Editors: Collins, Jannette; Stern, Eric J.
Title: Chest Radiology: The Essentials, 2nd Edition
> Table of Contents > Chapter 18 - Congenital and Acquired Cardiac Disease
Chapter 18
Congenital and Acquired Cardiac Disease

Heart disease is the leading cause of morbidity and mortality in industrialized countries. Echocardiography, single photon emission computed tomography (SPECT), scintigraphy, positron emission tomography (PET), and cardiac catheterization with cineangiography have long been used to assess the anatomy and function of the normal and diseased heart. Recent advances in CT and magnetic resonance imaging (MRI) have generated a renewed interest in cardiac imaging, particularly among radiologists. CT in particular is an examination with which radiologists are very comfortable, and it now provides a means to globally assess the heart and lungs simultaneously. This chapter will focus on the chest radiographic and CT findings of common congenital cardiac diseases seen in the adult, normal and abnormal cardiac anatomy, valvular disease, cardiomyopathies, cardiac tumors, complications of myocardial infarction and cardiac surgery, and pericardial disease.
Congenital Cardiac Disease
Whereas congenital abnormalities are the predominant form of heart disease in childhood, in adults, congenital disorders represent only 1% of recognized heart disease (1). In general, adults with newly discovered congenital heart disease are those whose anomalies produced no symptoms or mild symptoms in childhood, or those who were misdiagnosed in childhood only to become symptomatic in adult life. A discussion of all congenital heart defects that can be diagnosed in adults is beyond the scope of this chapter. What will be presented is a brief discussion of common left-to-right shunts that are diagnosed in adulthood and the developmental anomalies of the aorta that can be associated with congenital heart diseases.
Atrial Septal Defect
Atrial septal defect (ASD) accounts for 80% to 90% of congenital left-to-right shunts found in adults (2,3) and is three times more common in women than in men. Almost half of the patients with ASD in all age groups are asymptomatic, and in these cases the ASD is discovered incidentally on a routine chest radiograph. There are different types of ASD, with the ostium secundum type (consisting of an absence or deficiency of tissue in the region of the fossa ovalis) being the most common type seen in adult patients. In uncomplicated ASD, the chest radiograph shows enlargement of the right ventricle and all segments of the pulmonary arteries (“shunt vascularity”) (Fig. 18-1). The right atrium is also enlarged, but it is usually not distinguished from right ventricular enlargement on the chest radiograph. Because the radiograph does not accurately reflect the size of the right atrium and ventricle, the overall heart size may appear normal. On the lateral view, right ventricular enlargement results in a filling in of the retrosternal clear space and posterior displacement of the left ventricle toward the spine (4). There is no enlargement of the left heart in a simple ASD. The aorta appears small, relative to the pulmonary artery, and the superior vena cava appears small or "absent" because of rotation of the heart from right-sided cardiac enlargement (Fig. 18-2).
Long-standing large shunts lead to pulmonary arterial hypertension; when pulmonary arterial pressure exceeds systemic arterial pressure, a reversal of shunting of blood from left-to-right to right-to-left occurs (Eisenmenger physiology). In these cases, there is marked central pulmonary artery dilatation and narrowing of peripheral pulmonary artery branches (5). The central pulmonary arteries can become aneurysmal and, rarely, can be calcified (Fig. 18-3).
FIGURE 18-1. Atrial septal defect. A: Posteroanterior (PA) chest radiograph shows marked enlargement of the central and all segments of the pulmonary arteries. The cardiac silhouette is enlarged. B: Lateral view shows filling in of the retrosternal clear space, secondary to right ventricular enlargement, and pulmonary artery enlargement.

FIGURE 18-2. Atrial septal defect. A: PA chest radiograph of a 17-year-old boy with a heart murmur since birth shows enlargement of the cardiac silhouette, enlarged central and peripheral pulmonary arteries ("shunt vascularity"), a normal- to small-sized aorta, and "absent" superior vena cava shadow. B: Lateral view shows enlargement of the right ventricle, as evidenced by increased opacification posterior to the sternum.
FIGURE 18-3. Atrial septal defect with Eisenmenger physiology. PA (A) and lateral (B) chest radiographs of a 52-year-old woman with a large, long-standing ASD that has resulted in a reversal of shunting of blood and pulmonary arterial hypertension. There is aneurysmal enlargement and calcification of the central pulmonary arteries, enlargement of the right heart, and "absence" of the superior vena cava shadow. C: CT shows large main (M), right (R), and lower (L) lobe pulmonary arteries. Long-standing left-to-right shunting of blood has resulted in pulmonary artery aneurysms, which contain low-attenuation thrombus (arrowheads), and calcification (arrows). D: CT at a level inferior to (C) shows enlarged lower lobe pulmonary arteries containing thrombus (T) and calcification (C), enlarged right atrium (RA), and enlarged right ventricle (RV), causing leftward bowing and hypertrophy of the interventricular septum (arrows). The pulmonary artery lumina are outlined by high-attenuation contrast material (L).

ASD closure can be accomplished with a variety of percutaneously placed devices. A catheter that is placed via the common femoral vein is fed through the cardiac defect into the left atrium using fluoroscopic and echocardiographic guidance. A commonly used device is the Amplatzer Septal Occluder (AGA Medical Corporation, Golden Valley, MN) (Fig. 18-4). This is a two-part closure device. One of two nitinol mesh disks is pushed out through the catheter into the left atrium; this is followed by release of the second disk into the right atrium to close the defect.
Ventricular Septal Defect
Ventricular septal defect (VSD) is the most common congenital heart disease in childhood, but it represents only 10% of

