ACP medicine, 3rd Edition
Diseases of the Pericardium, Cardiac Tumors, and Cardiac Trauma
- William Hancock M.D., F.A.C.P.1
1Professor of Medicine Emeritus (Cardiovascular Medicine), Stanford University School of Medicine
The author has no commercial relationships with manufacturers of products or providers of services discussed in this subsection.
Diseases of the Pericardium
The pericardium provides a protective sac around the heart. The sac contains a thin layer of fluid that permits the heart to move with minimal friction during the cardiac cycle. Neither the sac nor the fluid appears to be necessary for normal function. When one or more of the cardiac chambers dilate acutely, the pericardium restrains the heart. In chronic dilatation of the heart, however, the pericardium stretches and therefore does not exert a restraining effect, except during exercise or other acute stresses.
Pericardial disease results from diverse causes, many of which lead to responses to injury that are pathologically and clinically similar. There are three clinicopathologic responses to injury: acute pericarditis, pericardial effusion, and constrictive pericarditis.
Viral infection is usually assumed to be the cause of acute pericarditis that occurs as an apparently primary illness. Because most cases follow a brief and uncomplicated natural course, the syndrome is often termed acute benign pericarditis. Cases resulting from other conditions or treatments, such as rheumatic disease or radiotherapy, often exhibit clinical features similar to those of acute benign pericarditis.
The clinical diagnosis of acute pericarditis rests primarily on the findings of chest pain, pericardial friction rub, and electrocardiographic changes. The chest pain of acute pericarditis typically develops suddenly and is severe and constant over the anterior chest. In acute pericarditis, the pain worsens with inspiration—a response that helps distinguish acute pericarditis from myocardial infarction. Low-grade fever and sinus tachycardia also are usually present.
A pericardial friction rub can be detected in most patients when symptoms are acute. Pericardial friction rubs are typically triphasic: systolic and early diastolic components are followed in later diastole by a third component associated with atrial contraction.
Electrocardiographic changes are common in most forms of acute pericarditis, particularly those of an infectious etiology in which the associated inflammation in the superficial layer of myocardium is prominent. The characteristic change is an elevation in the ST segment in diffuse leads. The diffuse distribution and the absence of reciprocal ST segment depression distinguish the characteristic pattern of acute pericarditis from acute myocardial infarction. However, the normal variant pattern of ST segment elevation often complicates the differential diagnosis [see Figure 1]. Depression of the PR segment, which reflects superficial injury of the atrial myocardium, is as frequent and specific as ST segment elevation and is often the earliest electrocardiographic manifestation.1
Figure 1. ECG in Acute Pericarditis
Electrocardiograms contrast the pattern of ST segment elevation characteristic of acute pericarditis (a) with the normal variant (early repolarization) pattern of ST segment elevation (b). The normal variant pattern is associated with a normal or slow heart rate and has relatively tall R waves and T waves in V4, V5, and V6. The ST segment elevation is less than 25% of the T wave amplitude. In contrast, the acute pericarditis has PR depression and lower T wave amplitude.
Analgesic agents, such as codeine (15 to 30 mg taken orally every 4 to 6 hours) or hydrocodone (5 to 10 mg taken orally every 4 to 6 hours), are usually effective in providing symptomatic relief. Salicylates given at an initial dosage of 4 to 6 g a day or a nonsteroidal anti-inflammatory drug (NSAID) such as ibu profen given at an initial dosage of 800 mg three times daily is often effective in reducing pericardial inflammation.2 Corticosteroids such as prednisone given at an initial dosage of 40 to 60 mg/day often greatly relieve symptoms; however, steroid therapy should be reserved for severe cases that are unresponsive to other therapy, because symptoms may recur after steroid withdrawal. The corticosteroid dose should be reduced as soon as a clinical response is observed and should be tapered to zero over a period of 2 to 4 weeks.
Other Forms of Acute Pericarditis
Acute pericarditis of any etiology may follow a recurrent or chronic relapsing course. In many instances, subjective manifestations (e.g., weakness, fatigue, or headache) are present in addition to the chest discomfort. Analgesic agents provide symptomatic relief, and a very slow tapering of the dose of a corticosteroid usually resolves the relapsing course eventually. Treatment with 1 mg of colchicine daily, meth y lprednisolone in 1 g pulses daily for 3 days, or an immunosuppressant such as prednisone (60 to 100 mg daily) or azathioprine (50 to 100 mg daily) has proved successful in patients with relapsing pericarditis, particularly in patients whose symptoms are mainly related to withdrawal of prednisone.2,3
Progression to constriction
In a few instances, acute pericarditis progresses to subacute or chronic constrictive pericarditis. In such cases, the pericarditis may be idiopathic or have a bacterial, viral, rheumatoid, radiation-induced, or dialysis-related origin. These patients usually have subacute rather than acute pericarditis initially; pericardial effusion is present at onset, usually with some degree of cardiac tamponade. Acute benign pericarditis unaccompanied by tamponade or substantial pericardial effusion in the acute phase rarely progresses to constrictive pericarditis.
