Natural history of pulmonary thromboemboli in dogs. Serial radiographic observation of clots labeled with powered tantalum.
Powdered tantalum was blown onto the surface of blood clots from 10 dogs. After autologous, tantalum-labeled clots were injected into a systemic vein in each dog, the dogs were sacrificed at varying times over a 5-week period. Microscopic sections showed the tantalum remained attached to the intraluminal clots throughout this period. No appreciable dispersion of label into extravascular parenchyma was observed. Serial roentgenograms demonstrated (a) initially, the labeled clots in the pulmonary arterial tree, (b) lysis of the clots, as indicated by progressive decrease in the breadth of the tantalum labels, (c) peripheral movement of the labeled clots, and (d) eventual fragmentation of the labels.