The statistical analysis of distribution of blood deposits in arterial prostheses after short-term exposure to reduced blood flow in dogs: a computerized study using radioisotopes.

This study was undertaken to analyse the distribution pattern of blood elements deposits in 15 cases of vascular prostheses submitted, ex vivo, to reduced blood flow in a canine model. Autologous blood platelets labeled with Indium-111 and human 125 Iodinated fibrinogen were injected into the animals. Ten minutes later, the blood flow in the aorta was reduced to 50 ml/min and the prostheses (Woven DeBakey, 30 cm long and 6 mm internal diameter), were implanted as substitutes for the infrarenal abdominal aorta. The blood flow was then reestablished to 50 ml/min and controlled throughout the entire experiment. When a thrombosis occurred, or after 4 hours of low blood circulation, the prosthesis was collected, weighted and chemically fixed, and the radioactivity was measured by means of a two-channel gamma scintillation counter. These data were then formatted and processed by a special computer program. Final values were processed for graphical representation and analysed statistically. Results show a lack of correlation between weight of thrombotic matrix, platelet accumulation, and fibrin deposits retained from one animal to the other. There is, though, an appearance of a complex interrelationship between the mean pattern of longitudinal distribution of these elements, which shall be qualified as contagious distal accumulation of the deposits. The influence of each animals' blood characteristics, as evaluated by means of regression analysis, account for 40 to 60% of the interindividual variance in blood deposits. Data corrections following evidence of undesirable influences due to uncontrolled parameters are presented. This experimental method permits simultaneous graphical representation of the distribution of several elements in the thrombotic matrix, and at the same time an elaborate numerical analysis of their longitudinal distribution and total accumulation. The method is easy to use, does not require sophisticated equipment, and is less expensive than scintigraphy.