10 Masses and Devices

Massimiliano Meineri, Patricia Murphy

Key Points

• The knowledge of normal anatomic variants is critical. Incorrect identification of a mass as pathologic may lead to unnecessary diagnostic tests and treatments including surgery.

• In the left atrial appendage (LAA), pectinate muscles may be mistaken for thrombus.

• The “coumadin ridge,” if not imaged correctly, may appear as a free-floating structure in the left atrium (LA).

• Lambl’s excrescences are degenerative strands on the aortic valve (AV) and are of no clinical significance.

• The transverse pericardial sinus, when fluid-filled, may appear as a distinct vascular structure.

Several normal cardiac structures may mimic abnormal masses. In this section, we describe some of the structures (Table 10-1) that are frequently mistaken for pathologic entities.

TABLE 10-1 ANATOMIC VARIANTS

Right Atrium

Crista Terminalis

• Prominent muscle ridge (Figure 10-1A).

• Junction of the right atrium (RA) and the superior vena cava (SVC).

• Trabeculations of the right atrial appendage (RAA) originate from the crista terminalis.

• Can be misinterpreted as tumor or thrombus.

• Characteristic appearance and position confirm correct identification.

• Best seen in the midesophageal (ME) bicaval view, adjusting the probe depth to display the SVC-RA junction.

Figure 10-1 Several normal anatomic variants can be mistaken for intracardiac masses. In the RA, we can often distinguish the embryologic remnants (arrows): crista terminalis (A) at the junction of the SVC and the RA, eustachian valve (B) at the junction of the IVC and the RA, and Chiari network from the eustachian valve to the interatrial septum (C). Normal variants affecting the IAS are aneurysmal septum (D) and the typically bell-shaped lypomatous septal hypertrophy (E). In the LAA, we can often note a regular network of parallel fine muscle fibers known as pectinate muscles (F). In the LA, the coumadin ridge (G), a prominent muscle bridge, that divides the LAA from the LUPV. Within the RV, a transverse muscle ridge, known as the moderator band (H), characterizes the RV and can be mistaken for thrombus. Distal hypertrophy of the IVS with sigmoidal appearance: normal variant of aging and hypertension (I) is typical of longstanding hypertension. Normal filaments attached to the edges of the AV leaflets are the Lambl’s excrescences (J). They can be mistaken for endocarditic vegetations. The transverse sinus is a pericardial reflection between the ascending aorta and the PA. When expanded by minimal pericardial fluid, it becomes evident in the ME LAX (K) and the ascending aorta SAX (L) views.

Eustachian Valve

• Originates at the junction of the inferior vena cava (IVC) and the RA (see Figure 10-1B).

• Embryologic remnant of the right venous valve.

• Can be misdiagnosed as thrombus.

• Typically appears as a thin and mobile structure attached to the RA wall.

• Can be differentiated from thrombus by its typical location, attachment to the RA, and filamentous appearance.

• Best seen in ME bicaval view, advancing the probe to visualize the IVC-RA junction.

Chiari Network

• Found in 2% to 3% of the patients by transesophageal echocardiography (TEE).

• Vestigial remnant of the IVC valve.

• Fine meshwork of fine fibers that cross the RA (see Figure 10-1C).

• Runs between the eustachian valve and the interatrial septum (IAS).

• Connects the eustachian valve to the thebesian valve at the orifice of the coronary sinus (CS).

• Has no clinical relevance.

• Can be misdiagnosed as thrombus or other atrial mass, or the interatrial septum.

• Typical location and appearance allow correct identification.

• Best seen in the ME four-chamber view by rotating the probe to the right to display the RA and in the ME bicaval view.

Thebesian Valve

• Embryologic remnant of the valve to the CS.

• Prevents regurgitation of blood into the CS.

• May prevent insertion of retrograde cardioplegia cannula in the CS.

• Best seen in the ME four-chamber view by advancing the probe to visualize the CS.

• Can also be visualized in a modified ME bicaval view at 110 degrees adjacent to the septal leaflet of the tricuspid valve (TV).

Interatrial Septum

Interatrial Septal Aneurysm

• Prevalence is between 2% and 10%.

• Mobile or redundant septum.

• IAS right-left displacement of more than 1 cm.

• Fixed IAS bulge of more than 1.5 cm (see Figure 10-1D).

• Increased risk of stroke due to thrombus.

• Fifty percent are associated with patent foramen ovale (PFO).

• Characteristic sigmoid shape of IAS.

• May mimic mobile atrial mass.

• Best viewed in the ME four-chamber focusing on the IAS or in the ME bicaval view.

Lipomatous Hypertrophy of the Interatrial Septum

• Infiltration of the atrial septum by adipocytes.

• It normally spares the fossa ovalis.

