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At least 865 records · Page 48Linked to original sources
PubMed1989

[Clinical characteristics of the Soviet low-profile heart valve prostheses EMIKS and LIKS].

The present work is devoted to the clinical assessment of the Soviet-made cardiac valve prostheses 'EMIKS' and 'LIKS'. From 1983 to May 1, 1988, 632 prostheses were implanted to 508 patients. A group of 348 patients were assessed: 139 after mitral (M) replacement, 130 after aortal (A) replacement, and 79 after mitral-aortal (M+A) replacement. Hospital mortality rate was: in M group--4.3 per cent, in A group--5.3 per cent, in M+A group--8.8 per cent. Survival rate on the fifth postoperative year was: in M group--89.5 +/- 9.2 per cent, in a group--90.0 +/- 4.2 per cent, in M+A group--91.0 +/- 6.2 per cent, the stability of the good results being 85.5 +/- 7.2, 79.5 +/- 6.2, and 75.0 +/- 9.1 per cent, respectively. At year 5 of the follow-up, patient numbers without thromboembolic complications amounted to 95.0 +/- 4.7 per cent in M group, 95.5 +/- 4.2 per cent in A group, and 85.0 +/- 9.1 in M+A group. 95.1 per cent patients belong to functional classes I and II. In mitral replacement, the mean 'EMIKS' gradient was 4.2 +/- 0.58 mm Hg, the 'LIKS' one--4.58 +/- 0.62 mm Hg. Intravascular hemolysis was not observed. The 'EMIKS' and 'LIKS' prostheses match the models produced in other countries. No significant differences between the two models were found.

Aortic Valve↗
PubMed1989

Late results of aortic valve replacement with Bjork Shiley prostheses: a comparison of standard aortic valve prosthesis with reversed mitral valve prosthesis implanted in aortic position.

Between 1976 and 1983, 435 patients underwent aortic valve replacement (AVR) with Bjork Shiley prostheses. Standard aortic Bjork Shiley prostheses (ABP) were used in 150 patients (Group I) and a reversed mitral Bjork Shiley prostheses in 285 (MBP in 250 and MBC in 35) patients (Group II). There was no significant difference in the number of the patients with valve calcification or the size of aortic root in the 2 groups. There was no significant difference in the early mortality in these two groups. The total follow up period in Group I was 912 years and 2130 years in Group II. The incidence of major aseptic prosthetic dehiscence and valve occlusion with tissue ingrowth were higher in Group I than in Group II. Reversed Bjork Shiley mitral valve prosthesis was successfully used in aortic position with reduced incidence of valve related complications.

Aortic Valve↗
PubMed1989

Isolation of vascular endothelial cells for investigations on hybrid prostheses.

Hybrid vascular prostheses are coated with vascular endothelial cells (EC) in an attempt to reduce thrombogenicity through the metabolic activities of living cells. The present studies were planned to develop a standardized method of isolating bovine aortic EC with high yield for studies of endothelial coating of vascular prostheses. The best results were achieved using a combination of incubation with collagenase and mechanically scraping the mobilised cells from the donor vessel. Isolated adult male bovine endothelial cells were identified by the typical "cobble stone" morphology in culture and characterized by factor VIII related antigen immunofluorescence microscopy. The cells were seeded successfully on PTFE vascular prostheses.

Animals↗
PubMed1989

[Bone scintigraphy in patients with hip joint prostheses. Use of bone scintigraphy in hip pain after total hip replacement].

A retrospective investigation was undertaken to assess the value of bone scintigraphy with 99mtechnetium methylene-diphosphonate in patients referred with hip pain after total hip replacement. The material comprized 68 patients with a total of 68 prostheses. This review revealed that 10/25 of the patients with pathological scintigrams and 6/28 of the patients with normal scintigrams were submitted to replacement of the prostheses. In the way in which it was carried out and interpreted in this department, scintigraphy was of limited value in selection of the patients who required replacement of the prostheses.

Aged↗
PubMed1989

[Results of using high porosity aortofemoral bifurcation prostheses].

The authors report on their four-year experience with the use of extremely highly porous vascular polyester prostheses of Czechoslovak proveniencè, whose wall was sealed with fibrin. Aortofemoral bifurcated prostheses with a permeability of 6 100 ml/cm2/min were implanted in 102 patients. The method of fibrination appears to be simple and safe. No hemorrhage through the prosthetic wall was observed. The authors expect the high porosity of the prostheses to result in longer lasting patency of the grafts and thus in improvement of long-term results.

Adult↗
PubMed1989

[The neoartery, myth or reality? Study of 79 explanted arterial prostheses].

