Ayerza \ä-ˈyer-sä\ Abel (1861–1918), Argentinean physician. Ayerza was a professor of clinical medicine at the National University of Buenos Aires. In 1901 he studied a case in which cyanosis and sclerosis of the pulmonary vessels appeared during autopsy. He reported his findings only in a lecture. A student, Francisco C. Arrillaga, incorporated the observations into a 1912 thesis and published a full description of the disease in 1925.