PERICARDIAL EFFUSION AND CARDIAC TAMPONADE
Fluid may accumulate in the pericardial cavity in virtually any form of pericardial disease. The fluid may be a transudate or an exudate and is often serosanguineous in neoplastic, idiopathic, dialysis-related, radiation-induced, and tuberculous cases. The fluid is serosanguineous or frankly bloody in cases of coagulopathy, trauma, rupture of acute myocardial infarction, and aortic dissection. Chylopericardium and pneumopericardium also can occur, although rarely.4 Cardiac tamponade or compression of the heart by effusion is the most important complication of pericardial effusion.
The physiologic effect of the accumulation of pericardial fluid depends on whether the fluid is under increased pressure.5 If effusion develops gradually, the pericardium stretches enough to accommodate volumes that may exceed 2,000 ml. However, if the effusion develops acutely, as little as 200 ml of accumulated fluid may raise the intrapericardial pressure and cause cardiac tamponade.
As the pericardial fluid pressure rises, the right atrial and central venous pressures increase correspondingly. Thus, reading the central venous pressure gives an accurate reflection of the intrapericardial pressure.
Cardiac tamponade should be viewed as a spectrum of hemodynamic abnormalities of various severities rather than an all-or-none phenomenon. Depending on the severity of the tamponade, the blood pressure may be lowered or maintained near the normal range; in patients with preexisting hypertension, it may even be increased. The central venous pressure is almost always increased, except in the rare instances of low-pressure cardiac tamponade, which may occur when intravascular volume is depleted.
As a rule, paradoxical pulse—a marked decrease in arterial pressure during inspiration—is present in patients with cardiac tamponade, although it may not be easy to detect on clinical examination [see Figure 2]. The arbitrary value of 10 mm Hg is commonly used to indicate the upper limit of the normal decrease in arterial pressure with inspiration.
Figure 2. Pressure Readings in Cardiac Tamponade
The aortic pressure and right atrial pressure are recorded during quiet breathing in a patient with cardiac tamponade. The marked fall in arterial pressure that occurs during inspiration is a paradoxical pulse. The decrease in pulse pressure, defined as the difference between systolic and diastolic pressures, that accompanies the fall in systolic pressure indicates that left ventricular stroke volume decreases during inspiration. Central venous pressure, as indicated by the right atrial pressure, also falls during inspiration.
The inspiratory drop in arterial pressure reflects a selective impairment of diastolic filling of the left ventricle, probably the combined effects of two factors. First, when the filling of the right ventricle is augmented in inspiration, the simultaneous filling of the left ventricle is limited because the entire heart is enclosed in a fixed volume. Second, during inspiration, blood is sequestered in the lungs and pulmonary veins as a result of impaired transmission of changes in intrapleural pressure to the left atrium and to the intrapericardial portions of the pulmonary veins.
Echocardiography is the most accurate and easily applied method for the clinical detection of pericardial effusion [see Figures 3a and 3b]. Echocardiograms detect effusions as small as 20 ml and show characteristic findings with effusions larger than 100 ml. Computed tomography is also a reliable method for detecting both pericardial effusion and pericardial thickening. Magnetic resonance imaging provides information similar to that provided by CT [see Figure 4].6
Figure 3a. Echocardiogram: Apical 4-Chamber View
Pericardial effusion is seen in the two-dimensional echocardiogram as an echo-free space outside the cardiac chambers. Two characteristic sites are lateral to the left ventricle in the apical four-chamber view (shown here) and posterior to the left ventricle in the parasternal long-axis view (see Figure 3b).
Figure 3b. Echocardiogram: Parasternal Long-Axis View
Pericardial effusion is seen in the 2-D echocardiogram as an echo-free space outside of the cardiac chambers. Two characteristic sites are lateral to the left ventricle in the apical four-chamber view (see Figure 3a) and posterior to the left ventricle in the parasternal long-axis view, shown here.
Figure 4. CT Scan: Pericardial Effusion
In a CT scan of the chest of a patient with pericardial effusion, pericardial fluid appears less dense than the heart and is separated from the myocardium by epicardial fat in some areas.
