Clotting and arteriosclerosis occasionally occur in the small pulmonary arteries as a direct result of repeated showers of emboli from leg veins in an otherwise normal individual. More often, however, the arteriosclerosis is associated with cardiovascular or pulmonary disease such as rheumatic disease with mitral stenosis or pulmonary emphysema. The common denominator, according to Thomas,1 is thrombo-embolism. Harrison2 produced plaques in the small pulmonary arteries of rabbits by repeated intravenous injection of fragments of blood clots. Thomas, in extending Harrison's studies, incorporated carbon particles into clots before injection, and later was able to demonstrate the carbon particles in them, thus providing evidence that the plaque arose from a clot.
These plaques were devoid of fat, in contrast with plaques in human vessels such as the coronary arteries. The difference might be related to the fat content of food. Rabbits' chow contains about 2% of fat by weight, while
ARTERIOSCLEROSIS, LIPIDS, AND CLOTTING MECHANISM. JAMA. 1961;177(7):506. doi:10.1001/jama.1961.03040330042009