Cardiac Masses and Potential Cardiac Source of Embolus

Basic Principles

▪ The first step in evaluation of a cardiac mass on echocardiography is to determine if the findings are due to an ultrasound artifact or an actual anatomic finding (Fig. 15.1).
▪ A prominent normal cardiac structure of a normal anatomic variant may be mistaken for an abnormal mass (Table 15.1).
▪ Ultrasound has limited utility for determination of tissue type; diagnosis of a cardiac mass is based on location, attachment, appearance, and any associated abnormalities.

Key Points

□ Image quality for evaluation of a cardiac mass is optimized by using:
- □ Highest transducer frequency with adequate tissue penetration
- □ Acoustic access adjacent to the structure of interest (e.g., transthoracic apical for ventricular thrombi versus transesophageal echocardiography [TEE] for atrial thrombi)
- □ Visualization of the motion of the mass with the cardiac cycle
- □ Use of a narrow sector and zoom mode once a mass is identified
- □ Careful gain and processing adjustments (excessive or inadequate gain can obscure a mass)
- □ Off-axis views from standard image planes
□ A detailed knowledge of cardiac anatomy and normal variants allows recognition of structures that may mimic a cardiac mass.
□ Echocardiography cannot identify the etiology of a cardiac mass based on appearance. A differential diagnosis for the echocardiographic finding is based on the location, appearance, size, mobility, physiologic effects, and other findings associated with the mass.
□ Clinical data and other echocardiographic findings often provide clues about the identity of a cardiac mass (e.g., a left atrial mass in a patient with severe rheumatic mitral stenosis likely is an atrial thrombus).

Step-By-Step Approach

Step 1: Left Atrial Thrombi

▪ Left atrial thrombi most often form in the atrial appendage, particularly in patients with atrial fibrillation (Fig. 15.2).
Fig. 15.1 Normal cardiac structure.In this apical 4-chamber view, an apparent mass (arrow) is seen in the LV chamber. Given the relationship of this mass to the anterior mitral leaflet, this most likely is a normal papillary muscle tip, seen in oblique view. This diagnosis can be confirmed by scanning posteriorly to show its connection to the lateral LV wall.

TABLE 15.1

Structures That May Be Mistaken for an Abnormal Cardiac Mass
Left atrium	Dilated coronary sinus (persistent left SVC) Raphe between left superior pulmonary vein and LA appendage Atrial suture line after cardiac transplant Beam-width artifact from calcified aortic valve, aortic valve prosthesis, or other echogenic target adjacent to the atrium Interatrial septal aneurysm
Right atrium	Crista terminalis Chiari network (Eustachian valve remnants) Lipomatous hypertrophy of the interatrial septum Trabeculation of RA appendage Atrial suture line after cardiac transplant Pacer wire, Swan-Ganz catheter, or central venous line
Left ventricle	Papillary muscles LV web (aberrant chordae) Prominent apical trabeculations Prominent mitral annular calcification
Right ventricle	Moderator band Papillary muscles Swan-Ganz catheter or pacer wire
Aortic valve	Nodules of Arantius Lambl excrescences Base of valve leaflet seen en face in diastole
Mitral valve	Redundant chordae Myxomatous mitral valve tissue
Pulmonary artery	LA appendage (just caudal to pulmonary artery)
Pericardium	Epicardial adipose tissue Fibrinous debris in a chronic organized pericardial effusion

From Otto CM: Textbook of Clinical Echocardiography, ed 6, Philadelphia, 2018, Elsevier.

Fig. 15.2 LA appendage thrombus.Transesophageal biplane views of the LA appendage (left) shows an irregular echodensity consistent with an atrial thrombus (arrows) in a patient with atrial fibrillation. The 3D zoom image (right) shows the relationship of the thrombus to the atrial appendage in more detail.
▪ Thrombi may be seen in the body of the left atrium (LA) with severe stasis of blood flow (e.g., with mitral stenosis).
▪ TEE is required to exclude LA thrombi when clinically indicated.

Key Points

□ Transthoracic echocardiography (TTE) is not sensitive for the diagnosis of LA thrombi due to the distance between the transducer and LA (limiting image quality at that depth) and the small size and location in the atrial appendage of most thrombi.
□ The LA appendage may be visualized on transthoracic imaging in a parasternal short-axis view or in an apical 2-chamber view, but image quality often is limited.
□ TEE images of the LA appendage are obtained from a high esophageal position. Evaluation includes:
- □ Use of a high transducer frequency (typically 7 MHz)
- □ A narrow image sector and zoom mode
- □ Visualization in at least two orthogonal views, typically in views rotated to 0° and 60° (Use of simultaneous biplane imaging with a three-dimensional [3D] probe is optimal.)
- □ Pulsed Doppler recording of atrial appendage flow with the sample volume about 1 cm from the junction of the atrial appendage with the LA chamber
□ The normal Doppler velocity with atrial contraction is more than 0.4 m/s; lower velocities in sinus rhythm suggest contractile dysfunction.
□ The LA appendage has normal trabeculations that are distinguished from thrombus by their continuity with and echogenicity similar to the appendage wall, as well as their lack of independent mobility (Fig. 15.3).
□ Reverberation artifact from the ridge between the left upper pulmonary vein and LA appendage may hinder definitive exclusion of an appendage thrombus.

