Echocardiography in malignant cardiac tumors (diagnosis, approach, and follow-up)

Key points

• Most malignant cardiac tumors are metastatic, most commonly from lung and breast carcinomas, melanomas, soft tissue sarcomas, and renal carcinomas.

• Malignant primary cardiac tumors are rare and mostly consist of various sarcomas and lymphomas.

• Twenty-five percent of primary cardiac tumors are malignant.

• Echocardiography is a readily available, portable, low-cost imaging modality that gives the first clue as to the etiology of a cardiac mass. The characteristics of a mass such as location, mobility, attachment, and appearance can help determine whether a mass is benign or malignant.

• Magnetic resonance imaging offers incremental value owing to its larger field of view, superior tissue contrast, versatility in image planes, and unique ability to enable the discrimination of different tissue characteristics such as water and fat content, causing particular signal patterns with T1- and T2-weighted techniques ( Table 9.1 ; Chart 9.2 ; Figs. 9.3 and 9.4 ).

  Table 9.1

  Imaging features suggesting benign and malignant cardiac tumors .

  Imaging features suggesting benign and malignant cardiac tumors
  Features	Benign	Malignant
  Site/number	Small (< 5 cm), single lesion	Large (≥ 5 cm), multiple lesions
  Location	Left ≫ Right	Right ≫ Left
  Morphology	Intracameral	Intramural
  Attachment	Narrow stalk, pedunculated	Broad base
  Borders	Smooth/well defined	Irregular
  Invasion	None	Free wall and adjacent structures
  Pericardial effusion	None	May be present
  Calcification	Rare	Large foci in osteosarcomas
  CT enhancement	Absent/minimal	Modest/intense
  CMR T1W-TSE	Predominantly isointense	Predominantly isointense
  CMR T2W-TSE	Predominantly hyperintense	Predominantly hyperintense or isointense
  First-pass perfusion	May be present	Very frequent (70%)
  Delayed enhancement	Usually present	Very frequent (80%)

  CMR , cardiac magnetic resonance; CT , computed tomography; T1W-TSE , T1-weighted sequences turbo-spin-echo; T2W-TSE , T2-weighted sequences turbo-spin-echo.

  
  
  

Primary cardiac lymphomas are extremely rare in that they account for fewer than 2% of heart tumors. The most common pathological type is diffuse large B-cell lymphomas, followed by Burkitt lymphomas, T-cell lymphomas, small lymphocyte lymphomas, and plasmablastic lymphomas. The most frequent pathological types of secondary cardiac lymphoma are diffuse large B-cell lymphomas, T-lymphoblastic lymphomas, and Hodgkin lymphomas. Because most cardiac lymphomas are secondary, tumors outside the heart appear before cardiac tumors. Through the invasion of the mediastinum or the surrounding mass, the lymphatic circulation, or blood dissemination, the heart is involved and heart-related symptoms appear. Therefore most of the relevant cardiac symptoms are late or mild, indicating that they can be easily ignored .

Cardiac lymphomas are easily missed or misdiagnosed, and medical personnel must increase their awareness of this malignancy. Echocardiography cannot be excluded from diagnostic examinations. In addition, the extensive application of positron emission tomography, which combines imaging and functional metabolism, effectively reveals the proliferation and metabolism of tumors throughout the body. It represents a more accurate method for the diagnosis and treatment of lymphomas with cardiac involvement ( Fig. 9.5 ).

Although osteosarcomas are known to spread hematogenously, few imaging findings of cardiovascular involvement by osteosarcomas have been reported. Imaging findings of cardiovascular involvement by osteosarcomas can be subtle and are, thus, likely to be missed or misinterpreted, with potentially undesirable consequences. The incidence of cardiovascular metastases and the impact of its early recognition are not clear. Cardiovascular involvement usually happens early in the course of the disease within the systemic vein draining the primary tumor and in small pulmonary arterial branches, and in advanced cases within the veins draining the lung and extrapulmonary metastases. Extension into the left atrium is generally considered a feature of advanced osteosarcomas ( Figs. 9.6–9.8 ).

