Changes in blood coagulability as it traverses the ischemic limb

We undertook this study to determine whether changes in blood coagulability associated with peripheral arterial occlusive disease are due to contact with the atherosclerotic arterial wall or passage through distal ischemic tissue.

Thirty patients with peripheral arterial occlusive disease undergoing angiography participated in the study. Ankle-brachial pressure index was recorded before intervention. Blood samples taken from the aorta, common femoral artery, and common femoral vein were analyzed at thromboelastography. Angiograms were scored for stenotic disease by a radiologist blinded to the other results.

When femoral artery samples were compared with aortic samples there was a decrease in reaction time (R; P <.05), an increase in maximum amplitude (MA; P <.05), and an increase in coagulation index (CI; P <.002), indicating an increase in coagulability as blood flowed down the iliac segment. These changes also correlated (DeltaR, r = 0.442, P <.05; DeltaMA, r = 0.379, P <.05; DeltaCI, r = 0.429, P <.05) with the severity of disease in the ipsilateral iliac segment. Significant differences in R (P <.05), angle (P <.05), MA (P <.005), and CI (P <.001) between common femoral arterial and venous samples confirmed that venous samples were more coagulable in this group of patients. This difference in Thromboelastography parameters across the arteriovenous segment correlated inversely with the degree of ischemia (represented by ankle-brachial pressure index; DeltaCI, r = -0.427, P <.05; DeltaMA, r = -0.370, P <.05) in the puncture side limb.

Passage of blood down an atherosclerotic artery leads to an increase in coagulability proportional to the degree of stenosis in that vessel. Passage of blood through ischemic tissue may also contribute to increased coagulability in peripheral arterial occlusive disease.