INTRACARDIAC MASSES
Jake Christensen, MD
Primary Children’s Hospital
Salt Lake City, Utah
Cardiac Tumors
Cardiac tumors have a wide range of clinical manifestations, with patients often asymptomatic until incidental finding or sudden death. Symptoms, when present, can be cardiac, systemic, or embolic in nature. Cardiac symptoms can present as dynamic inflow or outflow obstruction, arrhythmias (including life-threatening rhythm disturbances), pericardial effusion, tamponade, embolization, or cardiac failure. Almost any organ can be affected by embolism, fragments, or thrombus from a left or right-sided cardiac tumor.
In all age groups, intracardiac tumors are rare. In adults most are found in the left atrium, however in children, they affect all four cardiac chambers. Echocardiography is the primary diagnostic modality providing an accurate assessment of mass size, shape, location, attachment, and hemodynamic consequences. Frequently, the histological nature of the mass may be predicted accurately from imaging, underscoring the importance of echocardiography as a diagnostic modality. Cardiac tumors presenting in childhood can be malignant or benign in nature and may either be likely to progress or to reliably spontaneously regress. This tutorial, while not comprehensive, conveys basic characteristics of pediatric cardiac tumors including their echocardiographic features.
Rhabdomyomas
Fortunately, rhabdomyomas (the most common pediatric cardiac tumors) are benign and usually regress spontaneously. For this reason, resection is unlikely unless the secondary effects are life-threatening. Rhabdomyomas are highly associated with tuberous sclerosis. Echocardiographic features of a rhabdomyoma typically include multiple highly echogenic, homogenous, finely speckled, well-circumscribed, intramural, or intracavitary nodules. They can occur anywhere in the heart but with a preference for the ventricular chambers. Rhabdomyomas, as is the case of other cardiac tumors described below, are rarely associated with significant pericardial effusions.
Video 1: Rhabdomyoma. Transthoracic apical 4-chamber view showing multiple echogenic masses along the left ventricular free wall and interventricular septum, characteristic of rhabdomyomas.
Fibromas
Cardiac fibromas are the second most common primary cardiac tumors diagnosed in infants and young children. By echocardiography they appear largely solitary, echogenic, bright, intramural, and well-circumscribed tumors associated with areas of calcification and cystic degeneration. They are usually located at the ventricular septum or left ventricular wall at the apex. More rarely, multiple fibromas involving the right ventricle or atrium can be intracavitary with broad or narrow attachments. Fibromas are slow-growing tumors and do not spontaneously regress. However, these can be extensive and obliterate the intracavitary spaces causing significant hemodynamic compromise. Surgical resection is standard, and cardiac transplantation may be necessary depending on the extent of the tumor.
Video 2: Cardiac fibroma. Mid-esophageal four-chamber TEE view depicting a fibroma. The tumor is seen almost completely encompassing the left ventricular cavity.
Myxomas
Myxomas are the most common cardiac tumors in the overall population, including both adults and children, accounting for about 50% of all cardiac tumors. These are most often diagnosed in adults later in life but might be seen in adolescents, accounting for around 6-14% of pediatric cardiac tumors. Cardiac myxomas are usually attached to the atrial septum, with roughly 75% originating in the left atrium. Myxomas, as shown by echocardiography, typically form a pedunculated friable, lobular, gelatinous, sometimes calcified mass extending into a cardiac chamber. In most cases, a single tumor is attached to the fossa ovalis, extending into the left atrium. However, attachments can be to either the right or left atrial free wall, sometimes biatrial and even in multiples. The pathognomonic finding of an atrial myxoma is a large tumor with atrial septal attachments obstructing or protruding through an atrioventricular valve. The to-and-fro, ball-and-chain motion blocks during diastole and expels during systole. Peripheral emboli of tumor fragments or thrombus fragments occur in >70% of pediatric patients. Although myxomas are considered benign and are rarely malignant, their consequences, such as embolization or obstruction to flow, can result in significant morbidity or even mortality.
Video 3: Atrial myxoma. Mid esophageal four-chamber TEE view showing an atrial myxoma. A large pedunculated left atrial mass is seen attaching to the inferior atrial septum and resting on the anterior leaflet of the mitral valve.
