed at three-, six-, and 12-month intervals, or whenever a graft occluded. At three months, eight of 11 PTFE and 11 of 11 Dacron grafts were patent; at six months, two of three PTFE and three of three Dacron grafts were patent; at 12 months, one of two PTFE grafts and the one remaining Dacron graft were patent. All grafts were examined grossly and microscopically. The PTFE grafts showed increasing degrees of calcification and intimal fibrin deposition; the Dacron grafts had no calcification and less intimal fibrin deposition. The model was satisfactory for studying long, small-diameter vascular grafts, but PTFE was not found to be superior to Dacron in this study.     

Efficacy of TachoSil? patches in controlling Dacron suture-hole bleeding after abdominal aortic aneurysm open repair

Purpose  

The aim of this study is evaluate the efficacy of TachoSil^? patches in controlling suture-hole bleeding after elective infrarenal abdominal aortic aneurysm (AAA) replacement with Dacron graft.     

An experimental study of the strength in arterial prosthetic anastomoses: relationship between anastomotic tensile strength and its organization]

Five types of 6-mm diameter arterial prostheses, i.e.m woven Teflon, woven Dacron, velour woven Dacron, velour knitted Dacron and expanded polytetrafluoroethylene (E-PTFE), were studied in the dog to assess anastomotic tensile strength and its organization. Five types of composite grafts, about 3.0cm in length, were implanted in the abdominal aorta of fifty-two adult mongrel dogs using absorbable polyglycolic acid suture. At 16 weeks after the implantation, if the composite graft was patent, tensile strength of the bilateral anastomoses were measured and its organizations were examined microscopically. The mean forces required to disrupt the anastomoses of velour woven Dacron, velour knitted Dacron and E-PTFE were greater than those of woven Teflon and woven Dacron. At the disrupted sites of woven Teflon and woven Dacron, which were non-velour grafts, fibrous outer sheath were remarkably separated from the grafts. This results indicate that organization and fixation of fibrous outer sheath are the most important factors in the strength of arterial prosthetic anastomoses and velour grafts have superiority over non-velour grafts. The organization of E-PTFE was poor, but its tensile strength was equal to velour grafts. It is considered E-PTFE has an advantage due to non-crimped structure and requires further evaluation over longer period.     

Improvement in experimental vascular graft patency by controlled defibrinogenation.

A sensitive animal model was used to investigate treatment designed to improve vascular graft patency. A Dacron graft was inserted into the infrarenal vena cava of 30 rabbits. Half were treated with subcutaneous Arvin for 28 days after operation. This produced a significant lowering of the post operative plasma fibrinogen. The patency rate of the grafts in the treated rabbits was significantly greater than in the control rabbits.     

The role of endothelium in the patency of small venous substitutes

Twenty-one dogs received Dacron grafts (9 dogs) or silastic Replamineform prostheses (12 dogs) as unilateral segmental femoral vein substitutes. Eight autogenous endothelialized Dacron grafts and eleven autogenous endothelialized silastic Replamineform grafts were also placed as femoral vein substitutes. The latter two groups of grafts had been implanted into the infrarenal aorta for 12 weeks and were well endothelialized as demonstrated by scanning and transmission electron microscopy. Patency was assessed by venography immediately and on Days 3, 7, 14, and 21 post-operatively. Endothelialized Dacron grafts had greater percentage patency ($\text{4}\text{8}$, 50%) than Dacron grafts ($\text{1}\text{9}$, 11% (P = N.S.). Endothelialized silastic Replamineform prostheses had significantly better patency ($\text{9}\text{11}$, 82%) than silastic Replamineform prostheses ($\text{0}\text{12}$, 0%) (P < 0.02). The combined results of the endothelialized grafts ($\text{13}\text{19}$, 69%) were better than the combined results for the Dacron-silastic Replamineform grafts ($\text{1}\text{21}$, 5%) (P < 0.005). These data indicate that Dacron and silastic Replamineform grafts are not suitable small venous substitutes. Conversely, endothelialization significantly improves the early and late patency of both silastic Replamineform grafts and Dacron grafts. The endothelialized silastic Replamineform prosthesis is the only prosthesis which achieved continuous patency (comparable to autogenous vein grafts) in this experimental model.     

Serious complications that require surgical interventions after endoluminal stent-graft placement for the treatment of infrarenal aortic aneurysms