congenital cardiac lesions in the adult patient. Surgical correction and spontaneous closure of the defect account for the decreased incidence in the adult patient (6). Most patients with VSD who survive into adulthood without intervention have small and physiologically inconsequential defects. Patients who reach adult life with large VSDs have pulmonary arterial hypertension, progressive right-to-left shunting (Eisenmenger physiology), and cyanosis. Small shunts cannot be identified on chest radiography. With large shunts (VSDs with a shunt ratio greater than 2:1) and normal pulmonary vascular resistance, the chest radiograph shows “shunt vascularity,” enlargement of the left atrium and both ventricles, a normal or small aorta, and a normal right atrium. The left ventricular apex projects to the left, inferiorly and posteriorly. On frontal chest radiographs, enlargement of the left atrium is seen as a “double density” behind the right atrium, and straightening or focal convexity of the left mediastinal border is seen below the pulmonary artery shadow.
FIGURE 18-4. Atrial septal defect occluder. A: PA chest radiograph of a 50-year-old woman with a history of transient ischemic attacks shows an Amplatzer Septal Occluder device (AGA Medical Corporation, Golden Valley, MN) (arrow) in the location of the foramen of ovale. B: Lateral view confirms appropriate placement of the device (arrow).
Patent Ductus Arteriosus
The ductus arteriosus is a portion of the sixth aortic arch in the fetus that connects the left pulmonary artery to the descending thoracic aorta. Twelve to 24 hours after birth, the ductus is functionally closed, and anatomic closure occurs 1 to 2 weeks later. However, for unknown reasons, the ductus arteriosus may remain patent, creating a left-to-right shunt and varying degrees of overcirculation to the lungs, left atrium, left ventricle, and the ascending and arch portions of the aorta. If the ductus does not close, Eisenmenger physiology develops when pulmonary vascular resistance exceeds systemic resistance and causes a right-to-left shunt across the ductus arteriosus. The radiographic features of an uncomplicated patent ductus arteriosus (PDA) are similar to those of a VSD, except for the size of the aorta. In PDA, the ascending and arch portions of the aorta can enlarge (with the degree of enlargement dependent on the size of the shunt), indicating that the shunt is extracardiac, as opposed to an intracardiac shunt, such as a VSD, with which the size of the aorta is normal or small. However, aortic size is not always a reliable criterion, and in practice it can be difficult to distinguish VSD from PDA on chest radiography. Another finding of PDA in an adult is calcification of the ductus.
Anomalies of the Thoracic Aorta
Congenital bicuspid aortic valve is a relatively common malformation. As the valve thickens and becomes fibrotic, it becomes stenotic. When this occurs, the valve becomes calcified. A densely calcified aortic valve, as seen on chest radiography or CT in a patient under the age of 55, should prompt consideration of this anomaly.
In left aortic arch with aberrant right subclavian artery, the right subclavian artery, instead of the first branch, takes off as the final branch of the aorta. Patients with this common anomaly are usually asymptomatic but may present with dysphagia as a result of the retroesophageal course of the aberrant artery. The frontal chest radiograph often shows an abnormal mediastinal contour at the level of the aortic arch, where the proximal portion of the aberrant artery is dilated - the so-called "diverticulum of Kommerell." The lateral chest radiograph may show anterior displacement of the trachea.
A right aortic arch occurs when there is interruption of the embryonic left aortic component of the hypothetical double aortic arch. Two types are described: Type 1 is a mirror image of left aortic arch and is associated with cyanotic congenital heart disease in more than 95% of patients, most of whom have tetralogy of Fallot (7). Type 2 right aortic arch - a right aortic arch with an aberrant left retroesophageal subclavian artery - is common, occurring in 1 in 2,500 persons, and is usually found incidentally (1). Additional cardiac anomalies occur in only 5% to 15% of patients with type 2. Chest radiographs of a right aortic arch show that the trachea is bowed to the left at the level of the right aortic arch, producing a convex bulge just above the azygous vein (Figs. 18-5 and 18-6). It is typical for a right-sided arch to be high riding and present as a "mass" in the right paratracheal area. An aortic diverticulum, or proximal arterial dilation, is seen to the left and slightly below the usual site of a left-sided aortic arch. The diverticulum may be of sufficient size to produce a large bulge immediately above the left main pulmonary artery and simulate a left aortic arch or a nonvascular mediastinal mass. Most often, the left mediastinal bulge is a result of the aortic diverticulum rather than the aberrant left subclavian artery itself. As the left subclavian artery crosses from right to left, it will cause a posterior impression on the air-filled esophagus and the trachea, which is seen best on the lateral chest radiograph. The right aortic arch usually crosses to the left side posteriorly, in the middle of the thorax behind the right pulmonary artery, to descend into the abdomen on the left side. A double aortic arch forms a complete vascular ring and on occasion can first present in adulthood.
Pseudocoarctation is a term used to denote a focal narrowing of the aortic arch that has the same morphology as classic coarctation but does not produce obstruction. This anomaly is a buckling of the aorta at the isthmus with little or no pressure gradient across the buckled portion (less than 30 mm Hg) (8). Because there is no obstruction, there is no collateral flow, and there is no rib notching as is seen with classic coarctation. The chest radiograph shows a left "mediastinal mass" that represents an elongated, redundant, and high aortic arch. Sagittally reconstructed CT of the chest can show the high arch with a kink at the isthmus, resembling the numeral 3, in which the midportion of the 3 corresponds to the attachment of the ligamentum arteriosum (Fig. 18-7). A "cervical aortic arch" can resemble pseudocoarctation of the aorta on chest radiographs, but with a cervical arch, the aortic arch lies in the neck, above the clavicles, usually on the right side.
Acquired Heart Disease
Valvular Disease
The radiologic signs of uncomplicated valvular lesions are relatively straightforward (Table 18-1). Valve stenosis produces pressure overload and myocardial hypertrophy without dilatation. Dilatation indicates that heart failure has developed. Valve insufficiency produces volume overload and a combination of dilatation and hypertrophy of the involved cardiac chambers. With insufficiency, a dilated heart does not indicate cardiac decompensation.
Aortic Stenosis
Aortic stenosis (AS) can exist at the valvular, subvalvular, or supravalvular level. The chest radiographic abnormalities depend on the age of the patient as well as on the severity of the stenosis. The adult heart is of normal size and the lungs are normal, because left ventricular failure and dilatation occur only in terminally ill patients. Radiographically detectable calcification in the aortic valve occurs in all types of aortic stenosis and marks the stenosis as clinically severe. Dilatation of the ascending aorta is frequent in aortic stenosis but correlates poorly with severity or with the site of the stenosis. Poststenotic dilatation of the ascending aorta is caused by the jet of blood through the stenotic valve striking the lateral aortic wall. The lateral wall


