In every patient with a large pulmonary embolus, one may consider the possibility that the embolus is caused by a benign cardiac tumor, primary cardiac cancer, or a metastasis to the heart.
A 29-year-old man presented with severe dyspnea and chest pain on the right side. Computed tomographic angiography revealed a filling defect in the main and right pulmonary arteries that was consistent with pulmonary embolism. Diagnostic procedures were performed. A new Case Record summarizes.
Clinical Pearl
• What is the most common cause of pulmonary embolism?
The most common cause of pulmonary embolism is venous thromboembolism, in which a thrombus forms in the deep veins of the legs or pelvis and then the clot breaks free and migrates to the pulmonary arteries through the inferior vena cava, right atrium, and right ventricle. Occasionally, the migrating thrombus can be visualized while it is moving in the right atrium or right ventricle and tethered to the right ventricular trabeculae or eustachian valve. Clots associated with venous thromboembolism are often heterogeneous, containing both acute and chronic elements. Thrombi associated with venous thromboembolism usually have a solid or sausagelike appearance that represents a cast of the vessel from which the thrombi were derived.
Clinical Pearl
• Is there a laboratory or imaging test that can provide prognostic information in a patient with pulmonary embolism?
Unfortunately, no single examination or imaging study accurately predicts the likelihood of decompensation from suspected pulmonary embolism. Many patients appear to be well but in reality are extremely ill. In patients with pulmonary embolism, clinical instinct alone can fool the clinician, especially in young patients who may compensate very well but then precipitously decline. Patients with pulmonary embolism can be stable one moment and near death the next. An elevated level of troponin in a patient with pulmonary embolism suggests right ventricular myocardial injury, and an elevated level of N-terminal pro–B-type natriuretic peptide (NT-proBNP) suggests right ventricular strain. Other laboratory results, such as an elevated d-dimer level and leukocytosis, are not prognostically specific. Right ventricular failure is most likely the main factor that causes death from pulmonary embolism, and thus findings of right ventricular dysfunction and dilatation are prognostically important and help to define the urgency of therapy for patients who otherwise appear to be stable. Many investigators have tried to develop scoring systems that are based on clot burden, but these systems have not necessarily been predictive of outcome.
Morning Report Questions
Q: List some benign tumors that can involve the heart.
A: Benign tumors include cardiac myxomas, which represent about 25% of all cardiac tumors; these are usually tethered to the interatrial septum, but 80% are located in the left atrium and only 20% are located in the right atrium. Papillary fibroelastoma is the most common valvular tumor; the appearance is often likened to a sea anemone. Lipomas and fibromas are generally not mobile. Rhabdomyomas are most commonly seen in children. Leiomyomas, hemangiomas, and teratomas are rare; teratomas are generally of pericardial origin.
Q: Is a malignant tumor involving the heart more likely to be a primary tumor or a metastasis?
A: Malignant primary cardiac tumors are extremely rare; they are predominantly manifested by sarcomatous tumors and occasionally by lymphoma. Several types of cancer can migrate to the heart and establish an intracardiac metastatic focus of disease, although this is a rare occurrence. These types include lung, breast, renal, hepatic, adrenal, and germ-cell tumors, as well as melanoma, sarcoma, lymphoma, squamous-cell carcinoma, and thyroid carcinoma. Some extracardiac tumors, most commonly renal-cell or hepatocellular carcinoma, invade the heart and pulmonary arteries through the inferior vena cava. The majority of malignant cardiac tumors are secondary metastases.
Figure 1. Imaging Studies of the Chest.
Figure 2. Echocardiographic Images.