Late rupture of knitted velour Dacron arterial prostheses

Rupture of a Dacron arterial prosthesis is a most unusual complication, although it has been reported previously. Three further such cases are reported with a brief review of the relevant literature.     

The effects of aortic reconstruction and collagen impregnation of Dacron prostheses on the complement system.

Complement activation has been associated with numerous clinical hazards such as platelet aggregation, adult respiratory distress syndrome, and renal dysfunction. The complement system is activated by exposure of different biomaterials to blood. Recently a watertight knitted Dacron aortic prosthesis impregnated with bovine collagen has been developed. One potential disadvantage is that this bovine collagen may activate the complement system and evoke the production of inflammatory mediators. We conducted a prospective randomized trial to study the systemic effects of collagen-impregnated prostheses and of aortic surgery with implantation of Dacron prosthesis on the complement system in the perioperative period and at 3 months after operation. Forty-one patients randomly received either a collagen-impregnated (n = 20) or a nonimpregnated prosthesis (n = 21). Twelve patients who had cholecystectomy served as controls. CH50 consumption and C3a generation were determined to study overall complement activation. Furthermore, C3a/C3 fractions were calculated. Finally, C4 and factor B consumption were determined to evaluate the complement stimulation via the classic and the alternative pathways, respectively. We found significant activation of the complement system during the operation in both the collagen group (CH50 consumption: 40%, p = 0.03; C4 consumption: 74%, p < 0.0001; factor B consumption: 73%, p < 0.0001; C3a/C3 fraction increase: 173%,p = 0.04), and the nonimpregnated group (CH50 consumption: 40%, p < 0.0001; C4 consumption: 71%, p < 0.0001; factor B consumption: 76%, p < 0.0001; C3a/C3 fraction increase: 165%, p = 0.025), with no statistically significant differences between the groups of prostheses. Activation was initiated via both the classic and the alternative pathway. This indicates aortic implantation significantly activates the complement system, but that collagen-impregnated prostheses do not stimulate the complement system any more than its nonsealed substrate. Comparing results in patients with vascular disease with controls, a significantly increased complement activation was observed in the vascular group (CH50 consumption: 40%, p < 0.0001; C4 consumption: 74%, p < 0.0001; factor B consumption: 75%, p < 0.0001; C3a/C3 fraction: 169%, p = 0.002), compared with the controls (CH50 consumption: 71%; C4 consumption: 104%; factor B consumption: 94%; C3a/C3 fraction: 119%, all p = NS), with statistical significant differences between the vascular group and cholecystectomies (CH50: p = 0.005; C4: p = 0.002; factor B: p < 0.0001, and C3a/C3 fraction: NS). This observation demonstrates that aortic surgery with the implantation of a Dacron prosthesis significantly activates the complement system.     

Late rupture of knitted Dacron double velour arterial prostheses. Report on four cases

Late fibre breakage with longitudinal tears occurred in 4 patients of a series of some 300 implanted knitted Dacron double velour arterial prostheses. The four patients all received their grafts for occlusive aortoiliac disease in the year 1978, and the rupture was found 4 to 6 years later. Three of the failures occurred in axillo-bifemoral bypass grafts, whereas the fourth patient had a bifurcated aortic prosthesis. Dilatation was significant in the latter graft only. Structural weakness might appear during production, during later handling, or possibly as a result of interference from infected material or host factors. The cause of graft failures in the present series could not be ascertained. Whatever type of knitted Dacron used, a 2-3% incidence of graft deterioration might be expected. Therefore regular, life-long follow-up of patients with Dacron arterial prostheses seems warranted.     

Comparison of knitted and woven aortoiliac and aortofemoral Dacron prostheses in the same patient: a 10-year prospective study

This study represents the final and concise evaluation of all data obtained in a ten-year follow-up period and is a continuation of our previously published investigations. A specially manufactured bifurcated aortic graft with one limb woven and the other knitted was implanted in the aortoiliac or aortofemoral position in 158 patients. During an observation period ranging up to 10 years, no statistically significant difference was found either in platelet adherence or in clinical patency. According to the results of this and previous studies, the pore size of Dacron grafts in these positions does not seem to play any significant role either in platelet adherence or in patency rate. A high mortality rate from cardiovascular disease in the same patient population was also noted.     