of the aorta becomes both dilated and elongated, accentuating the rightward displacement of the aorta. In most children and adults with pure, severe aortic stenosis, the left ventricle is a small cavity that is hypercontractile and has the usual signs of hypertrophy. In the absence of other anomalies, left ventricular dilatation in pure aortic stenosis is direct evidence of heart failure.
FIGURE 18-5. Right aortic arch. A: PA chest radiograph shows a right-sided aortic arch and descending aorta. The trachea is not deviated to the right, as is usually seen with a left aortic arch. B: Lateral view shows a posterior impression on the tracheal air column, secondary to compression from the aberrant left subclavian artery crossing from right to left.
FIGURE 18-6. Right aortic arch with aberrant left subclavian artery. A: Scout view from a CT of a 29-year-old man with dysphagia shows deviation of the trachea to the left (arrowheads) and a right-sided descending thoracic aorta (arrows). B: CT shows the right-sided aortic arch (A) and an aberrant left subclavian artery (SCA) arising from the posterior arch and coursing posterior to the trachea (T) and esophagus (E). Note the compression of the esophagus from the aberrant vessel, causing the patient's dysphagia. There is also a persistent left superior vena cava (arrow), in addition to a right superior vena cava (arrowhead). C: CT at a level inferior to (B) shows the persistent left superior vena cava (arrow) coursing in a left paramediastinal location before draining into the coronary sinus more inferiorly. The descending aorta is midline at this level.
FIGURE 18-7. Pseudocoarctation of the aorta. A: PA chest radiograph of a 50-year-old woman shows a left paratracheal "mass" (arrows). Sternotomy wires are present from previous coronary artery bypass graft surgery. B: CT shows the left subclavian artery (S), right (R) and left (L) brachiocephalic veins, and the high-riding, "buckled" aortic arch (A). C: Sagittal reconstruction shows the buckled aortic arch (arrows) and focal kinking of the aorta at the isthmus (arrowhead). This reconstruction shows how an axial view at the level of the aortic arch (dashed line) will show "two" rounded, contrast-enhanced structures adjacent to each other.
Calcific AS in the adult can be caused by rheumatic heart disease, a congenital bicuspid aortic valve, or advanced age and degeneration of the valve (8). The average age at which aortic valve calcification is first detected is 25 years for congenital AS, 47 years for rheumatic AS, and 54 years for degenerative AS (9). Valve calcification is best seen on the lateral chest radiograph, because the valve usually projects over the spine in the frontal projection. An important clue to the diagnosis of rheumatic disease in the aortic valve is the presence of mitral stenosis or regurgitation.
AS in elderly patients results from degeneration of the valve leaflets, with subsequent thickening and calcification. These aortic valves are tricuspid and have clumps of calcium within the webs of the leaflets. Some of these elderly patients also have coronary artery calcification and calcification in the mitral annulus and aortic arch.
Aortic Insufficiency
Stenotic aortic valves generally also have some insufficiency. If the aortic insufficiency (AI) is both chronic and severe, the chest radiograph shows left ventricular enlargement and dilatation of the entire aorta. This pattern follows the principle that insufficiency of any of the heart valves enlarges structures on both sides of the insufficient valve. Isolated AI most commonly results from a congenital bicuspid aortic valve. Other rare causes of AI include syphilitic aortitis (presenting between 45 and 65 years of age and associated with calcification of the ascending aortic aneurysm), Marfan syndrome (presenting before age 30 and not associated with calcification of the aneurysm), ankylosing spondylitis, relapsing polychondritis, and traumatic rupture of the aortic valve.
Mitral Stenosis
Most mitral stenosis (MS) is acquired and usually results from rheumatic carditis that occurred at least 5 to 10 years previously. Less common etiologies include left atrial myxoma, thrombus, or a tumor that may prolapse through the mitral orifice during diastole and create functional stenosis. Early in the course of rheumatic MS in the adult, the pulmonary blood flow

redistributes to the upper lobes. Later, the pulmonary arteries enlarge as pulmonary arterial hypertension develops. Later still, the right ventricle fails, from both a pressure overload from pumping into hypertensive pulmonary arteries and from pulmonic insufficiency secondary to a dilated annulus (Fig. 18-8). The chest radiograph in MS physiologically reflects the left atrial hypertension. The left atrium is enlarged, but the left ventricle is normal in size (unless there is coexisting mitral insufficiency). Left atrial enlargement can manifest as straightening of the left heart border or a convex shadow just below the left mainstem bronchus on the posteroanterior chest radiograph (indicating enlargement of the left atrial appendage), splaying of the tracheal carina, and posterior displacement of the pulmonary venous confluence and left lower lobe bronchus on the lateral chest radiograph (Fig. 18-9). The lungs show a diffuse increase in interstitial markings that is likely related to both fibrosis and edema. Patients with severe MS can have hemoptysis caused by bleeding of the engorged plexus of vessels around the middle to smaller bronchi, with a late sequela of pulmonary hemosiderosis, the deposits of which can calcify. The amount of calcium in the mitral valve roughly correlates with the degree of MS, but, unlike the aortic valve, the mitral valve may be severely stenotic and have no radiologically visible calcification. To distinguish aortic from mitral valve calcification on a lateral chest radiograph, one can draw a line from the inferior aspect of the right pulmonary artery along the right middle lobe branch to the tip of the xiphoid; the aortic valve is above this line, and the mitral valve is below this line.
Valvular disease Radiographic findings
Aortic stenosis
  • Calcification of aortic valve
  • Dilatation of ascending aorta
  • Dilated left ventricle and pulmonary edema only with left ventricular failure
Aortic insufficiency
  • Calcification of aortic valve
  • Dilatation of ascending aorta
  • Dilated left ventricle
  • Pulmonary edema with left ventricular failure
Mitral stenosis
  • Enlargement of left atrium, right ventricle, and pulmonary trunk
  • Cephalization of pulmonary vasculature
  • Septal (Kerley B) lines
  • Calcification of mitral valve
Mitral insufficiency
  • Markedly dilated left atrium
  • Mildly dilated left ventricle
  • Moderate enlargement of pulmonary trunk and right ventricle
Tricuspid stenosis
  • Systemic venous dilatation
  • Pulmonary oligemia
Tricuspid insufficiency
  • Dilatation of right ventricle and right atrium
  • Dilatation of venae cavae
  • Pulmonary oligemia
Pulmonic stenosis
  • Right ventricular enlargement
  • Poststenotic dilatation of the pulmonary trunk and left pulmonary artery
  • Increased pulmonary blood flow to the left lung and decreased pulmonary blood flow to the right lung
Pulmonic insufficiency
  • Dilatation and hypertrophy of the right ventricle
  • Systolic enlargement of the pulmonary trunk and central pulmonary arteries
Mitral Insufficiency
Acute mitral insufficiency (MI) can be traumatic, infectious, degenerative, or idiopathic. The pathology is usually a rupture of a chorda, a papillary muscle, or a mitral leaflet. Acute MI leads to acute left ventricular failure with severe pulmonary edema and a normal-sized heart or minimal cardiomegaly.
The major causes of chronic MI are rheumatic fever, mitral valve prolapse, coronary heart disease, and cardiomyopathy. Typical radiographic manifestations include a markedly dilated left atrium, a well-contracting but only mildly enlarged left ventricle, cephalization of the pulmonary vasculature without frank pulmonary edema, and moderate pulmonary trunk and right ventricle enlargement. MI can also be associated with focal edema in the right upper lobe. The pathogenesis for this condition is the vector of the regurgitant jet of blood flow from the left ventricle to the left atrium, toward the right superior pulmonary vein, which locally accentuates the forces for edema formation in the right upper lobe (10) (Fig. 18-10). With coronary heart disease and cardiomyopathy, the left ventricle is usually markedly dilated with poor contractility, with only mild enlargement of the left atrium.
Mitral Annulus Calcification
The mitral valve ring may calcify in individuals over age 60; this occurs more commonly in women than in men. The calcification often forms a pattern resembling the letter "J," the letter "O," or a reverse letter "C" (Fig. 18-11). In most instances, mitral annulus calcification has little clinical significance and is a


