Cardiac thrombi and imaging modalities (diagnosis, approach, and follow-up)





Key points





  • Intracardiac thrombi constitute an important clinical condition because of their potential complications.



  • Detection of ventricular thrombi is generally performed by transthoracic echocardiography, while atrial thrombi are generally evaluated by transesophageal echocardiography.



  • Contrast-enhanced computerized tomography is more sensitive for detecting ventricular and atrial thrombi than transthoracic echocardiography, but the technique has been demonstrated to be inferior to transesophageal echocardiography for displaying atrial thrombi.



  • Cardiac magnetic resonance imaging provides superior specificity for the evaluation of tissue characteristics and helps differentiate thrombi from other masses ( Table 6.1 ).



    Table 6.1

    Differentiating intracardiac thrombi from cardiac tumors .






































    Differentiating intracardiac thrombi from cardiac tumors
    Imaging feature Intracardiac thrombus Intracardiac mass
    Location Left heart is more common Right heart is more common
    Morphology Intrachamber masses
    Rarely sessile
    Infiltrative masses
    Multiple masses
    Appearance Usually homogeneous Usually heterogeneous
    MRI T2 hypointense when chronic T2 hyperintense
    Enhancement No internal enhancement
    Rarely peripheral pseudoenhancement when chronic
    Often enhancing
    Gadolinium-enhanced MRI Progressively hypointense on contrast-enhanced inversion time scout sequence Avid first-pass perfusion
    Late gadolinium enhancement
    Other discriminators Pericardial disease is not directly associated
    Left atrial enlargement or left ventricular infarction
    Pericardial effusion is most common
    Extracardiac cancer


Fig. 6.2


Transthoracic echocardiography of a patient with anterior ST-elevation myocardial infarction shows apical left ventricular mobile thrombosis in the parasternal long-axis (A) and apical 4-chamber (B) views.



Fig. 6.3


Pathophysiologic factors involved in left ventricular thrombosis formation are presented herein. LV , left ventricle; TIMI , thrombolysis in myocardial infarction; MI , myocardial infarction; vWF , von Willebrand factor.



Fig. 6.4


Transthoracic echocardiography of a patient with regional wall motion abnormalities in the left ventricular apical segments shows a large, round hypermobile thrombus with central liquefaction mimicking a cystic mass.




Cystic masses of the left ventricle are rare. The differential diagnosis includes epithelial-lined cystic tumors, intracardiac teratomas, benign blood cysts, pericardial cysts, bronchogenic cysts, hydatid cysts, and thrombi. Echocardiography is a widely applied technique for the estimation of left ventricular masses; however, CMR has evolved to confer the capability for imaging cardiac masses and in some cases may offer additive information to echocardiography because of its high spatial accuracy and expanded possibilities for tissue characterization. Spontaneous clot dissolution can begin soon after its formation, and clot lysis is an integral part of this process. Be that as it may, a more rapid resolution has rarely been reported.


Fig. 6.5


The images demonstrate multiple left ventricular clots in the transthoracic echocardiographic examination of a patient with metastatic lung cancer. The parasternal short-axis view at the mitral valve level (A) shows a bright homogeneous echo density attached to the base of the interventricular septum ( white arrow ), suggestive of a thrombus. Two similar echo densities are depicted at the mid-ventricular level of the parasternal short-axis view (B, white arrows ). The apical 4-chamber view (C) shows a small bright echo density attached to the apical segment of the lateral wall ( white arrow ), which is adjacent to another large thrombus in the left ventricular apex, which is best shown in the off-axis apical 2-chamber view (D) (Supplementary Video 6.1).



Algorithm 6.6


The image depicts the proposed algorithm for the diagnosis, management, and follow-up of LV thrombi . MI , myocardial infarction; LVEF , left ventricular ejection fraction; TIA , transient ischemic attack; DCM , dilated cardiomyopathy; TTE , transthoracic echocardiography; CMR , cardiac magnetic resonance; CT , computed tomography; LV , left ventricle; VKA , vitamin K antagonist; INR , international normalized ratio; LMWH , low molecular weight heparin; DOAC , direct-acting oral anticoagulant; FU , follow-up.



