Blood Coagulation Detector Helps Monitor Stroke Risk

Atrial fibrillation (AF) causes an irregular and sometimes fast heart rate, and is a common risk factor for stroke.

A novel dielectric blood coagulometry (DBCM) has been invented for the evaluation of the coagulability and the DBCM measures the temporal change in the whole blood dielectric permittivity, which represents the aggregation of red blood cells. The CHADS2 score or CHA2DS2-Vasc predictive score are widely utilized for the risk stratification of strokes and used to guide anticoagulation therapy in patients with AF.

Scientists at the Tokyo Medical and Dental University (Tokyo, Japan) and their colleagues analyzed 133 blood samples that were drawn from subjects with or without heparin administration. A DBCM analysis was performed to find the adequate coagulation index, and to delineate its measurement range by adding recombinant human tissue factor (TF) or heparin. Then the coagulability was assessed by DBCM and conventional coagulation assays in 84 subjects without AF, who were divided into three groups by their CHADS2 score. Another 17 patients who received warfarin were also assessed by DBCM to evaluate the effect of anticoagulants.

DBCM was performed using a prototype dielectric coagulometer (Sony Corporation, Tokyo, Japan). The DBCM measured the dielectric permittivity in frequencies ranging from 100 Hz to 16 MHz, with sampling intervals of one minute. The measurement was completed 60 minutes after the recalcification. The dielectric permittivity was normalized compared to its initial value, and represented normalized permittivity. The result of the DBCM was analyzed by conducting a 5-point smoothing derivative of the dielectric permittivity at 10 MHz using the linear/quadratic Savitzky-Golay filter. Comparisons between untreated blood and that with added heparin (a blood thinner) or tissue factor (a blood-clotting accelerator) enabled derivation of a coagulability index.

The investigators found that found that patients receiving warfarin had a significantly longer end of acceleration time (EAT) than those without, confirming the anticoagulation effect. They also showed that patients with a high CHADS2 score had a significantly shorter EAT that represented hypercoagulability compared with patients with lower CHADS2 scores. The authors concluded that the DBCM, is a novel highly sensitive measurement method for whole blood coagulation, can identify small changes in the coagulation status. Patients with higher CHADS2 or CHA2DS2-Vasc scores exhibited hypercoagulability without AF. The study was published on June 8, 2016 in the journal Public Library of Sciences ONE.

Related Links:
Tokyo Medical and Dental University
Sony Corporation