Aortocoronary bypass grafting with expanded polytetrafluoroethylene: 12-year patency

The size of CAG repeats was compared in lymphocytes and skeletal muscle from nine patients with Huntington disease (HD) and two patients with Kennedy disease (KD). In HD, the number of CAG repeats did not differ between lymphocytes and skeletal muscle. In the two KD patients, however, the CAG expansion was larger in muscle than in lymphocytes. The difference in trinucleotide expansion between lymphocytes and muscle cells is not a universal phenomenon in trinucleotide repeat disorders, but seems to occur in disorders primarily affecting the neuromuscular system.     

MRI of pseudoaneurysm of a brachial venous coronary bypass graft

We studied the following responses to restriction of dietary calcium and phosphorus in the growing hamster: (i) serum concentrations of calcium, inorganic phosphorus, magnesium, and vitamin D metabolites; and (ii) calcium transport by ileum. Diets fed were normal calcium with normal or low phosphorus or low calcium with normal or low phosphorus. We found serum 1 alpha,25-dihydroxycalciferol (1,25-[OH]2D) concentration did not differ significantly among the diet groups. Calcium absorption, measured as serosal/mucosal calcium concentration ratio produced by everted ileal sac, was greater in the low calcium, normal phosphorous group than in all other groups. The other groups did not differ from one another in calcium absorption. Feeding the low calcium, normal phosphorus diet increased inorganic phosphorus and magnesium but decreased calcium concentration in serum in comparison with the three other diets. Both low phosphorus diets were without effect on serum calcium, but the low calcium, low phosphorus diet increased serum inorganic phosphorus and magnesium above that of the normal calcium, low phosphorus diet. Ileal calcium absorption in hamster (i) was independent of serum 1,25-(OH)2D concentration; (ii) increased in response to low dietary calcium if dietary phosphorus was normal; and (iii) was independent of dietary calcium, if dietary phosphorus was low. Despite increased calcium absorption, serum calcium was decreased in the low calcium-normal phosphorus group as compared with all other groups. Feeding low calcium diets increased serum inorganic phosphorus and magnesium as compared with feeding the corresponding normal calcium diets (i.e., independently of whether dietary phosphorus content was normal or low). These studies demonstrate that the interrelationships between calcium absorption and vitamin D and mineral metabolism in hamster differ from other mammals.     

Clinical experience with expanded polytetrafluoroethylene (Gore-Tex) grafts for femoropopliteal arterial bypass

Thirty-seven grafts of expanded polytetrafluoroethylene were implanted in 28 patients in whom autogeneous saphenous vein was not available, either for symptoms of severe claudication or limb salvage. The length of follow-up ranges from 8 to 28 months . The patency rate is 86.9 percent for the patients with severe claudication and 71.4 percent in the limb salvage group; the overall patency rate is 81 percent. We believe that expanded polytetrafluoroethylene is a good prosthetic substitute when autogenous vein is unavailable.     

Repair of ventral hernias with expanded polytetrafluoroethylene patch

BACKGROUND: Operations for large and recurrent abdominal hernias have a high associated recurrence rate, although it is lower when prosthetic material is used. Expanded polytetrafluoroethylene (ePTFE) seems to be the best tolerated prosthetic material in surgery. METHODS: A series of 45 ventral hernias repaired using ePTFE for closure or reinforcement of the herniorrhaphy has been evaluated prospectively. Thirty-six were midline incisional hernias and nine were transverse or pararectal ventral hernias. There were 13 recurrent ventral hernias and three defects were operated as an emergency procedure. The patch was sutured to the anterior aponeurosis with a running non-absorbable suture. Some other kind of intra-abdominal procedure was undertaken in 12 cases. RESULTS: ePTFE was well tolerated. Complications occurred in five patients. Major complications were found in three patients: cutaneous necrosis requiring a myocutaneous flap; and infection of the prosthesis (primary, and secondary to enterocutaneous fistula due to diverticulitis, both requiring removal of the patch). Mean follow-up was 39 months and hernia recurrence occurred in only one patient. CONCLUSION: This clinical experience shows that ePTFE is a very reliable prosthetic material for the repair of abdominal wall hernias.     

