**4.3. Cardiac device-related infections**

be obscured by artifact from the valve prosthesis [34]. Mechanical prosthetic valves are susceptible to formation of adherent thrombus and pannus, while bioprosthetic valves degenerate over time and can develop tissue strands or leaflet tears which can mimic vegeta-

Transesophageal echo is superior for assessment and detection of mitral and aortic prosthetic valve abnormalities, including endocarditis, thrombus, and degenerative changes, particularly for mechanical prosthetic valves [36]. Imaging with TTE is limited by the availability of an acoustic window, intervening anatomical structures between the probe and the heart, lower transducer frequency, and acoustic shadowing [36]. Multiplane TEE is highly effective for detecting mechanical valve periprosthetic mitral regurgitation (**Figure 9**), unlike TTE in which

**Figure 9.** TEE color compare showing prosthetic annular dehiscence (arrow) associated with significant mitral regurgi-

Although color and spectral Doppler assessment of prosthetic valves should be performed during TTE and TEE examinations, transthoracic echo is preferred for assessment of hemodynamics. In the case of a mechanical prosthetic aortic valve, TTE is also superior when assessing the anterior aortic root for abscess as acoustic shadowing is posteriorly directed

Aortic and mitral mechanical valve occluder motion is difficult to assess with TTE. The use of 2D and 3D TEE offers excellent assessment of mitral occluder motion; however, it is often suboptimal at visualizing the aortic occluders. The addition of cine fluoroscopy can definitively assess occluder-opening angles, while multidetector-row computed tomography (MDCT) is

Right-sided endocarditis (RSE) is epidemiologically distinct from left-sided cardiac infection and is associated with a lower mortality, except when vegetations are ≥20 mm [39]. Often vegetations are larger in size nevertheless infrequently associated with periannular extension

useful for evaluating occluder motion and identifying any mass lesions [38].

acoustic artifact obscures the left atrial aspect of the image [37].

tions [35].

68 Contemporary Challenges in Endocarditis

tation.

[40].

obscuring the TEE image.

**4.2. Right-sided endocarditis**

Cardiac device-related endocarditis occurs in patients with pacemakers or implantable cardiac defibrillators, which are more prevalent in the older patient cohort. Endocarditis usually involves the presence of vegetations on the device lead, valves, or mural endocardium. Infective endocarditis must be distinguished from localized pocket site infection.

Echocardiography is fundamental for early diagnosis of CDRIE; nonetheless, it can be technically challenging due to artifact shadowing from the pacing leads. Transesophageal imaging is usually required and permits visualization of the leads, venae cavae, and high right atrial wall, which are often difficult to comprehensively investigate with TTE.

Small strands known as accretions are noted incidentally on device leads in approximately 30% of patients without clinical evidence of IE [41, 42]. The lesions appear as thin (1–2 mm) strands or occasionally as fixed small nodular echogenic structures on the leads and are not associated with a poorer prognosis [41].

#### **4.4. Congenital heart disease**

The incidence of IE in children is estimated at 0.34–0.64 per 100,000 person years, respectively, approximately ten times less common than in adults. Underlying CHD is found in 11–13% of adults with IE [43]. The most common underlying risk factor in children for endocarditis is CHD, followed by indwelling catheters. Rheumatic heart disease is now rare in developed countries. Only 2–5% of cases of IE occur in children with structurally normal valves compared to 25–45% of adults [44].

The main advantage of TTE over TEE is the need for anesthesia and intubation is avoided [44]. Transesophageal echocardiography should be utilized when TTE is negative but a high-clinical suspicion of IE remains, especially for periannular complications [45]. There are limited data comparing TEE with TTE in adult CHD. Both TTE and TEE may not adequately visualize vegetations or periannular complications associated with prosthetic shunts and conduits. Cardiac CT or MRI could be helpful in this setting [46].
