The Role of Echocardiography in the Management of the Sources of Embolism

Roberta Esposito; Rosa Raia; Daniela De Palma; Ciro Santoro; Maurizio Galderisi


Future Cardiol. 2012;8(1):101-114. 

In This Article

Endocarditis Vegetations

Embolic events are one of the most severe complications of infective endocarditis (IE),[24,25] in particular cerebral embolism which is associated with increased morbidity and mortality.[26] Systemic embolism occurs in 20–50% of IE but embolic events can be totally silent in an additional 20% of cases.[27–29] Embolism may occur either before diagnosis or during antibacterial therapy.

Echocardiography (TTE and particularly TEE) is a key examination in the management of IE, it being useful for diagnosis in either unexplained embolism or embolisms for known IE.[30,31]

Echo Diagnosis of IE

Three echo findings are considered major criteria for IE: vegetation, abscess, and new dehiscence of a prosthetic valve.[27,32] Vegetation (Figure 5), the true hallmark of IE, appears as a chaotic mass with acoustic features different from that of the underlying cardiac structures, adherent to a valve leaflet (and less frequently on mural endocardium or papillary muscles) and with a mobility which is independent on the adjacent valves. TTE, which must be performed first, has a sensitivity of approximately 60%; TEE – mandatory in cases of doubtful TTE, in prosthetic and pacemaker IE and when an abscess is suspected – has 85–90% sensitivity for the diagnosis of vegetation and its additive value is even more important for the detection of abscess and other forms of perivalvular extension.[27,32] Although new imaging approaches including multislice computer tomography appear very accurate in comparison with TEE for IE diagnosis, TEE maintains superiority in the detection of complications such as leaflet perforation.[33]

Figure 5.

Transesophageal echocardiogram evidence of a floating vegetation of the mitral valve (arrow) floating in the left atrial chamber.
The strong mobility of a vegetation is a recognized predictor for embolic events.

Specific Clinical Conditions

Prosthetic valve IE (1–6% of patients with valve prosthesis) is characterized by lower incidence of vegetations and higher incidence of abscesses and perivalvular complications.[27,32] While IE of biological valve behaves similar to that of native valves (involvement of valve leaflets and subsequent perforation), IE of mechanical prostheses involves the junction between the sewing ring and the annulus, leading to perivalvular abscess, dehiscence and pseudoaneurysm.

IE of cardiac devices (permanent pacemakers and implantable cardioverter defibrillators) are associated with important rate of morbidity (1.9 per 1000 devices/year) and mortality.[27,32] The main pathogenetic mechanisms of this kind of IE involve contamination by bacteriological flora at the time of implantation and/or replacement. Vegetations may be attached to the electrode lead (Figure 6), tricuspid laeflets and endocardial walls of either right atrium or ventricle. TEE has higher sensitivity and specificity than TTE, whereas reverberation lead echos, atypical location of vegetations (especially within the superior inferior cava) and inadequate acoustic window limit the application of TTE.[27] Cardiac device related IE shall be treated with prolonged antibiotic therapy and percutaneuous or surgical (vegetations >25 mm) device removal.[27]

Figure 6.

Transthoracic echocardiogram evidence of a vegetation rising from a pacemaker.
(A) Pacemaker lead identifiable in a subcostal view. (B) Apical 4-chamber view. (C) 'Off-axis' apical view. Combined together, the images (A) and (B) allow a vegetation floating between right atrium (A) and right ventricle (B) to observed.

Echo Predictors of Embolism in IE

Box 3 summarizes main clinical and echo predictors of embolism in IE. Echocardiography plays a hinge role in identifying a subgroup of patients who may benefit from early surgery.[5,27] However, the ability of echo in predicting the individual risk for embolic events remains limited and other factors (i.e., biological factors, specific microorganisms) play a significant role. The Task Force on the Prevention, Diagnosis and Treatment of Infective Endocarditis of the European Society of Cardiology recommends surgery to be performed when a large and floating vegetation (>10 mm) is present following ≥1 embolic episodes and when valve repair seems possibe, particularly in mitral valve IE.[32] The benefit of surgery to prevent embolization is greatest during the first week of antibiotic therapy when the embolic rate is highest.


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