Teratomas
Most cardiac teratomas are extracardiac and intrapericardial; half are diagnosed in newborns and infants. Intracardiac teratomas are exceedingly rare and predominately right-sided in nature. Teratomas are seldom malignant and contain, by definition, elements derived from all three germ layers of the body. They are typically firmly attached to the base of the heart at the root of the great vessels, likely located between the aorta and superior vena cava. In newborns and infants, the tumor can be three to four times the size of their heart. Infants with intrapericardial teratomas present with a sizeable pericardial effusion, features of obstruction, compression, tamponade, and cardiovascular collapse. By echocardiography, teratomas are intrapericardial, solitary, encapsulated, nonhomogeneous, lobular, and multicystic masses. Imaging a pericardial teratoma can also show possible associated effusions.
Cardiac Hemangiomas
Cardiac hemangiomas are benign, typically solitary, tumors that occupy the epicardial, intramural, or intracavitary area. By echocardiography, these highly vascular tumors have vascular channels which appear as large echolucent areas. These tumors are polypoid or sessile and can have central areas of necrosis and calcification. In addition, they are highly associated with non-hemorrhagic pericardial effusions. Recent experience suggests these may resolve with steroid or interferon administration.
Video 4: Cardiac hemangioma. Mid-esophageal aortic valve short axis TEE view demonstrating a hemangioma. This non-homogenous mass is nearly completely encompassing the right atrial cavity. The image sweeps to a mid-esophageal four-chamber view showing the mass impinging on the tricuspid valve.
Primary Malignant Cardiac Tumors
Less than 10% of pediatric cardiac tumors are primary malignant tumors. They are divided into primary cardiac sarcomas (angiosarcomas), endomyocardial-based tumors, and striated muscle forms. Angiosarcomas are the most common type, often involving the right atrium and pericardium. They can present with cardiac tamponade, right-sided heart failure, and/or superior vena cava obstruction. Echocardiography can show progressive myocardial infiltration. Metastatic involvement of the liver, lungs, and central nervous system is common, and despite the early diagnosis, the prognosis is poor.
Video 5: Cardiac sarcoma. Mid-esophageal four-chamber TEE view demonstrating large biatrial masses in a patient with a tissue diagnosis of spindle cell sarcoma impinging on both atrioventricular valves.
Video 6: Cardiac sarcoma. Mid-esophageal bicaval TEE view showing a large right atrial mass passing in and out of frame with the cardiac cycle which appears to have an atrial wall attachment in a patient with tissue diagnosis of spindle cell sarcoma.
Secondary Cardiac Tumors
Secondary cardiac tumors present more often than primary cardiac tumors. They directly invade the myocardium, as in non-Hodgkin lymphoma, rhabdomyosarcoma, hepatoblastoma, Ewing sarcoma, testicular carcinoma, or malignant melanoma. Another presentation is a direct extension from the inferior vena cava into the right atrium, as can occur with Wilms tumor, renal myosarcoma, and others. In pediatrics, non-Hodgkin lymphoma is increasing in prevalence, among those immunosuppressed, due to the Epstein-Barr virus. Cardiac presence of non-Hodgkin lymphoma on echocardiography will show significant ventricular wall thickening and dyskinesis as well as pericardial effusion. A Wilms tumor with cardiac extension can present initially with symptoms of right heart failure before developing symptoms of an abdominal mass. A Wilms tumor extending into the atrium can mimic an atrial myxoma’s to-and-fro motion across an atrioventricular valve.
Video 7: Wilms tumor. Mid-esophageal aortic valve short-axis TEE view showing a large right atrial mass in a patient with a Wilms tumor with intracardiac extension
Intracardiac Thrombi, Vegetations and Other Conditions
Intracardiac Thrombi
Thrombus formation can occur in any cardiac chamber for a variety of reasons, such as endothelial damage, regional stasis of blood flow as can occur around intracardiac tumors, presence of foreign bodies such as catheters, prosthetic valves, pacemaker leads, assist devices or in hypercoagulable conditions. Thrombus risk is more common in the left atrial appendage, such as in patients with atrial fibrillation. In some cases, echocardiographic imaging may show spontaneous echo contrast and reduced left ventricular systolic function being associated with a left atrial appendage thrombus. When imaging a cardiac tumor, the presence and extension of thrombus on the tumor’s surface requires evaluation due to the risk of embolization. Transesophageal echocardiography can be extremely helpful in management; however, consider caution as the imaging approach has rarely been reported to cause tumor emboli, particularly with large atrial masses or thrombi.
Video 8. Left atrial appendage thrombus. Mid-esophageal view displaying an echogenic density in the left atrial appendage several days after congenital heart surgery consistent with a thrombus. Note at this moves within the appendage.