Electrocardiograms usually show low voltage in patients with large pericardial effusions, but this finding is nonspecific. Electrical alternans occurs occasionally when the pericardial effusion is large and permits a beat-to-beat oscillation of the heart from one position to another within the pericardial sac [see Figures 5a and 5b]. Electrical alternans is most common with effusion caused by neoplasm. This type of electrical alternans must be differentiated from other types, such as that occurring in supraventricular tachycardias or alternating intraventricular conduction defects.
Figure 5a. ECG: Pericardial Effusion
The electrocardiogram (V2 lead) from a patient with pericardial effusion caused by malignant melanoma reveals a low voltage and electrical alternans.
Figure 5b. Echocardiogram: Pericardial Effusion
The echocardiogram demonstrates that the heart moves forward (F) and backward (B) within the effusion on alternate beats, thus producing the alternation of the QRS axis characteristic of electrical alternans. The heart also moves with inspiration (Insp) and expiration (Exp), which accounts for a change in anterior wall motion with every two cardiac cycles.
The diagnosis of cardiac tamponade is often difficult.7 The diagnosis is one of the most common important diagnoses made at autopsy but not during life.8 This diagnosis should be based on a synthesis of various clinical findings, because no single finding is pathognomonic or necessarily present. Echocardiography, although essentially definitive for the demonstration of pericardial effusion, is not as certain a method of assessing tamponade. Several echocardiographic features are helpful, however, particularly the observation of an early diastolic inward motion (so-called collapse) of the right atrial wall or right ventricular wall, indicating similarity of intracavitary and intrapericardial pressures.9 Another useful sign is an exaggerated respiratory variation in the velocity of flow through the mitral and tricuspid valves or in the left ventricular ejection, as detected in pulsed Doppler recordings [see Figure 6]. This phenomenon has the same significance as paradoxical pulse. A third sign suggestive of cardiac tamponade is plethora of the inferior vena cava, which occurs in the more severe cases and is a better guide to the need for pericardiocentesis than the other echocardiographic features.10
Figure 6. Differential Diagnosis of Cardiac Tamponade vs. Chronic Constrictive Pericarditis
Differences between the central venous pulse contours characteristic of cardiac tamponade (left) and chronic constrictive pericarditis (right) provide the basis for differential diagnosis. The pressure contour in a patient with pericardial effusion and tamponade has a prominent systolic dip (X) but little or no diastolic deflection. The central venous pulse pattern in a patient with chronic constrictive pericarditis displays an M or W contour consisting of both systolic dip (X) and diastolic dip (Y), with the Y descent being more prominent.
Loculated pericardial effusions may selectively compress one or more chambers of the heart, producing regional cardiac tamponade. This condition is seen most frequently after cardiac surgery, when bloody fluid accumulates behind the sternum and selectively compresses the right atrium and right ventricle11; less often, the left ventricle and left atrium are compressed locally. Similar conditions may occur after closed chest trauma. Fluid accumulations in the mediastinum can compress the heart even when they are not truly within the pericardial space. Transesophageal echocardiography is superior to transthoracic echocardiography in demonstrating such local fluid accumulations, particularly those along the right heart border.
Occasionally, a syndrome of idiopathic chronic large pericardial effusion is seen, usually without tamponade. Colchicine may be effective in such cases.12
In patients with pericardial effusion but no tamponade, pericardiocentesis is rarely performed for the sole purpose of providing diagnostic studies of the fluid, because such specific diagnoses are uncommon in those patients, at least in regions of the world where tuberculous pericarditis has become rare.13 Pericardial biopsy can be obtained by any of the usual surgical methods. However, pericardiocentesis can be useful in diagnosing infection or neoplastic disease. In addition, pericardioscopy can be performed in association with subxiphoid pericardiostomy; biopsy under direct vision may permit the diagnosis of tuberculosis or neoplasm in some instances in which studies of the fluid alone might be inconclusive.14 Surgery is usually not necessary in chronic idiopathic pericardial effusion in the absence of tamponade and effusive-constrictive disease.15
Mild cardiac tamponade may be managed conservatively in some cases, but removal of the fluid is required for definitive treatment and should be carried out in most instances when the central venous pressure is increased. Pericardial fluid may be removed by needle pericardiocentesis or by a surgical technique (subxiphoid pericardiostomy, thoracoscopic pericardiostomy, or thoracotomy).16,17
The most acute forms of cardiac tamponade, such as hemopericardium secondary to aortic dissection, penetrating cardiac trauma, or rupture of acute myocardial infarction, require immediate surgery. Tamponade caused by cardiac perforation during invasive intravascular procedures can usually be managed by pericardiocentesis.18 Pericardiocentesis is effective in most sub-acute forms of tamponade, such as those associated with idiopathic or viral acute pericarditis, rheumatic diseases, dialysis, or neoplasm.