Step 2: Left Ventricular Thrombi

▪ Left ventricular (LV) thrombus formation occurs in regions of blood flow stasis or low-velocity flow.
▪ LV thrombi most often form in an akinetic or dyskinetic apex after myocardial infarction (Fig. 15.4).
Fig. 15.3 Normal atrial appendage anatomy.Transesophageal imaging of the LA appendage at about 50° using a 7-MHz transducer frequency. The normal ridge between the LA appendage and left superior pulmonary vein is clearly seen (arrow). The LA appendage was imaged in several planes to evaluate for possible thrombus. The small circular echolucent structure seen between the LV outflow tract and LA is a cross section of the circumflex coronary artery.
Fig. 15.4 LV thrombus.In a low parasternal long-axis view (left), an echogenic mass is seen in apical region of the LV. In a foreshortened apical view (right), the large echogenic mass is seen in an akinetic apex consistent with LV thrombus. Ao, Aorta.
▪ LV thrombi also are seen in patients with severely reduced LV systolic dysfunction.

Key Points

□ TTE from the apical window is the optimal approach to detection of LV thrombi, with a sensitivity of 92% to 95% and a specificity of 86% to 88%.
□ Detection of LV apical thrombi is enhanced by:
- □ A steep left lateral decubitus patient position on a stretcher with an apical cutout
- □ Use of a high transducer frequency (typically 5 to 7 MHz)
- □ Standard and oblique image planes of the apex, especially medial angulation from a lateral transducer position
- □ A shallow depth setting
□ Myocardial trabeculations are differentiated from thrombi by their linear shape with an echodensity similar to and attachment to the myocardium (Fig. 15.5).
□ Left echo contrast is helpful in identifying thrombus when image quality is suboptimal.
□ Transesophageal imaging is not sensitive for diagnosis of LV apical thrombi, because the apex is in the far field of the image and the true apex may not be included in the image plane.

Step 3: Right Heart Thrombi

▪ RA thrombi may be seen in patients with central lines that abrade the RA wall.
▪ Thrombi also may form on permanent pacer leads in the right atrium (RA) or right ventricle (RV).
▪ Peripheral venous thrombi may embolize to the right heart and become entangled in the tricuspid valve chords or a RA Chiari network (Fig. 15.6).

Key Points

□ Normal echogenic structures in the RA that may be mistaken for a thrombus include:
Fig. 15.5 LV web.A thin bright linear echodensity is seen in the LV apex that connects with myocardium at both ends and is not associated with wall motion abnormalities. This finding is consistent with an LV “web” or aberrant trabeculation and is a normal variant. Often slightly off-axis views (as in this example) are needed to show the connections of the web to the myocardium at both ends.
Fig. 15.6 Thrombus in transit.(A) In this TEE long-axis view of the RA, a large, echogenic, tubular, mobile mass (arrow) is seen. (B) Slight medial turning of the TEE probe demonstrates that the mass (arrow) originates from the region of the superior vena cava (SVC). By imaging in multiple planes, the attachment of this mass to a chronic indwelling catheter was demonstrated. The location, clinical setting, and appearance of the mass are most consistent with thrombus.
- □ Eustachian valve or Chiari network (Fig. 15.7)
- □ Crista terminalis (Fig. 15.8)
□ Eustachian valves and Chiari networks are thin filamentous structures that extend from the region of the inferior vena cava (IVC) toward the superior vena cava (SVC). The bright mobile echoes of a Chiari network may look similar to echo contrast in the RA.
Fig. 15.7 Eustachian valve.In this TEE bicaval view, a linear mobile echo originating from the junction of the inferior vena cava (IVC) and RA is seen, consistent with a normal eustachian valve. In some patients, this embryologic remnant is more extensive, forming a network of filamentous strands extending from the region of the inferior to the superior vena cava (SVC). This finding, called a Chiari network, may appear on TTE imaging as bright mobile echoes with chaotic motion in the RA often best appreciated in parasternal short-axis, RV inflow, and subcostal 4-chamber views.
□ The RA and RV are examined in parasternal short-axis and RV inflow views, in the apical 4-chamber view, and from the subcostal window.
□ Transesophageal imaging provides improved visualization of the right heart when thrombi are suspected.

Step 4: Nonprimary Cardiac Tumors

▪ Nonprimary cardiac tumors are 20 times more common than primary cardiac tumors.
▪ Nonprimary tumors can involve the heart by:
- ○ Direct extension
- ○ Metastatic spread of disease
- ○ Production of biologically active substances
- ○ Side effects related to treatment of the primary tumor
▪ Nonprimary cardiac tumors most often involve the pericardium but also may invade the myocardium. They rarely appear as intracardiac masses (Fig. 15.9).

