Cardiac Lumps & Bumps
The cardiac abnormalities in this chapter are infrequent and require much study and experience to master.
TECHNICAL REMINDER: All of these lesions require careful assessment of size, shape, character, and location so optimization of sector width, depth, and focus position is important to get the best frame rate and image size for any abnormality. Zooming may be needed for the smallest structures. There is variability in size and shape of many of these lesions, but we will only show representative images for most things.
VALVE VEGETATIONS AND MIMICS
Infectious endocarditis vegetations usually occur on the upstream side of the valve, which is the LV side of the aortic valve and the atrial side of the mitral and tricuspid valves. However, vegetations with elongated stalks can move back and forth to both sides of a valve, so it may be difficult to determine the origination site of the vegetation. Infectious vegetations vary in shape and size, but acute/subacute lesions should look “soft” or “jelly-like” and not be hyperechoic.
The following apical5 view comes from a clinic patient with non-specific symptoms who had infectious endocarditis about 6 months after a TAVR procedure.
It is difficult to distinguish vegetations in the presence of significant mitral valve prolapse, because these valves have myxomatous degeneration and an increased likelihood of flail leaflets, both of which can mimic vegetations. Severe fibrosis and calcification of a valve can also be confused with a vegetation, resulting in both under- and over-diagnosis in elderly patients with severe aortic or mitral valve sclerosis.
Non-bacterial thrombotic endocarditis (NBTE, Libman Sacks, marantic) can be difficult to distinguish from infective endocarditis because the vegetations usually occur on the same upstream side of the mitral or aortic valves. However, NBTE vegetations are usually very small and occur on top of a thickened valve. IMBUS would often not see the small vegetations but would see the thickened valve, which could be an important clue in the right clinical circumstances. An occasional infectious vegetation can also be fairly flat and look like only a thickened valve. Blood cultures and TEE would be needed to sort things out.
The following on-line example of NBTE shows a PLAX view of a mitral valve. The valve thickening appears hyperechoic in this over-gained image. Some build-up of vegetation may be seen on the posterior leaflet, but blood cultures and a TEE would likely be needed in such a case.
Lambl excrescences are filamentous lesions of valve leaflets, most typically aortic, and occur in elderly patients. The typical ultrasound appearance is very thin, lint-like threads arising from the edges of the valve leaflets. Multiple-such lesions occasionally stick together and form “giant Lambl excrescences” which might be confused with an infected vegetation. There is suggestive evidence that Lambl excrescences may embolize or infect. Valve regurgitation is rare with a Lambl excrescence.
The following online clip shows the subtlety of a Lambl excrescence, even with this TEE image. An IMBUS exam will need good image quality to see typical Lambl lesions. It is likely that some combination of temperature monitoring, blood cultures, follow-up TTE, or a TEE will be needed in some patients.
Papillary fibroelastomas occur more often on the mitral than on the aortic valve. Characteristically, a small mobile tumor is seen with a fine frond-like or jelly-like surface that attaches with a small stalk to the downstream side of the valve (LV side with mitral valve, aortic side with aortic valve). Valve regurgitation is rare. These are usually incidental and asymptomatic but surgical resection is sometimes performed with larger lesions because of the potential for embolization.
Here is an apical2 view of a papillary fibroelastoma of a mitral valve.
Next is a papillary fibroelastoma of an aortic valve. The location on the downstream side of the valve is an important clue.
IMBUS approach to valve lumps: Given our inevitable small practical experience with valve lumps and the severe consequences of a delay in diagnosis of infectious endocarditis, the great majority of possible vegetations need an aggressive approach to diagnosis. We must be content with subsequent formal readings of non-infectious pathology as a consequence of being sensitive enough about infectious endocarditis vegetations. A patient with a clinical picture compatible with infectious endocarditis and a possible vegetation seen with IMBUS should be immediately hospitalized so that blood cultures and formal echocardiography can be immediately performed. This would be particularly true if the valve showed regurgitation. Asymptomatic patients without valve regurgitation may be initially cared for as an outpatient with blood cultures, temperature monitoring, and a prompt formal outpatient echocardiogram (TTE or TEE depending on the clinical situation). It is possible that we might diagnose an occasional classic Lambl excrescence or papillary fibroelastoma without formal echocardiogram in an asymptomatic patient with excellent IMBUS views, but this would require careful clinical decision making and probably image review with colleagues.