Thoracoscopy and thoracotomy are usually reserved for patients with recurrent tamponade after an initial pericardiocentesis or subxiphoid pericardiostomy, usually for neoplastic disease. Pericardiostomy by means of a balloon catheter as part of a pericardiocentesis is another alternative for such cases.19
SPECIAL ETIOLOGIC FORMS OF ACUTE PERICARDITIS AND PERICARDIAL EFFUSION
Pericarditis Related to Renal Failure and Dialysis
Acute pericarditis with pericardial effusion occurs in patients with end-stage renal disease and in patients who are on chronic dialysis [see10:X Chronic Renal Failure and Dialysis]. In dialysis patients, conservative management with more intensive dialysis and NSAIDs is usually successful. An unexpected decrease in blood pressure during a dialysis session may be the clue to the presence of tamponade. Pericardiocentesis is occasionally necessary for the relief of tamponade, although fluid overload and left ventricular failure are often important factors associated with causing increased central venous pressure. Cardiac catheterization in combination with pericardiocentesis is often useful in assessing the hemodynamic significance of those factors that contribute to an increase of pulmonary and systemic venous pressure in dialysis patients.
Radiation-Induced Pericardial Effusion
Pericardial effusion develops relatively frequently in patients with Hodgkin disease, other lymphomas, or breast carcinoma who survive for long periods after receiving large doses of radiation to the mediastinum. Radiation-induced effusion may evolve into chronic constrictive pericarditis after many years, usually with other forms of myocardial, coronary arterial, valvular, and pulmonary damage.20
Neoplastic Pericardial Effusion
Neoplastic pericardial effusion accounts for about one half of the cases of cardiac tamponade in patients who are seen in an internal medicine setting [see 12:XII Oncologic Emergencies]. Lung cancer and breast cancer account for the majority of the cases; lymphoma and leukemia account for most of the remainder.21 In most cases, the primary neoplasm has been previously diagnosed; patients in whom pericardial effusion is the first manifestation of the disease usually have primary cancer of the lung. Cytologic examination of the pericardial fluid is highly accurate in diagnosing common carcinomas but less accurate in diagnosing other neoplasms, especially the lymphomas and leukemias.22
Neoplastic pericardial effusion often can be managed conservatively when no symptoms directly related to the pericardial effusion are present. Symptomatic tamponade can be managed palliatively with pericardiocentesis, although recurrent effusion is more likely to form in such cases than in many other types of pericardial effusion. Subxiphoid pericardiostomy is often the preferred procedure, leading to a pericardial reaction that produces adhesion of the parietal and visceral layers of pericardium and thus prevents recurrent effusion. Balloon pericardiostomy is an alternative. Chemotherapy or radiotherapy may be of value, depending on the nature of the primary neoplasm. Intrapericardial instillation of chemotherapeutic agents has often been used with apparent success, but no results from controlled trials are available. Few patients survive longer than a year, and whether pericardiocentesis has a major effect on their longevity is difficult to determine, even when tamponade is relieved.23
Tamponade is usually present in purulent bacterial pericarditis; after pericardiocentesis, the effusion is highly likely to recur rapidly and progress to constrictive pericarditis. Purulent pericarditis therefore usually requires a surgical drainage procedure; a partial pericardiectomy by a limited left lateral thoracotomy is often the best choice. Surgery may not be required for patients in whom tamponade or constriction does not develop, because antibiotics enter the pericardial cavity in effective concentrations. Active tuberculous pericarditis with effusion is particularly likely to progress to constriction and to require pericardiectomy in addition to antituberculous chemotherapy.24,25 AIDS is a common cause of large pericardial effusions, the majority of which are not caused by identifiable opportunistic infective agents.26 However, the incidence of tuberculous and other forms of bacterial pericarditis has increased in the United States as a result of AIDS.
Several drugs have been implicated in the etiology of pericardial disease, including procainamide, which leads to a lupuslike syndrome; minoxidil, which has been linked to pericardial effusion; and methysergide, which may lead to constrictive pericarditis.
Pericarditis after Cardiac Surgery
The postcardiotomy syndrome presents primarily as acute pericarditis. Whether it has an infective or autoimmune cause is unclear. A similar condition occurs after blunt or penetrating trauma, hemopericardium from other causes, or epicardial pacemaker implantation. Cardiac tamponade and constrictive pericarditis occur occasionally.