Advanced hepatocellular carcinomas represent a disease with a poor prognosis and a median survival time of 4 to 7 months. Hepatocellular carcinoma metastases tend to spread through the intrahepatic blood vessels and the lymphatic system or direct infiltration. They frequently invade the vascular system at points such as the portal and hepatic veins. The extrahepatic metastases of hepatocellular carcinomas may reach around 18%, with the most common sites of involvement being the lungs, lymph nodes, adrenal glands, and bones. The intracardiac involvement of hepatocellular carcinomas rarely develops (2%), and the main mechanism of metastases into the cardiac cavity is the direct extension of the tumor to the heart via the hepatic vein and the inferior vena cava. The prognosis of hepatocellular carcinomas with intracardiac metastases is poor, with a median survival range of 1 to 4 months. The most common causes of death in patients with hepatocellular carcinomas with intracardiac involvement are heart failure and sudden death, which account for 25% of the patients. Most patients with right-sided metastases will have signs and symptoms of right-sided heart failure, or they could be totally asymptomatic. Irrespective of the symptoms, the presence of right-sided metastases renders the prognosis extremely poor. Other cardiac symptoms or findings such as dyspnea, lower extremity edema, dilatation of the jugular veins, and sudden death are generally seen in hepatocellular carcinomas with intracardiac involvement. Echocardiography is widely available, and it provides a simple, noninvasive technique for the initial evaluation of the cardiac involvement of any tumor. Echocardiography images both the myocardium and the cardiac chambers and can usually identify the presence of a mass in conjunction with its mobility and functional effects. Both computed tomography (CT) and magnetic resonance imaging (MRI) provide noninvasive, high-resolution images of the heart and the liver. MRI is generally preferred since, in addition to furnishing detailed anatomic images, it offers clues as to the type of tumor ( Fig. 9.9 ).

Metastases comprise the most common cause of death from lung cancer. The most common sites of the metastases of lung cancer are the lymph nodes, liver, brain, bone, and adrenal glands in decreasing order of frequency. Cardiac metastases occur predominantly between the sixth and eighth decades of life, and there is no sex predisposition. The rate of the metastases of lung cancer to the heart varies with the histopathological subtype. Adenocarcinomas metastasize to the heart in 26% of cases, as opposed to squamous cell carcinomas in 23.4%, undifferentiated carcinomas in 21.2%, and bronchoalveolar carcinomas in 17.4% of cases. The most common site of cardiac metastases is the epicardium/pericardium. Myocardial involvement is less common. Endocardial, intracavitary, and valvular metastases are very rare. The right atrium is the most commonly affected chamber, and 80% of metastases occur to the right chambers. This is due to the filtering role of the pulmonary circulation and the slower flow in the right chambers. The mechanisms of cardiac metastases are lymphatic spread (most common), direct extension from the adjacent viscera, hematogenous spread, and transvenous extension ( Fig. 9.10 ).

In the majority (approximately 90%) of patients, cardiac metastases are silent and diagnosed only on autopsy. The clinical features are extremely variable and depend on the anatomic location and size of the tumor, as well as the invasion of the adjacent tissues. Clinical manifestations are caused by the direct obstruction of cardiac or valve function, interruption of the coronary flow (by obstruction or embolization), interference with the electrophysiology of contraction, and pericardial effusion. Intramural tumors cause arrhythmias and may cause obstruction in the right or left outflow tract or the compression of the cardiac chambers. Intracardiac tumors cause clinical features of right-sided (peripheral edema) or left-sided (orthopnea) heart failure. Echocardiography is the investigation of choice for the diagnosis. TEE confers better visualization of the atria and the great vessels than TTE, CT, MRI, and angiography. CT and MRI are also useful tools in imaging cardiac metastases in that they image the location, morphological features, extent, the presence of local invasion, and mediastinal or pulmonary involvement. They also offer some degree of histological characterization of metastases by identifying fat, calcification, fibrous tissue, melanin, hemorrhage, and cystic changes. The administration of contrast assists in differentiating between tumors and thrombi ( Fig. 9.11 ).

Cardiac metastases of primary prostate carcinomas are extremely rare. Metastases of prostate cancer, similar to those of other solid tumors, involve multiple steps, including angiogenesis, local migration, invasion, intravasation, circulation, and extravasation of tumor cells and then angiogenesis and colonization in the new site ( Figs. 9.12 and 9.13 ).

The regional lymph nodes, liver, and lung are the most common sites of metastases from colorectal cancer, and cardiac metastases are extremely rare. In colorectal cancer, to our knowledge, only 9 reports have been published in the literature; however, the incidence of cardiac metastases is 1.4% to 7.2% in autopsy studies. Thus the true incidence of cardiac metastases from colorectal cancer might be higher than the cases reported so far. The differential diagnoses of cardiac myxomas and cardiac metastases from colorectal cancer might be difficult to determine by echocardiography alone, and MRI is effective in the evaluation of secondary cardiac tumors because it can accurately define the pericardium, the myocardial walls, and the cardiac chambers, especially in cases with an infiltrative nature. Surgery as a treatment modality has not been investigated, but it could be especially effective in occurrences of obstructive and solitary lesions to ensure relief from symptoms and prolongation of life expectancy. With the improvement of diagnostic procedures and a prolonged life span, the incidence of cardiac metastases from colorectal cancer is likely to increase. Therefore the delineation of the role of surgical treatment in cardiac metastases from colorectal cancer requires further studies ( Fig. 9.14 ).

