Primary Cardiac Tumors

Primary cardiac tumors are rare in all age groups. Reynen analyzed the data of 22 autopsy series and found a frequency of 0.02%, corresponding to 200 tumors in 1 million autopsies [12]. In the pediatric age group the incidence of primary cardiac tumors in autopsy series is reported to be 0.027% [13]. However, with the improvement in noninvasive imaging techniques and the more intensive routine echocardiographic screening of children in recent decades, pediatric cardiac tumors are diagnosed with increasing frequency [13]. Beghetti and associates analyzed 27,640 infants and children assessed for cardiac disease over a 15‐year period and noticed an increase in tumor recognition from 0.06% to 0.32% [14]. According to Burke and colleagues, only 14% of all cardiac tumors occur in patients under 16 years of age [15].

Secondary Cardiac Tumors

The incidence of cardiac metastases reported in the literature is highly variable, ranging from 2.3% to 18.3% of patients with extracardiac malignancies [16]. According to Bussani, cardiac metastases are found in 9% of autopsies where a primary malignant tumor is found and in 14% of metastatic cancer [16]. Chan and coworkers report an incidence of 1.6% (n = 59 patients) in a series of 3641 children with malignant solid tumor [17].

Primary Cardiac Tumors

The majority (72–94%) of primary cardiac tumors are benign [18–23]. Myxomas are the most common benign tumors in adult patients, accounting for approximately 50% of all primary tumors, followed by papillary fibroelastomas, fibromas, and lipomas [20, 21]. Approximately 10% of primary cardiac tumors diagnosed in adults are malignant. Most (75–95%) of these tumors are sarcomas [22, 24, 25]. Angiosarcoma and leiomyosarcoma are the most common histologic types [25].

In pediatric patients, more than 90% of primary cardiac tumors are benign. Nearly one‐half of theses tumors are rhabdomyomas, followed by fibromas, intrapericardial teratomas, myxomas, and hemangiomas [18, 26–30]. Rhabdomyomas, fibromas, and intrapericardial teratomas are more common in newborns and infants; myxomas predominate in older children and adolescents [28]. Primary malignant cardiac tumors in pediatric patients are exceedingly rare (<10%) [17, 18, 23, 31]. Rhabdomyosarcoma, leiomyosarcoma, and variants of malignant teratomas are the most common malignant tumors [30].

Genetic Predisposition

For some cardiac tumors a genetic predisposition is reported. Most rhabdomyomas are associated with tuberous sclerosis, an autosomal dominant inherited disorder with a highly variable phenotype characterized by the development of benign tumors (hamartomas) in multiple organ systems including skin, brain, heart, lungs, kidney, and liver [32, 33]. Cardiac myxoma may be part of the Carney complex, an autosomal dominant disorder associated with recurrent myxoma, cutaneous lentiginosis, and other myxoid tumors, with an associated 30% risk of endocrine neoplasia [34, 35]. Approximately 3% of patients with Gorlin syndrome have cardiac fibromas. Table 40.2 summarizes the features of these syndromes.

Symptoms Related to Intracavitary Obstruction and Infiltration

Right atrial tumors may cause symptoms of right heart failure and produce the characteristic murmurs of tricuspid insufficiency or stenosis. Tumors involving the right atrium have been mistaken for congenital cardiac lesions, including Ebstein malformation and tricuspid stenosis. Due to a substantial increase in right atrial pressure, these tumors may produce cyanosis by virtue of right‐to‐left shunting across a patent foramen ovale [41, 42]. Intracavitary tumors of the right ventricle also have been associated with right heart failure as a result of obstruction or valvular dysfunction. Tricuspid insufficiency and right ventricular outflow tract obstruction have been described [42], with the latter mimicking pulmonary atresia with intact ventricular septum. Right heart failure may also be a consequence of extensive intramural tumor infiltration of the right ventricle. Thrombi or tissue fragments from right‐sided cardiac tumors may embolize to the pulmonary circulation and cause pulmonary hypertension [41].

Left atrial tumors typically mimic mitral valve disease. Murmurs and hemodynamic findings consistent with mitral stenosis and insufficiency have been described. Left atrial myxomas may produce obstructive symptoms only intermittently, particularly when the patient assumes the upright position [17]. Systemic embolization of left atrial myxomas is a well‐documented phenomenon. Tumors encroaching on the left ventricular cavity may produce mitral regurgitation, or inflow or outflow tract obstruction. Extensive infiltration of tumor into the left ventricular myocardium has resulted in cardiac failure, as well as myocardial ischemia from coronary compression [43].

Arrhythmias

Virtually every type of arrhythmia has been reported [30, 44] in patients with underlying cardiac tumors, with the type of arrhythmia primarily related to the location of the tumor. Clinically significant arrhythmia occurs in 24% of pediatric patients with cardiac tumors [45]. Involvement of the conduction system may yield pre‐excitation syndrome, bundle branch block, or various degrees of atrioventricular block [44, 45]. In a series of 173 pediatric patients reported by Miyake and colleagues, ventricular tachycardia was the most common type of arrhythmia. Patients with large fibromas were the highest‐risk group, with ventricular tachycardia occurring in 64% [45].

Chest Roentgenography

Although over 80% of patients with cardiac tumors may present with abnormalities on their chest x‐ray, these abnormalities are not specific. Cardiomegaly, mediastinal widening, pleural effusions, and pulmonary edema are common findings. Occasionally, primary cardiac tumors, particularly fibromas, may calcify and become evident on plane chest radiographs [23, 41].