noninflammatory chronic degenerative process. AS and hypertension are associated with mitral annulus calcification, likely as a result of the increased strain exerted on the mitral valve apparatus from the left ventricular pressure overload. If the calcification grows posteriorly into the ventricular myocardium, heart block can occur. If it grows anteriorly into the mitral valve leaflets, MS and MI can occur. Mitral annulus calcification is also associated with increased risk of stroke.
FIGURE 18-8. Rheumatic mitral stenosis. PA (A) and lateral (B) chest radiographs of a 40-year-old woman show enlargement of the right ventricle (note increased opacity posterior to the sternum on the lateral view) and left atrium (note the convexity of the left heart border inferior to the left pulmonary artery shadow; arrows). The central pulmonary arteries are enlarged from pulmonary arterial hypertension, and there is pulmonary vascular redistribution. Unlike the aortic valve, the mitral valve may be severely stenotic and, as in this case, have no radiographically visible calcification.
FIGURE 18-9. Mitral stenosis. A: PA chest radiograph of a 43-year-old woman with atrial fibrillation and a history of rheumatic fever as a child shows abnormal convexity to the upper left heart border, indicating an enlarged left atrial appendage (arrow). B: Lateral view shows posterior displacement of the pulmonary venous confluence (arrows).
FIGURE 18-10. Mitral insufficiency. A: PA chest radiograph of an 84-year-old woman shows an enlarged cardiac silhouette and right upper lobe pulmonary opacity representing edema. B: CT shows an enlarged left atrium (LA) and bilateral pleural effusions. C: CT at a level inferior to (B) shows calcification of the mitral valve (arrow) and enlargement of the left ventricle (LV). D: CT with lung windowing shows ground-glass opacity limited to the right upper lobe. Right upper lobe edema in patients with mitral insufficiency is thought to be caused by the regurgitant jet of blood flow through the mitral valve to the right superior pulmonary vein.
Tricuspid and Pulmonic Valve Disease
Acquired disease isolated to the tricuspid and pulmonic valves is much less common than aortic and mitral valve disease. Primary disease of the tricuspid valve is most commonly caused by rheumatic disease and is associated with disease also involving the left-sided cardiac valves. Pulmonic stenosis is almost always congenital (Fig. 18-12), and pulmonary insufficiency is most commonly a result of severe pulmonic arterial hypertension of any etiology (e.g., severe MS and recurrent pulmonary thromboembolic disease).
Multivalvular Disease
Multivalvular involvement is common in patients with rheumatic heart disease, cardiomyopathies, and connective tissue disorders (Fig. 18-13). In general, the proximal valvular lesions tend to obscure the distal ones, both clinically and radiographically.
Cardiomyopathies can be classified as dilated, hypertrophic, or restrictive. Each can be further categorized as primary (affecting the myocardium but not other organs) or secondary (myocardial disease as one manifestation of systemic disease). Idiopathic dilated cardiomyopathy is characterized by dilatation of both ventricles or only the left ventricle, and it is either idiopathic or, in about half of cases, is thought to have a viral or immune etiology. Secondary dilated cardiomyopathy can be caused by ethanol toxicity, chemotherapeutic agents (e.g., doxorubicin), heavy metals, infection, connective tissue diseases, sarcoidosis, neuromuscular diseases, metabolic or endocrine

abnormalities (e.g., hypocalcemia or hypothyroidism), nutritional deficiencies (e.g., vitamin B12 deficiency), pregnancy, hypertension, or chronic myocardial ischemia; or it may be familial in origin. Chest radiography shows global cardiac enlargement and pulmonary edema.
FIGURE 18-11. Mitral annulus calcification. PA (A) and lateral (B) chest radiographs of an 87-year old woman show a C-shaped calcification in the expected location of the mitral annulus (arrows) and a dual-lead pacemaker. C: CT shows dense calcification of the mitral annulus (arrow).
Genetic hypertrophic cardiomyopathy is characterized by biventricular myocardial hypertrophy without chamber dilatation and is distinguished from acquired hypertensive heart disease. Initially this disease was called idiopathic hypertrophic subaortic stenosis, but it was recognized that subaortic obstruction was only one feature of cardiac hypertrophy. In some cases, the left ventricle or interventricular septum is predominantly involved. The disease is genetically transmitted as an autosomal-dominant trait. The disease can cause sudden death in young patients. Chest radiographs most commonly show normal heart size. This is because the hypertrophy decreases ventricular capacity but does not increase ventricular size. Acquired or secondary hypertrophic cardiomyopathy can be caused by essential hypertension, renal and adrenal disease, endocrine diseases, and left ventricular outflow obstruction (i.e., aortic stenosis).
Restrictive cardiomyopathy is characterized by impaired filling of noncompliant ventricles and diastolic dysfunction. Either right- or left-sided symptoms may predominate. Causes in-clude amyloidosis, scleroderma, endomyocardial fibrosis, carcinoid heart disease, sarcoidosis, radiation, and familial or id-iopathic origins. Heart size and contour are usually normal on chest radiography. As the disease progresses, a combination of both enlargement and a thick left ventricular wall may develop. Because of the stiff right and left ventricles, the right and left


