Diagnosis of rare cardiac tumors by echocardiography
Jia-Wei Tian
Second Affiliated Hospital of Harbin Medical University Department of Ultrasound (150086)
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Methods 100 Patients with rare cardiac tumors, benign or malignant, were enrolled in this study. GE Vivid 5 and GE Vivid 7 ultrasonographs equipped with 3.5MHz transducers were used by one skilled sonographer. Proper positions were performed to obtain the highest quality images without creating unnecessary discomfort for the patient. We usually tilted the patient into the left lateral position to get the transthoracic view, took a supine position with the patient’s legs flexed at the knees to gain the subcostal imaging, and placed a pillow behind his/her shoulders to gain the suprasternal notch ultrasound window. All the tumors were demonstrated using two-dimensional imaging to evaluate their location, size, shape, texture, boundary, et al. M-mode were carried out to reflect the relationship between the tumor mobility and cardiac cycle, to analyze the myocardium systolic and diastolic characteristics, and to show the heart function changes according to the myocardial damage. Color Doppler imaging could illustrate the occlusion degree and the contraflow area of the involved valve orifice. Color Doppler power imaging may reveal the intra-tumor blood vessel distribution: the intra-tumor generous vascular net and bright outer-surrounding blood vessels represented a plethoric tumor，while the rare intra-tumor blood and dull blood echo indicated the contra condition. Meanwhile, a close follow-up was conducted with the patients, focusing on their pathology results.
Results 83 cases were confirmed by the pathology among total 100 subjects. Primary cardiac tumors (71 cases) accounted for a large percentage; while the other tumors (12 cases) developed in the heart were the result of the direct invasion of adjacent malignancies or the spread from distant malignancies. Primary tumors can be either benign (65 cases) or malignant (6 cases) and can occur in all age groups. The most common benign primary tumor of the heart in the study is myxoma, accounting for approximately 69% (49/71) of all primary cardiac tumors, and myxoma was usually single and occurred in the left atrium (41 cases, 83.7% in our study) where they most often arose from the fossa ovalis area; while the others occurred in the right atrium (3 cases), both atria (3 cases) or the left ventricle (2 cases). The coordinate secondary common benign tumors in the study were leiomyoma and pericardial cyst (4 cases respectively). Leiomyoma usually rose from inferior vena cave (IVC) and developed into the right atrium, with relatively low uniform echo and spotted blood signals. They may occupy most of the right atrium and result into obstruction of the right ventricle filling during diastole. While the pericardial cyst, with its special characteristic, may have little influence to the heart movement and function especially when they were small in size. There were two cases of lipomas, two cases of rhabdomyomas, one case of hemangioma, one case of teratoma, one case of fibromas, and one case of inflammatory granuloma among all subjects. The two lipomas presented in the right ventricular outflow tract and the right ventricular posterior wall respectively appeared with round or elliptical shape, broad bases, complete capsule, high echogenicity, few blood signals, and movability. The rhabdomyomas grew quite slowly with a higher echogenicity. They may develop in the cavity or be embedded in the myocardium and may affect the wall motion and thickening rate of the lesion related myocardium. The hemangioma was found at the apex of heart and appeared just like a small myxoma. The teratoma was a cystic-solid mixture on echocardiography; the fibromas involved the left ventricular free wall of a child, with high and dense echo rose from subendothelial fibrous tissue of the heart valve. The inflammatory granuloma was an irregular strip-like high echo mass, occupying 60% of the right ventricular outflow tract (RVOT) and extending towards the pulmonary valve at the first sonography, and it increased rapidly in size at the second examination, surpassing the pulmonary valve and involving part of the main pulmonary artery and aggravating the occlusion of the RVOT (85%) with irregular shape and few activity. But the color Doppler showed no obvious change.
Primary malignant tumors of the heart were quite rare, such as rhabdosarcoma (2 cases), fibrosarcoma (2 cases), leiomyosarcoma (1 case) and malignant mesothelioma (1 case) in this study. The common features of their ultrasonic manifestation were as follows: ⑴the tumors protruded into the cavity from the cardiac wall, with irregular form and incomplete capsule; ⑵the inner echo was non-homogeneous; ⑶they all had broad bases and infiltrative growth, with unclear border and fixed on the wall; ⑷there were blood flow signals in and at the base of the tumors; ⑸they had rapid growth in short-term follow up.
Metastatic disease to the heart was relatively less often compared with other organs. They developed directly from the adjacent mass from mediastinum, lung, and thymus gland, or propagated through the venous system from distant organs, such as breast, liver and kidney. They always existed in the atrium and close to its posterior wall, with no boundary or capsule, and adhered firmly to the heart. Pericardial effusion and pleural effusion occurred in some cases on echocardiography. Color flow imaging and color Doppler power imaging demonstrated plenty of arterial blood in and around the tumors.
Finally, a large angiomyxoma that was extraordinarily rare of the mediastinum may arouse our attention, which invaded the pericardium and severely affected the ventricular diastole movement. The iso-echoic tumor had some honeycomb-shaped low echo and no blood signal inside. The echocardiography clearly illustrated the relationship between the tumor and its adjacent structures, therefore fully displayed the guiding significance of ultrasound to the operation strategy.
Conclusion Echocardiography is a highly versatile technique to identify conditions in which masses may develop, is an accurate method in detecting and characterizing masses once they occur, and provides a noninvasive means for surveillance after treatment.