Acute disruption of polytetrafluoroethylene grafts adjacent to axillary anastomoses: a complication of axillofemoral grafting

PURPOSE: Acute disruption at or adjacent to axillary anastomoses of axillofemoral grafts has been sporadically reported. We have recently reported the patency and limb salvage results of a large number of axillofemoral grafts. In this report we describe a series of axillary artery-graft disruptions that occurred in these patients. METHODS: Beginning in 1983, axillofemoral bypass was performed by the authors using standardized operative technique and a single prosthetic graft material (8 mm externally supported polytetrafluoroethylene). Axillary anastomoses were placed on the first portion of the artery and were performed with the arm abducted and with the graft redundant. The records and operative reports of all patients with disruption were reviewed for findings and subsequent hospital course. RESULTS: Two hundred two axillofemoral grafts were performed from 1983 to 1993. Ten patients (5%) had axillary disruption at intervals ranging from 1 to 46 days (mean 21 days) after operation. Ischemia was the indication for operation for seven of the patients and infected aortic prostheses for three. Infection did not occur in any of the axillary wounds and was not the cause of any of the disruptions. Four disruptions occurred with arm abduction/shoulder elevation movements; three awakened patients from sleep, and one occurred while the patient was sitting quietly. For the other two patients, preceding activity was unknown. Brachial plexus deficit was present in one patient. Four of the 10 disrupted grafts were also acutely occluded. Operative findings included sutures pulling out of the artery in four cases, tearing or sutures pulling out of the graft in four cases, and cause unknown in two cases. Treatment included arterial ligation in one patient, and restoration of circulation through revision of the axillofemoral grafts in the other nine patients. There were no operative deaths. One patient had a prolonged hospital course followed by nursing home placement and died 9 months later. The brachial plexus deficit did not resolve. There have been no repeat disruptions. CONCLUSIONS: We conclude that axillofemoral grafting includes the potential for disruption of the proximal anastomosis, which has occurred in 5% of our patients. Although multiple steps have been recommended to avoid this complication, occasional cases continue to occur despite observing all precautions.     

Expanded polytetrafluoroethylene graft fistula for chronic hemodialysis

In a retrospective study of 66 PTFE arteriovenous fistulae and 71 BCH arteriovenous fistulae for dialysis access, PTFE had a higher patency rate than BCH at 12 months (62.4 versus 32.5%). PTFE was easier to work with and easier to handle in the face of infection. The lateral upper arm approach to placement of the PTFE graft is desirable in patients who have had multiple previous access procedures because this area is usually free from scarring, is distant from neurovascular structures, and provides a greater length of graft for needle punctures.     

Polyurethane vascular prostheses decreases neointimal formation compared with expanded polytetrafluoroethylene

Water sorption by plant cuticular membrane isolates, mainly identified as polysaccharides, after selective extraction of the lipid components waxes and cutin was measured over the whole range of water activity. From water sorption isotherm, the strengths of water binding and water clustering were estimated. Data obtained by differential scanning calorimetry and Fourier-transform and near infrared spectroscopy confirmed the existence of water molecules in different macromolecular environments.     

Arterial prosthesis of microporous expanded polytetrafluoroethylene for construction of aorta-pulmonary shunts