This study represents the third stage of a personal study on the long term fate of reconstruction and arterial restoration materials presented to the Academie de Chirurgie. 79 explanted prostheses were studied. First of all by an in depth histological study (8 cases selected from 70 reinterventions carried out before 1980), and then by a more complete protocol: scanning electron microscopy, resistance testing, programmed differential calorimetry, X-ray diffraction and biochemical analysis (71 reinterventions carried out after 1980). Our findings agree with the studies of R. Guidoin. With the exception of structural manufacturing defects or defects related to surgical manipulation, mechanical fatigue in a Dacron (PET) arterial prosthesis is inevitable: on average by the 7th to 10th year, a prosthesis looses one half of its mechanical resistance. The covering tissue, like that of the external capsule, which has poor mechanical properties, cannot compensate for prosthetic deterioration which may be considered to be complete by the 25th year. Knitted arterial prostheses, especially aortic, more rapidly undergo dilatation than woven prostheses which are much more resistant. On the other hand, the poor compliance of the latter compared with the recipient artery, perhaps favorises late anastomotic rupture. At internal capsule or pseudo-intimal level, endothelium is never present, but rather there is a permanent turnover with a variable time course, the mechanisms of which are poorly understood (role of prostaglandins?). Rather than a neo-artery, the vascular surgeon is only capable of producing an imperfect arterial tube, fragile from many points of view, and having an evolution which remains poorly understood.

Aneurysm↗
PubMed1989

[Total hip prosthesis: what is the life expectancy? Survey of 430 prostheses with a 10 to 12 year follow-up in 253 cases].

In 1987 we made a review of all total hip prostheses inserted at Hopital Henri Mondor in 1974-1975-1976. These were of the metal-polyethylene Charnley-Muller or Lagrange-Letournel type (430 prostheses inserted in 349 patients). 178 hips were reexamined and 177 were lost to follow up. 61 patients had died. Overall, good results were found in 65% of patients reviewed - 12.5% had been reoperated upon. Although the newer models of prostheses are full of promise, none has stood the test of 10 years of use.

Follow-Up Studies↗
PubMed1988

[Experimental validation of a method for the early diagnosis of the infection of vascular prostheses using 99m-TC-labelled leukocytes].

Experiments on 9 dogs were staged for a study of a method of early diagnosis of infectivity of vascular prostheses of the abdominal aorta with the help of 99m-Tc-labelled leukocytes. A sterile synthetic vascular prosthesis was used for prosthetics of the abdominal aorta in the 1st control group of animals, a prosthesis, previously infected with St. aureus, was used in the 2nd group, a sterile prosthesis with its subsequent infecting by i.v. injection of St. aureus was used in the 3rd group. The role of antibiotic therapy in infectivity of vascular prostheses was studied on the animals of the 3rd group. A radionuclide study with autologous 99m-Tc-labelled leukocytes was conducted using the Deina-2 camera (Picker). Visualization of the prostheses was unobserved in the 1st control group; in the 2nd group the accumulation of 99m-Tc-leukocytes in the zone of the prosthesis and its visualization on the 4th-5th min. were noted; in the 3rd group the prosthesis was visualized on the 10th-15th min. After antibiotic therapy in the 3rd group visualization of the prosthesis was undetectable. The proposed method permitted visualization of a zone of infection in the early postoperative period, observation of the time course of infection development, and assessment of the efficacy of antibiotic therapy.

Animals↗
PubMed1987

The microbiology of explanted vascular prostheses.

The incidence of bacterial colonization and the microflora of prosthetic vascular graft material explanted from 44 patients undergoing graft revision was determined. Graft material for culture was obtained from aortofemoral or femoropopliteal vascular prostheses without signs of infection but requiring revision for femoral anastomotic aneurysm (n = 21) or thrombosis (n = 26). Explanted graft material was placed in tryptic soy broth and ultrasonically oscillated to disrupt the adherent graft surface biofilm, which is a technique that increases the recovery of microorganisms compared with standard microbiologic culture methods. Microorganisms were isolated from 90% (19/21) of grafts associated with anastomotic aneurysms and 69% (18/26) of thrombosed grafts. Staphylococcus epidermidis was the prevalent organism recovered and accounted for 69% of the isolates. Slime production, a growth characteristic of S. epidermidis associated with prosthetic device infection in humans, was demonstrated by 87% (13/15) of strains isolated from grafts with pseudoaneurysms compared with 33% (4/12) of strains isolated from occluded grafts (p less than 0.01). Despite the high incidence (79%) of colonization of vascular prostheses, no patient developed wound or graft infection after graft replacement and perioperative antibiotic administration. Low-virulent microorganisms, such as S. epidermidis, can colonize vascular prostheses and not provoke signs of graft infection. The high recovery rate of slime-producing S. epidermidis strains from grafts with anastomotic aneurysms and the adherence-mediated growth of these bacteria on biomaterials suggest this late graft complication is the sequelae of a bacteria-laden biofilm infection.

