Intraoperative Transesophageal Echocardiography for an Intracavitary Left Ventricular Lipoma

A 50-yr-old woman was found to have a left ventricle (LV) mass diagnosed from a transthoracic echocardiogram that was ordered as part of the routine work-up. An electrocardiogram also showed T-wave abnormalities in the lateral leads. To better characterize the mass, a subsequent cardiac magnetic resonance image suggested that the mass was an LV myxoma with calcification. Concern about the potential for thrombus formation and embolism led to surgery being scheduled for resection of the mass. After induction of general anesthesia, an intraoperative transesophageal echocardiogram (TEE) was performed. Midesophageal two-dimensional imaging confirmed the presence of a mass on the mid and apical anterior LV wall measuring 1.4 × 2.2 cm (Fig. 1, Video clip 1; please see video clip available at www.anesthesia-analgesia.org). The mass was echodense and homogenous with a well-defined border. It remained fixed to the LV with a broad-based attachment to the distal LV between the anterolateral papillary muscle and the septum. It did not seem to involve the mitral apparatus. LV function and outflow were not impaired. There was no associated thrombus nor were there any other masses in any other cardiac chamber or on any valve. There was no lipomatous hypertrophy of the interatrial septum. The patient was placed on cardiopulmonary bypass and the mass was resected without complication. Postbypass TEE examination revealed no residual mass. LV function and wall motion appeared normal with the exception of a void in the anterior-apical LV wall at the resection site (Fig. 2, Video clip 2; please see video clip available at www.anesthesia-analgesia.org). This likely was related to modeling of the LV wall by the tumor as well as the concomitant resection of some of the myocardium underlying the mass. Histopathology revealed mature adipocytes which were covered by a fibrous layer, findings which are consistent with a LV lipoma.Figure 1.: The midesophageal two-chamber view shows the broad-based attachment of the mass to the anterior left ventricular wall. The mass measures 2.2 × 1.4 cm.Figure 2.: The postcardiopulmonary bypass midesophageal two-chamber view shows complete resection of the mass with a void in the anterior left ventricular wall at the resection site.Cardiac lipomas are a relatively uncommon benign primary tumor of the heart, with an incidence of 8.4% in 1 series of 533 patients with cardiac tumors.1 Others have described it as being the second most common primary tumor of the heart, with an incidence of up to 20% of primary benign tumors.2 However, these figures include both highly encapsulated solitary lipomas and the more common lipomatous hypertrophy of the atrial septum. After a search of the literature, it remains difficult to determine the exact incidence of the highly encapsulated variety of lipoma. It seems that true lipomas are a rare finding, with the LV location being quite uncommon.3,4 Lipomas occur in all age groups and in equal frequency in males and females. They may present on either the subepicardial or subendocardial surfaces of any cardiac chamber; they have also been described to occur intramurally. They are most commonly sessile, but peduculated lipomas have been described.4 As in this case, lipomas are generally asymptomatic and discovered incidentally. However, they can cause intracavitary mechanical obstruction or extrinsic compression depending on their location. Lipomas have also been reported to produce electrocardiogram changes, but no consistent findings have been described.5 The echocardiographic features of lipomas are fairly nonspecific, but they have been described to be immobile, well circumscribed, with a bright homogenous appearance.3 When a mass is discovered with TEE, the differential diagnosis of an LV mass includes thrombus, an infectious process, and tumor, as well as normal nonpathologic structures that may be mistaken for masses. Thrombi are the most common LV mass and usually are associated with LV regional wall dysfunction or aneurysms. As vegetations are usually valvular, endocarditis of the LV wall would be a rare, but not unprecedented, finding.6 LV tumors have a wide differential diagnosis including both primary and metastatic tumors. The most common benign adult cardiac tumors include myxoma, papillary fibroelastoma, and lipoma/lipomatous hypertrophy.2 Intraoperative TEE is indicated for the evaluation of the resection of cardiac tumors. TEE can confirm the location, determine the size and attachment of masses and may guide surgical resection. Excluding the possibility of tumors at other sites and the assessment of any hemodynamic consequences is also an important role of the prebypass TEE examination.7 The postresection TEE examination is useful for the assessment of ventricular function, the completeness of tumor resection, and the possibility of damage to adjacent structures. Although preoperative testing in this case led to the presumptive diagnosis of myxoma, the intraoperative TEE examination indicated that features of the mass were more consistent with a lipoma. The mass was fixed by a broad attachment to the LV wall, whereas myxomas are often attached by a stalk to the endocardial surface. The lipoma was more echodense and homogenous than classically described myxomas. Another indication that points away from the diagnosis of myxoma is the rare incidence of myxoma in the LV location. However, the echocardiographic diagnosis of a cardiac tumor remains difficult given the variability of tumor appearance and histopathologic characterization is necessary for definitive diagnosis. In summary, we have presented the relatively rare intraoperative TEE findings and characteristics of a LV lipoma.

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