• Diagnostic thickness criteria are 1.5 to 2.0 cm.

• Echogenic typical “dumbbell” shaped (see Figure 10-1E).

• Characteristic shape differentiates lipomatous hypertrophy from other structures and masses.

• Fatty deposits cause prominent acoustic shadow.

• Best viewed in the ME four-chamber focusing on the IAS or in the ME bicaval view.

Left Atrium

Pectinate Muscles

• Parallel muscular ridges found in both atria.

• Are prominent in the LAA (see Figure 10-1F) and can simulate an LAA thrombus.

• Typically have a tissue characterization similar to muscle.

• Scanning multiple planes is essential to differentiate from thrombus.

• Trabeculations emanate perpendicular from the LAA wall in a regularly spaced pattern (see Figure 10-1F).

Coumadin Ridge

• A prominent muscular ridge formed between the LAA and the left upper pulmonary vein (LUPV) (see Figure 10-1G).

• Linear structure with bulbous ends that give it the “Q-tip sign.”

• Historically mistaken for a thrombus and triggered anticoagulation therapy, thus, its name.

• Lack of mobility and characteristic location distinguish it from an abnormal structure.

• Best visualized in the standard ME two-chamber view.

Right Ventricle

• Trabeculations: muscle bands in the right ventricle (RV).

• Moderator band: prominent apical muscle band from septum to the anterior papillary muscle (PM; see Figure 10-1H).

• PMs.

• Right ventricular (RV) structures most commonly confused as masses are the RV trabeculations.

• RV is heavily trabeculated, and with right ventricular hypertrophy (RVH) trabeculations, become very prominent.

• Catheters within the RV can appear as small mobile echo densities that resemble intracardiac masses.

• Catheters are echo dense and produce typical reverberations and side lobe artifacts shadowing other structures.

Left Ventricle

• Several normal structures in the left ventricle (LV) may be mistaken as masses.

• PMs: usually two, one in the parachute mitral valve (MV).

• Aberrant chordae tendinae: abnormal extra MV chordae without structural function. Typically attached to the MV leaflets or to primary or secondary chordae. Homogeneous in structure, can be thickened compared with other chordae.

• Distal hypertrophy of the interventricular septum (IVS) with sigmoidal appearance: normal variant of aging and hypertension (see Figure 10-1I).

• False tendons: fine filaments across the left ventricular (LV) near apex.

• If imaged tangentially, PMs can be mistaken for masses.

• The location and attachments of the MV apparatus are distinguishing features of PM.

Aortic Valve

• Nodules of Arantius: points of coaptation of the AV. Seen at the tip of the AV as small globular thickening.

• Lambl’s excrescences: degenerative strands on either side of the AV (see Figure 10-1J). Commonly seen in older patients. They have no pathologic implications.

• Lambl’s excrescences can be misinterpreted for endocarditis.

• Lambl’s excrescences are fine homogeneous filaments attached to the AV closure line of normal AV leaflets.

Pericardium

• Normal pericardium is an echolucent layer with a normal thickness less than 1 mm.

• There is good correlation between TEE and computed tomography (CT) measurements of pericardial thickness.

Transverse Sinus, Fat Pad, Cyst

Transverse Sinus

• A reflection of the pericardium.

• It is a virtual space in absence of any pericardial effusion.

• It is seen as a triangular echo-free space between the ascending aorta, pulmonary trunk, and LA when filled with pericardial fluid.

• May be misinterpreted as a thrombus, cyst, or abscess.

• Pericardial fluid or fat in the transverse sinus can also be misdiagnosed as a mass in the LA

• Best imaged in the ME long axis (LAX) view between the ascending aorta and the right pulmonary artery (PA; see Figure 10-1K).

• Can also be visualized in the ME ascending aorta short axis (SAX) view between the ascending aorta and the PA (see Figure 10-1L).

Fat Pad

• A hypoechoic space anterior to the parietal pericardium. It is most often found adjacent to the RV and the LV apex.

• May be misinterpreted as a pericardial effusion.

• Pericardial fat is slightly more echogenic than an effusion, and it moves in concert with the heart. Pericardial effusion is motionless.

Pericardial Cyst

• Remnant of defect in the embryologic development of the pericardium.

• Normally localized in the right or left costophrenic angle.

• Usually asymptomatic.

• The echo appearance is of a localized echolucent thin-walled spherical structure.

• Differential diagnosis is pericardial effusion and pericardial fat.

Transesophageal Echocardiography Assessment of Intracardiac Masses

• Cardiac pathologic masses are: thrombus, infective vegetations, or tumor.

• TEE allows superior images of the LA, LAA, RA, and aorta.

• TEE is the gold standard in the diagnosis of vegetations and intracardiac thrombi, although visualization of the ventricular apex may not always be accurate.