atria dilate in response to filling the ventricles under increased diastolic pressure. Dilated venae cavae, large atria, and small ventricles are also features of constrictive pericarditis, and the two may be difficult to distinguish. The presence of a thickened and calcified pericardium is relatively specific for constrictive pericarditis. However, not all constrictive pericarditis is calcified, and some patients with restrictive cardiomyopathy may have mild thickening of the pericardium.
FIGURE 18-12. Pulmonic stenosis. A: Anteroposterior chest radiograph of a 52-year-old man shows an abnormal opacity in the expected location of the main and left pulmonary arteries (arrow). B: CT shows marked enlargement of the main pulmonary artery (PA). C: CT at a level inferior to (B) shows marked enlargement of the left pulmonary artery (LPA) and a normal-size right pulmonary artery.
FIGURE 18-13. Multivalvular disease. PA (A) and lateral (B) chest radiographs of a 66-year-old woman with a history of rheumatic fever show mitral (solid arrows) and tricuspid (dashed arrows) valve prostheses.
FIGURE 18-14. Arrhythmogenic right ventricular dysplasia. MRI shows delayed hyperenhancement of the right ventricular free wall (arrows). (Image courtesy of David Bluemke, MD, PhD, Johns Hopkins Medical Institutions, Baltimore, MD.)
Arrhythmogenic right ventricular dysplasia (ARVD), an idiopathic cardiomyopathy, is a myocardial disorder of primarily the right ventricle that is more common in males than females and has a frequent familial occurrence (11). The disorder is characterized by transmural or nontransmural infiltration of the right ventricular myocardium with fat or fibrous tissue, diffuse thinning of the right ventricular myocardium, dyskinesia of the right ventricle, and abnormal enhancement on delayed images (12) (Fig. 18-14). MRI is the optimal technique for detection and follow-up of clinically suspected ARVD. Clinically, ARVD is characterized by ventricular arrhythmias with left bundle branch block that may lead to cardiac arrest. It is recognized as a major cause of sudden death in young adolescents. The differential diagnosis of ARVD includes idiopathic dilated cardiomyopathy (usually presenting with a progressive decline in left ventricular function, as opposed to the right ventricular failure seen in ARVD) and the Uhl anomaly (characterized by a paper-thin right ventricle owing to the nearly complete absence of myocardial muscle fibers, with no gender predilection or familial occurrence). The diagnosis of ARVD is based on the presence of structural, histologic, electrocardiographic, and genetic factors. Positive MRI findings serve as an important criterion in the clinical diagnosis of ARVD, although negative MRI findings do not rule out ARVD.
Lipomatous Hypertrophy of the Interatrial Septum
Lipomatous hypertrophy of the interatrial septum (LHIS) is a benign disorder characterized by the accumulation of fat in the interatrial septum. The term is actually a misnomer, as the disorder is caused by an increase in the number, and not hypertrophy, of adipocytes (13). It typically occurs in elderly and obese patients. The thickness of the fatty septum is typically between 2 and 6 mm (14). CT shows a mass of fat attenuation with sharp margins and sparing of the fossa ovalis (Fig. 18-15), resulting in a dumbbell shape. The diagnosis is most commonly made incidentally and is usually unassociated with symptoms, although it can lead to rhythm disturbances such as P-wave abnormalities, atrial fibrillation, and even sudden death.
FIGURE 18-15. Lipomatous hypertrophy of the interatrial septum. CT of a 72-year-old woman shows fatty infiltration of the interatrial septum (F), which spares the fossa ovalis (arrow).
Cardiac Masses
The most common intracardiac mass is thrombus, which is usually located within the left atrium or the left ventricle and is associated with mitral valve disease, atrial fibrillation, or cardiomyopathy. The distinction between tumor and thrombus is made on MRI by the difference in signal characteristics or on MRI or CT by the presence or absence of enhancement after administration of contrast material. Tumor is usually hyperintense in comparison with myocardium and skeletal muscle (and thrombus) on T2-weighted MRI images and typically enhances with contrast on MRI or CT images (whereas thrombus does not enhance).
In all age groups, benign primary cardiac neoplasms are more common than malignant ones (13). Myxomas are the most common primary cardiac neoplasms, accounting for about 50% of all primary cardiac tumors. They are located in the left atrium in 75% of cases and in the right atrium in 20%. Unlike thrombus, left atrial myxomas are typically attached by a narrow pedicle to the area of the fossa ovalis (Fig. 18-16). They usually have heterogenous low attenuation on CT and are frequently calcified. Rhabdomyomas are the most common cardiac tumors in children, with up to 50% occurring in children with tuberous sclerosis. They typically occur in the left or right ventricle. Other benign cardiac tumors include papillary fibroelastoma (usually attached to the valves by a short pedicle); fibromas (arising in the myocardial walls, commonly calcified, and associated with arrhythmias and sudden death); lipoma; pheochromocytoma (most often located outside the cardiac chamber); and hemangioma.
One fourth of primary cardiac tumors are malignant, with sarcomas representing the largest number, followed by primary

cardiac lymphomas. Malignant cardiac tumors typically involve more than one cardiac chamber; extend into pulmonary veins, pulmonary arteries, or vena cavae; have a wide point of attachment to the wall of a chamber or chambers; extend outside the heart; and are associated with internal necrosis and hemorrhagic pericardial effusion.
FIGURE 18-16. Left atrial myxoma. CT of a 63-year-old man shows a low-attenuation mass (arrow) in the anterior left atrium (LA), along the interatrial septum. Note the right atrium (RA), aortic outflow track (Ao), right ventricle (RV), and left ventricle (LV).
FIGURE 18-17. Pericardial metastases. A: PA chest radiograph of a 76-year-old woman with breast cancer shows an enlarged cardiac silhouette and numerous pleural-based masses. The left hemidiaphragm is elevated, and there is blunting of the left costophrenic angle. B: CT shows pericardial and left pleural effusions, as well as a soft tissue mass infiltrating the anterior pericardium (arrow). C: Coronal reformatted CT shows left pleural-based masses (arrows) and pericardial effusion (P). The more inferior mass involves the pericardium.
Metastases to the heart and pericardium are much more common than primary cardiac tumors (15). Melanoma, lymphoma, and breast cancer are the most common tumors to metastasize to the heart (Fig. 18-17). Tumors of the lung and mediastinum can locally invade the pericardium and heart (Fig. 18-18). Focal obliteration of the pericardial line with or without effusion indicates extension of tumor into the pericardial sac. If the effusion is hemorrhagic, extension is almost certain.
Coronary Artery Disease
Coronary arteriography is the accepted method used to examine the coronary arteries. However, technological advancements with CT and MRI have dramatically improved the ability to noninvasively image the coronary arteries. Electrocardiography-gated multidetector CT shows promise as

