Polish vascular prostheses

Vascular prostheses have been manufactured in Poland since 1960. Double velour crimped tube and bifurcation prostheses are currently available under the Trade Mark Dallon. The Authors present and discuss 812 grafting procedures for the aorto-iliac occlusive disease with the use of 457 Polish and 355 foreign-made vascular prostheses. Wound infection occurred in 7% of the patients with implanted Polish prostheses and in 6.8% of the patients with implanted foreign-made vascular grafts. The acute thrombosis of the operated artery was similarly frequent in case of Polish and foreign-made prostheses implantation, 7% and 6.8% respectively. Haemorrhagic complications were more frequent in patients with implanted Polish prostheses (1.7%) than those with foreign-made vascular grafts (0.8%). Early results of the grafting procedures (6-month follow-up) were nearly the same in both groups and the results reported in the available literature. The Authors conclude that the Polish knitted vascular prostheses have properties similar to the foreign-made ones.     

Soviet-made vascular prostheses

The authors present some facts concerning the history of developing synthetic vascular prostheses in the Soviet Union, the data pertinent to the Soviet and some foreign models of synthetic vascular grafts, dwell on their characteristics. The authors discuss further possible modifications of vascular prosthesis. The vascular prosthesis is considered as an artificial false aneurysm within a synthetic frame, in this connection they discuss favourable possibilities of application of vascular grafts in arterial injuries and its consequences. The authors also provide information on some new types of vascular prostheses, velour and rough ones in particular, as well as microprosthesis.     

Reduced thrombogenicity of vascular prostheses by coating with ADP-ase.

In this pilot study ADP-ase coated polyurethane (PU) vascular prostheses and noncoated (control) PU vascular prostheses (all vascular prostheses: ID 1.5 mm, length 1.5 cm) were implanted into the carotid artery of the rabbit to test whether ADP-ase might function as an adequate anti-thrombogenic coating. The prostheses were evaluated after 1 hour (n = 4) and 3 weeks (n = 8). After 1 hour, there was extensive accumulation of thrombus on the inner surface of the control PU vascular prostheses, in contrast to the ADP-ase coated prostheses. At 3 weeks, all control PU vascular prostheses (n = 8) were occluded, whereas only 1 of the 8 ADP-ase coated PU vascular prostheses. The patient ADP-ase coated PU prostheses showed already extensive endothelial healing. These results indicate the potential of ADP-ase to function as an effective antithrombogenic coating of small-caliber and microvascular PU prostheses.     

Morphology of healing in vascular prostheses

Vascular grafts differ in shape and size, material, mode of construction, and porosity. The latter was found to be of great importance with respect to tissue response of the host to the graft. The first reaction of the host after implantation represents the phase of exsudation. An aggregate of platelets and fibrin will cover most of the luminal and external surface of the graft, which is also seen between the interstices. The following phase of resorption develops within 2 weeks. It is characterized by replacement of the fibrinous material on the outer surface and between the interstices by capillaries, histiocytes, and myofibroblasts. Organisation of the outer capsule will then occur, and is also seen inside the transprosthetic bridges within one month. However, organization of the luminal lining remains very slow and is almost never completed. Healing depends on blood flow and local hemodynamic factors, and a mismatch in mechanical properties between the graft and host vessel may be important. Sources of endothelium in graft healing are anastomotic sites, pluripotent cells growing through the graft wall or deposition of pluripotent cells from the blood. Early failure of a prosthetic vascular graft occurs mainly as a result of separation at its sites of attachment. Late complications may be the result of mechanical failure (anastomotic sites or within the graft), kinking, inadequate or incomplete healing, and infection. The incidence of infectious complications varies from 0.25% to 6.0%, usually associated with high mortality rates.     

Atherosclerosis in vascular grafts for peripheral vascular disease. Part 2. Synthetic arterial prostheses

Thirty-nine synthetic (32 Dacron and 7 Teflon) arterial prostheses (from 38 patients with peripheral arterial disease) removed after periods between 2 months and 18 years, were examined by histology and immuno-histology. The grafts were initially permeated by thrombus containing platelet antigens and this became organised and converted to granulation, and then to fibrous, tissue. The newly-formed tissue contained 'foreign-body' giant-cells in contact with the plastic prosthesis and showed evidence of permeation by plasma proteins. In grafts of over 2 years duration, this reactive tissue no longer contained platelet antigens but invariably revealed bound lipid, identifiable as apolipoprotein-B-containing lipoproteins (LpB), and fibrinogen-related antigens (FRA), in a distribution resembling that seen in atherosclerotic arteries. LpB and FRA were also seen in organised, or partially organised, mural thrombi in older grafts. The oldest grafts additionally showed stenosis, calcification or aneurysm formation. Lipid deposition increases with the age of grafts; is independent of the nature of the plastic fibre used or its mode of fabrication; and sometimes contributes to graft failure. Immuno-histology indicates that this is an insudative process indistinguishable from 'true' atherosclerosis which occurs in graft-linings of prostheses of long duration and in old mural thrombi in grafts and that the lipid in these lesions derives from plasma LpB rather than from platelets. This source for the lipid suggests that the insudative and thrombogenic theories of atherogenesis can be reconciled.     

Interaction of Staphylococcus epidermidis from infected hip prostheses with neutrophil granulocytes.