Electrocardiography

In the presence of cardiac tumors, electrocardiographic findings are not uncommon, but are also nonspecific. In addition to the rhythm disturbances discussed above, electrocardiographic abnormalities include various degrees of atrioventricular block, ectopic atrial or ventricular beats, atrial flutter, and supraventricular tachycardia [30]. Focal ST‐T segment abnormalities may indicate myocardial ischemia due to coronary artery compression, while diffuse ST‐T segment abnormalities and low voltage have been associated with extensive intramural infiltration by the tumor.

Echocardiography

Echocardiography is the primary imaging technique for the evaluation of cardiac tumors [22, 23, 30]. Up to 42% of the tumors (predominantly rhabdomyomas) are discovered by routine prenatal echocardiography [35]. M‐mode and two‐dimensional echocardiography provide safe and effective means for noninvasive diagnosis in the fetus and in the child [40]. Tumor location, extent, and characteristics (single or multiple, intramuscular or intracavitary, solid or cystic) can be evaluated accurately and rapidly. Associated pericardial effusions are identified, and timely decompression of intrapericardial fluid collections may be performed under ultrasonographic guidance. With the addition of color‐flow Doppler echocardiography, the obstructive nature and hemodynamic significance of cardiac tumors can be assessed. The intraoperative use of transesophageal echo is particularly useful for assessment of valve function and detection of residual intracardiac defects and shunts [23]. Three‐dimensional echocardiography may provide a better definition of tumor characteristics and spatial relationship, thus facilitating operative planning [46].

Magnetic Resonance Imaging

Echocardiography is very sensitive in predicting the etiology of most intracavitary tumors. It is, however, less reliable in determining the nature of intramural or extramyocardial neoplasms [19].

Magnetic resonance imaging (MRI) provides complementary information to echocardiographic studies [22, 23]. MRI helps to elucidate the relationship of the tumor to the normal myocardium and the great vessels. It provides information on tumor location, size, and boundaries (Figure 40.1). Another attribute of MRI is its ability to differentiate certain tissue types based on the signal characteristics, thus enhancing its value as a noninvasive diagnostic tool [47]. For example, a lipoma exhibits a characteristic appearance on MRI (Figure 40.2) [48]. This feature is particularly valuable in planning the extent and feasibility of operative resection [49]. In general, tumor size, location, and borders are best determined by T1‐weighted standard spin echo or by fast spin echo with double inversion recovery sequences [50]. Fast‐gradient cine MRI sequences provide information on the hemodynamic consequences of the tumor. The addition of spatial modulation of magnetization (tagging) is helpful in the differentiation of normal myocardial motion from that of the noncontracting tumor [49]. In distinguishing vascular tumors such as hemangiomas from avascular tumors such as fibromas, a T2‐weighted spin echo sequence is useful [50]. Generally, malignant tumors appear inhomogenous, infiltrate the adjacent tissues, and are more often associated with pericardial or pleural effusions [51]. According to Beroukhim and coworkers, a correct diagnosis of the tumor can be achieved in more than 90% of cases with a complete MRI examination and a set of predefined diagnostic criteria [47]. The major shortcoming of MRI for imaging cardiac tumors in younger patients is that it requires deep sedation or even general anesthesia to eliminate artefacts caused by respiration and patient movement. Furthermore, uncontrollable tachyarrhythmias may also produce motion artefacts and thus jeopardize the quality of imaging [48]. In addition, cardiac MRI does not distinguish between specific types of highly vascular tumors such as hemangioma, angiosarcoma, or paraganglioma [47].

Computed Tomography

Cardiac computed tomography (CT) has several advantages: high spatial resolution, fast acquisition times, and multiplanar image reconstruction. The use of electrocardiography (ECG)‐gated CT offers a better soft tissue contrast than echocardiography. Particular calcifications, common in tumors such as fibroma, myxoma, and teratoma, are easily detectable. CT can differentiate serous form hemorrhagic pericardial effusions. Multislice CT allows assessment of the coronary arteries. It is particularly useful to detect metastases in patients in whom an extracardiac malignancy is suspected, especially when coupled with ¹⁸F‐fluorodeoxyglucose (FDG) positron‐emission tomography (PET) [52]. Known drawbacks are high‐dosage radiation and the need to administer potentially nephrotoxic contrast material, which may preclude use in infants.

Angiography

Cardiac catheterization is complementary in cases with associated congenital heart disease or in selected cases where hemodynamic evaluation is required. It is of particular importance in patients with suspected coronary artery disease [19, 23]. In addition, electrophysiologic mapping at the time of angiography may identify the exact arrhythmogenic site in children with small or multiple tumors [14, 31].

Biopsy

In most cases echocardiography and CT/MRI combined with the clinical data provide accurate diagnosis and eliminate the need for percutaneous or open surgical biopsy [22]. However, preoperative or intraoperative tissue diagnosis may be useful in some instances to determine the feasibility and extent of surgical resections or to determine the chemotherapeutic regimen for unresectable tumors [23]. In those cases in which a tissue diagnosis is desired, cytologic evaluation of pericardial and/or pleural fluid and thoracoscopic or transcatheter biopsy may be employed, with the inherent risk of tumor hemorrhage and tumor fragment embolization [23, 53]. Table 40.3 summarizes imaging features to aid in differentiation of primary benign and malignant tumors.