a comprehensive method for evaluating cardiac and noncardiac chest pain in stable emergency department patients (16). Among the diagnoses that can be made on CT in addition to coronary artery disease are aortic dissection and pulmonary embolism (the so-called "triple rule-out"). Further hardware and software improvements will be necessary before CT can replace coronary arteriography and become widely used in clinical practice.
FIGURE 18-18. Carcinoma invading the heart. CT shows a large right lung mass compressing the superior vena cava (arrow) and left atrium (LA). The right superior and inferior pulmonary veins are obliterated.
Cardiac Anatomy
Multidetector CT, even in routine use to evaluate the lungs, can provide information about the morphology of the heart and coronary arteries. Therefore, it is important to have an understanding of the normal anatomy and CT appearance of these structures. On axial imaging, the right ventricle is anterior and has a triangular appearance, whereas the left ventricle is posterior and more ovoid. The maximum internal diameter of the right ventricle in its small axis should be equivalent to that of the left ventricle (17). The normal myocardial thickness of the right ventricle is 3 to 4 mm, approximately three times thinner than that of the left ventricle. The interventricular septum does not normally measure more than 13 mm in thickness. Anterior and posterior trabecular muscles, and the smaller medial papillary muscle, are connected to the tricuspid valve leaflets via the chordae tendineae in the right ventricle. The moderator band extends from the interventricular septum to the anterolateral aspect of the right ventricle in the region of the ventricular apex, where it inserts at the base of the anterior papillary muscle. It conveys the electrical apparatus of the right bundle of His. Anterior and posterior papillary muscles can also be seen in the left ventricle connecting to the leaflets of the mitral valve via chordae tendineae.
The crista terminalis can be recognized as a muscular prominence on the posterolateral aspect of the right atrium extending from the orifice of the superior vena cava to that of the inferior vena cava, and should not be mistaken for intracavitary tumor or thrombus on CT. The atrioventricular valves are located at the base of each ventricle.
The coronary arteries arise from the right and left coronary cusps, which are anatomic dilations of the ascending aorta at the aortic root, just above the aortic valve. (Figs. 18-19 and 18-20). Each aortic sinus can also be referred to as a sinus of Valsalva. The left main coronary artery arises from the left coronary cusp and passes behind the pulmonary trunk. It divides into the left anterior descending (LAD) and left circumflex (Cx) arteries. Occasionally, the left main coronary artery terminates in a trifurcation, giving rise to an intermediate coronary artery (ramus intermedius) that is directed laterally. The LAD artery courses along the anterior interventricular groove. Diagonal branches arise from the LAD and course at downward angles to supply the anterolateral free wall of the left ventricle. The LAD supplies the anterior two thirds of the septum, the anterior and anterolateral walls, the apex, and the anterolateral papillary muscle. The Cx artery extends laterally and posteriorly in the left atrioventricular groove and gives rise to obtuse marginal branches that extend on the lateral and posterior wall toward the apex. The Cx artery supplies the lateral left ventricular wall and anterolateral papillary muscle.
The right coronary artery typically arises from the right coronary cusp. It passes between the right ventricular outflow tract and the right atrial appendage and then runs in the right atrioventricular sulcus. The right coronary artery supplies the posterior one third of the septum, the inferior surface of the left ventricular and right ventricular free wall and the posteromedial papillary muscle. The distal right coronary artery courses along the diaphragmatic surface of the heart. The right coronary artery branches are the conus branch, the right ventricular branches, the acute marginal branch and the posterior descending artery. The posterior descending artery arises from a dominant right coronary artery in 85% of individuals and it courses in the posterior interventricular sulcus.
Anomalous origin of a coronary artery can occur from the pulmonary artery or aorta (Figs. 18-21 and 18-22). Ectopic origin of coronary arteries from the aorta is found in approximately 1% of the population (18). On occasion, these anomalies are seen incidentally on CT. The most common anomaly is ectopic origin of the Cx artery from the right coronary cusp or right coronary artery. When a major coronary artery such as the left main or LAD passes between the pulmonary artery and the aorta, the patient can suffer from angina pectoris, myocardial infarction, or sudden death.
Coronary Artery Calcification
Electron beam or helical multidetector CT of the coronary arteries is being used increasingly often for the detection and quantification of calcium deposits. A calcium "score" is computed and compared with data normalized by sex and age. An elevated score may be a signal of clinically significant disease. There are several limitations to this test. Not all calcium deposits in the coronary arteries mean that there is a blockage, and not all blocked arteries contain calcium. A high heart rate may interfere with the test. Exactly how the calcium score relates to the likelihood of experiencing angina, myocardial infarction, and sudden cardiac death remains uncertain. Men younger than 35 years of age and women younger than 40 are not likely to benefit from the test unless there are risk factors such as diabetes or a strong family history of heart disease. Men older than 65 years and women older than 70 are not likely to be treated differently as a result of test findings.
Calcification of the coronary arteries is a frequent incidental finding on chest radiography and routine chest CT (Fig. 18-23). In this setting, the observation should not be considered clinically significant unless the patient is under the age of 40.
Cardiac Postoperative Complications
Coronary artery bypass grafting (CABG) and percutaneous coronary intervention have long been the definitive aggressive options for treating patients with coronary artery disease (19). These treatments, particularly CABG, are associated with a variety of acute and chronic postoperative complications. Similar complications are seen after valve replacement, although anticoagulation therapy for valve replacement results in more problems with bleeding. Acute complications resulting