This study focuses on the interaction of Staphylococcus epidermidis isolated from granulation tissue covering infected hip prostheses and neutrophil granulocytes. Bacterial strains isolated from normal flora were used as controls. The bacteria were well characterized with routine methods and further characterized with random amplified polymorphic DNA analyses and slime tests. Phagocytosis and chemiluminescence (CL) assays were used in the neutrophil interaction studies. The prostheses strains were ingested to a lesser extent than strains from normal flora (p < or = 0.001). There was no significant difference between the prostheses strains and the normal flora strains in terms of total CL response. However, the extracellular CL response from the neutrophils was lower in comparison with the normal flora when interacting with the prostheses strains. The results of this study support the notion that S. epidermidis strains isolated from infected hip prostheses have an enhanced capacity to resist phagocytosis and that most of these strains elicit a reduced inflammatory response, measured as the production of extracellular oxidative metabolites from the neutrophils, compared to normal flora.     

Prevention of enteric erosion by vascular prostheses

Aortoenteric fistula is an uncommon but disastrous complication of aortic reconstruction with a prosthetic graft. Prevention of enteric erosion when using a vascular prosthesis must be a foremost consideration. For these occasions, greater omentum may be used to cover the graft. However, when use of the greater omentum is not possible, the interposition of a prosthetic patch is a means of preventing duodenal erosion. We review the usual procedures for reperitonealization and report on an original method of using a prosthetic patch to prevent erosion.     

The use of fibrin glue for sealing vascular prostheses of high porosity

Vascular prostheses of different porosity (Cooley Very Soft; Miliknit Lo-Por; Microvel; Sparks Mandril) were pretreated with fibrin glue and the permeability was assessed both in vitro and in 12 dog experiments by descending aorta replacement under full systemic heparinization. It was found that all types of prostheses were completely sealed after the pretreatment. In 28 patients undergoing descending or abdominal aorta replacement under systemic heparinization high porosity knitted Dacron grafts were pretreated with the fibrin glue only. There was no blood loss across the prosthetic wall. It is concluded that graft-pretreatment with fibrin glue allows for combining full heparinization and the use of high porosity vascular grafts.     

The management of infected grafts in reconstructive vascular surgery

Aseptic bypass graft and graft-preserving open local treatment have proved to be the 2 suitable procedures for therapy of infected grafts in vascular surgery (stage III Szilagyi) with preservation of the limb extremity. After 685 reconstructive operations (1982 to 1984) for chronic arterial occlusive disease in the supraaortic as well as in the iliac and femoral segments, 9 infections involving the graft (1.31%) occurred. These infections were more common in superficial extra-anatomical bypass. The incidence of inguinal infection was 0.44%. In 2 cases an aseptic bypass with abandonment of the infected vascular segment and in 4 cases open local treatment of the infected graft proved successful in treating the infection and led to secondary wound healing. The transplant had to be abandoned and an amputation performed in 3 patients, one of whom died. That is to say, the infection was successfully treated (with respect to the original aim of the operation) in 66.7% of cases. The aforementioned methods do not represent alternative procedures: the aseptic bypass is considered in retroperitoneal and inguinal infections, whereas the open local treatment is used in cases of superficial extra-anatomical bypass grafts and in the infrainguinal and supraaortic artery segments. The success of the latter treatment, however, depends on several preconditions. In former years, loss of the limb extremity was almost unavoidable and, because of septicemia, the outcome often lethal. By applying the above-discussed principles of management this could be drastically improved.     

Perigraft-reaction after implantation of vascular prostheses. Pathogenesis, clinical picture and treatment

This report is based on 18 perigraft reactions in 2237 implanted vascular prostheses (1970-1985). The incidence of this complication is 6.8-9.5/1000 both for Dacron-double-velour and expanded PTFE-prostheses. The clinical picture is characterized by localized or extended fluid accumulation around the artificial graft (perigraft cysts or "swimming prosthesis"). Including 271 reports from the literature, 75% of vascular prostheses in extraanatomical positions were affected. The time interval between vascular substitution and clinical manifestation is on average 23.5 months. The pathogenesis of this aseptic late complication is still unclear. Several disposing factors are under discussion: (a) physico-chemical irritation of the surrounding tissue by the fabric itself (release of monomers, emulgators etc.), (b) mechanical trauma (continuous movement of the graft in the tissue bed, i.e. insufficient tissue fixation resulting in gaps and exudation of fluid round the prosthesis), (c) latent or manifest renal insufficiency. The partial or total removal of the affected prosthesis and its substitution by another type of vascular prosthesis offers the best chance of definitive cure. Repeated puncture of perigraft cysts produces frequent recurrencies and the danger of secondary infections. Therefore only an exchange of the graft can be recommended.     

Infections of vascular prostheses of the abdominal aorta. Diagnostic and therapeutic problems]

Aortic graft infection is one of the most serious complication of vascular surgery. While the incidence of such infections has declined over the years, it continues to be associated with high mortality and high rates of limb loss. Graft implanted in the inguinal area have a higher rate of infection than those that lie entirely within the abdomen. Infection of the intraabdominal extremities of vascular grafts is most frequently associated with prostheto-enteric fistula. DIAGNOSIS AND TREATMENT: Despite the many available sophisticated imaging techniques diagnosis remains difficult, particularly with intra-abdominal grafts because of nonspecific clinical and imaging findings. A variety of approaches to aortic graft infection have been proposed and optimal treatment usually requires an association of systemic antibiotic administration with surgery. Removal of the entire infected graft is often necessary for cure and there are only few situations in which conservative treatment is acceptable. A careful identification of the infecting microorganisms and in vitro susceptibility testing are essential for successful therapy. PREVENTION: Prevention consists in a strict adherence to principles of asepsis and the use of prophylactic antibiotics in vascular surgery. The use of antibiotics-bound knitted grafts has been recently proposed.