*5.3.2. Abscess*

Three landmark studies from the 1990s investigated diagnosis of abscess by echocardiography comparing findings with surgery or autopsy. Daniel et al. [67], Choussat et al. [12], and San Román et al. [24] found that the sensitivity of TEE for abscess was 87, 80, and 90%, respectively. However, other studies have reported greater variability, with sensitivities ranging from 48 to 93%. Specificity has consistently remained high at >90% (**Table 3**).

It is unclear whether detection rates for abscesses have improved since the introduction of multiplane TEE. Although more recent studies in **Table 3** utilized biplane and multiplane imaging, the results did not demonstrate a significant improvement in diagnostic accuracy.

#### *5.3.3. Other complications*

and/or TEE and up to 70% of echocardiograms were negative in palliated complex conditions

In young children, TTE is often sufficient to diagnose IE due to superior acoustic windows compared to adults. Transthoracic echo in children with IE has a high rate of detection of

Transesophageal echo using monoplane imaging transducers was introduced into clinical practice in the early 1980s. The spatial resolution and utility of 2D TEE has continued to improve with the introduction of biplane and subsequent multiplane TEE transducers along

During the 1980s and 1990s, with the introduction of monoplane TEE, a number of landmark studies were published comparing the diagnostic accuracy of TEE for identification of vegetations against the gold standard of surgery or pathological findings. Reported sensitivities and specificities of TEE for detection of left-sided vegetations ranged from 94 to 100% and 77 to 95% for native and prosthetic valves, respectively. Specificity was consistently high at

A few studies compared monoplane, biplane, and multiplane TEE. Earlier work found marginally higher detection rates of vegetations and/or abscesses, but differences were minimal [82, 83]. Monoplane TEE not only underestimated vegetation size and extent but also was found to be less accurate at detecting small vegetations [83]. Contemporary studies using multiplane imaging report sensitivities >90% [68, 84]. Considering TEE imaging has always demonstrated high sensitivity and specificity for detection of vegetations, it is unclear if

The reported sensitivity of 2D TEE for detection of vegetations in CDRIE ranges from 73 to 96% (**Table 4**) and is also superior over TTE for distinguishing site of attachment, whether

Three landmark studies from the 1990s investigated diagnosis of abscess by echocardiography comparing findings with surgery or autopsy. Daniel et al. [67], Choussat et al. [12], and San Román et al. [24] found that the sensitivity of TEE for abscess was 87, 80, and 90%, respectively. However, other studies have reported greater variability, with sensitivities ranging from 48 to

It is unclear whether detection rates for abscesses have improved since the introduction of multiplane TEE. Although more recent studies in **Table 3** utilized biplane and multiplane imaging, the results did not demonstrate a significant improvement in diagnostic accuracy.

vegetations (>90%) when compared with TEE as the gold standard [81].

with other advances in probe technology, digital processing, and image display.

multiplane imaging has improved the diagnostic accuracy.

93%. Specificity has consistently remained high at >90% (**Table 3**).

**5.3. Transesophageal echocardiography**

74 Contemporary Challenges in Endocarditis

[80].

*5.3.1. Vegetations*

>90% (**Table 1**).

valvular or on a lead.

*5.3.2. Abscess*

Similar to TTE, there are limited studies with small patient cohorts assessing the diagnostic accuracy of TEE for identifying the complications of IE, other than vegetation and abscess.

Accurate detection of perforations is relatively high, ranging from 75 to 100% [68, 70, 71]. Transesophageal echo is the imaging modality of choice for identifying valve aneurysms, although sensitivity is unknown [73, 85], while aorto-cavitary fistulas are almost always identified correctly, with a sensitivity of 97–100% [23, 24]. Perivalvular dehiscence can be accurately diagnosed in the majority of cases with a sensitivity of 71–100% [68, 69, 86, 87] and specificity of >90% [69].

#### **5.4. Three-dimensional echocardiography**

Three-dimensional TTE and TEE have been part of clinical practice now in excess of 10 years. Over time, equipment has dramatically improved with the latest TEE matrix array transducers composed of up to almost 3000 piezoelectric elements. This leap of technology has been accompanied by improved digital processing power and miniaturization, along with other software and hardware improvements.

Three-dimensional echocardiography provides a choice of acquisition modes including multiplane (X-plane), real-time 'live' 3D, full-volume (stitched or single beat) 3D, zoom 3D and 3D color Doppler. Live 3D and 3D zoom modes are single-beat acquisitions and represent cardiac structure and function in real time. Full-volume acquisitions have the option of 'stitching' sequential volume datasets over a few cardiac cycles, providing a larger field of view. Single-beat full volume is available; however, it is limited by reduced temporal and spatial resolution.

#### *5.4.1. Vegetation*

The role of 3D echocardiographic imaging of vegetations is not well studied. A few case reports or small series confirm, as would be expected, that 3D TEE provides better morphological characterization and localization of lesions compared to 2D TEE. Three-dimensional TEE was shown to improve detection of vegetations in some case reports [88–91]; however, small vegetations may theoretically be more reliably detected with 2D due to higher temporal and spatial resolution.

A major benefit of 3D is the ability to visualize the entire valve and annulus in a single beat, enabling identification of eccentrically located vegetations that may otherwise be missed on a standard 2D TEE examination. Also, 3D imaging provides more accurate assessment of vegetation size. In a direct comparison by Berdejo et al. [92], mitral vegetation length of ≥16 mm on 2D and ≥20 mm with 3D best predicted embolic events.

#### *5.4.2. Abscess*

There are no published data to reliably estimate the diagnostic accuracy of 3D TTE or TEE for detection of abscess. However, 3D TEE imaging has been shown in case reports to provide useful additional information regarding the periannular extent of abscess and the relation to surrounding anatomical structures, including the coronary arteries [90, 93].