Pericardial Complications of Invasive Procedures
Cardiac tamponade occurs as a complication of various invasive procedures in the cardiac catheterization laboratory and in the intensive care unit. Particularly important, and usually preventable, is the perforation of the heart by central venous cath eters that have been allowed to lie in the right atrium rather than in the superior vena cava.27 The use of newer devices (e.g., stents) and procedures (e.g., rotational atherectomy) has increased the incidence of percutaneous coronary interventions with cardiac tamponade complications.28 Most of these cases are managed successfully by pericardiocentesis.18
Constrictive pericarditis was formerly widely considered to be primarily a tuberculous lesion and is still so regarded in many areas of the world. Most cases now seen in the United States are idiopathic or are related to previous cardiac surgery or radiotherapy.29,30 Fewer cases result from purulent pericarditis, rheumatic diseases, dialysis, and various rarer conditions.
In the classic form of chronic constrictive pericarditis, fibrous scarring and adhesion of both pericardial layers obliterate the pericardial cavity. The resulting fibrotic lesion has been likened to a rigid shell around the heart, particularly when there is considerable calcification of the pericardium, a feature seen in long-standing cases. The subacute form of constrictive pericarditis is now more common than the chronic calcific type. In the sub acute variant, the constriction is rather fibroelastic and may be produced by fibrous contracture of the visceral pericardial layer (epicardium) alone. The fibroelastic constriction may also exist in combination with persisting loculated or totally free pericardial effusion; this form is termed effusive-constrictive pericarditis, and it can be documented by measuring pericardial and central venous pressures before and after removal of the fluid.
The pathophysiology of constrictive pericarditis is similar to that of tamponade in that both conditions impede diastolic filling of the heart and lead to increased venous pressure and ultimately to reduced cardiac output. Differences exist in the diagnostic signs, however. Paradoxical pulse is a regular feature of cardiac tamponade but may be inconspicuous or absent in constrictive pericarditis. The Kussmaul sign (an increase in venous pressure with inspiration) is seen in some patients with constrictive pericarditis but not in patients with pure cardiac tamponade. When tamponade is present, the venous pulse shows a predominant systolic dip, whereas in constrictive pericarditis, the early diastolic dip is the more prominent deflection [see Figure 6].
An early diastolic sound (pericardial knock) is often heard in constrictive pericarditis but not in tamponade; this sound is directly related to the extent to which ventricular filling is restricted to early diastole, being abruptly checked at the peak of early filling when the heart reaches the fixed volume imposed by the constricting shell surrounding it.
ECG and imaging studies
Constrictive pericarditis is difficult to diagnose, frequently being misdiagnosed for prolonged periods as liver disease or idiopathic pleural effusion. Clinical diagnosis of constrictive pericarditis depends on the recognition of increased venous pressure in a patient who may not have other obvious signs or symptoms of heart disease. The heart size and lung fields often appear normal in the chest radiograph, and the ECG shows only minor nonspecific abnormalities. Echocardiography is also nondiagnostic in many instances, although the appearance of abnormal septal motion and pericardial thickening often provide clues. Transesophageal echocardiography and chest CT are superior to echocardiography for the demonstration of pericardial thickening [see Figure 7]; however, the pericardium is not measurably thicker than normal in noninvasive imaging studies in some patients with constriction.31
Figure 7. CT Scan in Chronic Constrictive Pericarditis
In this CT scan of the chest of a patient with chronic constrictive pericarditis, the dense layer on the anterior surface of the heart represents thickened and partially calcified pericardium.
As in cardiac tamponade, pulsed wave Doppler studies show exaggerated respiratory variation in the mitral and tricuspid diastolic flow velocity in most cases of constrictive pericarditis. Doing the study in the upright position improves the sensitivity of this test.32 False positive results occur in patients with chronic obstructive pulmonary disease, but that can be recognized by performing Doppler studies of flow velocity in the superior vena cava; the changes in velocity with respiration are much greater in pulmonary disease than in constrictive pericarditis.33
Cardiac catheterization shows characteristic abnormalities, with increased central venous pressure, nondilated and normally contracting right and left ventricles, and near equilibration of the cardiac filling pressures of the right and left sides. These features may also be present in idiopathic restrictive cardiomyopathy or in specific myocardial diseases, especially cardiac amyloidosis; in such cases, the demonstration of pericardial thickness by CT or MRI and the use of endomyocardial biopsy are helpful.34 Many other clues can assist in this differential diagnosis [see Table 1]. The increased interdependence of the two ventricles in constrictive pericarditis causes the right and left ventricular systolic pressures to vary out of phase with each other in respiration; in conditions other than constrictive pericarditis, the two systolic pressures increase and decrease together with respiration. This is perhaps the most useful information yielded by cardiac catheterization in patients with suspected constrictive pericarditis.35
Table 1 Clinical Features That Differentiate Constrictive Pericarditis from Amyloidosis and Idiopathic Restrictive Cardiomyopathy
Constrictive pericarditis occasionally resolves spontaneously when it develops as a complication of acute pericarditis.35 In nearly all instances, however, relief of constrictive pericarditis requires surgical stripping and removal of both layers of the adherent, constricting pericardium. This operation is far more difficult to perform than the operation for relief of pericardial effusion. The operation must be thorough, which carries the risk of hemorrhage from perforations in the wall of the heart. Inadequate long-term relief after surgical removal of the pericardium may reflect the presence of associated myocardial disease, particularly in instances of radiation-induced pericardial disease.36 In most other forms of constrictive pericarditis, however, myocardial function is normal.
