Cardiac Tumors
Parag R. Patel
I. INTRODUCTION.
Cardiac neoplasms are rare in comparison with other forms of heart disease. Although secondary tumors of the heart are by definition malignant, primary tumors may be either benign or malignant. Primary cardiac tumors occur approximately 30 times less frequently than cardiac metastases. In most autopsy studies, the reported prevalence of primary tumors of the heart ranges from 0.001% to 0.03%, and about 75% are benign. Despite the relatively low prevalence, advances in curative operative therapy have made antemortem diagnosis of these tumors more clinically relevant.
II. CLINICAL PRESENTATION.
Cardiac tumors often present with very nonspecific signs and symptoms. Patient complaints may be attributable to constitutional manifestations, embolic phenomena, or direct cardiac invasion/mass effect.
A. Constitutional symptoms.
Many tumors, especially myxomas, are associated with a wide variety of systemic manifestations. Fever, chills, malaise, cachexia, and weight loss are not uncommon. Corresponding laboratory abnormalities, including leukocytosis, thrombocytosis or thrombocytopenia, hypergammaglobulinemia, as well as elevated erythrocyte sedimentation rate and C-reactive protein levels are frequently present as well. These findings are likely attributable to the constitutive production of inflammatory cytokines by the tumor or due to release from tumor necrosis. Myxoma cell production of interleukin-6 and elevation of antimyocardial antibodies have been documented, with levels of these serum markers normalizing after tumor resection. Not surprisingly, patients with cardiac tumors often carry an incorrect antecedent diagnosis of collagen vascular disease, chronic infection, or noncardiac malignancy.
B. Embolic phenomena.
Tumor embolization may account for the initial presenting symptoms, via either direct embolization of tumor fragments or thromboemboli released from the tumor surface. The type of emboli is dependent on tumor location as well as the presence of intracardiac shunts. Right-sided tumors, and leftsided tumors with left-to-right shunts, result in pulmonary emboli and if untreated may result in cor pulmonale. It may be difficult to clinically differentiate pulmonary tumor emboli from those due to venous thromboembolic disease. Chest radiography is usually not helpful. However, noninvasive imaging often has two unique characteristics that help differentiate tumor emboli from venous thromboemboli. First, tumor emboli may result in completely unilateral defects. Second, defects caused by tumor emboli generally do not resolve with time. Left-sided tumor emboli may result in visceral infarction, limb ischemia, myocardial infarction, or transient ischemic attack/stroke. In addition, multiple vascular aneurysms may develop. Of the benign primary cardiac tumors, embolization is most frequently noted with cardiac myxomas and even more so if the tumor has a villous surface. The brain is the most common site for systemic embolization in primary cardiac neoplasms, involving both hemispheres in approximately 40% of cases. Embolic findings in a young
person, in sinus rhythm and without valvular disease or endocarditis, should raise suspicion for the presence of an embolic source related to an intracardiac tumor.
person, in sinus rhythm and without valvular disease or endocarditis, should raise suspicion for the presence of an embolic source related to an intracardiac tumor.
C. Direct cardiac invasion/mass effect.
Signs and symptoms are governed by tumor location and size. Intramyocardial tumors, which are most often found in the left ventricular free wall and intraventricular septum, generally remain asymptomatic when the tumor size is small but can result in arrhythmias, conduction abnormalities, and sudden cardiac death if they become larger. Impaired ventricular performance may mimic restrictive or hypertrophic cardiomyopathy. Rarely, ventricular rupture has been the initial presentation. Tumors of the left atrium, especially if mobile, may prolapse into the mitral valve, resulting in obstruction of atrioventricular (AV) blood flow. This results in signs and symptoms similar to mitral stenosis, such as dyspnea, orthopnea, paroxysmal nocturnal dyspnea, edema, and fatigue. Importantly, syncope and sudden death may also occur.