Aneurysm↗
PubMed1988

Fractures of the polyethylene bearing insert in Bateman bipolar hip prostheses.

Six cases of fractures of the polyethylene bearing insert of Bateman bipolar hip prostheses were observed in three patients at four to eight years after implantation. Three fractured prostheses were salvaged by replacement with new bearing inserts. In three patients, excessive acetabular cartilage wear was the indication for revision to total hip arthroplasty. Although dislocation and component disassembly have been reported as complications of the Bateman and other bipolar prostheses, fractures of the polyethylene bearing insert seems not to have been previously reported. The presumed mechanism of failure is cyclic loading of a femoral cup that is tipped into varus alignment. This concentrates stress on the weakest part of the polyethylene insert--the deep circumferential groove that joins the leaflets to the main body of the insert. Obesity and overuse were associated factors in this rare complication.

Adult↗
PubMed1988

Medtronic Hall valve replacement in a third-world population group. A review of the performance of 1000 prostheses.

Between May 1980 and December 1984, 1000 Medtronic Hall prostheses (538 mitral and 462 aortic) were implanted in 852 patients (mean age 30 +/- 15 years) of a third-world type of population group. The most common valve lesions were aortic and mitral regurgitation, and 32% of the patients were in New York Heart Association class IV or greater. Double valve (aortic and mitral) operations were performed in 209 patients. The 782 operative survivors were followed up for 2 to 6.5 years (mean 3.5 years) for a cumulative 2676 patient-years. Valve performance was analyzed in each position separately for valve-related complications. Results for the whole group for the following events are expressed in both linearized (percent/patient-year) and actuarial (percent +/- standard error of the mean freedom at 5 years) terms, respectively: valve-related mortality, 2.9 and 92 +/- 2; reoperation, 1.9 and 90 +/- 2; systemic thromboembolism, 3.3 and 85 +/- 2; thrombotic obstruction, 1.2 and 95 +/- 1; prosthetic valve endocarditis, 0.7 and 97 +/- 1; anticoagulant-related hemorrhage, 0.7 and 98 +/- 1; and periprosthetic leak, 0.7 and 97 +/- 1. Corresponding composite figures for valve failure were 4.3 and 85 +/- 2, and for all valve-related morbidity and mortality were 6.7 and 75 +/- 3. Thrombotic obstruction (fatal in 71% of the cases), anticoagulant-related hemorrhage (61% fatal), and prosthetic endocarditis (44% fatal) were the most lethal complications. Although the differences did not reach statistical significance, aortic prostheses appeared to have a higher incidence of complications than the mitral prostheses. When analyzed against the background of an essentially noncompliant population group, the Medtronic Hall prosthesis proved to be reliable and remarkably free from structural failure. The high incidence of thromboembolism and thrombotic obstruction still mandates anticoagulation.

Adult↗
PubMed1987

[Electron microscopic studies of pseudointima in synthetic prostheses].

Thirty one prostheses made of Lavsan (therylene) or teflon-lavsan that had been functioning in human patients for 16 months to 21 years were examined. No continuous endothelial lining was found present on the pseudointimal surface of any of the prostheses. The major cell types in a formed, well-vascularized pseudointima were fibroblasts and smooth-muscle cells. Cells of the macrophage series were involved in forming the granulation tissue seen around fibers of the prostheses.

Blood Vessel Prosthesis↗
PubMed1987

[The healing process after implantation of bilateral velour vascular prostheses of the Dallon type into the abdominal aorta of dogs].

In the defect of the resected part of the abdominal aorta in 36 dogs vascular prostheses were implanted. The prostheses were bilaterally veloured of the Dallon type, produced in Poland. The process of healing of the vascular prostheses proceeded two stages. In the first stage the structures were produced. In the second stage the connective tissue developed and endothelium cells on the surface of the newly produced internal layer. The analysis of morphological test results allows us to state that in the process of reconstruction of the arteries we have to the with a certain balance in the regenerative and reperative processes.

Animals↗
PubMed1986

Myoelectric control of prostheses.

The development of myoelectric control systems for powered limb prostheses has advanced rapidly in recent years. The main thrusts in this development have been in realizing self-contained prostheses and in realizing better prostheses control through improvements in the myoelectric signal processing techniques. This review considers the latter of these two areas. It first presents an historical look at myoelectric signal processing and identifies the problems. It then presents a general look at the myoelectric signal and those characteristics which give rise to these problems. A review of the literature related to various control strategies and signal processing techniques to overcome these problems is given. Finally, future trends to be expected in this area are discussed.

Arm↗
PubMed1986

[False aneurysms in prostheses of the aortic bifurcation. Apropos of 34 case reports].

