Venous thrombosis in relation to fibrinogen and factor VII genes among African-Americans

We evaluated the relation between venous thrombosis and plasma fibrinogen levels, the HaeIII and BcI polymorphisms of the beta fibrinogen gene, and the MspI polymorphisms of the factor VII gene in a case-control study of African-Americans. The study included 91 venous thrombosis cases and 185 control subjects obtained from a hospital in Atlanta, Georgia. High plasma fibrinogen was associated with increased risk of venous thrombosis, but the finding was not statistically significant. There was little association between the HaeIII polymorphisms and the BclI polymorphisms and the risk of venous thrombosis. The prevalence of the M2/M2 genotype of the factor VII gene was higher among cases than controls, but the difference was not statistically significant. The prevalence of the HaeIII H2 allele and the BclI B2 allele of the beta fibrinogen gene, both of which have been associated with slightly higher levels of plasma fibrinogen in most studies, is considerably lower among African-Americans in this study than it is among Whites in the United States and among Northern Europeans. The study is limited by its small size. However, despite this limitation, it supports the belief that increased plasma fibrinogen levels are associated with increased venous thrombosis risk. The study also indicated that the HaeIII and the BclI polymorphisms of the beta fibrinogen gene and the MspI polymorphisms of the factor VII gene are not strong determinants of venous thrombosis.     

Venous stasis syndrome: the long-term burden of deep vein thrombosis

Currently there is no cure for venous stasis syndrome, a common complication of deep vein thrombosis. Prophylaxis with anticoagulant agents, including new drugs presently under investigation, may decrease the incidence and costs associated with this condition.     

Venous thrombosis risk: Effects of palm oil and hydrogenated fat diet in rats

Objective

We tested whether diets containing partially hydrogenated fat (PHVO, rich in trans fatty acids) or palm oil (PO, rich in saturated fat—C16 palmitic fatty acid) had different effects on the propensity for venous thrombosis, a marker of haemostatic cardiovascular risk.

Methods

Female Wistar rats were fed normolipidic diets containing PHVO or PO during lactation, and their young male pups were fed the same diets from weaning until the 180th day of life. We evaluated platelet fatty acid composition, serum lipids, platelet aggregation, clotting time, and venous thrombus formation.

Results

A significant and cumulative incorporation of trans fatty acid was observed only in the platelet lipids from the PHVO group, associated with an increased sensitivity to adenosine diphosphate (ADP) and venous thrombus formation in vivo. Platelets from rats raised on the PO diet also exhibited platelet aggregation induced by ADP and an increase in venous thrombus weight, with a concomitant increase in serum triglycerides.

Conclusion

The prolonged replacement of dietary hydrogenated fat by PO impaired platelet aggregability and venous thrombosis, suggesting an increased risk of thromboembolic diseases.     

Deep-vein thrombosis and pulmonary embolism due to air travel

In recent years, the association between air travel and the incidence of deep-vein thrombosis or pulmonary embolism has become clearer. Epidemiologic studies reveal an increased relative risk of thromboembolism after flights of more than 8 hours and especially in subjects at higher risk for this disease, due, for example, to congenital thrombophilia or the use of oral contraceptives. However, the absolute risk of deep-vein thrombosis or pulmonary embolism after prolonged air travel is very small. Studies have shown that a combination of factors present during prolonged air travel may account for increased activation of coagulation. There is no definitive proof that elastic stockings are effective in reducing the incidence of clinically relevant thromboembolism during air travel. Acetylsalicylic acid is not effective in the prevention of thrombosis during air travel and may be dangerous. Prophylactic subcutaneous low molecular weight heparin may be effective to prevent air travel-associated thrombosis. However, pending more solid evidence, this strategy should only be used cautiously, e.g. only in patients with a high risk of thrombosis who are planning a long flight.     

Vascular thrombosis and pulmonary thrombo-embolism due to harness suspension

BACKGROUND: In many sports (such as rock-climbing and caving) and working activities (e.g., construction and maintenance of buildings, pruning of lung-trunked trees, abseiling in wells) people run the risk of falling from a height. To prevent the effects of any potential fall, personalprotection devices consisting of at least a body holding device (i.e. a harness of some type), a lanyard and a reliable anchor are used. OBJECTIVES: Reporting on the occurrence of vascular thrombosis in subjects undergoing prolonged hanging in a harness, either for work or recreation. METHODS: We investigated patients treated for vascular thrombosis in our hospital in the last 5 years to identify subjects with frequent use of a harness. RESULTS: We identified a 36-year-old rock-climber who developed pulmonary thrombo-embolism and infarction 5 days after he had been wearing a harness for 12 hours consecutively, and a 32 year-old worker who often used a harness to fix wire-nettings to prevent rocks falling from steep places and suffered thrombosis of the left superficial femoral artery. A feature of both cases was the considerable length of time spent hanging in the harness and the absence of alternative risk factors for thrombosis. CONCLUSIONS: Prolonged hanging in a harness can be dangerous in itself because it can produce vascular thrombosis. Reduction of intravascular blood flow (stasis) and compression of the femoral veins by harness groin straps were the likely pathogenetic mechanisms of the described diseases. The importance is stressed of prevention, which must be based on planned regular breaks in the hanging position, checking on the fit and comfort level of the harness before it is first used, as well as medical surveillance of the subjects who spend prolonged periods in a harness for work or recreation.     

Venous thrombosis during total parenteral nutrition with central venous catheters--role of nutritive solutions

Contrast venograms were performed after removal of the catheter in 17 cases with isolated fever during a study of 187 patients treated by total parenteral nutrition with silicone central venous catheters. Thrombosis of the superior vena cava or of one of its collaterals was present in 7 cases and comparison with the 10 cases who had normal venograms showed a significant difference in the composition of the nutritive solutions infused. Patients with thrombosis received more hypertonic solutions with higher concentrations of glucose and nitrogen in their daily infusions.     

Venous gas embolism: time course of residual pulmonary intravascular bubbles

The time course of pulmonary intravascular air emboli was studied in anesthetized dogs. In one series of experiments air was infused into the right atrium at 0.10 ml.kg-1.min-1 or 0.25 ml.kg-1.min-1 for 15 min or given as a bolus injection of 2 ml/kg at 2 ml/sec. In a second series of series of experiments venous air was infused into dogs (0.25 ml.kg-1.min-1, 15 min) ventilated with 100% oxygen for 0, 30, or 210 min before the embolization. After the air infusions the animals were allowed to recover, breathing 70% nitrogen:30% oxygen. At 10-min intervals during recovery, the nitrogen was replaced with nitrous oxide (N2O) for 5 min to expand any residual pulmonary vascular bubbles. Subsequent changes in pulmonary artery pressure (Ppa) and end-tidal carbon dioxide (PETCO2) concentrations, pulmonary vascular resistance (PVR) and carbon dioxide tensions (PaCO2) as a result of the N2O challenges indicated the presence of residual gas bubbles in the pulmonary arterial system. Residual times of the pulmonary bubbles were 24.5 +/- 12.3 min (0.10 ml.kg-1.min-1 air dose), 43 +/- 10.8 min (0.25 ml.kg-1.min-1 air dose), and 17.8 +/- 2.5 min (bolus). The latter two were significantly different from each other. With 100% oxygen breathing the residual times were 19 +/- 2.2 (0 min), 22 +/- 6.7 min (30 min), and 17 +/- 4.0 (210 min). These values were reduced significantly when compared to the dogs ventilated with 30% oxygen.(ABSTRACT TRUNCATED AT 250 WORDS)