Nonneoplastic diseases of aorta and pulmonary trunk—Part V

Abstract

Th~s 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.Key words: pulmonary arteries, pulmonary trunk, pulmonary aneurysm, pulmonary artery dissection Pulmonary Trunk and Right and Left Main Pulmonary ArteriesIn contrast to multiple congenital and acquired diseases affecting the aorta, relatively few entities affect the pulmonary trunk and/or the right and left main pulmonary arteries, and the frequency of these lesions is considerably lower than that for the aorta. Acquired nonneoplastic diseases of the pulmonary trunk and/or the main pulmonary arteries includes aneurysm, embolism, medial degeneration, dissection, arteritis, atherosclerosis, and trauma. These conditions alter the pulmonary trunk and the main pulmonary arteries by wall thinning or widening (aneurysm, medial degeneration), wall tearing or rupturing, narrowing (embolism), or various combinations of these. Of these conditions, luminal narrowing by 6, 1997 emboli is the most common. Congenital diseases of the pulmonary trunk and the main pulmonary arteries include stenosis, atresia, and aneurysm. General Considerations Normal Pulmonary 'hunk and Main Pulmonary ArteriesThe pulmonary trunk is defined as that segment of the pulmonary artery that arises from the right ventricular outtlow tract to its division to the right and left main pulmonary arteries. The length of the pulmonary trunk is about 4 to 5 cni. Its internal diameter ranges from 2 to 3 cm, and the thickness of the media is between 600 and 900 pm.2 Both diameter and medial thickness increase with advancing age.3 The right main pulmonary artery forms a right angle with the pulmonary trunk and follows a horizontal course posterior to the hilus. The left main pulmonary artery is a continuation of the trunk. The pulmonary hunk and its two main branches are elastic arteries. At the time of birth, the pulmonary trunk and the aorta have approximately the same medial thickness and the same dense layering of elastic fibers within the media. Within the first year of life, the ratio in thickness of the media of the pulmonary trunk to that of the aorta decreases to about 0.6.2~~ During the same period, the elastic configuration in the pulmonary trunk changes from that in the aorta. In the adult pulmonary trunk, the amount of elastic tissue per histologic unit of medial surface area is only 50 to 60% of that in the aorta.3 This implies that, although in the aorta the elastic layers are fairly regular and parallel and densely arranged, in the pulmonary trunk these layers are interrupted and are in iragments. The elastic fragments often appear swollen. The intiina of the pulmonary trunk and ...

Cardiovascular Magnetic Resonance in Marfan syndrome

“…Aneurysms of the pulmonary trunk in MFS are rare [41], although dilatation of the main pulmonary artery is relatively common, occurring in over 10% patients [31,42]. …”