Evaluation of Intracardiac Masses

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Chapter 16 Evaluation of Intracardiac Masses

Introduction

Perhaps no finding on echocardiography creates a bigger diagnostic challenge than the presence of an intracardiac mass. This is because tissue characterization by any imaging modality is limited. The advent of tomographic imaging in general, including computed tomography (CT), magnetic resonance imaging, and echocardiography, has dramatically improved the detection of intracardiac masses, but mass characterization remains challenging. The diagnosis of some masses, particularly thrombi, can be reasonably certain on the basis of the company that they keep, such as the association of thrombi and regional wall motion abnormalities. Likewise, papillary fibroelastomas are classically seen on the ventricular side of the semilunar valves, and atrial myxomas frequently attach to the interatrial septum. Angiosarcomas typically originate from a vascular structure, particularly the inferior or superior vena cava.

Beyond these generalities, additional deductive reasoning is limited when it comes to the diagnosis of an intracardiac mass. Although real-time three-dimensional echocardiography (RT3DE) can add some information about the tissue characterization of cardiac masses, its true strengths are accurate assessment of size and volume of the mass as well as the relationship of the mass to adjacent cardiac structures. Both RT3D transthoracic echocardiography (TTE) and more recently RT3D transesophageal echocardiography (TEE) have been extensively used, even within the brief time of their existence, for imaging cardiac masses.

General Benefits of Three-Dimensional Echocardiography Over Two-Dimensional Echocardiography

The potential and realized benefits of 3DE for mass evaluation include (1) improved spatial relationships to adjacent anatomic structures; (2) improved accuracy of size and volume of the masses; (3) improved detail of the homogeneity (or lack thereof) of the mass using the cropping function of 3D software; (4) involvement or noninvolvement of adjacent structures, such as interatrial or interventricular septum, valves, or myocardium; and (5) mobility in 3D space and, as a correlate, identification of the stalk of the mass, if present.

Tumors: Generalities

Primary tumors of the heart are extremely rare, with a reported prevalence of 0.001% to 0.03% by autopsy series.1 The most common primary cardiac tumor is the myxoma, even though myxoma is relatively uncommon. Myxomas are most common in the atria, particularly the left atrium. They often have a clear stalk attached to the interatrial septum and clearly visualized with 3DE. Myxomas typically are benign, but the most common primary malignant tumors are sarcomas, which are highly invasive and uniformly fatal tumors. Angiosarcoma is the most common of this group. Metastatic tumors to the heart are much more common than are primary tumors, with the most common being breast and lung tumors; the usual cardiac site of metastasis is the pericardium. In fact, secondary involvement of the heart by extracardiac tumors is 20 to 40 times more common compared with primary cardiac tumors.13 Melanoma is a tumor that has particular propensity to metastasize to the heart.4

Individual Tumors: Myxomas

As mentioned, myxomas are the most common primary cardiac tumors (Figures 16-1 to 16-3; Videos 16-1 to 16-6). 3D imaging of atrial myxomas has been reported by transthoracic and transesophageal methods. The main benefits of 3DE over 2DE for myxomas are (1) identification of the stalk of the tumor and (2) evaluation of the heterogeneity of the mass. In fact, both characteristics often are seen with 2DE. The first case of imaging a right atrial myxoma by RT3DTEE was reported by Scohy et al (Figure 16-4).5 At the time of surgical excision, it was noted that the size of the mass correlated extremely well with the estimate by RT3DTEE. In fact, the volume of 6.4 mL was the same as shown by 3DTEE and by ex vivo measurement. Butz et al6 also measured a left atrial myxoma preoperatively by using 3DTEE and determined excellent correlation with the excised mass at the time of surgery. In another case study, a right ventricular and tricuspid valve myxoma was identified by 2DTTE; it measured 5.5 × 3.8 cm but was remarkably larger as shown by 3DTTE (12 × 6 cm). 3DTTE improved the visualization of the special relationship with surrounding structures and identified the involvement of the tricuspid valve, which was not appreciated by 2DTTE (Figure 16-5).7 Two cases of giant myxoma resulting in significant mitral valve obstruction were described by Culp et al.8 RT3DTEE volume measurement coordinated well with the ex vivo measurement. 2DTEE underestimated the volume (Figure 16-6).

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Figure 16-4 Volume rendering of the right atrial mass offline by TomTec (Munich, Germany) four-dimensional imaging showing that volume measurement can be performed. The result was 6.36 mL, comparable with the in vitro measurement of 6.4 mL.

(From Scohy TV, Lecomte PV, McGhie J, et al: Intraoperative real time three-dimensional transesophageal echocardiographic evaluation of right atrial tumor. Echocardiography 25:646–649, 2008.)

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Figure 16-5 A and B, A right ventricular myxoma with involvement of the tricuspid valve. The tricuspid valve involvement was not appreciated by two-dimensional echocardiography. LV, left ventricle; RA, right atrium; RV, right ventricle.

(From Reddy VK, Faulkner M, Bandarupalli N, et al: Incremental value of live/real time three-dimensional transthoracic echocardiography in the assessment of right ventricular masses. Echocardiography 26:598–609, 2009.)