Thrombi can be seen in any cardiac chamber. They may be present in the RV associated with various causes of serious RV dysfunction, but RV and RA thrombi can also be transient during their travel from the lower body to the lungs. Here is an alarming clip of a patient with acute emboli in the RA.
LV thrombi are usually chronic and associated with severe LV disease. If LV disease is not severe, lumps become more likely to be tumor. It may require atypical views to bring an LV apical thrombus into view. Here is a well seen apical LV thrombus associated with apical dysfunction.
Chronic thrombi in the main LA are unusual but can occur with severe LV and LA dysfunction. In atrial fibrillation, the left atrial appendage is the important site for thrombus. TEE is the best way to see the LA appendage, but IMBUS can view the LA appendage with a view that is in between the apical4 and apical2 views. Here is an online TTE with an easy to see clot in the LA appendage. The mitral valve is also abnormal, but the cause was not noted.
Metastatic tumors of the heart are more common than primary tumors. One autopsy series showed that 8% of patients dying of a variety of cancers had cardiac involvement and most of this was pericardial. Metastasis is infrequently in the myocardium and would need to be distinguished from primary tumors and thrombus.
Primary cardiac tumors are 75% benign, with myxomas more common than lipomas. Myxomas are most common in the LA but in the RA they arise from the interatrial septum around the fossa ovalis. Myxomas are globular or spherical masses with a friable surface and heterogenous internal echogenicity. They can be large, pendunculate, and can embolize and cause fever.
Here is a remarkable case of a younger athlete who developed shortness of breath and was found to have a very large LA myxoma that was obstructing the mitral valve opening.
This is a smaller LA myxoma.
Lipomas are described in the LV and RA and differentiating them from myxomas is difficult. MR can help with this differentiation. Lipomatous hypertrophy of the inter-atrial septum is not a true lipoma but a prominent thickening of the interatrial septum caused by excessive fatty infiltration of extra cardiac spaces. On ultrasound a marked interatrial septal thickening to > 1.5-2.0 cm is seen. The region of the fossa ovalis is typically spared, which makes a characteristic dumbbell or hourglass-shaped lesion. The subcostal window may be a good view for this lesion. Patients also tend to have heavy pericardial fat infiltration.
The following subcostal view shows good lipomatous hypertrophy of the inter-atrial septum.
Primary Malignant cardiac tumors are angiosarcomas, rhabdomyosarcomas, lymphomas, and mesotheliomas. There is nothing particular on echo that can distinguish them from other causes of myocardial mass.
RIGHT ATRIAL STRUCTURES MIMICKING MASSES
The Crista terminalis is a well-defined fibromuscular ridge separating the smooth and trabeculated parts of the RA. It extends from the SVC to the IVC along the lateral RA wall. A crista terminalis can be more prominent than normal and be confused with an RA mass. It appears as a small knob-like structure that lacks mobility and has an echogenicity that is similar to the adjacent myocardium. A crista terminalis should also become thicker or larger during atrial systole. Here is a prominent crista terminalis in the RA.
Pectinate muscles arise on top of the crista terminalis in the RA and can also be more prominent than normal so as to be seen along the lateral RA wall. Here is a TEE view of an RA with prominent pectinate muscles.
Persistent fetal structures: Special structures were necessary during fetal development to direct oxygenated blood from the IVC through the foramen ovale into the systemic circulation and these may sometimes regress incompletely and raise the possibility of a mass in the right atrium.
