**9. Imaging protocol for infective endocarditis**

possibly >15 mm) or recurrent emboli (>10 mm), (d) difficult to treat organisms such as *S. aureus,* multiresistant microbes, or fungi, (e) prosthetic valve endocarditis especially with Gram-negative, non-HACEK organisms, and (f) persistent sepsis or uncontrolled intracardiac

Perioperative pre-pump 2D and 3D TEE provides the surgeon with a comprehensive real-time assessment of the extent of intracardiac pathology and cardiac hemodynamic status immediately prior to the procedure. A decision can be made on the feasibility of repair versus valve replacement and allows planning of the surgical strategy. The postpump TEE assesses cardiac function, hemodynamics, and the adequacy of surgical procedure. In addition, imaging can ensure the heart is appropriately 'de-aired' prior to removal of the cardiac vent. Intraoperative TEE for IE has been shown to positively impact on at least one of these factors in approximately

Image optimization is particularly important in IE to ensure early diagnosis and accurate identification of complications. Despite advances in TTE imaging quality, TEE still provides superior diagnostic capability. A TEE probe is in close proximity to the heart, with minimal intervening tissues and therefore less attenuation of the ultrasound waves. This allows the use of a higher frequency (5–7.5 MHz) transducer and provides superior spatial resolution.

The same principles of image optimization apply to both TTE and TEE. To obtain superior spatial resolution, select the highest frequency transducer that will maintain adequate depth penetration. Position the focal zone adjacent to the region of interest and adjust depth and sector width to optimize spatial and temporal resolution [47, 121]. Gain, time gain compensation (TGC), and dynamic compression of the gray scale are adjusted to optimize image contrast,

Three-dimensional image resolution is dependent on the quality of the 2D picture; therefore, optimizing the image prior to changing to 3D mode is essential. Select the imaging plane or acoustic window with the highest resolution. Imaging in the axial plane provides superior resolution (0.5–1 mm) followed by lateral (1.5–2 mm) and finally elevational resolution (2.5–3 mm) [123]. When performing 3D TTE, select the window that transects the structure of interest through the axial and lateral plane such as the parasternal long axis for the mitral valve.

To allow for optimal postprocessing, it is recommended the gain, compensation, and compression be in the midrange, with the TGC adjusted to display a uniform, slightly brighter image [124]. As spatial resolution increases, temporal resolution is reduced and vice versa. This is due to the limited number of scan lines that can be performed in a fixed period of time.

while zoom function in real time improves spatial and temporal resolution [122].

infection including enlarging vegetations, despite appropriate antibiotics [17, 27].

one-third of operations [120].

78 Contemporary Challenges in Endocarditis

**8. Image optimization**

**8.1. Two-dimensional echocardiography**

**8.2. Three-dimensional echocardiography**

Imaging for IE requires a methodical approach and follows the same principles for TTE and TEE. All standard TTE and/or TEE transducer positions and views should be obtained with meticulous scrutiny of the cardiac valves and periannular tissues. Use zoom mode to focus on each valve individually to ensure subtle pathology is not overlooked.

It is important to pan through the cardiac valves and adjacent supporting structures using multiple angles and off-axis imaging. This can be achieved with TEE probe manipulation, such as anteflexion, retroflexion, lateral flexion, probe turning, and probe advancement or withdrawal. Careful manipulation of the probe is required to avoid trauma or perforation of the upper gastrointestinal tract. Similarly, the TTE transducer can be angulated, rotated, or repositioned on the chest wall to maximize diagnostic utility.

With the introduction of multiplane TEE, the 2D image can be effortlessly rotated through 180 degrees. Thorough inspection of the valves, with 2D and color flow Doppler, should be undertaken at frequent intervals, as the angle is increased. This is particularly useful for detecting mitral annular complications and/or localized perivalvular regurgitation.

Interrogation of valvular function with color Doppler along with hemodynamic assessment is essential. Attention should be paid to abnormal color flow arising from valves, fistulae, or other shunts. Images along the direction and path of any pathological color flow are used to identify abnormal communications and exclude jet lesions. Assess cardiac chambers for mural vegetations and the vasculature for endarteritis.

Finally, it is imperative to complete a comprehensive echocardiographic study to assess cardiac function, hemodynamics, filling pressures, and pulmonary artery pressure.

Three-dimensional functionalities such as X-plane, real-time, and multibeat 3D should be routinely incorporated, especially for TEE examination of the mitral and aortic valves. Transthoracic 3D of the tricuspid valve is useful for assessing valve anatomy and pathology, particularly in patients with regurgitation associated with pacing leads [126]. For valvular complications of endocarditis, 3D zoom is preferred, providing good spatial and temporal resolution with a single-beat acquisition [123]. However, if assessing extensive perivalvular pathology or ventricular size and function, then change to a wide-angle full-volume 3D multibeat acquisition.