from cardiac surgery include atelectasis, edema, hemorrhage, pericardial effusion, and extrapulmonary air collections (e.g., pneumothorax, pneumomediastinum). Chronic complications include postpericardiotomy syndrome (a febrile illness consisting of various combinations of pericarditis, pleuritis, and pneumonitis); constrictive pericarditis; postoperative infection; pseudoaneurysm; and aortic dissection.
FIGURE 18-19. Cardiac anatomy. A: Electrocardiography-gated multidetector CT shows a normal left main coronary artery (arrow) arising from the left coronary cusp. B: The left anterior descending coronary artery (arrow) arises from the left main coronary artery and courses anteriorly in the interventricular groove. C: Occasionally, as in this case, the left main coronary artery terminates in a trifurcation, giving rise to an intermediate coronary artery (ramus intermedius; solid arrow), left anterior descending coronary artery (coursing anteriorly), and left circumflex coronary artery (dashed arrow). D: The right coronary artery arises from the right coronary cusp (solid arrow). Note the left anterior descending coronary artery (dashed arrow) and circumflex coronary artery (curved arrow). E: The circumflex coronary artery gives rise to marginal branches (arrow). Note the left (L), right (R), and noncoronary (N) cusps. F: Papillary muscles (solid black arrow) are connected to the mitral valve leaflets via the chordae tendineae (dashed black arrows). Note the right coronary artery (curved white arrow). G: Anterior papillary muscles are seen in the left ventricle (arrow). H: The coronary sinus (arrow) drains into the right atrium (RA). I: The posterior descending coronary artery (arrow) arises from the right coronary artery in 85% of individuals and courses in the posterior interventricular sulcus.
FIGURE 18-20. Coronary artery stent. A: Lateral chest radiograph of a 46-year-old man shows a right coronary artery stent (arrows). B: CT shows calcification in the left main and left anterior descending arteries (arrow).
FIGURE 18-21. Anomalous origin of coronary artery. CT shows the right main coronary artery arising from the right coronary cusp (solid arrow). The left main coronary artery also arises from the right coronary cusp and courses posterior to the aorta (dashed arrows). This is considered a benign anomalous course. (Case courtesy of Cris A. Meyer, MD, and Rhonda Strunk, RT, R(CT), University of Cincinnati 3D Post Processing Lab, University of Cincinnati Medical Center, Cincinnati, OH.)
CT is helpful in evaluating poststernotomy complications. Expected postoperative changes, which can persist for 2 to 3 weeks, include minimal presternal and retrosternal soft tissue infiltration with edema and blood, focal retrosternal air and fluid, localized hematoma, postincisional bone defects, minor sternal irregularities or offset, and minimal pericardial thickening (20). After this period of time, these changes should prompt

consideration of infection, especially when focal collections of presternal or retrosternal air and fluid are seen (Figs. 18-24 and 18-25). Noninfected mediastinal fluid collections can also be seen at this time, and only bacteriological analysis can differentiate bland from infected fluid collections.
FIGURE 18-22. Anomalous origin of coronary artery. CT shows the right main coronary artery arising from the right coronary cusp (solid arrow). The left main coronary artery also arises from the right coronary cusp. The left anterior descending coronary artery courses anterior to the pulmonary artery, a benign course (dashed arrow). The circumflex coronary artery (angled arrow) courses posteriorly, between the aorta and pulmonary artery (PA). This anomaly can result in angina pectoris or myocardial infarction. (Case courtesy of Cris A. Meyer, MD, and Rhonda Strunk, RT, R(CT), University of Cincinnati 3D Post Processing Lab, University of Cincinnati Medical Center, Cincinnati, OH.)
FIGURE 18-23. Coronary artery calcification. A: CT of a 66-year-old man shows dense calcification in the left anterior descending coronary artery (arrow). B: CT at a level inferior to (B) shows dense calcification of the circumflex coronary artery (dashed arrow) and a stent in the right coronary artery (solid arrow).
FIGURE 18-24. Poststernotomy infection. A: CT of a 47-year-old woman who underwent coronary artery bypass grafting shows fluid in the presternal and retrosternal areas and an air–fluid level in the presternal area (arrow). B: CT at a level inferior to (A) shows abnormal air and fluid in the retrosternal area (arrow).
Aneurysms of saphenous vein grafts to coronary arteries are unusual complications of CABG surgery, with only 50 cases reported since 1975 (21). True aneurysms are atherosclerotic in nature and appear as a late postoperative complication more than 5 years after CABG. Pseudoaneurysms may occur early as well as late after initial surgery, at the anastomotic site in most cases. Whenever a new mediastinal mass is seen on chest radiography in a patient who has undergone CABG, a graft aneurysm should be considered, and CT or MRI with intravenous contrast should be obtained. CT shows a round mass adjacent to a graft site with variable degrees of luminal enhancement or thrombus (Fig. 18-26).
FIGURE 18-25. Poststernotomy infection. A: CT performed 13 days after coronary artery bypass grafting shows air in the presternal area (solid arrow) and fluid in the retrosternal area (dashed arrow). B: CT at a level inferior to (A) shows a focal fluid collection with an enhancing rim (arrow) encasing the right coronary artery.

FIGURE 18-26. Coronary artery bypass graft aneurysm. A: PA chest radiograph of a 70-year-old woman with a history of coronary artery bypass grafting shows an abnormal left mediastinal contour (arrow). B: CT shows a round mass with peripheral calcification (arrows) at a graft site. C: MRI shows the graft aneurysm (arrows) adjacent to the main pulmonary artery (P). Note the ascending aorta (A), superior vena cava (SVC), and descending aorta (D).
More and more patients are undergoing percutaneous stenting of diseased coronary arteries as an alternative to CABG. These stents can be visualized on routine chest radiography and CT (Figs. 18-20 and 18-23).
Complications After Myocardial Infarction
Ischemic myocardial disease may be associated with a normal chest radiograph, or the radiograph may show nonspecific signs of cardiac failure. Ventricular aneurysm formation can complicate previous myocardial infarction in up to 10% of cases, occurring between 2 weeks and 2 years after ischemic myocardial necrosis and being located most often on the anterior wall of the left ventricle or at the cardiac apex (17) (Fig. 18-27). An abnormal bulge to the lower left heart border on a frontal chest radiograph may be seen. CT can show thinning of the involved myocardium, hypodensity in the abnormal ventricular wall that approaches that of fat, myocardial calcification, or local endoluminal thrombus. True ventricular aneurysms arising from previous myocardial infarction with associated scar formation and thinning of the myocardium should be differentiated from ventricular pseudoaneurysms, which are characterized by actual rupture of the myocardium and containment of the aneurysm by only the thin pericardium and which are at high risk of fatal rupture (17). Pseudoaneurysms are typically inferior in location and have a more discrete, narrower neck than true aneurysms. CT is helpful in distinguishing aneurysm from pseudoaneurysm by demonstrating a narrow orifice or "neck" leading from the ventricular chamber to a pseudoaneurysm.
Pericardial Disease
The pericardium is outlined by epicardial and pericardial fat, and the two layers of the pericardium together normally measure no more than 3 mm in thickness. It is important to understand the anatomy of the pericardial recesses and not mistake them for enlarged lymph nodes or other masses, especially in the right paratracheal region (Fig. 18-28), in the aortopulmonary window, in the subcarinal region, and around the insertion of the pulmonary veins (Fig. 18-29). When visible, pericardial recesses can usually be recognized as having fluid attenuation on CT.
The more common causes of pericardial effusion are listed in Table 18-2 (8). Cardiac tamponade is a low cardiac output state caused by excess fluid in the pericardial space that compresses the heart (Fig. 18-30). This can occur when as little as 150 to 250 mL of fluid accumulate acutely. In chronic or recurrent pericarditis, pericardial fluid may accumulate slowly, so that several liters may be present without tamponade occurring. Enlargement of the cardiac silhouette on the chest radiograph usually is not apparent until 250 mL of fluid are in the pericardial space. A typical chest radiograph of a patient with a pericardial effusion shows a wide cardiac silhouette with little abnormality in the lungs. The classic appearance is that of a “water bottle–shaped heart,” in which both sides of the