Cardiac tumors may be either primary or secondary, and they may be either benign or malignant. Metastatic cardiac involvement occurs 20 to 40 times more frequently than primary tumors. However, primary tumors are often benign and curable by surgery.
About 10% of patients who die of malignant disease have metastatic cardiac involvement, but the metastases produce symptoms in only 5% to 10% of the affected patients. Neoplasms particularly likely to metastasize to the heart are cancers of the lung or breast, melanoma, leukemia, and lymphoma.37
The most frequent clinical manifestation is pericardial effusion with cardiac tamponade. In such cases, the mass of the tumor is often relatively small. Extensive solid tumor in and around the heart is less common but may resemble constrictive pericarditis or effusive-constrictive pericarditis. Invasion of the myocardium most often manifests clinically as arrhythmias; atrial flutter and atrial fibrillation are particularly common.
Usually, the only effective treatment in metastatic involvement of the heart is relief of cardiac tamponade. Otherwise, treatment depends on the nature of the primary tumor.
PRIMARY BENIGN TUMORS
Eighty percent of all primary cardiac tumors are benign; myxomas account for more than half of these in adults, whereas rhabdomyomas and fibromas are the most common benign cardiac tumors in children.38,39,40 Cardiac rhabdomyomas in infancy and childhood have a high incidence of spontaneous regression; although they are sometimes responsible for a remarkable syndrome of paroxysmal ventricular tachycardia in infancy, this syndrome can be cured by surgical removal of the tumor. Echocardiography and MRI are both excellent methods for demonstrating intracardiac tumors [see Figures 8a and 8b] and [see Figure 9].
Figure 8a. Large Myxoma in Left Atrium During Systole
This transesophageal echocardiogram demonstrates a large myxoma (M) in the left atrium (LA) of a 23-year-old man. The picture shown here was taken during early systole and the picture shown in Figure 8b was taken during early diastole. The marked mobility of the tumor is evident as it moves from the left atrium to the left ventricle (LV). The right atrium (RA) and right ventricle (RV) are also visible.
Figure 8b. Large Myxoma in Left Atrium During Diastole
This transesophageal echocardiogram demonstrates a large myxoma (M) in the left atrium (LA) of a 23-year-old man. The picture shown in Figure 8a was taken during early systole and the picture shown here was taken during early diastole. The marked mobility of the tumor is evident as it moves from the left atrium to the left ventricle (LV). The right atrium (RA) and right ventricle (RV) are also visible.
Figure 9. MRI Showing Left Atrial Myxoma
This magnetic resonance image, coronal view, shows a large left atrial myxoma (M). The left ventricle (LV), aorta (Ao), left pulmonary artery (LPA), and inferior vena cava (IVC) are also visible.
Myxomas consist of scattered stellate cells embedded in a mucinous matrix. They are found in the cavities of the heart, attached to the endocardial wall (or, in rare cases, attached to one of the heart valves) by either a narrow stalk or a broader pedicle. The tumor often shows considerable movement within the cardiac chamber during the cardiac cycle [see Figures 8a and 8b]. About 70% of myxomas are in the left atrium; the rest are mostly in the right atrium. Echocardiography is a reliable method with which to predict tumor size and morphology.41
Myxomas are most often manifested clinically by mechanical hemodynamic effects, which often simulate mitral or tricuspid stenoses when they obstruct the valve orifice. They may simulate mitral or tricuspid regurgitation when they interfere with valve closure or cause a so-called wrecking-ball type of trauma to the mitral or tricuspid valve. Intermittent obstruction of the valve orifice can lead to such dramatic symptoms as syncope or to remarkable changes in physical signs that are sometimes related to changes in body position.