The biologic fate of Dacron double velour vascular prostheses —A clinicopathological study—

Thirty-one Dacron double velour prostheses removed from 16 patients were studied microscopically in order to elucidate the changes they underwent following implantation. The process of incorporation was divided into three phases. In the initial phase, immediately following the implantation, the prostheses became surrounded by a fibrin meshwork. In the organizing phase, which sets in 10 weeks after the implantation, there was an external fibrous capsular formation around the initially fibrin-infiltrated grafts. There was also fibroblastic ingrowth and granulation formation among the interstices and the prostheses showed firm adhesion to the surrounding tissues. One year following the implantation, after most of the luminal surfaces had been covered with collagen tissues, the cellular infiltration subsided and the graft passed into the stable phase. Foreign body giant cells and lymphocytes were seen throughout the study period. These prostheses were then compared with other prostheses which do not have velour structures. The nonvelour grafts showed less adhesion to the surrounding tissues. Microscopically, cellular reaction and collagenous ingrowth were also less. The velour surface thus seems to stimulate granulation ingrowth and to contribute to the firm adhesion of the graft to the surrounding tissues. This firm adhesion enhances resistance to infection and is considered safer in case of suture aneurysm formation.     

A comparison of knitted Dacron velour and bovine heterograft for hemodialysis access.

Knitted Dacron velour prostheses (D) and bovine heterografts (BH) were alternately used for vascular access in 35 adult male patients with chronic renal failure. These conduits (21 D, 23 BH) were placed in the arm between the brachial artery and axillary vein in patients with failed Brescia-Cimino fistulas. Results were expressed as a cumulative function rate (CFR) and cumulative patency rate (CPR) for each material, and were compared using the life table method. CFR and CPR at 24 months were 79 and 32%, respectively, for D, while these values were 60 and 41%, respectively, for BH, and these differences were not significant (P > 0.05). Complications of thrombosis, infection, pseudoaneurysm, and distal ischemia occurred in comparable numbers of D and BH. However, D resisted infection with local treatment, was more readily available at lower cost, and proved easier to revise as required clinically. We recommend greater use of D in vascular access for hemodialysis.     

Use of Dacron velour in choledochoplasty. An experimental study

Patch choledochoplasty for experimentally produced defect and annular stricture and replacement choledochoplasty with Dacron velour was carried out in 20 healthy mongrel dogs with a maximum follow-up of 485 days. There was no derangement of liver functions after patch choledochoplasty for defect and replacement choledochoplasty. Elevated levels of serum bilirubin and alkaline phosphatase observed after stricture production returned toward normal following choledochoplasty. Flat diameter of the common bile duct could be increased significantly after patch choledochoplasty for defect and annular stricture. There was no change in the flat diameter of the common bile duct at the anastomotic sites after replacement choledochoplasty. The graft became completely incorporated in the common bile duct. Neobiliary and glandular regeneration occurred over the graft, which persisted without shrinkage or fibrosis.     

Systemic effects of collagen-impregnated aortoiliac Dacron vascular prostheses on platelet activation and fibrin formation.

To minimize intraoperative blood loss a watertight knitted Dacron aortoiliac prosthesis has been developed by impregnation with bovine collagen. A potential disadvantage is that collagen may be associated with an increase in thrombus formation. We conducted a prospective randomized trial to study the systemic effects of collagen-impregnated prostheses and of aortoiliac operation as such on the coagulation mechanism during the first 10 days after operation. Forty-one patients randomly received either a collagen-impregnated (n = 20) or a nonimpregnated prosthesis (n = 21). Twelve patients who underwent cholecystectomies served as controls. Three markers of the coagulation mechanism were monitored: beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation products. We found no significant differences in median beta-thromboglobulin, fibrinopeptide A, and fibrin/fibrinogen degradation product levels between patients in the collagen-impregnated prosthesis group and patients in the nonimpregnated prosthesis group. This indicates that collagen does not stimulate the coagulation cascade any more than conventional Dacron protheses do. In a comparison of patients who underwent aortoiliac reconstruction and patients who underwent cholecystectomies, the results indicated a significant increased platelet activation and fibrin metabolism in aortoiliac reconstruction group compared with the control group. Finally, we observed a significantly higher preoperative fibrin metabolism in patients with vascular disease than in control subjects. This difference is attributable to the high preoperative fibrin/fibrinogen degradation product values in patients with aortic aneurysms.     