Fig. 6.7


The images depict intramyocardial dissecting hematomas in the transthoracic echocardiographic examination of two patients (A and B) after anterior myocardial infarction. Large echolucent cavitation almost occupies the akinetic left ventricular apex, surrounded by a thin and mobile endomyocardial border and filled with fresh thrombi and bulges into the left ventricle in the systole. The finding demonstrates intramyocardial dissecting hematomas.




Intramyocardial dissecting hematomas constitute a rare complication of myocardial infarction, chest trauma, and percutaneous interventions. They can develop in the left ventricular free wall, the right ventricle, or the interventricular septum. Intramyocardial dissecting hematomas consist of a cavity filled with blood. The outer wall of the cavity is the myocardium and pericardium, and the inner wall, facing the ventricular cavity, is part of the myocardium and the endocardium.


Differential diagnosis includes pseudoaneurysms, intracavitary thrombi, and prominent ventricular trabeculations. Establishing the integrity of epicardium differentiates intramyocardial dissecting hematomas from pseudoaneurysms, as pseudoaneurysms comprise a complete rupture of the myocardial wall contained by the pericardium. The distinction from intracavitary thrombi relies on the clear identification of the endocardial layer surrounding the neoformation and its systolic expansion ( Table 6.2 , Algorithm 6.1 , Supplementary Videos 6.1 and 6.2 ).



Table 6.8

Predisposing conditions for left ventricular thrombi .












Predisposing conditions for left ventricular thrombi
Left ventricular thrombi with impaired left ventricular function (more common) Left ventricular thrombi with preserved left ventricular function (extremely rare)
Left ventricular apical aneurysms
Following myocardial infarction with apical akinesia
Following myocardial infarction in segments other than the left anterior descending territory
Left ventricular pseudoaneurysms
Dilated cardiomyopathy
Apical ballooning (Takotsubo) syndrome
Hypercoagulable states
Antiphospholipid antibodies
Protein C deficiency
Myeloproliferative disorders
Essential thrombocythemia
Myelofibrosis
Salmonella septicemia
Cardiac trauma
Eosinophilic endocarditis
Connective tissue disease
Systemic lupus erythematosus
Behçet disease
On the surface of left ventricular tumors
On device leads that inadvertently migrate to the left ventricle
Administration of large doses of erythropoietin


In more than 90% of cases, rupture occurs after the first myocardial infarction, and it has a strong correlation with single-vessel disease, reflecting a lack of collateral circulation. Risk factors include anterior wall infarct, large transmural infarction, age over 60 years, hypertension, female sex, single-vessel disease, and the absence of previous cardiac events.


Echocardiographic features of intramyocardial dissecting hematomas include the formation of 1 or more neocavitations within the tissue with an echolucent center, a thinned and mobile endomyocardial border surrounding the cavitary defect, ventricular myocardium identified in the regions outside of the cystic areas, and changes in the echogenicity of the neocavitation, suggesting blood content.


The management of intramyocardial dissecting hematomas depends on multiple factors, including the patient’s age, hemodynamic stability, the size of the hematoma, the presence of ventricular septal defects, left ventricular function, and pericardial effusion. Intramyocardial dissecting hematomas limited to the apex have a high probability of spontaneous reabsorption, and an initial conservative approach may be reasonable. Patients with the expansion of dissection on serial echocardiography, ventricular septal defects, compromised hemodynamics, and low ejection fractions in the anterior wall myocardial infarction should undergo surgery .


Fig. 6.9


The images illustrate a large thrombus in a left ventricular pseudoaneurysm in the transthoracic echocardiographic examination of a patient with a history of old inferoposterior myocardial infarction in (A) the parasternal long-axis view and (B) the parasternal short-axis view. The images demonstrate a large, echo-free space attached to the posterior wall of the left ventricle with a narrow neck, containing a large heterogeneous mass ( black arrow ). All the earlier mentioned findings are in favor of a large left ventricular pseudoaneurysm with an organized clot (Supplementary Video 6.2).