A new arterial prosthesis made of polytetrafluoroethylene (OTFE) was evaluated in 10 infants with complex cyanotic congenital heart disease. All grafts used were 4 mm. in diameter and varied in length from 0.8 to 6 cm. The grafts were anastomosed to the main pulmonary artery or its bifurcation in 8 infants and to the right and left pulmonary arteries in one each. There were two early deaths, one of which was related to shunt failure. The advantages of a shunt to the main pulmonary artery are obvious, and the intraoperative procedure is facilitated with the prosthesis. Follow-up averages 9 months in the 8 survivors, and the patients have nearly doubled their preoperative weight. A shunt murmur is present in each case and the children have mild-to-moderate cyanosis at rest. Repeat aortograms in 2 patients, 8 and 10 months postoperatively, show a smooth graft without luminal narrowing. The aortic oxygen saturations were 73 per cent. The PTFE graft and/or anastomoses will not grow with the growth of the child and therefore may not accommodate growth by increased flow. This may prove to be a limiting factor in its long-term use in fants. We reserve the use of these grafts for infants with complex cyanotic defects undergoing emergency surgery or in older children in whom a conventional shunt is not possible or a previous shunt has failed.     

Long-term results of femorotibial bypass with vein or polytetrafluoroethylene

OBJECTIVE: The purpose of this study was to determine predictors of posttraumatic stress disorder (PTSD) in health care workers exposed to a disaster, in order to facilitate early case identification and prevention of subsequent morbidity. METHOD: Following an air disaster, 355 military medical health care workers were studied over an 18-month follow-up period. Measures included assessment of peritraumatic reactions associated with the disaster, the frequency of other stressful events after the disaster, and standard PTSD rating scales at 6, 12, and 18 months. RESULTS: Multivariate logistic regression of data on health care workers who cared for victims of the air disaster showed that PTSD was more likely to develop in those who had not completed college, those who had worked with burn victims, those who had experienced more stressful life events in a period of approximately 6 months following the disaster, and those who experienced emotional numbness immediately after the disaster. CONCLUSIONS: Results suggest that lower levels of education, exposure to grotesque burn injuries, stressful life events following exposure, and feelings of numbness following exposure are useful predictors of subsequent development of PTSD.     

Effects of omental wrap on performance of small-caliber high-porosity expanded polytetrafluoroethylene grafts

The purpose of this study was to evaluate the effects of omental wrap on the performance of small-caliber expanded polytetrafluoroethylene (ePTFE) grafts, with a special reference to transmural capillary ingrowth. High-porosity ePTFE grafts with a fibril length of 60 micrometer, an internal diameter of 4 mm, and 40 mm in length were implanted into the canine bilateral carotid arteries. The grafts on the right side were wrapped in an omental pedicle flap (omentum-wrap grafts), while those on the left were not (nonwrap grafts). The grafts were retrieved at intervals of 4 and 12 weeks. At 4 weeks, the patency rates of the omentum-wrap grafts and nonwrap grafts were almost the same (5/6 vs 6/6). At 12 weeks, patency tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (3/5 vs 1/5). At 4 weeks, the thrombus-free surface score (TFS) was significantly higher in the omentum-wrap grafts than in the nonwrap grafts (44.8% vs 30.2%, P < 0.05). At 12 weeks, the TFS tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (84.6% vs 62.4%). At 4 weeks, both the capillary transsectional area score (CTS) and capillary density were significantly higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 3.3% vs 1.1%, P < 0.05; capillary density, 196.0/mm2 vs 83.3/mm2, P < 0.05). At 12 weeks, both CTS and capillary density tended to be higher in the omentum-wrap grafts than in the nonwrap grafts (CTS, 1.1% vs 0%; capillary density, 69.4/mm2 vs 0/mm2). At 4 weeks, in the omentum-wrap grafts, extracellular matrices and cells in the interstices of the graft were stained with an antibody against VEGF. In conclusion, the omental wrap enhances transmural capillary ingrowth and thereby promotes endothelialization in small-caliber high-porosity ePTFE grafts. VEGF appears to play an active role in transmural capillary ingrowth enhanced by omental wrap.     