A persistent, prominent Eustachian valve (sometimes called the valve of the inferior vena cava) is a remnant that runs from the IVC to the fossa ovalis. It may or may not be accompanied by a patent foramen ovale. The Eustachian valve appears as a thin, floppy, linear structure beginning at the posterior margin of the IVC. The subcostal view may be nice to see this structure because it can show the close relationship of the valve to the IVC. Sometimes, a particularly prominent Eustachian valve appears to divide the RA into two separate chambers, but the separation is always incomplete in an adult. A Eustachian valve can be mistaken for thrombus or vegetation.
This first Eustachian valve clip is from a subcostal view of a small child. Because the child is thin, the heart is fairly vertical, so the view resembles an apical4 view. The floppy, linear structure in the RA is easy to see.
The next clip is a clinic patient with a good Eustachian valve
Color Doppler in this patient showed the close relationship of the Eustachian valve to prominent IVC inflow to the RA.
A Chiari network is also a remnant of the fetal structures. The network is a thin, web-like fenestrated membrane that runs from the IVC to the inter-atrial septum. It appears as a free-floating curvilinear structure that waves with blood flow in the RA. The Chiari network is more mobile and thinner than a Eustachian valve. A Chiari network can be confused with a tricuspid vegetation, a flail tricuspid valve, free RA thrombus, or a pedunculate tumor. A Chiari network usually has no adverse clinical consequences, but it can cause troubles with some catheter procedures through the RA.
The next clip shows a subcostal view of a chiari network and the latter part of the clip nicely shows the close relationship of the network to the IVC.
Here is an apical4 view of a Chiari network. It is in the same location as a Eustacean valve, but it is a lace-like network, not a linear structure.
LEFT ATRIAL STRUCTURES MIMICKING MASSES
Extensive calcification of the mitral annulus can suggest a mass. These lesions are sometimes called “caseous calcification” or “toothpaste” lesions, because of the consistency of the material in the mass. Here is an apical 4 view showing such a lesion in the posterior leaflet of the mitral valve. An MR or CT might be needed for differentiation, but the marked hyperechogenicity distinguishes it from other masses and abnormalities of the leaflets.
A prominent left lateral ridge is a band-like embryological remnant between the left superior pulmonary vein and the left atrial appendage. It is sometimes called a Coumadin or warfarin ridge because it was commonly misdiagnosed as a thrombus, leading to anticoagulation. An MR may be needed to differentiate this structure. The following still image demonstrates the location of the structure in the apical4 view and why it can be misinterpreted as a thrombus or mass.
RIGHT VENTRICULAR STRUCTURES MIMICKING MASSES
Right ventricular muscle bundles or prominent trabeculations can suggest a mass. The moderator band is an important trabeculation that is more anterior in the RV and extends from the base of the anterior papillary muscle to the antero-septum. The best view to see a moderator band is the apical5 view, but it can be seen in other views. The moderator band contains the right bundle and can sometimes be prominent and worrisome for a mass.
This first clip starts with a standard apical4 view of the RV and then moves to an apical5 view, with the moderator band appearing.
The next clip is a PSAX view that nicely demonstrates the moderator band joining the antero-septum.
This view demonstrates why measurement of the anteroseptum in the PLAX view can be falsely increased, depending on whether the imaging plane is anterior enough in the septum. It is often impossible to tell what tissue is IVS and what is moderator band. The inferoseptum is free of this possible confusion.
LEFT VENTRICULAR STRUCTURES MIMICKING MASSES
False “tendons” or aberrant cords occur in the left ventricle and can look suspicious. LV bands may pass between papillary muscles, from papillary muscles to the IVS, between free walls, or from free walls to the IVS. All of these patterns are different from true chordae tendineae which connect papillary muscles to the mitral valve leaflets. False tendons can be found in about half of normal hearts at autopsy. LV bands look string-like as they pass across the LV cavity in a variety of directions. Muscular bands become shorter and thicker in systole while fibrous bands become straight and taut in diastole.
Here is an example of a false tendon in an apical4 view of the LV.
Papillary muscles can be more prominent than normal and sometimes more apically located than usual, suggesting a mass. Occasionally there is an accessory papillary muscle that can be confusing. The key would be seeing chordae originating from the structure, going to the valve leaflets.