III. PHYSICAL EXAMINATION.
Physical examination may show signs of pulmonary venous congestion. A fourth heart sound (S4) may be present, as may a widely split, loud first heart sound (S1). The loud S1 is caused by late closure of the mitral valve, when the left ventricular—left atrial pressure crossover occurs at a higher pressure. Although this finding is also seen with mitral stenosis and preexcitation, the absence of a diastolic rumble or a short PR on an electrocardiogram should raise the possibility of left atrial tumor. Left atrial tumor may cause a holosystolic murmur at the apex radiating to the axilla (if tumor causes mitral incompetence) as well as diastolic murmur if the tumor obstructs mitral outflow. If the tumor obstructs the AV valve, a presystolic crescendo murmur may be present, which typically begins during ventricular systole as the tumor moves through the mitral orifice. This finding is present in approximately one-half of all patients with myxoma. The pathognomonic tumor plop manifests as an early diastolic sound, after an opening snap but before a third heart sound (S3). Tumors of the right atrium often result in systemic venous congestion. Once significant pulmonary hypertension occurs, systemic hypoxia, clubbing, and polycythemia may develop as a result of right-to-left shunting. Right atrial tumors and intracavitary right ventricular tumors may present as right heart failure. A diastolic rumble that varies with inspiration may be noted and is due to tricuspid valve obstruction. The P2 is delayed and may have varying intensities. Jugular venous pressure waveform examination may demonstrate prominent a waves and Kussmaul’s sign. Recurrent pulmonary emboli can potentiate pulmonary hypertension. Left ventricular tumors, when not intramural, typically result in signs and symptoms of pulmonary venous congestion or low-output states. Upon examination, findings may mimic aortic stenosis, subvalvular stenosis, or hypertrophic cardiomyopathy.
IV. DIAGNOSIS.
Because no clinical sign or symptom is specific, more advanced diagnostic methodology is universally required.
A. Electrocardiography (ECG).
In isolation, ECG provides little added clue to the diagnosis. However, changes in rhythm or voltage or development of new AV block on serial tracings may be the first sign of either extension of a primary cardiac tumor or development of secondary cardiac involvement.
B. Radiography.
Chest radiography may be helpful in identifying epicardial tumors. Cardiomegaly, mediastinal widening, or cardiac silhouette irregularities may suggest the diagnosis. Calcifications are seen occasionally. Pulmonary congestion or oligemia may be noted in patients with large left or right intracavitary tumors, respectively.
C. Echocardiography.
M-mode and two-dimensional echocardiography help establish the diagnosis in most patients. If a tumor is strongly suspected or a mass is noted by transthoracic echocardiography (TTE), transesophageal echocardiography (TEE) should be performed. TEE provides improved sensitivity (97% vs. 93% for TTE) and specificity, particularly with atrial masses, and allows for superior visualization of
anatomic details, such as contour, cysts, calcification, and presence of a stalk. Threedimensional echocardiography is also increasingly helpful in evaluation due to its ability to visualize complex cardiac masses.
anatomic details, such as contour, cysts, calcification, and presence of a stalk. Threedimensional echocardiography is also increasingly helpful in evaluation due to its ability to visualize complex cardiac masses.
D. Radionuclide imaging.
Although gated blood pool scanning has been used to identify cardiac tumors in the past, the inferior resolution and sensitivity have made this form of imaging uncommon in the workup. Positron emission tomography scanning is useful in identifying cardiac involvement in metastatic tumors and atrial myxomas.
E. Computerized tomography (CT).
CT, especially multislice CT with contrast, is often used in the diagnosis and evaluation of cardiac masses. It can define tumor extension, although not as effectively as cardiac magnetic resonance (CMR), assess tumor calcification, and evaluate the adjacent extracardiac structures (pericardium and great vessels).
F. Cardiac magnetic resonance.
Like CT, CMR has an important role in the evaluation of cardiac tumors. Specifically, it characterizes size, shape, and surface features, as well as evaluating tissue composition—giving information regarding the type of tumor that is present. Magnetic resonance imaging (MRI) has the highest soft tissue contrast of the imaging modalities, and it is particularly helpful in distinguishing thrombus from tumor. It is also the most sensitive imaging modality for detecting the extent of tumor infiltration.
G. Angiography.
Cardiac catheterization is not necessary in most cases. However, in the following scenarios, the risk and cost of angiography may be worthwhile: clarifying inadequate noninvasive imaging, defining blood supply for suspected malignant tumors, and evaluating coexistent valvular or coronary artery disease that could alter surgical approach. The major additional risk of angiography is embolization of tumor or thrombus. A transseptal approach is relatively contraindicated in cases of suspected left atrial myxoma, given the high frequency of involvement of the fossa ovalis and the accompanying risk of embolization.
H. Endomyocardial biopsy (EMB).
Limited data exist on the utility of EMB in the management of cardiac tumors. Generally, diagnosis is made from noninvasive imaging; however, EMB can be considered if imaging is equivocal or if a tissue sample is required prior to treatment decisions (i.e., chemotherapy).
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