Myxomas also cause thromboembolic complications when portions of the tumor or thrombi from the surface of the tumor are detached. Another manifestation is a constitutional disturbance consisting of fatigue, fever, erythematous rash, myalgias, and weight loss, accompanied by anemia and an increased erythrocyte sedimentation rate. The constitutional symptoms may be caused by production of interleukin-6 by the myxoma.42
About 5% of cases of cardiac myxoma are familial, multicentric, or associated with a genetic syndrome that includes cutaneous lentiginosis, cutaneous myxomas, myxoid fibroadenomas of the breast, pituitary adenomas, adrenocortical micronodular hyperplasia with Cushing syndrome, and Sertoli cell tumors of the testis. These cases are referred to as complex myxoma, myxoma syndrome, or the Carney complex. A genetic mutation underlying this syndrome has been identified.43
Surgical treatment of cardiac myxomas is usually curative, particularly if the resection includes the portion of the atrial septum or atrial free wall from which the tumor has arisen. Recurrence and distant metastases are rare except in myxoma syndrome.44
Papillary fibroelastomas are small tumors, usually attached to cardiac valves, that can be a cause of cardioembolic stroke. They have been recognized with increasing frequency since echocardiography has come into more widespread use.45 Surgery may be indicated, especially if embolism recurs.
PRIMARY MALIGNANT TUMORS
Most malignant tumors of the heart are sarcomas, of either the spindle cell or the round cell type. Spindle cell tumors include fibrosarcomas, hemangiosarcomas, leiomyosarcomas, rhabdomyo sarcomas, and fibromyxosarcomas. Round cell tumors include lymphosarcomas or reticulum cell sarcomas. Primary lymphoma of the heart, which is usually seen only in immune-compromised patients, is increasing in incidence.46
Malignant tumors are more apt to occur in the right side of the heart than in the left, being about equally frequent in the right atrium and the right ventricle. Signs and symptoms usually stem from intracavitary growth of the tumor, causing obstructive phenomena that simulate congestive heart failure. Pericardial effusion and tamponade are also common.
Malignant pericardial mesothelioma usually presents as pericardial effusion with tamponade or as subacute constrictive pericarditis.
Although surgical excision of malignant cardiac tumors is often attempted, cure is only rarely achieved. The tumors are usually unresponsive to radiation or chemotherapy, and most are fatal within a few months.
Cardiovascular injury may be either blunt (i.e., nonpenetrating) or penetrating.47 Automobile accidents are the most common cause of blunt cardiovascular trauma; gunshots and stabbings are the most common causes of penetrating trauma. Both types of injury can damage the myocardium, the valves, the coronary arteries, the pericardium, and the great vessels, especially the aorta [see Figure 10]. Diagnosis in such instances is often difficult because the associated injuries can mask the cardiovascular trauma; cardiac trauma should therefore be suspected in all patients with chest injuries or severe generalized trauma.
Figure 10. Cardiac Injuries Caused by Blunt Trauma
Blunt trauma, such as that caused by the impact of the chest against the steering wheel in an automobile accident, may injure various cardiac structures. Myocardial contusion is the most frequent injury, but rupture may occur at several sites, including the interventricular septum, the walls of the cardiac chambers, the papillary muscles, and the chordae tendineae. The shearing forces that accompany abrupt deceleration may also cause tearing of the aorta and the valve cusps and cracking of the annulus.
BLUNT CARDIAC TRAUMA
Myocardial contusion is the most common blunt injury.48 The right ventricle, because of its immediately substernal location, is the chamber most often involved. The pathologic changes in myocardial contusion consist of myocardial necrosis with hemorrhage, which may range in severity from scattered petechiae to intramural extravasations with associated transmural necrosis. In some instances, coronary arterial occlusion with secondary myocardial infarction is present. Seemingly innocuous blows to the chest by missiles such as baseballs or hockey pucks may cause sudden arrhythmic death, probably when they strike directly over the heart during the vulnerable portion of the T wave and induce ventricular fibrillation.49
The most important complication of myocardial contusion is cardiac arrhythmia. Hypotension, intracardiac thrombus, congestive heart failure, and cardiac tamponade occur occasionally.
Myocardial contusion is best recognized clinically by echocardiography, which shows localized areas of impaired wall motion. Transesophageal echocardiography is often superior to the transthoracic evaluation.50 The abnormalities of wall motion usually resolve within a few days. Increases in the concentrations of creatine kinase (CK) and its MB fraction (CK-MB) in the blood are difficult to interpret because of the release of CK from injured skeletal muscle. Cardiac troponin-I is a more specific marker.51 Diffuse nonspecific ST-T abnormalities in the electrocardiogram are common in injured patients, even in the absence of echocardiographically detected abnormalities in wall motion. However, localized changes, especially ST segment elevation, are more specific for contusion. Patients with Q wave infarct patterns and irreversible wall motion defects are likely to have a coronary arterial occlusion secondary to trauma with myocardial infarction. Severe contusions may also lead to the formation of traumatic left ventricular aneurysms or pseudoaneurysms that are sometimes detected months or years after the initial trauma. Management of myocardial contusion is conservative unless one or more specific complications (e.g., arrhythmia, tamponade, aneurysm, or perforation) are present.
