I. Biomaterials

1. M. Andrews: Thrombotic complications in indwelling catheters in pediatric patients were considered. Thromboembolic complications by central catheters of 40-80%, and by femoral catheters of 10-40% (DVT). Umbilical catheters may produce peripheral ischemia. Benefit of low-dose heparin is unclear, whereas coumadin reduces the thrombotic events.

2. M. Barstad: Presented a novel technique to assay potential effects of X-ray contrast media (CM) on thrombus formation at arterial shear in native human blood. It was concluded that the effect of CM on the clotting time in classical coagulation assays and on platelet aggregation in PRP did not parallel the influence of CM on thrombus formation in native blood.

II. Aneurysms/Arterial Stenosis/Blood Flow

1. V. T. Turitto: Reported on computational analysis of pressure and flow in various types of intracranial aneurysms. A subcommittee report on these issues will be submitted to the ISTH/SSC publication committee in the near future.

2. P. A. Holme: Presented a novel technique to assay platelet activation in flowing native human blood. It was concluded that constant shear up to 2600s-1 did not activate platelets. However, significant platelet activation was observed at eccentric stenoses with shear rates exceeding 10500s-1 at the apex. This activation was potentiated when collagen-induced thrombus formulation was triggered at the apex. Activation markers used were PAC1, Annexin V, and microvesicles.

3. L. Harker: Reported on platelet activation epitopes in stroke and other thrombotic disorders. A number of activation markers were used, including PAC1, Annexin V, LIBS, F9F, microvesicles, and bTG. Platelet activation was observed during 1 to 3 days following the onset of the thrombotic events.

4. V. T. Turitto: Discussed the need for advanced computational routines of complex blood flow patterns, particularly at arterial stenoses and aneurysms. Application of these results should be used as rough estimates of flow geometry. Programs available are FIDAP, FLUENT, and Flow-3D. These programs require data on luminal geometry dimensions and boundary definitions.

III. Working Parties

1. G. Lowe: Informed the committee by message that the working party on red cells WBC count and other rheological variables from 25 studies are analysed. It is planned to present the analysis at Barcelona in 1996.

2. Ph. de Groot: Presented a study on mesothelial cell seeding on vascula graft. Fibronectin is necessary for cell attachment. The cells possesses anti-thrombotic properties and they remained attached to the graft for up to 2 hours at a shear rate of 1000s-1. This presentation was within the framework of the working party on the use of flow chambers.

IV. Future Activities

Following activities are planned to be reported on or finished within the next subcommittee meeting in Barcelona:

1. Final standardization of technique to study potential effects of CM on thrombus formation in flowing native human blood. Responsible: K. S. Sakariassen, S. R. Hanson and D. A. Gabriel

2. Initiate new working party on standardization of potential effects of CM on cultured human endothelium. Responsible: E. Dejana

3. Submit a Subcommitte paper on flow and pressure at intracranial aneuryours. Responsible: V. T. Turitto

4. Present a summary of the current situation of commercial available programs for computational routines of complex flow patterns. Responsible: E. Grabowski

5. Final analysis of data from working party on hematocrit and other rheological variables from 25 studies. Responsible: G. Lowe

6. Report on working party activities on standardization of the use of flow chambers. Responsible: J. Hubbell

Subcommittee publications

(1) E. F. Grabowski. Guidelines for hematological evaluation of contrast media. Thromb Haemostasis. 72: 322, 1994.

(2) S. M. Slack and V. T. Turitto. Flow chambers and their use in studies of thrombosis. Thromb. Haemostasis. 72: 777, 1994.