Fig. 6.10


The images present a left atrial thrombus in the transthoracic echocardiographic examination of a patient with severe mitral stenosis. A free-floating thrombus in the left atrium is visualized. (A) The apical 4-chamber view shows the protrusion of the left atrial thrombus into the mitral inflow. (B) The apical 2-chamber view reveals the left atrial thrombus in the middle of the left atrial cavity. (C) Live 3D acquisition of the left atrial thrombus is shown herein.



Fig. 6.11


(A) The transesophageal echocardiographic examination of a patient with rheumatic mitral stenosis shows a large, oval-shaped mobile clot in the LAA protruding into the LA (Supplementary Video 6.3). (B) The upper panel presents transthoracic echocardiography and the lower panel transesophageal echocardiography. The image reveals a huge LAA aneurysm or diverticulum with a large, heterogeneous well-defined mass ( arrow ), measuring 5.5 cm × 4.5 cm, attached to the body of the LAA. The mass is suggestive of a thrombus or a primary tumor. The patient underwent surgery, and the pathology results revealed a fresh thrombus. LA , left atrium; LAA , left atrial appendage.




Cardiac thromboemboli may be implicated in more than 15% of ischemic strokes, and the left atrial appendage may be the site of more than 90% of thrombi originating in the left atrium. Fifty percent of left atrial thrombi occur in patients with rheumatic valvular disease, and nearly 90% of left atrial thrombi in patients with nonvalvular atrial fibrillation are limited to the left atrial appendage. TEE findings associated with the increased risk of thromboembolism include left atrial and left atrial appendage smoke, decreased left atrial appendage emptying velocity, left atrial enlargement, increased severity of mitral stenosis, and multiple left atrial appendage lobes. A left atrial appendage emptying velocity of less than 40 cm/s is associated with the increased risk of spontaneous echo contrast. As this velocity decreases below 20 cm/s, there is an even greater risk of visual left atrial appendage and thromboembolism. Patients with mitral stenosis in sinus rhythm should be treated with anticoagulation therapy if they have a history of paroxysmal atrial fibrillation, left atrial appendage thrombi, previous embolism, spontaneous echo contrast seen on TEE, or a left atrial diameter of greater than 50 mm .


The terms “left atrial diverticulum” and “accessory left atrial appendage” have both been used to describe structures protruding from the left atrium that have normal myocytes and are clearly different from a left atrial aneurysm. The incidence rate of left atrial diverticulum/accessory appendage is between 10% and 23%. This condition is thought to be associated with ectopic foci that initiate atrial fibrillation, incomplete ablation lines on the left atrial roof, and potential complications such as thrombus formation and cardiac tamponade during atrial fibrillation ablation ( Supplementary Video 6.3 ).



Fig. 6.12


The images demonstrate a ball valve left atrial thrombus in the transthoracic echocardiographic examination of a patient with a history of severe rheumatic mitral stenosis. The large ball valve thrombosis, which floats freely in the left atrium with central liquefaction, is demonstrated in the systole (A) and the diastole (B).




Left atrial ball thrombi appear to be an unusual occurrence in mitral stenosis. Symptoms are dyspnea, syncope, peripheral arterial embolism, and sudden cardiac death. The physical examination is the same as that for mitral stenosis. TEE has been recommended as the best choice for identifying the presence of left atrial thrombi and for guiding further therapy designed to reduce the thromboembolic risk. The presence of free-floating thrombi may be expected to indicate a higher embolic potential. Anticoagulation and thrombolytic therapies do not appear to have a role in the acute management of left atrial ball thrombi, although the importance of anticoagulation in the prevention of recurrence is obvious. Surgical removal of the thrombus with the simultaneous treatment of the underlying cause is the first choice treatment with good results in most cases ( Tables 6.13 and 6.14 ).


Fig. 6.15


The images depict the classification of left atrial thrombi.



Fig. 6.16


The images illustrate a worm-shaped right atrial thrombus. The orange arrows point to a large, elongated, worm-shaped, highly mobile mass in the right atrium in the systole (A and B) that protrudes into the right ventricle in the diastole (C and D). Enlargement of the right and left ventricles is suggestive of hemodynamically significant pulmonary emboli (Supplementary Video 6.4).

Nov 10, 2024 | Posted by in CARDIOLOGY | Comments Off on Cardiac thrombi and imaging modalities (diagnosis, approach, and follow-up)

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