• TEE allows differentiation of normal variants (see Table 10-1) and pathology.

• It can guide surgical therapy for intracardiac masses.

Systematic Transesophageal Echocardiography Assessment of Intracardiac Masses

Step 1: Describe shape, size, echodensity.

Step 2: Define number, location, and attachment.

Step 3: Identify coexisting pathology.

Step 4: Assess hemodynamic impact (e.g., flow obstruction).

Step 5: Quantify tissue invasion to determine resectability and its impact on adjacent structures.

Intracardiac Thrombi

• Appear as homogeneous and more echogenic than normal myocardium.

• Sessile or pedunculated; can reach a large size.

• Fresh thrombi are more mobile and friable, thus at higher risk of embolization (see Case 10-3 on the Expert Consult website).

• Older thrombi are more stable, are organized in layers, and may present initially with calcification.

• Predispositions to clot formation are blood stasis, hypercoagulable state, and rough surfaces.

• Can be found in all cardiac chambers. Predisposing factors vary (Table 10-2).

• TEE is indicated when transthoracic echocardiography (TTE) is inconclusive.

TABLE 10-2 INTRACARDIAC THROMBI

Spontaneous Echocardiographic Contrast

• Dense swirling pattern seen in situations of low-flow states resembling smoke (Figure 10-2A) (see Case 10-4 on the Expert Consult website).

• May be a prodrome to clot formation and coexist with thrombi.

• Can be appreciated in the atrial and ventricular cavities during cardiopulmonary bypass (CPB).

• Thick spontaneous contrast in the LA can be confused with thrombus.

• Assess underlying anatomy and valvular and ventricular function.

Figure 10-2 A, Spontaneous echo contrast indicates stagnant blood flow (arrow) and increased risk of thrombus formation. B, ME two-chamber view in a patient with LAA thrombus (arrow) underwent surgical removal. C, 3D TEE assessment of the LAA for thrombi includes X plane mode that allows simultaneous display of two perpendicular planes; in this example, the second plane (green) is positioned on the first to cut though the center of the LAA. D, Zoom and full-volume modes provide an en face view of the LAA inlet (arrow) from the LA.

Left Atrium

• Thrombi present as irregular masses of variable echogenicity that move with the underlying structure.

• LAA is the most common location of intracardiac thrombi (see Figure 10-2B).

• Very often associated with atrial fibrillation.

• LAA thrombi are rare in patients in sinus rhythm.

• LAA must be carefully assessed in the presence of mitral stenosis, LA enlargement, and stagnant flow with spontaneous echocontrast.

• Can be attached to a prosthetic MV and MV annuloplasty rings.

• TEE is the gold standard in the assessment of LAA.

• Location can help differentiate from tumors because thrombi are rarely attached to the IAS.

• TEE assessment of LAA implies two-dimensional (2D), color flow, and pulse wave (PW) Doppler.

• LAA PW Doppler has a typical biphasic trace. A peak velocity less than 40 cm/s indicates a low-flow risk of thrombus formation.

• 3D TEE allows superior visualization of the LAA using all 3D modalities (see Figure 10-2C and D).

Left Ventricle

• Rare in the absence of severe LV dysfunction.

• LV thrombi coexist with left ventricular wall motion abnormalities, LV dilatation (Figure 10-3C), and aneurysm.

• Attached to the endocardium of the akinetic segment (see Figure 10-3A and B).

• Can be attached to hardware (e.g., left ventricular assist device [LVAD] cannulas).

• Can be surrounded by spontaneous echocontrast.

• Can be sessile or pedunculated.

• Apical thrombi can often be better viewed on TTE.

• Assess underlying ventricular function and presence of hardware.

• Use multiple views and try to visualize the true LV apex.

Figure 10-3 Patient presented for an LVAD implant in dilated cardiomyopathy. A and B, An independently mobile mass (arrow) is noted in the LV. C, LV function is severely compromised, as shown by end-systolic frame on 3D LV reconstruction.

Inferior Vena Cava, Right Atrium, Right Ventricle

• Appear as irregular masses of variable echogenicity that move with underlying structure.

• Seen in the RA in the presence of venous thromboembolism and pulmonary embolism (Figure 10-4B) (see Case 10-3 on the Expert Consult website).

• Occur on pacer wires and catheters in low-flow states.

• RA thrombi can cross a PFO and result in systemic embolism (see Case 10-3 on the Expert Consult website).

• IVC thrombi are often observed in patients with renal cell carcinoma (Figure 10-5).

• Thrombi in RA are often associated with thrombi in IVC, RV, and PA (see Figure 10-4).

• TEE can visualize the right PA and the proximal left PA; the distal left PA is usually obscured by the left mainstem bronchus.

• The absence of thrombi in the PA by TEE does not exclude pulmonary embolism.

