Acquired valvular heart disease is caused by rheumatic heart disease,³² arteriosclerosis,⁹ hypertension, or congenital heart defects. The mitral and aortic valves usually are involved.

Imaging Findings

Chest radiographs of patients with valvular heart disease typically demonstrate changes in the size of the cardiac shadow, alterations in the size and configuration of specific heart chambers, and alterations in pulmonary vascularity (Fig. 23-1). Valvular calcification also may be present, suggesting mitral and aortic stenosis of the involved valve. Specific radiographic findings are listed in Table 23-1.

TABLE 23-1

RADIOGRAPHIC APPEARANCE OF ACQUIRED VALVULAR HEART DISEASE

Condition	Radiographic Appearance
Mitral stenosis	Large left atrium, right ventricle, and pulmonary trunk; long, straight left heart border; cephalization of pulmonary blood flow; narrowed retrosternal clear space and occasional calcification
Mitral insufficiency	Large left atrium and left ventricle, pulmonary edema in severe cases
Mitral prolapse (floppy mitral valve syndrome)	Normal (unless regurgitation develops)
Aortic stenosis	Large left ventricle, prominent ascending arch, small aortic knob, valve calcification
Aortic insufficiency	Large left ventricle, prominent aortic knob
Tricuspid stenosis	Large right atrium
Tricuspid insufficiency	Large right atrium and right ventricle, dilated superior vena cava and dilated azygous vein
Pulmonary stenosis	Large left pulmonary artery, increased left lung vascularity, and large right ventricle
Pulmonary insufficiency	Large right ventricle

Magnetic resonance imaging (MRI) may be helpful in providing anatomic and functional information about patients with valvular heart disease.^8,18

Aneurysms are circumscribed dilatations of an arterial wall. Whereas saccular aneurysms involve part of the circumference of the vessel, fusiform aneurysms involve the entire circumference. If all three arterial layers (the tunica intima, media, and adventitia) are affected, the aneurysm is called a true aneurysm. False aneurysms disrupt arterial walls but are contained by the surrounding connective tissue. A number of conditions, including atherosclerosis, syphilis, mycoses, posttraumatic conditions, congenital conditions, cystic media necrosis, and arteritis, have been named as possible causes of aneurysms (Table 23-2; Figs. 23-2 to 23-6). Atherosclerosis is the most common cause and usually involves the descending aorta.

Aortic dissection occurs when a hematoma in the middle to outer third of the aortic wall longitudinally separates the aortic wall proximally and distally. Hematomas often develop as a result of a vasa vasorum hemorrhage, which is seen in patients with hypertension. The tunica intima may rupture and reconnect the hematoma with its aortic lumen, creating a “double barrel” aorta. A number of classification schemes have been developed to describe the nature and region of aortic involvement (e.g., DeBakey, Stanford).

Juxtaductal, or adult type, coarctation of the aorta is a discrete narrowing of the aortic isthmus (the region between the arch and descending aorta) distal to the origin of the left subclavian artery and near the ductus or ligamentum arteriosus.⁴⁷ Tubular hypoplasia, or infantile-type coarctation of the aorta, is less common and involves narrowing of a segment of the transverse aortic arch. Coarctation is more common in males and often develops in conjunction with other cardiovascular defects, particularly when it is found in infants.

Although the aorta is narrowed, the collateral circulation typically prevents hypoperfusion of the trunk and lower extremities. In one such collateral path, blood from the subclavian arteries (before the coarctation has developed) enters the internal mammary arteries. It flows to the anterior intercostals and across the intercostal anastomoses, reversing the normal blood flow of the posterior intercostals and causing it to enter the aorta distal to the coarctation that developed. The hypertrophy of the intercostal arteries causes characteristic inferior rib notching.

Pseudocoarctation is kinking of the aorta that commonly is seen secondary to arteriosclerosis in elderly patients.