Failure of ultralightweight knitted Dacron grafts in arterial reconstruction.

We have observed 11 cases in which the use of the ultralightweight knitted Dacron arterial graft made by the United States Catheter and Instrument Co. (USCI) was complicated by Interstitial hemorrhage dilation, or both. Although the incidence and specific cause of failure of this graft are unknown, we have discontinued its use on the basis of this experience.     

Presence of endothelium in an axillary-femoral graft of knitted Dacron with an external velour surface.

An axillary-bilateral common femoral graft of knitted Dacron with an external velour surface was examined within one hour after the patient's death from non-graft-related causes. The prothesis, implanted for 20 months, was patent and was completely healed over 32% of the flow surface--that is, full wall fibrous tissue encapsulation of the graft had occurred, and 32% of the flow surface was endothelialized. The remaining flow surface was formed of fibrin, but fibrous tissue healing had reached the inner surface of the graft material, and the fibrin overlay was very thin. The healed protions of the graft included not only the areas adjacent to the anastomoses, but were scattered throughout the 45 cm length of the prosthesis. To our knowledge, this is the first report of complete healing (fibrous tissue encapsulation and endothelialization) documented at points beyond the plannus ingrowth at the prosthesis-artery anastomosis.     

Do collagen-impregnated knitted Dacron grafts reduce the need for transfusion in infrarenal aortic reconstruction?

The purpose of this study was to evaluate the benefits of collagen-impregnated Dacron grafts in patients undergoing infrarenal aortic reconstruction. We therefore prospectively compared two consecutive series of patients undergoing infrarenal aortic reconstruction with Dacron grafts between January 1991 and December 1992. The first group (group A) included 83 high-density knitted prosthetic grafts (Dialine I), whereas the second included 82 grafts of the same type but impregnated with collagen (Dialine II). The two groups were comparable with regard to age, sex, and operative risk factors. They were also comparable in terms of the proportion of patients with occlusive disease or aneurysms, that is, there were 39 and 36 patients with occlusive disease and 44 and 46 patients with aneurysms in groups A and B, respectively. The type of bypass was similar in both groups with 17 and 19 tubular grafts and 66 and 63 bifurcated grafts being inserted in groups A and B, respectively. Thirteen parameters were studied and compared within each group including (1) number of infected grafts, (2) number of postoperative occlusions, (3) maximum postoperative temperature, (4) number of positive postoperative blood cultures, (5) number of postoperative deaths, (6) intraoperative and (7) postoperative quantities of blood transfused, (8) difference between pre- and postoperative hemoglobin concentrations, (9) difference between pre- and postoperative fibrinogen levels, (10) difference between pre- and postoperative platelet counts, (11) duration of aortic clamping,(12) date of return of intestinal function, and (13) mean duration of pre- and postoperative hospital stays. One death, one graft occlusion, and one postoperative infection were observed in group A, whereas there were three deaths, two occlusions, and one postoperative infection in group B (difference not significant). Of all the parameters studied, the only significant difference concerned the reduction in transfusion requirements of units when a collagen-impregnated graft was inserted (p<0.05). These results are similar to those observed with other standard or collagen-coated knitted grafts. Less loss of blood, resulting in a reduced theoretic risk of viral contamination, appears to be the main advantage of collagen-coated grafts.     

Preclotting of knitted Dacron prosthesis. A scanning electron microscope study.