• Assess the right circulation from the IVC to the distal right PA.

Figure 10-4 Emergent TEE is performed for cardiac arrest following graft reperfusion after liver transplant. A, Modified ME bicaval view displays IVC and IVC-RA junction: thrombotic material (arrow) is noticed in the IVC. B, ME RV inflow-outflow view shows thrombi in the RV. C, Modified ME ascending aorta SAX view shows thrombus (arrow) in the distal right PA.

Figure 10-5 Patient with renal cell carcinoma (A), scheduled for nephrectomy and IVC thrombectomy. B, IVC thrombus is displayed and the distance between the thrombus and the IVC-RA junction is measured (arrow). C, IVC flow limitation is displayed by color Doppler. D, 3D TEE allowed an en face view of the IVC thrombus from the RA and its relation to the hepatic vein.

Infective Endocarditis

• Infective endocarditis (IE) is a severe condition that carries a 6-month mortality of 25%.

• The diagnosis is based on clinical and echocardiographic data according to the modified Duke Criteria (Table 10-3).

• Positive TTE or TEE is a major criterion.

• TEE is indicated whenever TTE is inconclusive.

• TEE is also indicated in patients with prosthetic valves or elderly patients with valve abnormalities.

• IE can affect normal valves, but it mostly occurs on abnormal cardiac valves.

• Presence of foreign material as well as intravenous drug use increases the risk for IE.

• Advanced forms of IE result in abscess and fistulae, especially when the aortic valve is involved.

• A form of noninfective endocarditis is marantic endocarditis. It may be observed in patients with adenocarcinoma and antiphospholipid syndrome. Lesions are very difficult to differentiate from IE.

TABLE 10-3 MODIFIED DUKE CRITERIA

Vegetations

• Common appearance is as irregular sessile or pedunculated masses.

• In active endocarditis, masses are more soft and friable.

• In chronic IE, they become more stable and dense.

• Fungal endocarditis presents with larger but less invasive vegetations.

• Independently mobile; embolization is not uncommon.

• TEE has a sensitivity of 90% to 100% and a specificity of 88% to 100% in detecting vegetations.

• Each cardiac valve is affected with a different frequency and pattern.

Aortic Valve

• Commonly attached to the ventricular side of the AV (Figure 10-6A and E).

• Predisposing conditions are bicuspid AV, rheumatic deformities, and valve degeneration.

• Vegetations may move back and forth during the cardiac cycle.

• Common evolution is aortic root abscess (see Figure 10-6A and E) and invasion of the intervalvular fibrosa.

• In case of aortic regurgitation, vegetations may also be found on the chordae tendinae and the anterior MV leaflet.

• IE on the AV can result in leaflet perforation and aortic regurgitation and are at high risk of embolization.

• Assessment of the AV is performed on multiple views. Zoom is used to better assess the AV leaflets.

Figure 10-6 Patient presented with shortness of breath, fever, and chest pain. Severe AV regurgitation is noticed (A) on a bicuspid AV (B). Large vegetations are attached to the ventricular aspect of the AV. Aortic root is enlarged and presents an abscess of the sinus of Valsalva (arrow in A). C, Color flow Doppler reveals an aortic root to RA fistula with a left-to-right shunt. D, A large, independently mobile mass is noticed at the base of the TV septal leaflet in proximity to the exit point of the ascending aorta fistula. The mass indicates spread of infection to the right side of the heart. Pulmonary valve was spared in this case. E, Discrete abscess.

Mitral Valve

• Most frequently involved valve in IE.

• Commonly attached to the atrial side of the MV (Figure 10-7A).

• Predisposing conditions are rheumatic heart disease, valve degeneration and calcifications.

• MV IE commonly evolves into leaflet perforation and mitral regurgitation (MR; see Figure 10-7B).

• AV has to be assessed for new AR or leaflet abnormalities (see Figure 10-7C).

• Vegetations on the MV can be distinguished from torn chordae because the latter results in flail of the respective MV segment.

Figure 10-7 Patient scheduled for MV replacement for endocarditis. Vegetations on the atrial aspect of the MV leaflets (arrow in A) and severe MV regurgitation (B) are displayed. All other valves are carefully inspected for vegetations and regurgitant lesions. C, The AV is noticed to be thickened. The AV was surgically inspected and found mildly sclerotic and was not replaced. D, In another patient with MV endocarditis, central coaptation (arrowhead) and a perforation of the anterior mitral leaflet (AML) (arrow) are seen. Two areas of proximal flow acceleration are seen on the ventricular side of the valve (double arrow). In the right panel, 3D TEE replicating the “surgeons view” of the mitral valve demonstrates the perforation (arrow). (D courtersy of Jorg Dziersk and Eliot Fagley.)

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