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Figure 16-6 A giant myxoma of the left atrium causing obstruction of the mitral orifice.

(From Culp WC Jr, Ball TR, Armstrong CS, et al: Three-dimensional transesophageal echocardiographic imaging and volumetry of giant left atrial myxomas. J Cardiothorac Vasc Anesth 23:66–68, 2009.)

Prior to these publications, incremental value for the characterization of internal composition of masses and volume calculation had been appreciated with RT3DTTE imaging for myxomas and a hemangioma. In this small series, four left atrial tumors, including three myxomas and one hemangioma, were imaged by RT3D and correlated with histopathology specimens. Echolucencies suggestive of intramass hemorrhage were more frequently seen with 3D imaging compared with 2DE. In addition, 3DTTE detected more extensive and closely packed echolucencies involving the whole extent of the tumor in the hemangioma compared with more scattered echolucencies in myxomas (Figure 16-7).9

Fibroma

Fibroma is a congenital neoplasm that usually affects children. A right ventricular fibroma was diagnosed by 2DTTE in a patient with previous incomplete resection of the same. The fibroma (Figure 16-8) was dramatically larger (9.0 × 2.8 cm) by RT3DTTE compared with 2DE (2.6 × 2.7 cm).7 A left atrial fibroma (Figure 16-9) was associated with Gardner syndrome.10

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Figure 16-8 A right ventricular fibroma in a patient with history of previous incomplete resection of the same. The fibroma was much larger by three-dimensional compared with two-dimensional transthoracic echocardiography. RV, right ventricle.

(From Reddy VK, Faulkner M, Bandarupalli N, et al: Incremental value of live/real time three-dimensional transthoracic echocardiography in the assessment of right ventricular masses. Echocardiography 26:598–609, 2009.)

Papillary Fibroelastoma

Papillary fibroelastoma is the third most common tumor of the heart, with an incidence of 0.33% among autopsy series.11 It is the most common tumor of the heart valves and is most frequently identified on the aortic valve (Figure 16-10), although all valves have been described (Figure 16-11; Video 16-7). The value of RT3DTTE was illustrated in a case presented by Singh and colleagues12 with a papillary fibroelastoma of the pulmonary valve. RT3DTTE pinpointed the attachment point, which was helpful in planning valve-sparing surgery. Also, 3D cropping through multiple orthogonal planes revealed frondlike projections and no echolucencies, which helped differentiate the mass from a myxoma or thrombus (Figure 16-12). Le Tourneau and associates13 studied seven consecutive patients with this lesion who had surgical resection of the lesion and found feasibility of imaging the mass to be 100%. Correlation of the 3D volume size with the actual resected tumor was very good. They believed RT3DTTE helped with surgical planning in three of the seven patients; surgical planning is key when valve-sparing surgery is planned. Most of the lesions (five of seven) were on the aortic valve.13

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Figure 16-10 A, An aortic fibroelastoma is seen protruding from the ventricular side of the aortic valve (arrow). B, Aortic fibroelastoma. LCC, left coronary cusp; NCC, noncoronary cusp; RCC, right coronary cusp.

(From Le Tourneau T, Polge AS, Gautier C, Deklunder G: Three-dimensional echography: cardiovascular applications. J Radiol 87:1993–2004, 2006.)

Sarcomas

Sarcomas are quite rare primary tumors of the heart but are, in fact, the most common type of primary malignant cardiac tumor, at least in the adult population. Angiosarcoma is the most common among cardiac sarcomas and typically arises in the right atrium, often adjacent to the inferior or superior vena cava. These tumors often are large and aggressive, sometimes occupying much of the right atrium (Figures 16-13 to 16-16; Videos 16-8 to 16-10). Suwanjutah et al14 described a case of leiomyosarcoma imaged by RT3DTTE (Figure 16-17). The notable incremental value of RT3DTTE was the composition of the mass. RT3DTTE, again, thanks to its cropping capability, allowed imaging of an area of echolucency, suggesting necrosis or hemorrhage surrounded by bandlike structures consistent with collagen. This image created a “donut” appearance. Excision and evaluation of the resultant histopathology revealed the same pattern of necrosis and vascular channels within the fibrotic tumor. The morphology seen in this case of the tumor by RT3DTTE was suggestive of tumor as opposed to a thrombus. Just as important, the size of the mass by RT3DTTE was significantly larger than when measured by 2DTTE.

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Figure 16-16 Right ventricular sarcoma (arrow). LV, left ventricle; RA, right atrium; RV, right ventricle.

(From Reddy VK, Faulkner M, Bandarupalli N, et al: Incremental value of live/real time three-dimensional transthoracic echocardiography in the assessment of right ventricular masses. Echocardiography 26:598–609, 2009.)

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Figure 16-17 Leiomyosarcoma. Arrows depict area of tumor necrosis. AO, aorta; LV, left ventricle.

(From Suwanjutah T, Singh H, Plaisance BR, et al: Live/real time three-dimensional transthoracic echocardiographic findings in primary left atrial leiomyosarcoma. Echocardiography 25:337–339, 2008.)