Blunt trauma may injure any of the cardiac valves and lead to valvular regurgitation. Traumatic valvular regurgitation is more likely to be recognized after the patient has recovered from the acute injuries; it is less likely to play a major role in the early postinjury course.52
Injuries of the aorta result from abrupt deceleration in violent thoracic trauma and are relatively common. The most common injury results from a tear in the wall of the aorta at a point just distal to the left subclavian artery, where the aorta is fixed to the dorsal thoracic cage. Usually, complete transection of the aorta is quickly fatal. Less extensive tears can result in a localized hematoma or a localized false aneurysm. Such aneurysms may be recognized months or years after the initial injury, when they cause symptoms by gradually enlarging, or may be discovered incidentally by chest radiography [see Figures 11a and 11b].
Figure 11a. X-Ray of Posttraumatic Aortic Aneurysm
A posteroanterior chest x-ray reveals a posttraumatic aortic aneurysm at the aortic isthmus. Calcification (arrows) is evident in the wall of the aneurysm, which arose in a 45-year-old policeman who had sustained chest injuries in a motorcycle accident 24 years earlier. The lesion had gradually enlarged during a 10-year period of observation after its discovery.
Figure 11b. Angiography of Posttraumatic Aortic Aneurysm
The aneurysm, oulined by angiography, was successfully excised.
A widened mediastinal shadow in the chest radiograph is often the first clue to the presence of a traumatic aortic rupture. The chest CT and the transesophageal echocardiogram are useful aids in making the diagnosis.
At least 50% of patients with aortic rupture die before they reach a hospital, often of injuries unrelated to the aortic trauma. Surgical therapy should be undertaken as soon as possible, even if the bleeding from the ruptured aorta has stabilized; such therapy results in survival of about 80% of those patients who are still alive when they reach a medical facility. Resection of the injured segment and replacement with a prosthetic graft are usually required.
Usually, false aneurysms that are diagnosed long after the initial injury should be resected electively. Their natural history in most instances is to enlarge gradually and eventually rupture.
Penetrating injuries of the heart and great vessels are caused either by stab wounds or by gunshot wounds. Any of the cardiac chambers or great vessels may be punctured, and injury of multiple structures is common. The most common sites of involvement, in order of decreasing frequency, are the right ventricle, the left ventricle, the right atrium, and the left atrium.
Stab wounds and, especially, bullet wounds of the heart often are immediately fatal. However, if the penetrating wound is relatively small, cardiac tamponade can occur, and the buildup of pressure in the pericardial sac may help reduce the severity of bleeding and thus increase the chance of survival.
Other sequelae of penetrating trauma include laceration of the aorta or the pulmonary artery; defects in the ventricular or atrial septum; fistulas between the great vessels and between the coronary arteries and the cardiac chambers; coronary arterial fistulas; puncture of any of the heart valves; and atrioventricular block as a result of disruption of the conduction system. Occasionally, a missile that lodges in a cardiac chamber or in one of the great arteries will embolize to a distal site, whereas missiles that initially lodge in distal sites may work their way through the veins to lodge in the chambers of the heart or the pulmonary artery.
The existence of intracardiac shunts, fistulas between the heart and great vessels, coronary arterial fistulas, or valve disruption is usually suggested by the presence of new murmurs. Echocardiography and Doppler studies generally allow precise definition, localization, and quantitation of the lesions.
Penetrating cardiac trauma usually requires prompt surgical intervention, even performance of a thoracotomy in the emergency department. The immediate availability of echocardiography in the emergency department or trauma unit is extremely valuable in management of penetrating wounds of the heart. The survival rate of patients who reach the hospital alive is about 50% for those with knife wounds of the heart and 30% for patients with gunshot wounds.53
Electrical injury, a special type of cardiac trauma, is produced by a direct electrical effect on the tissues, the generation of heat from the passage of current from a high-voltage source through tissue with high electrical resistance, extreme release of catecholamines, or extreme autonomic stimulation. Sudden cardiac arrest occurs with exposure to either household AC current or a lightning strike. Lightning strikes also cause myocardial injury, which may be extensive; in such cases, ECG patterns change, concentrations of cardiac enzymes increase, and wall motion exhibits abnormalities. Pericarditis and pericardial effusion also occur. The abnormalities usually resolve within several weeks.54
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Editors: Dale, David C.; Federman, Daniel D.