New quantitative enzyme immunoassays for degradation products of fibrin and fibrinogen in plasma: A comparison with other laboratory methods

Changes in functional activities of plasma fibrinogen after treatment with methylene blue and red light

BACKGROUND

Methylene blue (MB) plus light treatment used for virus inactivation of human plasma units may lead to changes in the functional activities of fibrinogen.

STUDY DESIGN AND METHODS

Single-donor units of fresh plasma were treated with 1.0 microM MB and a red light dose of 48 J per cm2. The effects of MB plus red light treatment on fibrinogen clottability, fibrin polymerization and gelation, clot stabilization, and fibrinolysis were studied.

RESULTS

The concentration of clottable fibrinogen was unchanged during MB plus red light treatment, but a light-dose-dependent decrease of the concentration of functional fibrinogen was found. The initial release rate of fibrinopeptide A was slightly increased after MB plus red light treatment. Turbidity measurements of fibrin gel showed prolonged clotting time, lower fibrin fiber mass-to-length ratio, and slightly smaller fiber diameter. At a given clotting time, a gel with lower fibrin fiber mass-to-length ratio was produced. Clot stability and fibrinolysis remained normal. l-Histidine added to plasma before MB plus red light treatment normalized the thrombin-induced coagulation time in a dose-dependent way.

CONCLUSION

MB plus red light treatment affected the polymerization and gelation phase of fibrin. A tighter fibrin gel structure was formed. No effect on stabilization of fibrin clot or fibrinolysis was found.

Cross-linked fibrin degradation products (XL-FDP) as marker of early rethrombosis in percutaneous transluminal angioplasty

The thrombotic response to percutaneous transluminal angioplasty (PTA) was investigated in 31 patients treated for 1-10 cm femoropopliteal (n = 28) and tibial (n = 3) artery obstructions by measurement of cross-linked fibrin degradation products (XL-FDP) in peripheral blood samples drawn before and 30 min after PTA. XL-FDP increased from 400 +/- 147 ng/ml to 700 +/- 445 ng/ml (median +/- S.E., p = 0.0005). XL-FDP rose from 320 +/- 110 ng/ml to 540 +/- 102 ng/ml in 23 patients, whose ankle/brachial systolic blood pressure index (ABI) increased > 0.15 after PTA, whereas XL-FDP increased from 850 +/- 450 ng/ml to 2620 +/- 1472 ng/ml in eight patients, who failed to increase ABI in spite of preceding recanalisation. XL-FDP increased by more than 1000 ng/ml in 1/23 (4.3%) patients with uncomplicated PTA and in 6/8 (75%) patients with haemodynamic failure (p = 0.0005). Using a XL-FDP increase of 1000 ng/ml as cut-off, estimates of positive and negative predictive values (95% confidence limits) for early failure of PTA were 85.7% (42.1-99.6%) and 91.7% (73.0-99.0%), respectively. We conclude from this pilot study that femorotibial PTA produces a hypercoagulable state which may result in failure of early patency due to rethrombosis. We suggest for the first time XL-FDP as a marker of early rethrombosis in PTA, and report a sequential XL-FDP assay which may be useful for identification of high-risk patients requiring thrombolytic therapy after PTA for maintenance of early vascular patency.