Key Points

□ The most common nonprimary cardiac tumors, in order of frequency, are:
- □ Lung
- □ Lymphoma
- □ Breast
- □ Leukemia
- □ Stomach
- □ Melanoma
- □ Liver
- □ Colon
Fig. 15.8 Crista terminalis.(A) This TEE long-axis image of the superior vena cava (SVC) and RA demonstrates the crista (arrow), the ridge at the junction of the trabeculated and smooth segments of the RA wall. (B) The crista terminalis often is seen in the transthoracic apical 4-chamber view as a slight bump on the superior aspect of the RA wall (arrow).
Fig. 15.9 Direct extension of non-cardiac tumor.In the parasternal short-axis view (top left), a mass (arrows) is seen in the LA that appears to be protruding from the right upper pulmonary view. The apical 4-chamber view (top right) confirms an irregular mass protruding from the right upper pulmonary vein with some areas of independent mobility. A computed tomography (CT) scan done later that day (bottom) better shows the mass protruding into the LA by direct extension from a large lung tumor. Ao, Aorta.
□ All these tumors may involve the pericardium by direct extension (breast, lung) or by metastatic spread, presenting with a pericardial effusion, sometimes with tamponade physiology.
□ Renal cell carcinoma may extend up the IVC into the RA and may be removed surgically en bloc with the primary tumor.
□ Carcinoid heart disease is characterized by thickening and shortening of the right heart valve leaflets, resulting in pulmonic and tricuspid regurgitation (Fig. 15.10).
□ Some forms of chemotherapy affect myocardial function, so periodic monitoring of ejection fraction by echocardiography often is recommended.
□ Radiation therapy that included cardiac structures in the treatment field may have very late (20 years or greater) adverse cardiac effects, including valve disease, accelerated coronary atherosclerosis, pericardial constriction, and myocardial fibrosis.
□ TTE in standard views usually is adequate for evaluation of nonprimary cardiac tumors, but TEE provides improved image quality when needed.
□ 3D imaging may be helpful in defining the relationship of the mass to other cardiac structures.

Step 5: Primary Cardiac Tumors

▪ Primary cardiac tumors in adults usually are histologically benign.
▪ Benign cardiac tumors result in adverse clinical outcomes due to both:
- ○ Obstruction of blood flow
- ○ Embolization
▪ Primary cardiac tumors most often present on echocardiography as an intracardiac mass.

Key Points

□ The most common primary cardiac tumors in adults, in order of frequency, are:
- □ Myxoma (Fig. 15.11)
- □ Pericardial cyst
- □ Lipoma
- □ Papillary fibroelastoma (Fig. 15.12)
- □ Angiosarcoma (malignant)
- □ Rhabdomyosarcoma (malignant)
□ Myxomas most often are seen in the LA (75% of cases), attached by a narrow stalk to the center of the interatrial septum. Myxomas less often are seen in the RA, LV, and RV.
□ A pericardial cyst is a single or multilobed sac lined by mesothelium that communicates with the pericardial space. Pericardial cysts are rare but, when present, most often are seen adjacent to the RA.
□ Papillary fibroelastomas typically are small masses attached to the downstream side of a cardiac valve. The appearance is similar to a vegetation (except that vegetations usually are on the upstream side of the valve), but blood cultures are negative and clinical signs of endocarditis are absent.
□ Lipomatous hypertrophy of the interatrial septum is common, with a typical appearance of sparing of the fossa ovalis. If in doubt, computed tomographic imaging confirms adipose tissue.
□ Malignant primary cardiac tumors are rare, usually seen as an intracardiac mass.
□ The goals of echocardiography in patients with a cardiac tumor are:
- □ Define the location and extent of tumor involvement
- □ Evaluate obstruction or regurgitation due to the tumor
- □ Evaluate any associated pericardial effusion and signs of tamponade
□ Often both transthoracic and transesophageal imaging are needed to fully evaluate a cardiac tumor. Masses located in the LA may be missed on transthoracic imaging (Fig. 15.13).

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Tags: Echocardiography Review Guide

Apr 23, 2020 | Posted by admin in CARDIOLOGY | Comments Off

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Thoracic Key

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Cardiac Masses and Potential Cardiac Source of Embolus

Cardiac Masses and Potential Cardiac Source of Embolus

Basic Principles

Step-By-Step Approach

Step 1: Left Atrial Thrombi

Step 2: Left Ventricular Thrombi

Step 3: Right Heart Thrombi

Step 4: Nonprimary Cardiac Tumors

Step 5: Primary Cardiac Tumors

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Thoracic Key

Fastest Thoracic Insight Engine

Cardiac Masses and Potential Cardiac Source of Embolus

Basic Principles

Key Points

Step-By-Step Approach

Step 1: Left Atrial Thrombi

Key Points

Step 2: Left Ventricular Thrombi

Key Points

Step 3: Right Heart Thrombi

Key Points

Step 4: Nonprimary Cardiac Tumors

Key Points

Step 5: Primary Cardiac Tumors

Key Points

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