Laser-assisted microvascular anastomosis of human adult and placental arteries with expanded polytetrafluoroethylene microconduit

Laser-assisted microvascular anastomoses can be performed more quickly than sutured anastomoses, yet manifest similar patency rates and tensile strength. This study was undertaken to determine if in vitro laser-assisted microvascular anastomoses could be created between human adult arteries (anterior tibial arteries), human placental arteries, and expanded polytetrafluoroethylene microconduits. A CO2 laser was applied in single or continuous bursts with a matrix of variables encompassing power P = 80 to 160 mW, spot size SS = 150 to 500 microns, and exposure time EXP = 1.0-second continuous exposure (n = 2 each composite setting). The endpoints measured to assess the ability to laser-weld vessels were morphologic appearance by scanning electron microscopy and bursting strength. Scanning electron microscopy revealed apparent fusion of human placental arteries and human adult arteries to expanded polytetrafluoroethylene microconduits at settings of P = 130 mW, SS = 300 microns, and EXP = 1.0 second, though bursting pressure at all settings was less than 10 mmHg. Laser-assisted microvascular anastomoses of human placental artery to human placental artery and human adult artery to human adult artery were successful at this setting, though bursting pressures of anastomoses incorporating placental vessels were significantly weaker than those created with adult tissue. The relative weakness of laser-assisted microvascular anastomoses incorporating placental arteries might be explained by qualitative or quantitative differences in vessel wall collagen, as seen in fetal tissue, and deserves further characterization.     

Fifteen-year experience in axillofemoral bypass with externally supported knitted Dacron prosthesis in a Japanese hospital

Physicians and patients need convenient access to quality medical information. This study's goal was to place a medical resource on the World-Wide Web (WWW), allow access to it through a simple to use interface, and analyze the usage of such a resource. The Family Practice Handbook (TFPH) was digitized and placed onto the WWW. Usage data was obtained from June 1995-June 1996. 118,804 individuals accessed TFPH viewing 409,711 pages of information. A broad spectrum of topics was accessed. TFPH proved to be an extremely popular resource, servicing the broad information needs of an international audience. These preliminary findings suggest the future promise of Internet medical resources.     

Mouse model of venous bypass graft arteriosclerosis

Saphenous vein grafts are widely used for treatment of severe atherosclerosis via aortocoronary bypass surgery, a procedure often complicated by later occlusion of the graft vessel. Because the molecular mechanisms of this process remain largely unknown, quantitative models of venous bypass graft arteriosclerosis in transgenic mice could be useful to study this process at the genetic level. We describe herein a new model of vein grafts in the mouse that allows us to take advantage of transgenic, knockout, or mutant animals. Autologous or isogeneic vessels of the external jugular or vena cava veins were end-to-end grafted into carotid arteries of C57BL/6J mice. Vessel wall thickening was observed as early as 1 week after surgery and progressed to 4-, 10-, 15-, and 18-fold original thickness in grafted veins at age 2, 4, 8, and 16 weeks, respectively. The lumen of grafted veins was significantly narrowed because of neointima hyperplasia. Histological and immunohistochemical analyses revealed three lesion processes: marked loss of smooth muscle cells in vein segments 1 and 2 weeks after grafting, massive infiltration of mononuclear cells (CD11b/18+) in the vessel wall between 2 and 4 weeks, and a significant proliferation of vascular smooth muscle cells (alpha-actin+) to constitute neointimal lesions between 4 and 16 weeks. Similar vein graft lesions were obtained when external jugular veins or vena cava were isografted into carotid arteries of C57BL/6J mice. Moreover, no significant intima hyperplasia in vein-to-vein isografts was found, although there was leukocyte infiltration in the vessel wall. Thus, this model, which reproduces many of the features of human vein graft arteriosclerosis, should prove useful for our understanding of the mechanism of vein graft disease and to evaluate the effects of drugs and gene therapy on vascular diseases.     