A scanning electron microscope study of preclotting on knitted Dacron prosthesis is reported. Five steps of the interaction are well identified: (1) before any blood contact (virgin Dacron), (2) during the first 3 minutes (fibrin and platelet aggregates), (3) fifth minute of contact (clotting), (4) 15 minutes of contact with heparinized blood (thin fibrin network), and (5) the following minutes (invasion of fibrin, which enmeshes blood cells).     

Sealed versus unsealed knitted Dacron prostheses: a comparison of the acute phase protein response

Twenty patients were randomized to receive either an untreated Dacron aortic bifurcation graft (n = 10), or a similar graft impregnated with gelatin (n = 10). Venous blood samples were taken preoperatively and at frequent intervals until five weeks after surgery. C-reactive protein (normal range less than 10 mg/l) and alpha l-acid glycoprotein (normal range 0.3-1.0 g/l) were measured. The peak mean value of C-reactive protein for the sealed group was 226.3 +/- 49.2 mg/l and 221.3 +/- 56.4 mg/l for the unsealed group. The corresponding values for alpha 1-acid glycoprotein were 1.49 +/- 0.25 g/l and 1.44 +/- 0.3 g/l. The C-reactive protein response returned more quickly to normal, with only two patients in each group having a slightly elevated response after four weeks, while the value for alpha l-acid glycoprotein remained elevated at five weeks for the same two patients in each group. There was no significant difference between the serum acute phase protein response in either group. This suggests that a knitted Dacron graft sealed with gelatin does not exaggerate the inflammatory response.     

Randomized clinical trial of the effect of a saline-linked radiofrequency coagulator on blood loss during hepatic resection

BACKGROUND: Use of a saline-linked radiofrequency coagulator (dissecting sealer) has been suggested to reduce blood loss during hepatic resection. A randomized clinical trial was conducted to assess the effects of using the device on the amount of blood loss. METHODS: Patients scheduled to undergo hepatic resection were randomly assigned to either use of the dissecting sealer or the clamp crushing method. The primary outcome measure was blood loss during liver parenchymal division. Multivariate analysis was also performed. RESULTS: Ninety-four consecutive patients underwent hepatic resection and 40 patients were assigned to each group. There were no significant differences between the dissecting sealer and clamp crushing groups in blood loss during liver parenchymal division (median 373 versus 535 ml; P = 0.252) or total intraoperative blood loss (665 versus 733 ml; P = 0.450). Multivariate analysis revealed that use of the dissecting sealer offered no protection against blood loss compared with the clamp crushing method (odds ratio 1.17 (95 per cent confidence interval 0.39 to 3.53); P = 0.777), whereas number of resections, thoracotomy and type of resection had a significant effect. CONCLUSION: Use of a dissecting sealer offered no substantial benefit over the clamp crushing method in reducing blood loss during hepatic resection.     

Dacron arterial grafts: the influence of porosity, velour, and maturity on thrombogenicity

It has been claimed that the neointimal healing of Dacron arterial prostheses can be enhanced by increasing porosity and including both an internal and an external velour layer. To test this, 24 patients received at random either woven (USCI, DeBakey, C. R. Bard, Inc.) or more porous, double-velour, knitted (Microvel, Meadox Medicals, Inc.) Dacron aortobifemoral prostheses. Graft thrombogenicity was measured using autogenous 111In-labeled platelets shortly following surgery and 6 to 9 months later. The thrombogenicity index was defined as the mean daily rise in the ratio of emissions over the graft to emissions over a reference area (aortic arch) and is a measure of platelet deposition. At early study the mean (+/- SE) thrombogenicity index was similar in woven and knitted graft patients at 0.19 +/- 0.4 and 0.14 +/- 0.2, respectively. In both groups it was lower (P less than 0.05) 6 to 9 months later at 0.06 +/- 0.2 (woven( and 0.08 +/- 0.1 (knitted), with again no difference between materials. Although platelet survival was restored to near normal values in both groups by 6 to 9 months, only one woven graft failed to demonstrate continued platelet accumulation by gamma-imaging. Thrombogenicity in Dacron grafts diminishes in the early months of maturation but is not affected by porosity and velour. Moreover, this thrombogenicity persists beyond the period of altered platelet survival.     