Thrombosis, infection, false aneurysm and hemorrhage are all complications occurring following reconstructive arterial surgery. The authors study what is certainly the most unusual of these complications, i. e. development of false aneurysms of prostheses of the aortic bifurcation. They describe the various etiological factors responsible for their onset and also new diagnostic features and the principles of re-operation as well as results. This study is based upon a series of 34 cases of false aneurysm of prostheses of the aortic bifurcation inserted over a ten year period from 1974 to 1984. During this period, 1,400 prostheses of aortic bifurcation were inserted, essentially for two indications: chronic obliterative arterial disease of the lower limbs and aneurysmal disease. The mean latent period of onset of the complication was four and a half years. Removal followed by insertion of a new prosthetic graft is the basic treatment, overall mortality being 4% and morbidity being 30%, dominated by secondary thrombosis in 19% of cases, local infection in 8% of cases and recurrence of aneurysm in the same percentage of individuals. The overall figure of very good results was 70%. Whilst discussion is dominated by the role of different etiological factors, it nevertheless remains important to note that only progress in prosthetic and suture materials can allow a future decrease in the percentage of such false aneurysms, the factor inherent in the vascular surgeon, i. e. operative technique itself, being much easier to deal with on principle. This complication nevertheless remains very serious, best dealt with by surgery since the natural history of this false aneurysm is completely different from that of a classical femoral or popliteal aneurysm.

Aged↗
PubMedDate not supplied

Polyether-urethane elastomers for small-diameter arterial prostheses.

Textile polymers have been used for the manufacture of synthetic arterial prostheses. The extreme rigidity of these polymers has severely limited the nature of the structures that could be fabricated, so that the mechanical properties and structural form of the prostheses bear little resemblance to those of natural arteries. The variety of chemical structures, of mechanical properties and of means of fabrication make it possible to produce a compliant flexible prosthesis having a more delicate structure, thereby acquiring better tissue and blood compatibility and good long-term durability. These, and an acceptable form that encourages good surgical practice, account for the good performance of the prosthesis. By way of illustration, an electrostatically spun microfibrous arterial prosthesis of small diameter is described. It is made of a polyether-urethane urea (Biomer). We report good two-year patency for arterial prostheses of our design used to replace the common carotid artery in dogs.

Animals↗
PubMed1986

A laboratory model for the evaluation of thromboembolic complications of small diameter vascular prostheses.

Seventeen 2 mm and twenty-five 3 mm internal diameter petrafluoroethylene (PTFE) vascular prostheses were inserted as aortic interposition grafts in 42 rabbits. The 3 month patency with 2 mm grafts was disappointingly low at 24% whereas patency with 3 mm grafts was 82%, comparable to other studies of small diameter prostheses. Hind limb paralysis occurred in 18 animals and proved a reliable indicator of graft thrombosis. Unexpected and previously unreported lower limb ulceration occurred in nine of the 23 long term survivors. Angiographic studies indicated that these ulcers were due to distal embolization of loosely attached mural thrombi. These were found in four of eight patent grafts removed from animals with leg ulcers. Aortic grafting in the rabbit is an economic model for the study of thromboembolic phenomena in small diameter vascular prostheses and their modification by pharmacological agents.

Animals↗
PubMed1986

[Noninvasive determination of the orifice area of aortic valve prostheses using Doppler echocardiography].

In aortic valve stenosis, Doppler echocardiography enables reliable estimation of the orifice area with the use of the continuity equation. This study was carried out to determine the usefulness of the method in evaluation of prosthetic aortic valve area. Accordingly, 32 patients with normally-functioning mechanical Björk-Shiley prostheses underwent Doppler investigations two to three weeks after aortic valve replacement. Pre(v1)- and post(v2)-prosthetic velocities were recorded by pulsed and continuous-wave Doppler, respectively, and the prosthetic annulus used as cross-sectional area of flow (A1). For calculation of prosthetic orifice area (A2), the continuity equation at peak flow (v1,p) was employed where A2 = A1 X v1,p/v2 (at the point in time of v1,p). Mean pressure gradients across the prostheses were determined with the use of the modified Bernoulli equation. In addition, the ratio of acceleration to ejection time (AT/ET) was derived from the velocity profile of v2. Consistent with increasing prosthetic sizes (A 23 to A 29), there were increases in the calculated orifice areas A2 (A 23: 1.46 +/- 0.26, A 25: 1.71 +/- 0.24, A 27: 2.12 +/- 0.26, A 29: 2.53 +/- 0.35 cm2). Albeit with a substantial overlap between the various sizes, mean values for the respective sizes differed statistically significant and were comparably within the range established by in-vitro measurements. Pressure gradients across the prostheses were also different for the various sizes and were within the range reported from hemodynamic studies. In contrast, the AT/ET-ratio showed no significant difference between different prosthetic sizes.(ABSTRACT TRUNCATED AT 250 WORDS)

Aortic Valve↗