Use of expanded polytetrafluoroethylene grafts for vascular access in hemodialysis: laboratory and clinical evaluation

Vascular access for chronic hemodialysis has evolved considerably over the past 10 years with development of vascular substitutes. The bovine heterograft is the choice of most dialysis centers when a subcutaneous conduit is needed in lieu of an in situ arteriovenous fistula. Bovine grafts have solved some problems, but further improvement in blood access prostheses is needed. Polytetrafluoroethylene (PTFE) grafts were evaluated in a laboratory and clinical study. In animals, PTFE proved to be satisfactory for fistula construction based on patency, incorporation into tissue, and ease of puncture. Ten patients underwent 11 vascular access procedures using PTFE grafts as a conduit. There were no technical operative complications. One graft was occluded by extravasation during dialysis and flow could not be restored. Otherwise, all grafts are patent 9 to 18 months postoperatively. Grafts of 8.0 mm in diameter have not given desirable flow rates, whereas 6.0 mm grafts have. Prolonged bleeding from puncture has been a problem in some cases. Otherwise, PTFE appears to be a satisfactory conduit for hemodialysis vascular access.     

Clinical trial of new polyurethane vascular grafts for hemodialysis: compared with expanded polytetrafluoroethylene grafts

We developed a new polyurethane vascular access graft coated with gelatin and reinforced with knitted polyester fibers (PE-PEUG). Advantages over expanded-polytetrafluoroethylene graft (E-PTFEG) were previously reported in experimental studies. Between May 1990 and August 1992, 39 PE-PEUGs including 34 loop and 5 straight and 18 E-PTFEGs including 18 loop were implanted to create arteriovenous (AV) fistulas in a total of 52 adult patients on maintenance hemodialysis (HD). They were followed up until October 1994. Hemostasis on the suture line was achieved within 3 min in all patients implanted with PE-PEUGs. Bleeding from the needle holes of PE-PEUG stopped within 10 min with gentle finger pressure. Minimal local edema developed in only a few patients implanted with PE-PEUG while most patients implanted with E-PTFEG developed moderate local edema. One seroma formation was found in an E-PTFE case. Aneurysmal dilatations were observed twice in a PE-PEUG patient 9 and 17 months after the implantation and once in a E-PTFEG patient 2 years after the implantation. The cumulative patency rate at 1 year in the PE-PEUG and E-PTFEG groups were 53.2 and 70.8%, respectively. Our clinical study showed that the PE-PEUG had several advantages over E-PTFEG: prompt hemostasis, no persistent edema and no formation of seroma, no change in elasticity, and sufficient mechanical strength. However, the cumulative patency rate was inferior to that with E-PTFEG implanted in our series. Further modifications are therefore necessary to improve the patency rate.     

The axillo-axillary bypass graft: further experience

The recent utilization of the axillo-axillary bypass graft for revascularization of proximal subclavian or innominate artery occlusions has proved to be a successful operation, technically simple with a low operative morbidity. We have reviewed the reported experience to date and have added our experience of nine additional cases. The procedure has produced excellent results in all patients, with no evidence of postoperative "steal" from the donor limb. Preoperative hemodynamic defects were corrected. Our experience has led us to the conclusion that this simpler and safer extrathoracic approach should be considered as the procedure of choice when arterial lesions allow for its selection and use.     

The femoral artery-femoral vein polytetrafluoroethylene graft: a 14-year retrospective study

The purpose of this study was to determine the relationship between sarcoma tumor grade and the quantitative tumor metabolism value for [F-18]fluorodeoxyglucose (FDG) determined by positron emission tomography (PET) imaging. Seventy patients with bone or soft-tissue sarcomas underwent PET scanning with quantitative determination of tumor FDG metabolic rate (MRFDG) before treatment. MRFDG (micromol/g/min) for each tumor was compared with National Cancer Institute tumor grade, S-phase percentage, and percentage of aneuploidy of the tumor population. The pretreatment quantitative determination of tumor MRFDG by PET correlates strongly with tumor grade but not with the other selected histopathological tumor correlates. In addition, overlap of MRFDG PET values with tumor grade suggests that PET, an objective tumor measurement, may provide an alternative means of assessing tumor biological potential or may have the potential to overcome some of the limitations of traditional pathological evaluation. FDG PET can uniquely provide a metabolic profile of a diverse group of sarcomas noninvasively and provide clinically relevant tumor biological information.