heart appear rounded and displaced laterally. The epicardial "fat pad" sign is produced when the pericardial layers and fluid widen the space between the anterior epicardial fat and substernal fat stripes by more than 4 mm. This is best appreciated on the lateral chest radiograph. Pulmonary edema is rarely seen in cardiac tamponade unless another disease, such as left ventricular failure from myocardial infarction, is also present. Diagnostic mimics of large pericardial effusions include pan-chamber cardiac enlargement and a large anterior mediastinal tumor in front of the heart.
FIGURE 18-27. Left ventricular aneurysm. A: Lateral CT scout image of a 78-year-old man with ischemic cardiomyopathy and previous anteroseptal and apical septal myocardial infarction shows a curvilinear area of calcification overlying the heart (arrow). B: CT shows a focal outpouching of the left ventricular apex with a densely calcified rim (arrow). Note the relatively wide aneurysmal neck, which is typical of true aneurysms and distinguishes this from a pseudoaneurysm.
FIGURE 18-28. Right paratracheal pericardial recess. A: CT shows a mass of fluid attenuation in the right paratracheal area (arrow). This fluid collection should not be mistaken for paratracheal lymphadenopathy. B: CT at a level inferior to (A) shows pericardial recess fluid (R) posterior to the ascending aorta.
In chronic constrictive pericarditis, ventricular filling is impeded by loss of compliance. The cardiac chambers are constricted by the thickened pericardium, and diastolic pressures are elevated. In constrictive pericarditis, the thickness of the pericardial layers typically exceeds 4 mm. The pericardium is calcified on the chest radiograph in about 50% of patients with constrictive pericarditis and presents as a curvilinear opacity conforming to the anatomy of the pericardial sac (Fig. 18-31).



When the calcifications are thin and linear, the etiology is usually viral or uremic pericarditis. Other causes include collagen vascular disease, trauma (including postsurgery), and radiation. When shaggy, thick, and amorphous, the calcification has historically been attributed to tuberculosis. Asbestos can also affect the pericardium, creating thick plaques similar to those occurring in asbestos-related pleural disease. MRI does not show calcification but demonstrates pericardial thickening and sometimes can be used to show impaired diastolic function. Because CT will detect minute amounts of calcium and MRI can miss significant deposits, some have advocated the use of MRI for the diagnosis of constrictive pericarditis only in those patients who have contraindications to iodinated contrast material (22). Additional findings seen with constrictive pericarditis include distorted contours of the ventricles (tubular-shaped ventricles), hepatic venous congestion, ascites, pleural effusions, and occasionally pericardial effusion. Often the atria, coronary sinus, inferior vena cava, and hepatic veins are dilated, reflecting elevated central venous pressure. Patients with constrictive pericarditis and restrictive cardiomyopathy can have similar clinical and physiologic findings. The presence of pericardial thickening or other signs of constriction suggests that the abnormality is pericardial in origin. A normal pericardium with thickening of the myocardium suggests cardiomyopathy as the diagnosis.
FIGURE 18-29. Right pulmonary vein pericardial recess. CT shows a focal fluid collection (arrow) adjacent to the right inferior pulmonary vein. This should not be mistaken for lymphadenopathy or other masses.
FIGURE 18-30. Acute infectious pericarditis. A: PA chest radiograph of a 26-year-old man with a neck abscess shows an enlarged cardiac silhouette. B: CT shows high-density pericardial fluid and thickening and enhancement of the pericardium (arrows). C: CT at a level inferior to (B) shows a focal pericardial fluid collection (solid arrow) compressing the superior vena cava (dashed arrow) and left atrium. The patient had clinical symptoms of pericardial tamponade.
Congestive heart failure
Collagen vascular disease
Hypothyroidism (myxedema)
Acute myocardial infarction
Trauma, including cardiac surgery (postpericardiotomy syndrome)
Chronic renal failure
Viral (especially coxsackievirus)
Fungal and parasitic
FIGURE 18-31. Constrictive pericarditis. PA (A) and lateral (B) chest radiographs show curvilinear calcification conforming to the anatomy of the pericardial sac (arrows).
FIGURE 18-32. Uremic pericarditis. A: PA chest radiograph of a 33-year-old woman with acute chest pain and a history of human immunodeficiency virus infection–related nephropathy shows a "water bottle"–shaped heart. B: After drainage of exudative pericardial fluid, the chest radiograph shows air outlining the pericardial sac (arrows). C: CT shows pneumopericardium (solid arrow), including air in the pericardial recess (dashed arrow).
FIGURE 18-33. Purulent pericarditis. A: PA chest radiograph of a 61-year-old man with acute chest pain shows pneumopericardium (arrows). The air in the pericardial sac does not extend above the aortic arch. B: CT shows air confined to the pericardial sac (P). One hundred forty milliliters of gas and pus were drained via pericardiocentesis.
Numerous congenital abnormalities of the pericardium can occur. Pericardial cysts are discussed in Chapter 6. Absence of the pericardium can be complete but is more often partial, with the defects more often left-sided. When most of the pericardium is absent, the heart axis will usually shift to the left and posteriorly. Partial absence of the left pericardium can result in a prominent-appearing left atrial appendage or pulmonary artery segment. Herniation of the heart through a congenital, traumatic, or surgical pericardial defect is rare but life threatening.
Pneumopericardium is gas in the pericardial sac and can rarely be idiopathic but more commonly results from trauma; infection with a gas-forming organism; increased intrathoracic pressure (e.g., asthma, barotrauma, Valsalva maneuver); adjacent lung cancer or infection; esophageal rupture; forceful coughing; cocaine abuse; gastric perforation; liver abscess; pancreatic pseudocyst; or pregnancy. When a large amount of air collects in the pericardial sac acutely, the patient can suffer from cardiac tamponade. On chest radiography, pneumopericardium presents as lucency confined to the pericardial sac that does not extend above the aortic arch (Fig. 18-32). CT clearly shows air confined to the pericardial sac, distinguishing it from pneumomediastinum (Fig. 18-33).
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