Video 9: Left ventricular thrombus. Transesophageal sweep starting from the mid-esophageal four-chamber view moving through the five-chamber, long axis, and transgastric short axis views. The images depict multiple echo bright foci in the left ventricular cavity consistent with thrombi, encompassing the apex and extending to the anterolateral papillary muscle and lateral free wall. Prominent thrombi are visualized on the chordal apparatus. There is mild to moderately depressed left ventricular systolic function.
Intracardiac Vegetations
Endocarditis, as occurs with rheumatic heart disease caused by group A Streptococcus, can result in small, friable vegetations that may arise on the atrial surface of the mitral valve or the ventricular side of the aortic valve. With time, thickening and fibrosis of the mitral valve can damage the chordae resulting in both regurgitation and stenosis.
Video 10: Intracardiac vegetation. Two-dimensional mid-esophageal four-chamber TEE sweep showing extensive vegetation on the posterior mitral valve leaflet with associated mitral regurgitation consistent with endocarditis
Other Conditions Mimicking Cardiac Masses
In rare cases the echogenic appearance of an inverted left atrial appendage early and late after a cardiac surgical intervention may suggest the presence of an intracardiac mass by echocardiography. Once the inversion is corrected the findings resolve.
Video 11: Inverted left atrial appendage. Mid-esophageal two chamber TEE view displaying a ‘mass’ in the left atrium with a lateral wall attachment. This image, taken post cardiopulmonary bypass after repair of congenital heart disease, demonstrates an inverted left atrial appendage. The initial impression mistakenly considered the inverted atrial appendage to be a newly formed thrombus.
SUMMARY
This tutorial provides a review of the main features of cardiac masses that affect the pediatric age group. Echocardiography remains the first line and primary modality for diagnosis, surveillance, and management of these pathologies. Benefits of the imaging modality in this setting are numerous given its ability to visualize intracavitary masses against what is otherwise an echolucent background. Transesophageal echocardiography guides intraoperative visualization and surgical management, as well as being uniquely advantageous at visualizing posterior cardiac structures. Three-dimensional echocardiography offers improved spatial definition of tumors and information as to how they relate to adjacent cardiac chambers. Complementary imaging modalities such as cardiac magnetic resonance (CMR) and cardiac computed tomography (cardiac CT) can provide useful additional information when necessary. In this regard, CMR is superior to echocardiography at delineating the soft tissue contrast separating tumor attachments as well as adjacent myocardium in intramural myocardial tumors. The advantage of magnetic resonance extends to pericardial masses as well as when imaging tumors extending to adjacent mediastinal structures. The high temporal and spatial resolution of cardiac CT may also be helpful to delineate the pathology, determine benign versus malignant nature in the case of tumors, and evaluate for distal extension (embolism). However, despite the benefits of these imaging approaches, echocardiography remains the universally established primary and main noninvasive diagnostic modality for intracardiac masses and many times obviates the need for further imaging.
SUMMARY OF MAIN FEATURES OF CARDIAC TUMORS
| Tumor type | Condition | Echocardiographic features | Preferred location | Pericardial effusion |
| Rhabdomyoma |
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| Fibroma |
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| Myxoma |
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| Teratoma |
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| Cardiac hemangioma |
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| Primary malignant cardiac tumor
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(may present as tamponade) |
| Secondary cardiac tumor
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Suggested Reading
- Marx GR, Moran AM. Cardiac Tumors. In: Shaddy RE, Penny DJ, Feltes TF, et al. Moss & Adams’ Heart Disease in Infants, Children, and Adolescents: Including the Fetus and Young Adult. 10th Philadelphia: Lippincott Williams & Wilkins; 2021. p. 1635-51.
- Friesen RM and Young LT. Applications for Non-Congenital Heart Disease in Pediatric Patients. In Wong PC, Miller-Hance WC. Transesophageal Echocardiography for Pediatric and Congenital Heart Disease. 2nd ed. Switzerland: Springer; 2021. p. 635-72.
- Bedard E, Becker AE, Gatzoulis MA. Cardiac Tumours. In: Anderson RH, Baker EJ, Penny DJ, et al. Paediatric Cardiology. 3rd Philadelphia: Elsevier Ltd; 2010. p. 1055-65.
- Auden S. Secondary Vascular Anomalies and Cardiac Tumors. In: Lake C, Booker P. Pediatric Cardiac Anesthesia. 4th Philadelphia: Lippincott Williams & Wilkins; 2005. p. 582-600.
- Motta, P. Congenital Cardiac Anesthesia Society QOW #271. 26 Aug. 2020, ccasociety.org/education/quiz/archives/week-271/.
