The full caption of this figure reads “Aneurismal dilatation (arteriovenous aneurism) of branches of coronary arteries in a case of anomalous origin of the left coronary from the pulmonary artery.” It’s from a book about congenital heart defects called Congenital Cardiac Disease (available on archive.org) by Dr. Maude E. Abbott, a pioneering medical researcher at McGill University.
The illustration here, showing aneurysms (or swollen/stretched out sections of blood-vessel wall), is signed by someone named “Nolan,” but I can’t tell who that is. Abbott, though, is pretty cool.