This five-part review focuses on selected nonneoplastic diseases of the aorta and pulmonary trunk. Because many more diseases affect the aorta compared with the pulmonary trunk and the right and left main pulmonary arteries, most of this review will be devoted to disorders of the aorta. Part V of this five-part series on diseases of the aorta and the pulmonary trunk focuses on nonneoplastic diseases of the pulmonary trunk and the right and left main pulmonary arteries.