Are synthetic prostheses really inert? Preliminary results of a study on the biocompatibility of Dacron vascular prostheses and Silicone skin expanders.

This study investigates the histo-pathologic reactions induced by implant of prostheses in Dacron knitted double velour and skin expanders in Silicone elastomers. Particular attention was paid to the effect of these reactions on the tissue itself. In the case of vascular prostheses it was found that fibrous connective tissue tended to accumulate in and around the prosthesis. We also observed widespread lymphohistiocytic infiltration and occasional plasmacytes. Numerous foreign body granulomas were found to be grouped around the filaments of plastic material. The prosthesis itself seemed to be composed of filaments of different calibre, fragmented into particles of varying size. Thus the structure of the prosthesis was modified and discontinued along its whole length. A similar granulomatous inflammatory reaction developed in the case of the skin expander, probably due to the leakage of particles of plastic material through the expander wall, which however did not seem to be affected by the tissue reaction. The findings indicate the need for more detailed research into the material used for prostheses, aimed at determining what modifications the tissues can produce in the synthetic material. Also, it is necessary to follow a multidisciplinary approach which takes into consideration the data available from the chemistry of polymers, fluid mechanics and cell biology.     

肾下腹主动脉重建术治疗腹主动脉瘤和主髂动脉闭塞症的风险比较

目的探讨肾下腹主动脉重建在腹主动脉瘤 (abdominalaorticaneurysm ,AAA)和主髂动脉闭塞症 (aortoiliacocclusivedisease ,AIOD)中的手术风险 ,分析造成差异的可能原因。方法回顾性总结 340例 (2 2 2例腹主动脉瘤和 118例主髂动脉闭塞症 )肾下腹主动脉重建手术的临床资料。结果手术总死亡率为 7 6 % ,其中主髂动脉闭塞症手术死亡率为 11 9% ,明显高于腹主动脉瘤的5 4 % (χ2 =4 5 5 1,P <0 0 5 )。手术总并发症发生率为 2 2 4 % ,其中主髂动脉闭塞症为 2 8 8% ,明显高于腹主动脉瘤的 18 9% (χ2 =4 346 ,P <0 0 5 )。多脏器功能衰竭为两组中主要的死亡原因 ,呼吸系统感染为最主要的术后并发症。危险因素中 ,男女性别比、吸烟状况、糖尿病 3个因素在AOID组明显高于AAA组 (P均 <0 0 1) ,高血压、心电图ST段改变、肺功能不全等AIOD组也高于AAA组 ,但差异无显著意义。年龄构成、肾功能不全和手术时间等两组无统计学差异 ,输血量AAA组明显高于AIOD组。结论主髂动脉闭塞症手术风险高于腹主动脉瘤 ,吸烟、糖尿病、重要脏器功能状况是造成手术风险差异的主要原因。     

Three-year outcome of the covered endovascular reconstruction of the aortic bifurcation technique for aortoiliac occlusive disease

Objective

The objective of this study was to demonstrate the 3-year outcome of the covered endovascular reconstruction of the aortic bifurcation (CERAB) technique for the treatment of extensive aortoiliac occlusive disease (AIOD).

Control of blood loss during sacral surgery by aortic balloon occlusion

Radical sacral surgery can be associated with life-threatening blood loss. Effective and safe methods for controlling this blood loss remain elusive. We here report the use of an inflatable sizing balloon to intermittently occlude the distal abdominal aorta and control blood loss during sacral tumor resections. The balloon catheter was introduced into the abdominal aorta via the femoral artery. Pulse oxygen saturation signals from bilateral toes and ultrasonography were used to guide and confirm the location of the balloon in the abdominal aorta and distal to the renal arteries. The balloon was deflated for 10 min after each 60 min occlusion period. In five patients undergoing sacral tumor resection, the estimated blood loss when using balloon occlusion was <300 mL, and surgical duration was <2 h. No significant change in kidney, pelvic organ, and lower extremity function was found after the surgeries. Percutaneous aortic balloon occlusion can provide safe and effective control of blood loss during sacrococcygeal tumor resection.