Sarcomas represent 65% of all malignant primary cardiac tumors. Because of their rarity, knowledge about this disease and possible therapeutic strategies are limited. Due to the silent progression and nonspecific symptoms caused essentially by mass location, cardiac sarcomas are usually diagnosed at advanced stages. Therefore the prognosis of primary cardiac sarcomas is very poor and worse than that of sarcomas in other anatomical districts. Clinical history focuses on previous extracardiac malignancies. Echocardiography can identify the mass and evaluate its mobility and hemodynamic impact. Cardiac magnetic resonance confers better soft tissue characterization, high resolution, and multiplane image acquisition. CT provides morphostructural information of the mass. Coronary artery imaging is the method of choice when cardiac magnetic resonance is contraindicated. Cardiac surgery aimed at radical resection is the cornerstone of the treatment, with chemotherapy used for neo- and adjuvant purposes. Radiation therapy, a still debated issue, is usually performed after surgery. Autotransplantation is a possible alternative approach, while conventional heart transplantation is to be reserved for patients in whom metastases have been excluded through a multidisciplinary evaluation ( Fig. 9.15 ).

Rhabdomyosarcomas account for almost 20% of all primary malignant neoplasms of the heart and are the second most common primary cardiac sarcomas. These tumors usually arise from the ventricular or atrial walls but tend to occur in multiple sites within the heart and can cause obstruction at multiple levels. They grow rapidly and invade the pericardium early in their course, resulting in a poor prognosis.

Sarcomas, in general, grow rapidly and extensively and metastasize early. Complete resection is the most ideal option; still, metastatic disease and recurrence limit long-term survival even with complete excision. Adjuvant chemotherapy and radiation have been tried to improve the poor overall survival; no randomized trials have been undertaken, however. Radiation typically is used for metastatic disease ( Fig. 9.16 ).

Rhabdomyosarcomas make up almost 20% of primary cardiac sarcomas. These tumors usually arise from the ventricular walls and frequently interfere with valvular motion because of their intracavitary bulk. The involvement of the ventricular septum and ventricular walls, which often occurs, makes complete excision impossible. In adult patients, these tumors sometimes arise from the atrial walls and mimic atrioventricular valve stenosis. Rhabdomyosarcomas of the heart are very aggressive; and although survival of up to 5 years has been reported, the prognosis is very poor. Indeed, the patients usually survive less than 1 year, despite the excision of the primary tumor and subsequent radiation and chemotherapy.

TTE and TEE can diagnose the presence of the mass. Nonetheless, these imaging techniques rarely define the true nature of the mass, especially when it is located in the atria. In such cases, the tumor is usually given a presumptive diagnosis of a thrombus or a myxoma, and the patient is sent to surgery. Nuclear MRI can be useful in defining the nature of an intracardiac mass. Despite its poor midterm prognosis, surgery is indicated to remove the mass, thereby relieving acute symptoms and extending the life of the patient by perhaps a few months ( Fig. 9.17 ).

There are “red flags” regarding malignancy: a diameter exceeding 5 mm, right-heart localization, pericardial effusion, and the involvement of the right atrioventricular groove. Primary cardiac angiosarcomas are primarily endothelial cell tumors. About 90% of the tumors are in the right atrium as multicentric masses. The aggressive and permeating growth within the surrounding myocardial wall may result in the filling of the atrial chamber and the invasion of the vena cava and the tricuspid valve. The involvement of the left heart occurs in fewer than 5% of cases ( Fig. 9.18 ).

Leiomyosarcomas are known as mesenchymal tumors arising from smooth muscle cells. Cardiac leiomyosarcomas are usually located in the left atrium with the involvement of the pulmonary veins. The common presentations include dyspnea, pericardial effusion, chest pain, atrial arrhythmias, peripheral embolism, and heart failure. The prognosis is poor (mean survival ≈ 6 months) owing to the rapid growth, high rates of remote metastases, and postremoval recurrence ( Fig. 9.19 ).

The clinical presentation of cardiac synovial sarcomas is nonspecific, so the diagnosis is almost always at the advanced stage in most cases. Patients usually present with more than 1 symptom such as shortness of breath, dyspnea, chest pain, and weight loss. Patients with left-sided tumors present earlier than those with right-sided tumors due to the effects of the mass and the obstruction of the pulmonary veins. The mean age at presentation of cardiac synovial sarcomas is 32.5 years with a range from 13 to 66 years. All 3 treatment modalities of surgery, chemotherapy, and radiotherapy are given to patients, but surgery is the mainstay of treatment. Wide excision of the tumor is required for better outcomes, although it is anatomically difficult to obtain large, tumor-free margins in the heart. The prognosis of synovial sarcomas is poor, with most patients dying within 1 year. The most common cause of death is local recurrence. Because synovial sarcomas are rare, prognostic factors are hard to ascertain; nevertheless, younger age at diagnosis, the absence of chromosomal abnormalities, and the origination of the tumor from the pericardium seem to be favorable factors ( Fig. 9.20 ).