BACKGROUND: Endoluminal stent-graft placement for the treatment of infrarenal abdominal aortic aneurysms has gained widespread acceptance because it is associated with lower peri-interventional morbidity than conventional transabdominal surgery. In this study the long-term morbidity of the procedure was evaluated. METHODS AND RESULTS: Between September 1994 and December 1998, 150 patients (age, 69.6 +/- 8.49 years; 142 men, 8 women) with abdominal aortic aneurysms were treated with the placement of an intravascular nitinol stent-graft (Stentor [55] and Vanguard-System [95]); there were eight tubular grafts and 142 bifurcated grafts. Initial placement of the stent-graft was successful in 144 patients. Mean follow-up was 49 +/- 25 months. In 13.3% of stent-graft placements we encountered the following complications: 4 cases of migration or dislocation of the prosthesis (30.5 +/- 7.4 months after placement); 2 ruptures of the aorta (26.7 and 15.0 months after placement); 3 recurrent thromboses of the stent-graft (25.5 +/- 5.3 months after placement); 3 endoleaks (27.5 +/- 15.7 months after placement); and 5 infections of the prosthesis (26.6 +/- 16.5 months after placement). There was no correlation between the complications and the type of stent used. All of these patients were treated by surgical replacement of the prosthesis with a Dacron graft. CONCLUSIONS: (1) The results suggest that most complications are due to a continuation of the disease process leading to loosening of the prosthesis. (2) Explantation of the prosthesis and surgical repair is feasible but bears additional risks. (3) Because the onset of reperfusion of the excluded aneurysm cannot be predicted, all patients with infrarenal aortic stent-grafts require frequent computer tomographic follow-up. (4) Finally, the results call for further improvements in the design of the stent-graft.     

Prospective randomized trial of polytetrafluoroethylene and dacron aortic prosthesis. I. Perioperative results

Over a two year period 80 patients were entered into a prospective randomized trial comparing polytetrafluoroethylene (PTFE) and Dacron infrarenal aortic reconstructions. Fifty-four patients were treated for aneurysm (30 single tubed grafts; 24 bifurcation grafts), and 26 patients were treated for occlusive disease (26 bifurcation grafts). The groups were matched for age, sex and preoperative risk factors. Five patients died after operation (6.3%) including two from hemorrhage, but there were no significant differences in mortality and morbidity between the PTFE and Dacron groups. The volume of blood lost at operation (1930 +/- 1340 ml, all patients); the volume of blood transfused (2.98 +/- 2.43 units); the volume of crystalloids infused (3050 +/- 1390 ml); the intraoperative heparin dosage (67.9 +/- 20.5 mg); the clamp time (71.6 +/- 34.5 min); and the total operating time (228.1 +/- 78.3 min) also showed no significant differences between PTFE and Dacron. The ankle systolic pressure index rose more for PTFE (0.96 +/- 0.24) than for Dacron (0.82 +/- 0.20; P less than 0.002) at the time of discharge. This partially reflects a difference in the index between the groups before operation (PTFE 0.79 +/- 0.30; Dacron 0.72 +/- 0.32), but it may also indicate that PTFE is less thrombogenic than Dacron.     

Open stent grafting for abdominal aortic aneurysm in a patient with a severely calcified abdominal aorta

We describe a 74-year-old male who underwent open stent repair for an infrarenal abdominal aortic aneurysm with a severely calcified aortic neck. The stent graft was constructed by covering a 50-mm long Gianturco Z stent (diameter: 20 mm) with a Dacron prosthesis (diameter: 20 mm). The stented Dacron graft was inserted into the calcified aortic neck, was then sutured to the trimmed aneurysmal wall, and was anastomosed to a bifurcated prosthesis. The distal ends of the bifurcated prosthesis were anastomosed to both common femoral arteries, and the terminal aorta was closed. The patient had an uneventful postoperative course. This procedure may be a feasible and safe way to repair infrarenal abdominal aortic aneurysm with a severely calcified aortic neck.     

Intrinsic Structural Failure of Polyester (Dacron) Vascular Grafts. A General Review

Intrinsic structural failure of Dacron prostheses is a late exceptional complication, resulting from a loss of structural integrity of the graft.

The authors report six cases of non-anastomotic false aneurysms in the mid-portion of a vascular Dacron graft, observed at a mean of 12 years after insertion. It concerns four femoro-popliteal bypass grafts, one cross-over graft and a branch of a bifurcated aorto-bifemoral graft, implanted between 1980 and 1990. This represents 0.2% of all vascular Dacron grafts implanted in authors’ department since 1980.

The degenerated prosthesis was excised, and a new bypass graft was inserted. In three cases, histological analysis revealed a foreign body giant cell reaction against fragmented Dacron fibers. In none of the cases there was evidence of graft infection.

The authors discuss the evidence and etiopathogeny of this late, unusual complication, inherent to the Dacron graft material. The most probable causative factor is material fatigue, leading to gradual breakdown and fragmentation of individual fibers, and subsequent biodegradation of the basic material. Such an intrinsic weakness of prosthetic fabric has only be observed in first and second generation Dacron grafts.     

Human umbilical cord vein as arterial substitute in the dog

The aim of this study was to compare human umbilical cord vein grafts (HUCV), treated in different ways, as arterial substitutes in the dog. A portion of the infrarenal abdominal aorta was replaced by a fresh HUCV in 18 dogs. Six HUCV grafts were covered with a vascular dacron prosthesis, 4 of them stayed open during a follow-up time of one year, 2 became occluded. Within an interval of 4 weeks, aneurysms developed in the uncovered 12 HUCV grafts. They also thrombosed within 3 months. The infrarenal abdominal aorta was replaced by HUCV grafts treated with glutaraldehyde in 39 dogs. Within a follow-up time of six months, all grafts were patent and no aneurysm formation could be observed. Eight biografts were compared with eight PTFE grafts ileofemoral positions. Six Biografts as well as six PTFE grafts were patent after six weeks.     

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.